3D flexible printed circuit board with redundant interconnects
阅读说明:本技术 3d可挠曲的印刷电路板具有冗余互连 (3D flexible printed circuit board with redundant interconnects ) 是由 R.K.威廉斯 F-H.林 于 2016-10-21 设计创作,主要内容包括:软硬结合印刷电路板包括由软性印刷电路板与硬性印刷电路板的“岛”阵列互连,形成软性连接器。软性印刷电路板的导电层和绝缘层延伸到硬性印刷电路板中,从而与硬性印刷电路板的电连接增加了抗断裂性能,因为刚软性印刷电路板通过弯曲和扭转力反复受到应力。此外,通过使电源和信号线驱动硬性印刷电路板成为冗余,从而增强了软硬结合印刷电路板的耐用性,从而使线路断裂并不一定会影响其所连接的硬性印刷电路板的操作。软硬结合印刷电路板特别适用于光疗中使用的光疗衬垫,其中安装在硬性印刷电路板上的LED通过软性印刷电路板中的冗余线供电和控制。(The rigid-flex printed circuit board includes a flexible connector formed by interconnection of a "island" array of rigid printed circuit boards with a flexible printed circuit board. The conductive layer and the insulating layer of the flexible printed circuit board extend into the rigid printed circuit board, so that the electrical connection with the rigid printed circuit board increases the fracture resistance because the rigid printed circuit board is repeatedly stressed by bending and twisting force. In addition, the power supply and the signal wire drive the rigid printed circuit board to be redundant, so that the durability of the rigid printed circuit board is enhanced, and the operation of the rigid printed circuit board connected with the rigid printed circuit board is not influenced by the broken circuit. Rigid-flex printed circuit boards are particularly useful as phototherapy pads for use in phototherapy, where the LEDs mounted on the rigid printed circuit board are powered and controlled by redundant wires in the flexible printed circuit board.)
1. A method of providing power from a hard power supply printed circuit board to a hard power reception printed circuit board in a rigid-flex printed circuit board array comprising a plurality of hard printed circuit boards and a flexible printed circuit board formed as a network of flexible connectors interconnecting the hard printed circuit boards,
the method comprises the following steps: transmitting a voltage from the hard power supply printed circuit board to the hard power receiving printed circuit board through at least two power supply paths, the at least two power supply paths including a first power supply path and a second power supply path, each of the first power supply path and the second power supply path including one or more flexible connectors, wherein the first power supply path includes at least one flexible connector that is not included in the second power supply path.
2. The method of claim 1, comprising: transmitting a ground potential from the hard power supply printed circuit board to the hard power reception printed circuit board through at least two power supply paths, the at least two power supply paths including a third power supply path and a fourth power supply path, each of the third power supply path and the fourth power supply path including one or more flexible connectors, wherein the third power supply path includes at least one flexible connector not included in the fourth power supply path.
3. The method of claim 1, wherein the first power supply path comprises only a single flexible connector directly connecting the hard power supply printed circuit board to the hard power receiving printed circuit board, and the second power supply path comprises at least one intermediate hard printed circuit board and at least two flexible connectors.
4. The method of claim 1, wherein the first power path comprises a first intermediate rigid printed circuit board and at least two flexible connectors and the second power path comprises a second intermediate rigid printed circuit board and at least two flexible connectors.
5. The method of claim 1, wherein the first and second power supply paths share at least one intermediate rigid printed circuit board.
6. The method of claim 1, wherein the first power path and the second power path share at least one flexible connector.
7. The method of claim 1, wherein the first power path and the second power path share at least one intermediate rigid printed circuit board and at least one flexible connector.
8. The method of claim 1, wherein the rigid-flex printed circuit board array comprises a plurality of rigid power receiving printed circuit boards, wherein the rigid power supplying printed circuit board transfers power to the rigid power receiving printed circuit boards through a plurality of power supply paths, each power supply path comprising a printed circuit board.
9. The method of claim 8, wherein each rigid printed circuit board in the array of rigid electrical power supply printed circuit boards is a rigid electrical power receiving printed circuit board in addition to a rigid electrical power supply printed circuit board, and wherein a rigid electrical power supply printed circuit board delivers electrical power to each rigid electrical power receiving printed circuit board in the array.
10. The method of claim 1, comprising connecting power supply and control circuitry to the hard power supply printed circuit board, the power supply and control circuitry being outside of the rigid flex printed circuit board and supplying power to the hard power supply printed circuit board.
11. The method of claim 1, wherein the array of rigid-flex printed circuit boards comprises more than one rigid power supply printed circuit board.
12. The method of claim 1, wherein the hard power receiving printed circuit board comprises circuitry that requires power to operate.
13. The method of claim 12, wherein the circuit comprises at least one Light Emitting Diode (LED) and a switching device for controlling current through and light emitted by the at least one LED.
14. The method of claim 12, wherein the circuit comprises a signal processing circuit.
15. The method of claim 12, wherein the circuit comprises a wireless communication circuit.
16. The method of claim 12, wherein the circuit comprises at least one sensor.
17. The method of claim 16, wherein the at least one sensor comprises a temperature sensor (500A).
18. The method of claim 16, wherein the at least one sensor comprises a fault detection circuit that generates a fault signal when a fault condition occurs in the hard power receiving printed circuit board.
19. A method of providing power from a hard signal producing printed circuit board to a hard signal receiving printed circuit board in a rigid-flex printed circuit board array comprising a plurality of hard printed circuit boards and a flexible printed circuit board formed as a network of flexible connectors interconnecting the hard printed circuit boards, the method comprising: transmitting an electrical signal from the hard signal generating printed circuit board to the hard signal receiving printed circuit board through at least two signal transmission paths, the at least two signal transmission paths including a first signal transmission path and a second signal transmission path, each of the first signal transmission path and the second signal transmission path including one or more flexible connectors, wherein the first signal transmission path includes at least one flexible connector that is not included in the second signal transmission path.
20. The method of claim 19, wherein the rigid-flex printed circuit board array comprises a plurality of rigid signal receiving printed circuit boards, the method comprising transmitting electrical signals to at least two rigid signal receiving printed circuit boards through two or more flexible connectors.
Technical Field
The present invention relates to printed circuit boards having low failure rates that are flexible using methods and apparatus including those designed for their manufacture and use.
Background
Printed Circuit Boards (PCBs) include one or more layers of conductors, typically copper, on which electronic components are physically mounted, separated by insulating layers such as glass, epoxy or polyimide, etc., to provide mechanical support for the electronic circuitry. Electronic devices such as integrated circuits, transistors, diodes, resistors, capacitors, inductors and transformers are electrically connected to each other by wires of the components soldered to conductive lines of a printed circuit board to form an electronic circuit. Applications for printed circuit boards include almost all types of electronic products, including cell phones, cameras, lithium ion batteries, tablet computers, notebook computers, desktop computers, servers, network appliances, radios, consumer electronics, televisions, set-top boxes, industrial electronics, automotive electronics, avionics, and more. Fig. 1 shows examples of various printed circuit boards reflecting their versatility in fit, form and function. In medical, sports and consumer electronics of choice, printed circuit boards may also be used in "wearable" electronic devices, which need to conform to the curved surface of the human body.
Printed circuit boards are dual role in electronics, being mechanical on the one hand, providing support for electronic components by acting as a component substrate, whether mounted on top of the printed circuit board or on top and bottom of the printed circuit board, and electrical on the other hand, providing multi-layer interconnection between these components and the electrical connector. Unlike integrated circuits, in which the silicon substrate serves both as a mechanical support and as a material for the fabrication and formation of component integrated semiconductor devices, the printed circuit board substrate is "passive" acting merely as an insulator. As shown in fig. 2, the insulating printed circuit board substrate (also referred to as a substrate laminate) may be rigid, soft or a combination of soft and hard. The rigid
Rigid printed circuit board-a rigid printed circuit board is a printed circuit board that does not bend, deform or flex when subjected to mechanical stress. Rigid printed circuit board technology is by far the most popular printed circuit board technology and is commonly used for any flat panel or case packaged product including cell phones, tablet computers, televisions and even kitchen appliances. One advantage of rigid printed circuit boards is that the substrate absorbs mechanical stress, thereby inhibiting damage to the components and their solder joints. One disadvantage of rigid printed circuit boards is that they are inherently planar and cannot be bent to accommodate curved surfaces. Therefore, they are not a good solution for flexible or wearable applications. (Note: as used herein, the term "rigid" is not used in an absolute sense, but means that the object in question (typically a printed circuit board) will not bend significantly or permanently when subjected to a bending force, and will return to its original shape, in particular the term "rigid" as applied to printed circuit boards is used in a relative sense to mean that the printed circuit board is more rigid than a flexible printed circuit board to which the rigid printed circuit board is connected.)
Rigid printed circuit board substrates typically include phenolic resins, polyimides, plastics or other rigid non-conductive materials. One common material used in the manufacture of rigid printed circuit boards is FR4, a substance that is "flame retardant", comprising woven glass fibre cloth pre-impregnated with the abbreviation epoxy resin. Such substrates may also be referred to as "prepreg" sheets, an abbreviation for prepreg adhesive sheets. In a manufacturing process known as "lamination", a copper foil is coated, i.e. "laminated", onto a prepreg sheet. During the manufacturing process, the combination of pressure and heat activates the epoxy in the prepreg sheet, causing it to flow conformally between the foil and the prepreg sheet, bonding them together. In this context, the term laminate means that the layers of material are joined by bonding or other means into a flat sheet or an interlayer which may be rigid or soft. This process may be repeated multiple times to create a multilayer printed circuit board. A more detailed description of the well-known manufacturing process of laminated printed circuit boards is described in the literature in the middle, such as http:// www.4pcb.com/media/presentation-how-to-build-pcb.
To achieve electrical interconnection, rigid printed circuit boards range from single layer printed circuit boards with only one conductive layer to multi-layer sandwiches containing four, six or so to ten copper foil "conductive layers" required to achieve complex systems. In "single layer" printed circuit boards, the copper layer is laminated or plated on only one side of the insulating substrate, and all components are mounted on the same side of the printed circuit board. In "two-layer" printed circuit boards, the same base insulating laminate is copper-plated on both sides, and electronic components can be mounted on either or both sides of the printed circuit board. A multilayer printed circuit board includes two or more layers of copper foil which are overlaid on an intermediate layer of insulating material to form a multilayer interlayer. The number of layers refers to the number of conductive copper layers in a printed circuit board, for example, a "four-layer" printed circuit board has four copper layers, three intermediate insulating layers together comprising a seven-layer sandwich. The outer copper layer may also be coated with a protective layer to prevent scratching and corrosion, but such a protective layer is not considered part of the lamination process.
The thickness of the copper varies with the amount of copper required to form each conductive layer in the printed circuit board, depending on its intended application. For convenience, the printed circuit board industry typically describes laminated copper thickness in terms of its "weight," where layer thickness scales linearly with the weight, rather than describing each layer by its precise layer thickness. For historical reasons, the printed circuit board industry has literally referred to the weight of copper measured in units of 1 square foot to units of ounces of english. For example, a 0.5 ounce copper printed circuit board having a copper thickness of 0.7 mils or 17.5 μm; a 1.0 ounce copper printed circuit board having a copper thickness of 1.4 mils or 35.0 μm; a 2 ounce copper printed circuit board having a copper thickness of 2.8 mils or 70 μm, and the like.
Extreme copper thicknesses produced from 20 ounces to 30 ounces are useful for high current and power electronics. Thick copper becomes very rigid and high stresses are generated between the copper and the printed circuit board due to differences in TCE of different materials, i.e. differences in temperature expansion coefficients of different materials. Extreme pressures can lead to various failure modes in printed circuit boards, including circuit board cracking, conductive layer delamination, and solder joint cracking.
In printed circuit board manufacturing, the copper layer is typically patterned by a "development etch" process to form the circuitry. Patterning is performed layer by layer, starting with a uniform, unpatterned copper laminate coated over the entire planar surface of the insulating substrate. In the development etching process, the copper layer to be patterned is first coated with a photosensitive emulsion, known as "photoresist", which is typically applied in a "dry film" sheet using heat and pressure. To transfer the image to the resist, an optical mask or "reticle" is used to control which portions of the sheet of dry resist are exposed to light and which are not. The photomask is first created using commercially available CAD software, creating a "Gerber file" that defines the mask pattern required for photomask fabrication. The resulting reticle may be defined on a printed circuit board with the functionality contained in those of the same size, or may be presented on the printed circuit board with optical magnification down using an optical instrument known as a "reticle aligner" for aligning the projected reticle image to any other feature already.
Next, the photoresist is exposed through a patterned mask, thereby transferring an image. After the photoresist is developed, the organic photoresist layer mimics the pattern of the reticle it exposes, covering copper metal in some areas and not in others.
The metal portions protected by the photoresist and the metal portions exposed to the etch depend on whether a "positive" or "negative" photoresist is employed. The positive and negative photoresists react to light in opposite or complementary ways. In particular, for positive photoresists, any photoresist regions exposed to light cause the exposed chemical bonds to break, washing away that portion of the photoresist during development. Since the photoresist is removed in the exposed areas, the photoresist remains only in the shadow of the reticle features, which means that the remaining photoresist pattern completely overlaps the reticle features, i.e., the dark areas are protected from etching. Elsewhere the metal will be etched away.
In the case of negative photoresists, any photoresist regions exposed to light cause exposed chemical bonds to crosslink during the development process, do not break, leave only the exposed portions of the photoresist, and wash away the photoresist in the shadow of the reticle. Since the developed resist remains only in the exposed areas, all the black areas in the mask result in unprotected metal being etched away. The resulting printed circuit board features are thus the exact opposite, i.e., the negative image of the mask.
The reticle polarity, i.e., the dark and clear portions of the reticle, must correspond to any developing etch paste employed in the reticle operation. After exposure, the developed etch resist is "hard baked" at high temperatures to enhance its ability to withstand prolonged exposure to acid etch. Because the photoresist comprises organic compounds, it is relatively insensitive to exposure to acids, particularly after hard baking. The metal is then etched with an acid and the mask is then removed. Copper etching typically takes the form of nitric, sulfuric, or hydrofluoric acid in pure form, diluted with water or mixed with hydrogen peroxide or other compounds. Ferric chloride or ammonium hydroxide may also be used. Various copper etch compositions can be found on the web, for example, http:// www.cleanroom.byu.edu/wet _ etch.
The development etch process must be repeated for each copper layer. For example, in a double-sided printed circuit board, copper interconnects are laminated on both sides of an intermediate insulator and using a development etch process, each side must be separately patterned using a different mask than the particular circuit layer. Interconnection through both sides of the insulating layer is facilitated by conductive vias. The conductive vias are mechanically drilled and lined or filled with a conductive metal, such as a plated metal. The concept of a two-layer printed circuit board can be extended to 3, 4, 6 or 8-layer printed circuit boards simply by repeating the process of lamination, development etch patterning and via formation. The conductive vias may interconnect any two conductive layers or pass completely through each layer of the printed circuit board.
While the entire electronic system may be integrated onto a single rigid printed circuit board, in many cases the resulting printed circuit board is too large or incorrectly shaped to fit into the available space. In such cases, the system must be divided into two or more printed circuit boards with wires or cables employed between the printed circuit boards to facilitate electrical interconnection of the various constituent printed circuit boards. For example, fig. 3 shows an application requiring a number of rigid printed
As shown, the rigid printed
The repeated movements exert mechanical stress on the solder joints between the wires and the printed circuit board lines, eventually resulting in a broken wire or broken solder joint printed
As shown in fig. 4B, examples of printed circuit board interconnect faults include
Replacing discrete wires with plugs and connectors can reduce the incidence of solder joint failure, but introduces several new failure modes, including pulling out wires from the plugs in
In such a solution, the sockets 5A and 5B are soldered directly to the printed circuit board and the
In applications of repeated movement and flexing, the plug and socket connection can suffer from a variety of failure modes-the most common failure including situations where the plug comes loose from the socket and no longer provides a reliable connection between the plug pins and the socket conductors. Disconnection faults of the socket can be largely avoided by using a clamping socket-a socket using tension or a spring clip to hold the plug firmly in place. Unfortunately, clamping the receptacle eliminates one failure mode, but introduces a new failure mode in the cable. In particular, if the plug is firmly fixed in place, the connection between the ribbon cable and the plug will fail when moved, twisted or pulled.
Whether repeated movement or flexing results in unplugging the connector or breaking the cable, the interconnection between the printed circuit boards will fail and result in an open circuit. In systems containing large numbers of rigid printed circuit boards, such as in a series of printed circuit boards used to cover a large area, the number of interconnections further exacerbates the problem of statistically increasing the probability of system failure for each connector.
While the use of ribbon cables and their associated plugs and connectors reduces the risk of system failure due to wired connection failures (e.g., wire pull or solder joint cracking), ribbon cables can still be affected by single point system failures, i.e., single wire breaks leading to partial or complete system failures. For example, if the control line is open, the system will not be able to receive commands. In situations where two wires are required to carry the required current, a break in either wire can result in excessive current being carried by a single wire, resulting in excessive voltage drop, overheating, instantaneous wire fusing, or ion migration failure.
Ensuring printed circuit board connection reliability is particularly problematic in applications that are subjected to repeated bending cycles. For example, in a
Each soft polymer pad is part of a larger system comprising a set of three pads 80a, 80b and 80c as shown in fig. 7A. Pad 80a is connected to an electronic driver circuit (not shown) by a plug 81 and cable 82 with strain relief and cable connection 83, and to pads 80b and 80c by connector cables 85a and 85b and socket 84. The pad connection is formed by pressure bending from a Velcro tape 87 bonded to a Velcro tape 88. Fig. 7B shows the bending that occurs in actual use when treating the knees and legs 91 in a medical application 90 and the legs 96 in an equestrian veterinary application 95. In this case, the soft polymer pads 80a, 80b and 80c and their components along with the Velcro strip 88 experience significant bending stresses and deformation during the treatment of repeated bending cycles each time the pad is reapplied to a new patient or treatment area.
In the case of a rigid printed circuit board, the damage to the deformation by the deformation of the printed circuit board as shown in fig. 8A may include a cracked printed circuit board coating 101 or a cracked substrate 103 in the printed
Flexible printed circuit board-another solution to implement a system comprising a series of interconnected rigid printed circuit boards is to use a flexible printed circuit board as shown in fig. 9. In contrast to rigid printed circuit boards, flexible printed circuit boards are printed circuit boards that are torsionally bent, bent or twisted. The flexible printed circuit board is bent in three axes, providing two-dimensional or full three-dimensional motion depending on its application. Flexible printed circuit boards are often used as a replacement for ribbon cable connectors or for replacing rigid printed circuit boards and closely-packed electronic devices in confined spaces. Applications that employ flexible printed circuit boards as interconnects include inkjet printers, clamshell phones, computer keyboards, and other mobile devices, such as mobile arms in hard disk drive data storage.
Most flexible printed circuit boards contain only element circuits for interconnection. In some cases, the flexible printed circuit board may also include components mounted on one or both sides of the flexible printed circuit board, primarily for mounting in small housings such as automobiles, industrial and medical equipment modules, and the like. The flexible printed circuit board with the accessory is also referred to as a flexible circuit. Flexible printed circuit boards typically use thinner copper layers and thinner insulating substrates than rigid printed circuit boards. The substrate may be polyester, silk, polyimide, semicrystalline thermoplastics (also known as PEEK polymers) or soft plastics and polymer materials. Like rigid printed circuit boards, flexible printed circuit boards may include single, double or multilayer structures that typically have conductive vias.
The construction of the flexible printed circuit board depends on its intended use. A flexible printed circuit board that operates purely as a "flexible connector" typically includes one to four layers and does not include any components mounted on both sides of the surface of the flexible printed circuit board. In use, such a soft-based connector may flex "frequently", i.e. alternately repeating at regular intervals between a bent (curved) and a non-bent (straight) state; occasionally the bend "changes little between the bent state and the non-bent state and" little "bends, which means that the shape of the printed circuit board is bent into place during manufacturing and remains unchanged thereafter. In the context of the present application, the term "curved" does not mean merely in a curved state, but means in a weightlifting metaphor repeatedly alternating between a straight state and a curved state, generally with an alternating repeating period.
One common example of frequent flexing applications includes the attachment of a flexible connector to a printhead in an inkjet printer. Flexible, occasional uses include flexible connectors that mount the display of a notebook computer in a hinged cover that connects to a computer body that houses a keyboard and a motherboard printed circuit board. In this example, each flexing cycle repeats every now and then every time the laptop is turned on and then turned off again.
In contrast, the softness of flexible printed circuit boards is not commonly used, whether for implementing flexible printed circuit board connectors or for flexible circuits, is best suited for the ability to accommodate small, flexible or odd shaped housings as part of the manufacturing process, and is not intended for use in applications where repeated flexing cycles occur. Applications for printed circuit boards with little flexing include flexible connectors in strip phones or digital cameras where flexing occurs only frequently, i.e., when the device is manufactured or repaired. Fig. 9 shows several examples of the use of a flexible printed circuit board in a flexible circuit, including a flexible printed circuit board 112 having many ICs and components mounted on top of the printed circuit board, as shown in inset 111. Another example of a flexible circuit integrates a moisture sensor including a microcontroller and uses printed circuit board conductive traces as the antenna 113.
Flexible printed circuit boards operating as flexible circuits typically comprise 2 to 6 layers and contain components mounted on one or possibly both sides of the flexible printed circuit board. As described above, the flexible printed circuit board is limited to "less flexible" applications due to the mismatch between the flexible printed circuit board and the rigid components mounted thereon. Flexible circuits, i.e., flexible printed circuit boards with mounted components, have problems in applications with repeated flex cycles, damage and breakage because the components themselves do not flex even if the printed circuit board is positive. An example of a component mounting failure is shown in fig. 10A, where an LED mounted on a printed circuit board 115 includes electrical bonding points 116 connecting the LED to printed circuit board traces. A cross-sectional micrograph 120Z showing a
As shown in fig. 10B, the size of the crack varies greatly depending on the degree of the flexural stress and the frequency of the flexural cycle. For example, in contrast to
Cracks may also occur in the solder joints where passive components such as resistors and capacitors are mounted. For example, in fig. 10C,
The combination of rigid and flexible printed circuit boards further exacerbates this problem by requiring a connection between the two. This connection suffers from the same socket failure as the ribbon cable described previously.
Rigid-flex printed circuit board-another variation of the flexible printed circuit board, the rigid-flex printed circuit board is a hybrid of laminating flexible and rigid printed circuit boards into a single printed circuit board, with the flexible portion providing interconnection between large rigid printed circuit boards. Fig. 11A and 11B show an example of a hard-and-soft combined printed circuit board. As shown, the interposer flex pcb connects one rigid pcb to another rigid pcb. For example, the notebook motherboard uses the flexible printed circuit board as the interconnection of the hinge display module of the notebook computer.
As used today, the main advantage of rigid-flex circuit boards is that no plug and socket are required to facilitate electrical connection between rigid printed circuit boards. Each flexible printed circuit board is incorporated into a rigid printed circuit board in the same manner as any multilayer printed circuit board. Interconnection with the flexible printed circuit board is achieved by using a multi-layer via connection, shorting the rigid printed circuit board layer with the flexible printed circuit board layer as needed. The main disadvantage is that due to the mechanical property mismatch between the rigid and flexible layers, it is easy to tear the flexible printed circuit board by applying any force perpendicular to the plane of the printed circuit board created near the bar-shaped interconnect area, as shown in the z-direction of diagram 170 of fig. 12A, where the rigid printed circuit board 171 extends along a thin strip in the cross-section 173 to the shared intersection point to connect to the flexible printed circuit board 173. Any substantial force may cause the flexible printed circuit board 173 to tear near the rigid printed circuit board.
The schematic and photograph of the flexible printed circuit board in fig. 12B illustrates this unique flex-rigid printed circuit board failure mode. As shown, after repeated bending, the flexible printed circuit board 183 connecting the rigid printed circuit board 181 to the rigid printed circuit board 182 fails, resulting in a torn flexible printed circuit board 184 adjacent to the rigid printed circuit board 181.
Failure of multiple printed circuit board systems-the use of rigid, flexible and rigid-flex printed circuit boards or combinations thereof in multiple printed circuit board electronic systems can make the electronic devices conform to any shape, greatly expanding the application range of the electronic devices. For example, with 3D folding, the printed circuit board may be pressed into the package, otherwise too small to accommodate the required printed circuit board surface area. By conforming to a curved surface, the printed circuit board can be mounted in a motor case, a watch case, a small-sized monitoring camera, and the like. Wearable electronic devices for sports applications and monitors and therapeutic devices for medical applications may benefit from improved sensor accuracy and improved therapeutic efficacy by adapting to better fit the human body contours.
However, from the perspective of electronic systems, such distributed circuits, where portions of the circuits are implemented on different printed circuit boards, suffer from a number of system reliability risks associated with communication between the various components. For example, fig. 13A shows a distributed electronic system 189A implemented across three rigid printed circuit boards 190A, 190B and 190C and connected by flexible printed circuit boards 191A and 191B, the flexible printed circuit boards 191A and 191B including connections 192 for power supply 193A, ground 193C and analog or digital signals 193B, with the magnification 192 of the connections being exaggerated as shown. As shown, each rigid printed circuit board contains different circuitry or unique functions throughout the system. For example, printed circuit board 190A is integrated
For example, in the distributed electronic system 189B shown in fig. 13B, a tear 194B in the flexible printed circuit board causes an open circuit in the power carrying conductor 193A, resulting in a temporary or permanent power interruption, resulting in an overall system failure. In contrast, in the distributed electronic system 189C of fig. 13B, a tear 194C in the flexible printed circuit board causes an open circuit in one or more conductors carrying the control signal 193B resulting in a system fault, affecting normal operation and depending on the function of the interrupt signal, possibly resulting in an overall system fault.
Humidity and corrosion failures-another physical mechanism that may lead to immediate or gradual system failure is moisture-induced electrical failure. If the printed circuit board is immersed in or subjected to any conductive or slightly conductive liquid, a short circuit may result, thereby damaging or potentially damaging the circuit or system. Common examples of fluids include beverages, fresh water and saline. For example, in the photograph of fig. 14A, water damage causes local defects 197C, 197D, and 197E to short the circuit and impair or disable system operation. In wearable electronics, the circuitry and printed circuit board may also be subject to rain and body perspiration. Sweat is particularly problematic because it contains salts and other electrolytes making it more conductive. Continued exposure to salt or acidic water may deposit salts on top of the printed circuit board or cause corrosion of the printed circuit board surface as indicated by damage to the printed circuit board surface 197B and electrical leads and pads 197A. The failure may include an electrical short or may also result in an open circuit due to corrosion. Operation of the electronic system under fluid, moisture or high humidity conditions may also result in the growth of conductive tin wires, as shown in photograph 197G in fig. 14B, or damage to the printed circuit board edge connectors as shown in 197F.
Coating flexible printed circuit boards with protective layers is problematic because the coating always cracks with repeated bending. Coatings for rigid printed circuit boards are beneficial, but do not support flexible or wearable printed circuit board applications.
Conclusion-what is needed is a technique that can reliably interconnect a variety of printed circuit boards over large areas that can flex to conform to any shape, contour, or form factor without being susceptible to moisture-related or mechanically-induced interconnect failures. Such a system should be suitable for use in large area distributed systems, ultra-compact systems, and medical and wearable electronics that fit to the body of any person or conform to any shape, fix or adapt to motion without breakage or electrical failure. Ideally, even if some breakage event occurs, the system can still sustain damage and continue to operate, even after breakage.
Disclosure of Invention
According to the present invention, the above problems are overcome in a set of rigid Printed Circuit Boards (PCBs) that are connected together. Each rigid printed circuit board is connected with at least one line, which can be a power line or a signal line. In most embodiments, each rigid printed circuit board is connected to at least two power lines, such as a power voltage line and a ground line, and a plurality of signal lines.
At least one rigid printed circuit board in the array is connected with at least two lines, and each line carries the same power supply voltage or signal. Thus, if one of the lines is broken, the rigid printed circuit board will still receive the power supply voltage or signal carried by the dashed line and will therefore continue to operate normally. In many embodiments, at least two wires connected to a rigid printed circuit board are housed in a flexible printed circuit board.
The at least two lines may include a first line and a second line. The first wire may be electrically connected between the rigid printed circuit board and a second rigid printed circuit board in the array. The second wire may be connected between the rigid printed circuit board and a third rigid printed circuit board in the array.
The at least two lines may include a first power line and a second power line, each of the first power line and the second power line carrying the same power voltage. The first power line is electrically connected between the rigid printed circuit board and a second rigid printed circuit board in the array. The second power line is connected between the rigid printed circuit board and a third rigid printed circuit board in the array.
The at least two lines may include a first signal line and a second signal line, each of the first and second signal lines carrying the same signal. The first signal line is electrically connected between the rigid printed circuit board and a second rigid printed circuit board in the array. The second signal line is connected between the rigid printed circuit board and a third rigid printed circuit board in the array.
In some embodiments, one of the rigid printed circuit boards in the array is connected to at least a first power line and a second power line, each of the first power line and the second power line carrying the same power voltage, and to at least a first signal line and a second signal line, each of the first and second signal lines carrying the same signal. The first power line and the first signal line are electrically connected to a second rigid printed circuit board in the array, and the second power line and the second signal line are electrically connected to a third rigid printed circuit board in the array.
In the above example, the Redundancy Factor (RF) of the rigid printed circuit board is 1, which means that the rigid printed circuit board is connected to an additional line transmitting a signal and an additional line transmitting a power voltage. The rigid printed circuit board may also be connected to a fourth rigid printed circuit board in the array via a third power line carrying a supply voltage and a third signal line carrying a signal, thereby giving it one RF or two RFs. Likewise, the rigid printed circuit board may be connected to any number of additional power lines with supply voltages and any number of additional signal lines to provide any desired RF to the rigid printed circuit board. In addition, carry multiple supply voltages (e.g., V) 1,V2...Vn) An additional power line (one of which may be a ground voltage) and carrying a plurality of signals (S)1,S2...Sn) May be connected to a rigid printed circuit board, and each of the power and signal lines may be multiplied by the RF desired for it. The various power and signal lines may have different RFs. For example, critical circuitry that is inoperable with a rigid printed circuit board may be given a high RF; less important lines may be given lower RF or no redundancy.
Some embodiments include an array of rigid printed circuit boards, each rigid printed circuit board in the array being connected to some other rigid printed circuit board in the array by a flexible printed circuit board (sometimes referred to as a "soft hard combined printed circuit board" configuration) that includes a sufficient number of power and signal lines to provide each rigid printed circuit board with a desired RF for each power voltage and signal used. Various components may be mounted on a rigid printed circuit board.
In one set of embodiments, a Light Emitting Diode (LED) is mounted on each rigid printed circuit board. These embodiments are particularly useful in the field of phototherapy, as described in No. 14/073,371 filed on 6.11.2013, No. 14/460,638 filed on 15.8.2014, and No. 14/461,147 filed on 15.8.2014, the entire contents of which are incorporated herein by reference. For durability and ease of use, the rigid and flexible printed circuit boards may be enclosed in a soft (e.g., polymer) liner, with openings formed in the cover to allow light emitted by the LEDs to reach the patient's body. The two-dimensional softness of the rigid pcb array and the flexible pcb allows the assembly to be wrapped around various body parts-arms, knees, shoulders, etc.
According to an aspect of the present invention, the rigid printed circuit board includes a rigid insulating layer, a patterned conductive layer, a flexible conductive layer and a flexible insulating layer, which are also included in the flexible printed circuit board. In the hard printed circuit board, a patterned conductive layer is formed on one surface of a hard insulating layer. The opposite surface of the hard insulating layer is bonded to the soft conductive layer or the soft insulating layer. The rigid printed circuit board may further comprise a stack of a plurality of conductive layers separated by rigid insulating layers. In many embodiments, the flexible conductive layer includes a metal layer.
The patterned conductive layer and the components connected thereto may be electrically connected to the flexible conductive layer. Such electrical connection between the patterned conductive layer and the flexible conductive layer may include conductive vias extending through the rigid insulating layer.
The rigid and flexible printed circuit boards may include a plurality of flexible conductive layers separated from each other and from the surrounding environment by flexible insulating layers. Any one of the rigid or flexible conductive layers may be electrically connected to any other rigid or flexible conductive layer by conductive vias through one or more of the insulating layers. If it is desired that the conductive via passes through the conductive layer without electrical contact, the conductive via may be electrically isolated from the conductive layer it must pass through the insulating layer of the via wall.
The invention also includes a method of manufacturing a rigid-flex printed circuit board. The method includes attaching a soft protective cap insulating layer to a soft conductive layer, attaching a printed circuit board conductive layer to a hard insulating layer, attaching the hard insulating layer to the soft protective cap insulating layer, patterning the printed circuit board conductive layer to form a patterned conductive layer removing the hard insulating layer in an area where the hard printed circuit board is to be located. The non-located areas of the rigid printed circuit board and the flexible printed circuit board may then be removed between the flexible protective cap insulating layer and the flexible conductive layer, preferably using a laser beam, thereby forming a flexible connector.
The method may further comprise one or more of the following steps: carrying out light shield and etching on the conductive layer of the printed circuit board to form a patterned conductive layer; developing and etching the soft conducting layer to form a patterned soft conducting layer, and filling an opening formed in the soft conducting layer with a planarization insulator; forming a through hole through the hard insulating layer and the soft protective cap insulating layer to expose the soft conductive layer, and depositing a conductive material in the through hole to form an electrical connection between the patterned conductive layer and the soft conductive layer; penetrating the hard insulating layer, the soft protective cap insulating layer and the soft conducting layer to form a through hole, and depositing a conducting material in the through hole; plating a metal layer on the patterned conductive layer; and applying a protective coating on portions of the electroplated metal layer.
The method may also include depositing an interfacial layer on the soft protective layer. The interface layer is treated to selectively harden portions of the interface layer in the rigid printed circuit board while leaving portions of the interface layer in the flexible printed circuit board in a less rigid state. The interface layer may comprise an uncured organic, epoxy or polymer material, and it may be chemically or optically hardened.
An intermediate insulating layer may be attached to the surface of the soft conductive layer opposite to the soft protective cap insulating layer, and a "mirror image" of the above method may be performed on the intermediate insulating layer to form thereon both sides of which components the rigid printed circuit board may mount, i.e., a double-sided rigid printed circuit board. In such a case, the method may include forming vias through the soft protective cap insulating layer and the soft conductive layer on both sides of the intermediate insulating layer, and depositing conductive material in the vias to form electrical connections between the soft conductive bodies to the layers on both sides of the intermediate insulating layer.
More generally, rigid and flexible printed circuit boards may include any number of flexible conductive layers, whether or not the rigid printed circuit board is double-sided. Indeed, in the case where multiple wires are connected to a rigid printed circuit board and two or more RFs are required for some of the wires, some of the wires will need to cross over each other and the flexible printed circuit board will include at least two flexible conductive layers so that the crossing wires do not electrically contact each other. Near the crossover point, a pair of vias between two flexible conductive layers may be used to route one of the wires under the other wire, referred to herein as "under the crossover". Of course, vias may be used to pass one of the traces through the other.
In many embodiments, the steps of patterning the printed circuit board conductive layer and removing the rigid insulating layer are performed so as to form an array of printed circuit board "islands" surrounded by a soft conductive material, and the step of removing the soft protective cap insulating layer and the step of performing the soft conductive layer so as to form a web of soft printed circuit board between the printed circuit board "islands" so as to provide a desired RF for each line in each printed circuit board "island".
In an alternative approach, no rigid conductive layer or printed circuit board conductive layer is used. Instead, a "quasi-printed circuit board" is formed by printing a relatively thick layer of, for example, a polymeric material or polyimide compound onto a flexible protective cap layer located in the region of the "quasi-printed circuit board" on a movable print head. The opening may be left in a relatively thick layer of the via hole where the flexible conductive layer is to be formed, and a thinner layer of the same material may be printed onto an area where the flexible printed circuit board is to be positioned. The thickness of the thinner layer can be calibrated so that the etching process removes the thinner layer while forming a via in the soft protective cap layer exposing the soft conductive layer, thereby eliminating the need for a mask. A movable print head may then be used to print a patterned layer of conductive material onto the relatively thick layer and fill the vias and contact the soft conductive layer.
Regardless of the method used to form the printed or quasi-printed circuit board and the flexible printed circuit board, electronic or other components may be mounted to the printed or quasi-printed circuit board and the electronic system may be protected from mechanical damage, moisture, and other environmental conditions.
For a fuller understanding of the various aspects of the present invention, reference is made to the following detailed description and accompanying drawings.
Drawings
In the drawings listed below, generally similar elements are denoted by the same reference numerals.
Fig. 1 contains photographs of various examples of printed circuit boards for circuitry and interconnections.
Fig. 2 is a top view showing examples of rigid, flexible, and soft and hard combined printed circuit boards.
Fig. 3 is a perspective view of a flexible polymer cushion used in medical phototherapy including a rigid printed circuit board and its electrical interconnections.
Fig. 4A is a collection of photographs showing a broken wire causing a failure of an electronic circuit.
Fig. 4B is a set of photographs illustrating solder cracking and trace lifting of a printed circuit board leading to electronic circuit failure.
Figure 4C is a photograph of a relatively good and defective printed circuit board solder joint.
Fig. 5A contains a photograph of a cable connector plug failure.
Fig. 5B contains a photograph of a connector failure of the ribbon cable plug and receptacle connection system.
Fig. 6 is a schematic cross-sectional view of a flexible LED pad that can be bent to accommodate use in medical phototherapy of living tissue.
Fig. 7A is a perspective view of a set of three flexible LED pads used for medical phototherapy and their interconnection.
Fig. 7B contains photographs of flexible LED pads for medical phototherapy, the LEDs being used for the legs of humans and horses.
Fig. 8A contains a photograph of a hard printed circuit board crack failure.
Fig. 8B includes a cross-sectional photograph of a rigid printed circuit board with a cracked via.
Fig. 9 illustrates a photographic example of the flexible printed circuit board.
Fig. 10A contains a photograph of a solder connection failure of the assembly and leadframe.
Figure 10B contains photographs of lead frame to printed circuit board solder connections with varying degrees of solder cracking,
fig. 10C contains a photograph of a component mounting on a printed circuit board showing solder and plastic cracking.
Fig. 10D contains photographs of components mounted on a printed circuit board with lead cracks and solder ball cracks.
Fig. 10E is a schematic cross-sectional view of a component mounted on a printed circuit board with solder ball fracture.
Fig. 11A includes a photographic example of a soft hard combination printed circuit board.
Fig. 11B contains an additional photographic example of a rigid-flex printed circuit board.
Fig. 12A is a schematic cross-sectional view of a rigid-flex printed circuit board.
Fig. 12B includes a photographic example of a tear in the flexible printed circuit board in the rigid-flexible printed circuit board.
FIG. 13A is a schematic diagram of a distributed circuit with a tear in one of its flexible printed circuit board interconnects.
Fig. 13B is a schematic diagram of a distributed circuit using a flex rigid printed circuit board, with damage resulting in power and signal interruption.
Fig. 14A contains a photographic example of moisture related and moisture induced corrosion failures in a printed circuit board.
Fig. 14B contains a photographic example of moisture related and moisture induced corrosion failures in a printed circuit board.
Fig. 15 is a schematic diagram of a rigid printed circuit board and an array of interconnected flexible printed circuit boards.
Fig. 16A is a schematic diagram of a rigid printed circuit board array highlighting the shortest conductive path for signal interconnection facilitated by a single flexible printed circuit board.
Fig. 16B is a schematic diagram of an array of rigid printed circuit boards highlighting the redundant conductive paths of signal interconnection facilitated by two rigid printed circuit boards and three flexible printed circuit boards.
Fig. 16C is a schematic diagram of an array of rigid printed circuit boards highlighting another redundant conductive path for signal interconnection facilitated by four rigid printed circuit boards and five flexible printed circuit boards.
Fig. 16D is a schematic diagram of an array of rigid printed circuit boards highlighting yet another redundant conductive path for signal interconnection facilitated by six rigid printed circuit boards and seven flexible printed circuit boards.
FIG. 16E is an alternative schematic diagram of a rigid printed circuit board array showing multiple redundant signal interconnects.
Fig. 16F is a schematic diagram showing the shortest signal path between rigid printed circuit boards.
Fig. 16G is a schematic diagram illustrating a redundant signal path bypassing a break in the shortest signal path through two rigid printed circuit boards.
Fig. 16H is a schematic diagram showing redundant signal paths bypassing two signal path breaks through four rigid printed circuit boards.
Fig. 16I is a schematic diagram showing a backup redundant signal path bypassing two signal path discontinuities via six rigid printed circuit boards.
Fig. 16J is a schematic diagram showing another alternative redundant signal path that bypasses two signal path discontinuities for six rigid printed circuit boards.
Fig. 16K is a schematic diagram showing yet another alternative redundant signal path that bypasses two signal path discontinuities through six rigid printed circuit boards.
Fig. 16L is a schematic diagram showing redundant signal paths bypassing two signal path breaks through four rigid printed circuit boards.
Fig. 16M is a schematic diagram showing redundant signal paths bypassing two signal path discontinuities through six rigid printed circuit boards.
Fig. 16N is a schematic diagram illustrating an alternative redundant signal path bypassing two signal path discontinuities via six rigid printed circuit boards.
Fig. 16O is a schematic diagram showing yet another alternative redundant signal path bypassing two signal path discontinuities via six rigid printed circuit boards.
Fig. 16P is a schematic diagram showing two signal path disruptions in a rigid printed circuit board array resulting in a system fatal interconnect failure.
Fig. 17A is a schematic diagram of a rigid printed circuit board array highlighting the shortest conductive path of power bus interconnects facilitated by a single flexible printed circuit board.
Fig. 17B is a schematic diagram of an array of rigid printed circuit boards highlighting the redundant conductive paths of the power bus interconnect facilitated by two rigid printed circuit boards and three flexible printed circuit boards.
Fig. 17C is an alternative schematic diagram of a rigid printed circuit board array showing multiple redundant power bus interconnects.
Fig. 17D is a schematic diagram showing the shortest power bus between rigid printed circuit boards.
Fig. 17E is a schematic diagram showing a redundant power bus bypassing a single power bus interrupt via two rigid printed circuit board bypasses.
FIG. 17F is a schematic diagram showing a redundant power bus bypassing two power bus interrupts through four rigid printed circuit boards.
FIG. 17G is a schematic diagram showing a standby redundant power bus bypassing two power bus interrupts through six rigid printed circuit boards.
FIG. 17H is a schematic diagram showing another alternate redundant power bus bypassing two power bus interrupts through six rigid printed circuit boards.
FIG. 17I is a schematic diagram showing another alternate redundant power bus bypassing two power bus interrupts through six rigid printed circuit boards.
Fig. 17J is a schematic diagram showing a redundant power bus bypassing two power bus interrupts via four rigid printed circuit board bypasses.
FIG. 17K is a schematic diagram showing a redundant power bus bypassing two power bus interrupts through six rigid printed circuit boards.
Fig. 17L is a schematic diagram showing a backup redundant power bus bypassing two power bus interruptions via six rigid printed circuit board bypasses.
Fig. 17M is a schematic diagram showing yet another backup redundant power bus bypassing two power bus interrupts through six rigid printed circuit board bypasses.
Fig. 17N is a schematic diagram showing the disconnection of two critical power buses in a rigid printed circuit board array, resulting in a system fatal power bus failure.
Fig. 18A is a schematic diagram of a phototherapy system lacking redundant power or signal distribution.
Fig. 18B is a schematic diagram of a phototherapy system including redundant power buses and redundant signal distributions.
Fig. 18C is a schematic diagram of a non-redundant and redundant electrical system during normal operation and connection failure.
Fig. 18D is a schematic diagram of multiple redundant electrical connections resulting in
FIG. 19 is a schematic diagram illustrating the definition of the Redundancy Factor (RF) by the number of redundant interconnects on a circuit or rigid printed circuit board.
Fig. 20 includes a block diagram representing an electrical topology and an exemplary physical layout of a 2-rigid printed circuit board system with
Fig. 21A includes a block diagram representing an electrical topology and an exemplary physical layout of a 3-rigid printed circuit board
FIG. 21B is a block diagram showing an electrical topology and an exemplary physical layout of a 3-rigid printed circuit board system in which RF ≧ 1.
Fig. 22A is a block diagram representing an electrical topology and an exemplary physical layout of a 4-rigid printed circuit board system where
FIG. 22B is a block diagram representing an exemplary physical layout and electrical topology of an alternative 4 rigid printed circuit board system in which RF ≧ 1.
Fig. 22C is a block diagram representing an electrical topology and an exemplary physical layout of a 4-rigid printed circuit board system where
Fig. 22D is a block diagram representing an electrical topology and an exemplary physical layout of an alternative 4-rigid printed circuit board system where
FIG. 23A is a block diagram showing the electrical topology and exemplary physical layout of a 5 rigid printed circuit board system where RF ≧ 1.
FIG. 23B is a block diagram representing an exemplary physical layout and electrical topology of an alternative 5 rigid printed circuit board system where RF ≧ 1.
FIG. 23C is a block diagram representing an exemplary physical layout and electrical topology of an alternative 5 rigid printed circuit board system in which RF ≧ 2.
FIG. 24A is a block diagram showing the electrical topology and exemplary physical layout of a 6 rigid printed circuit board system where RF ≧ 1.
FIG. 24B is a block diagram representing an exemplary physical layout and electrical topology of an alternative 6 rigid printed circuit board system in which RF ≧ 1.
Fig. 24C is a block diagram representing an electrical topology and an exemplary physical layout of a 6 rigid printed circuit board system where
FIG. 25A is a block diagram showing the electrical topology and exemplary physical layout of a 9 rigid printed circuit board system where RF ≧ 1.
FIG. 25B is a block diagram showing the electrical topology and exemplary physical layout of a 9 rigid printed circuit board system in which RF ≧ 2.
FIG. 26A is a block diagram showing the electrical topology and exemplary physical layout of a 12 rigid printed circuit board system in which RF ≧ 1.
FIG. 26B is a simplified block diagram showing the electrical topology of a 12 rigid printed circuit board system with RF ≧ 1.
FIG. 26C is a simplified block diagram showing the electrical topology of a 12 rigid printed circuit board system where RF ≧ 2.
FIG. 26D is a simplified block diagram showing an electrical topology of an alternative 12 rigid printed circuit board system including a diagonal interconnection where RF ≧ 2.
FIG. 27A is a simplified block diagram showing the electrical topology of a 20 rigid printed circuit board system where RF ≧ 1.
FIG. 27B is a simplified block diagram showing the electrical topology of a 20 rigid printed circuit board system where RF ≧ 2.
FIG. 27C is a simplified block diagram showing the electrical topology of a 20 rigid printed circuit board system including a diagonal interconnection where RF ≧ 2.
FIG. 27D is a simplified block diagram showing the electrical topology of an alternative 20 rigid printed circuit board system including diagonal interconnections where RF ≧ 2.
FIG. 27E is a simplified block diagram showing the electrical topology of another 20 rigid printed circuit board system with diagonal interconnections where RF ≧ 2.
FIG. 27F is a simplified block diagram showing the electrical topology of another 20 rigid printed circuit board system with diagonal interconnections, where RF ≧ 2.
FIG. 27G is a simplified block diagram showing the electrical topology of a 20 rigid printed circuit board system with diagonal interconnections and vertical end caps, where RF ≧ 3.
FIG. 27H is a simplified block diagram showing the electrical topology of a 20 rigid printed circuit board system with diagonal interconnections, with an inactive corner printed circuit board, where RF ≧ 4.
FIG. 27I is a simplified block diagram showing the electrical topology of a 20 rigid printed circuit board system with diagonal interconnections and RF ≧ 4 vertical and horizontal endcaps.
Figure 28A is a simplified block diagram showing a generalized rectangular electrical network topology.
Fig. 28B is a simplified block diagram showing a generalized rectangular grid topology including vertical end cap interconnects.
Fig. 28C is a simplified block diagram representing a generalized rectangular grid topology including diagonal interconnections and vertical end caps.
Figure 28D is a simplified block diagram representing a generalized rectangular electrical network topology including "x-shaped" diagonal interconnects and junction links with vertical end caps.
FIG. 28E is a simplified block diagram representing a generalized rectangular grid topology including "x-shaped" diagonal interconnects and junction links with vertical and horizontal end caps.
FIG. 29A includes redundant interconnected printed circuit board block cells for RF ≦ 1, RF ≦ 2, and RD ≦ 3.
FIG. 29B includes redundant interconnected printed circuit board block units for RF ≦ 4, RF ≦ 5, RF ≦ 6, and RD ≦ 7.
FIG. 30A is a graph showing the probability of system failure as a function of the interconnection failure probability and the redundancy factor for a redundant system of 12 circuits and 17 soft connections.
Fig. 30B is a graph showing the probability of system failure as a function of the redundancy factor and the probability of interconnect failure for a redundant system of 20 circuits and 31 soft connections.
Fig. 31 is a graph comparing cumulative time to Failure (FIT) versus mechanical bend cycle for non-redundant electrical systems with different aging failure distributions.
Fig. 32 is a graph comparing cumulative time to Failure (FIT) versus mechanical bend cycle for circuits with different Redundancy Factor (RF) levels.
FIG. 33 is a look-up table of circuit components that divide various circuit functions into various redundancy factors.
Fig. 34A includes a schematic example of a circuit of protection circuit connection.
Fig. 34B is a schematic example of a protection circuit connection with linear voltage regulation.
Fig. 34C is a schematic example of protected circuit connections with buck switching voltage regulation.
Fig. 34D is a schematic example of a high voltage protection circuit connection with buck switching voltage regulation.
Fig. 34E is a schematic example of protection circuit connections with high voltage boost switch voltage regulation and linear voltage regulation.
Fig. 34F is a schematic example of a battery and battery charger circuit.
Fig. 35A is a schematic example of a digital program control circuit.
Fig. 35B is a schematic example of an analog and digital signal processing circuit.
Fig. 35C is a schematic example of an analog and digital control circuit.
Fig. 35D is a schematic example of an RF communication circuit.
Fig. 36A includes a schematic example of a power sensor circuit of an important level.
Fig. 36B is a schematic diagram of a critical-class LED driving circuit.
FIG. 36C is a graph having I2Schematic example of a programmable LED driver circuit for a C-interface.
FIG. 36D is a graph having I2Illustrative example of a scratch pad circuit for the C interface.
Fig. 36E is a schematic example of a secondary protection external connection circuit.
Fig. 37A includes a schematic example of a basic level powered sensor circuit.
FIG. 37B is a schematic example of a distributed sensor array interconnected with local sensor interface circuitry.
Fig. 37C is a schematic example of interconnected sensor interface circuits.
Fig. 37D is a schematic example of a redundant power bus for a distributed sensor system.
Fig. 38A is a schematic example of a line or overheat protection circuit.
FIG. 38B is a view showing connection to a cable having I 2Illustrative examples of wires or interconnections of multiple over-temperature protection circuits of a C-connected local sensor interface.
FIG. 38C is a graph represented by the formula2A schematic diagram of a C-connected parallel distributed diode temperature sensor interconnected to a sensor interface circuit.
FIG. 39A is a drawing showing a cross-sectional view of a polymer having2Schematic example of a C-connected digitizing diode temperature sensor circuit.
FIG. 39B is a graph represented by the formula I2A schematic diagram of parallel distributed diode temperature sensors interconnected by a C-connected digitizing interface circuit.
FIG. 39C is a graph represented by the formula I2A schematic diagram of a multiplexed distributed diode temperature sensor interconnected by C-connected digitizing interface circuits.
FIG. 39D is a graph represented by the formula2Exemplary discrete diode temperature sensing for C-connected digitizing interface circuit interconnectA sensor is provided.
Fig. 40A is a schematic example of a basic-stage LED driving circuit.
Fig. 40B is a schematic example of a uniformly distributed array of LED driving circuits.
FIG. 40C is a graph having I2Illustrative example of a distributed uniform array of C-connected LED drive circuits.
Fig. 40D is a schematic example of an auxiliary level (RF ═ 1) distributed heterogeneous array of LED driver circuits.
Fig. 40E is a schematic example of a basic level (RF ═ 2) distributed heterogeneous array of LED driver circuits.
Fig. 40F is a schematic example of an alternative basic level (RF ═ 2) distributed heterogeneous array of LED driver circuits.
FIG. 41 is a schematic example of a POL regulator and several local electrical loads.
FIG. 42 is a schematic example of a local energy storage circuit and distribution circuit.
Fig. 43 includes a schematic example of a local energy storage circuit using a capacitor and a supercapacitor.
Fig. 44 includes schematic examples of various shapes of connecting links and underlying non-connecting crosses.
Fig. 45 is a schematic example of a distributed electronic system.
Fig. 46A is a schematic example of a power distribution circuit.
Fig. 46B is a schematic example of a power distribution circuit showing unregulated power interconnections.
Fig. 46C is a schematic diagram of a power distribution circuit illustrating the interconnection of regulated power supplies.
Fig. 47 is a schematic example of signal distribution in a distributed electronic system.
Fig. 48 is an idealized representation of three signal paths in a distributed system carrying the same analog signal.
Fig. 49 is a comparison of transmit and receive analog waveforms on three different signal interconnection paths in a distributed system.
Fig. 50A is a schematic illustration of the simulated summation of signals over three different signal interconnect paths in a distributed system.
Fig. 50B is a schematic representation of an analog summation of filtering signals on three different signal interconnect paths in a distributed system.
Fig. 50C is a schematic diagram of an analog summing node for mixing analog signals from three different signal interconnection paths in a distributed system.
FIG. 50D is a schematic diagram of an analog multiplex signal selector for selecting representative signals from three different signal interconnect paths in a distributed system.
Fig. 50E is a schematic diagram of a filtering "sample and hold" function for mixing analog signals from three different signal interconnect paths in a distributed system.
FIG. 51A is a schematic diagram of a Boolean logic OR gate for digitally mixing digital signals from three different signal interconnect paths in a distributed system.
FIG. 51B is a schematic diagram of a clocked logic OR gate for digitally mixing and filtering digital signals from three different signal interconnect paths in a distributed system.
Fig. 52 is a schematic diagram of a clock selection circuit.
Fig. 53A is a schematic diagram of a conventional master-slave system architecture using serial communication.
FIG. 53B is a schematic diagram of a redundant master-slave system architecture using serial communication.
FIG. 54A is a schematic diagram of a redundant serial bus interface in a read mode.
FIG. 54B is a schematic diagram of a redundant serial bus interface in write mode.
Fig. 54C is a serial data packet for redundant serial bus communication.
Fig. 55A is a plan view of a rigid-flex printed circuit board having 2 degrees of freedom.
Fig. 55B is a plan view of an improved strength rigid-flex printed circuit board with 2 degrees of freedom.
Fig. 56A is a plan view of a rigid-flex printed circuit board having 1 degree of freedom.
Fig. 56B is a plan view of an improved strength rigid-flex printed circuit board with 1 degree of freedom.
Fig. 57 is a plan view of two rigid-flex printed circuit boards with 0 degree of freedom.
FIG. 58 is a graph of damage resistance versus degree of freedom for various rigid-flex printed circuit board designs.
Fig. 59 is a graph of damage resistance versus bending resistance of flexible printed circuit board connections in a rigid-flex printed circuit board.
Fig. 60A is a plan view of a rigid-flex printed circuit board with interconnected square arrays and hexagonal cells on opposite sides.
Fig. 60B is a plan view of two alternating square arrays of rigid-flex printed circuit boards with straight and diagonal interconnections.
Fig. 60C is a plan view of a square array and rectangular rigid-flex printed circuit board with straight and X-shaped interconnects.
Fig. 60D is a plan view of two square array rigid-flex printed circuit boards with an irregular center rigid printed circuit board.
Fig. 60E is a plan view of two square array rigid-flex printed circuit boards with multiple irregular center rigid printed circuit boards.
Fig. 61 is a cross-sectional view of a rigid-flex printed circuit board having four conductive layers.
Fig. 62 is a cross-sectional view of an alternative rigid-flex printed circuit board having four conductive layers.
Fig. 63 is a cross-sectional view of a flexible printed circuit board having two conductive layers and conductive vias.
Fig. 64 is a cross-sectional view of the flexible printed circuit board under the intersection.
Fig. 65A is a plan view of a T-shaped flexible connector.
Fig. 65B is a plan view of the + -shaped flexible connector.
Fig. 65C is a plan view of a curved intersection.
Fig. 66A is a cross-sectional view of a rigid-flex printed circuit board with through-board vias.
Fig. 66B is a cross-sectional view of a rigid-flex printed circuit board with partial vias.
Fig. 67 is a plan view of a rigid printed circuit board power distribution bus.
Fig. 68 is a cross-sectional view of stacked signal distribution.
Fig. 69A is a cross-sectional view of a rigid flexible printed circuit board having three flexible embedded conductive layers corresponding to cross-section a-a' in fig. 69B.
Fig. 69B is a plan view of a stress relieving conductive mesh.
Fig. 69C is a cross-section of a via-anchored strain relief conductive mesh corresponding to section B-B' in fig. 69B.
Fig. 69D is a cross-sectional view of a rigid flexible printed circuit board having three flexible embedded conductive layers corresponding to section C-C in fig. 69B.
Fig. 69E is a cross section of a rigid printed circuit board with three conductive layers.
Fig. 70 is a flowchart of manufacturing a 3D flexible printed circuit board.
Fig. 71 is a flowchart of a curved portion capable of manufacturing a 3D flexible printed circuit board.
Fig. 72A includes a cross section of a two-layer metal flexible printed circuit board manufacturing step used in a 3D flexible printed circuit board.
Fig. 72B includes a cross-section of a soft metal patterning step used in 3D flexible printed circuit board fabrication.
Fig. 72C includes a cross-section of an additional soft metal patterning step used in 3D flexible printed circuit board fabrication.
Fig. 72D includes a cross-section of an additional soft metal patterning step used in 3D flexible printed circuit board fabrication.
Fig. 72E includes a cross-section of a soft planarization step used in 3D flexible printed circuit board fabrication.
Fig. 72F includes a cross-section of a curved cap fabrication step used in 3D flexible printed circuit board fabrication.
Fig. 73A includes a cross-section of a blind via fabrication step used in 3D flexible printed circuit board fabrication.
Fig. 73B includes a cross-section of an additional blind via fabrication step used in 3D flexible printed circuit board fabrication.
Fig. 73C includes cross-sections of various fabricated blind vias used in 3D flexible printed circuit board fabrication.
Fig. 74 is a partial flowchart of the manufacturing of the rigid-flex structure of the 3D flexible printed circuit board.
Fig. 75A includes a cross section for a top hard-to-soft lamination step for a 3D flexible printed circuit board.
Fig. 75B includes a cross section of a bottom hard-to-soft lamination step for a 3D flexible printed circuit board.
Fig. 76A includes a cross section of a top metal patterning step of a 3D flexible printed circuit board.
Fig. 76B includes a cross-section of a bottom metal patterning step of a 3D flexible printed circuit board.
Fig. 76C is a cross section of a rigid-flex printed circuit board having four conductive layers.
FIG. 77 is another partial flowchart of the manufacture of the rigid-flex structure of the 3D flexible printed circuit board.
Fig. 78A includes a cross-section of a top via fabrication step for a 3D flexible printed circuit board.
Fig. 78B includes a cross-section of an additional top via fabrication step for a 3D flexible printed circuit board.
Fig. 78C includes a cross section of an additional top via fabrication step for a 3D flexible printed circuit board.
Fig. 79A includes a cross-section of a via fabrication step for a 3D flexible printed circuit board.
Fig. 79B includes a cross-section of an additional via fabrication step for a 3D flexible printed circuit board.
Fig. 79C includes a cross-section of an additional via fabrication step for a 3D flexible printed circuit board.
Fig. 80A includes a cross-section of a bottom via fabrication step for a 3D flexible printed circuit board.
Fig. 80B includes a cross section of an additional bottom via fabrication step for a 3D flexible printed circuit board.
Fig. 80C includes a cross section of an additional bottom fabrication step for a 3D flexible printed circuit board.
Fig. 81 is a cross-sectional view of the rigid-flex printed circuit board after thick metal plating.
Fig. 82A is a cross-sectional view of a rigid-flex printed circuit board showing selective laser removal of a top rigid printed circuit board portion.
Fig. 82B is a cross-sectional view after selective removal of portions of the soft and hard bond printed circuit boards.
Fig. 82C is a cross-sectional view of a rigid-flex printed circuit board showing selective laser removal of a bottom rigid printed circuit board portion.
Fig. 82D is a cross-sectional view of the rigid-flex printed circuit board shown after selective removal of the bottom rigid printed circuit board portion.
Fig. 82E is a cross-sectional view of the rigid printed circuit board after top and bottom patterned packaging of the rigid printed circuit board portion.
Fig. 82F is a cross-sectional view of a rigid-flex printed circuit board showing laser removal of the soft material.
Fig. 82G is a cross section of the rigid-flex printed circuit board after removal of the soft material.
Fig. 82H is a cross section of an unaffected portion of the soft-hard bonded printed circuit board after laser bend removal.
Fig. 83A includes a cross section of a process step for developing an etch-defined etch.
Fig. 83B includes a cross section of a process step for screen printing and lacquer-defined etching.
Fig. 84 includes a cross-section of a process step for screen printing and painting a definition coating.
Fig. 85A shows a cross-section of a rigid-flex printed circuit board during rigid printed circuit board removal, shown after interface layer deposition.
Fig. 85B shows an additional cross section of the rigid-flex printed circuit board during the rigid printed circuit board removal process shown after selectively hardening the interface layer.
Fig. 85C shows a cross section of a rigid printed circuit board during the rigid printed circuit board removal process shown after thick metal plating.
Fig. 85D shows a cross section of the rigid printed circuit board during removal of the rigid printed circuit board, showing after removal of the rigid material.
Fig. 86A shows a cross section of a rigid printed circuit board removal process using an unhardened interface layer.
Fig. 86B shows a cross section of a rigid printed circuit board removal process using an air gap.
Fig. 87A includes a plan view of a rigid printed circuit board with soft and hard bonds during the rigid printed circuit board removal process, showing before and during the rigid material removal.
Fig. 87B includes a plan view of the rigid printed circuit board during the rigid printed circuit board removal process shown after the rigid material is removed.
Fig. 88 includes a plan view of a rigid-flex printed circuit board in an alternating design during rigid printed circuit board removal, showing before and during the rigid material removal.
FIG. 89A includes a cross-section of a quasi-rigid printed circuit board fabrication including a flexible substrate and a top QR polymer print.
FIG. 89B includes a cross-section of quasi-rigid printed circuit board fabrication, including bottom QR polymer printing and flex cap etching.
Fig. 89C includes a cross-section of a quasi-rigid printed circuit board fabrication, including top and bottom solder paste printing.
Fig. 89D is a cross section of a quasi-rigid printed circuit board after thick metal plating.
Fig. 89E is a cross-sectional view of the packaged quasi-rigid printed circuit board.
Fig. 90 is a cross-section of a quasi-rigid printed circuit board after surface mounting of components.
Fig. 91 is a cross-section of a quasi-rigid printed circuit board during surface mount assembly.
Fig. 92 is a cross-section of a quasi-rigid printed circuit board during application of a moisture barrier coating.
Fig. 93 is a cross-sectional view of a quasi-rigid printed circuit board after a moisture barrier coating is applied.
Fig. 94 is a cross-sectional view of a quasi-rigid printed circuit board after mounting in a polymer cover.
Figure 95A includes a perspective view of a phototherapy polymer pad of a ribbon design.
Fig. 95B includes a top view, a rear view, and an edge view of a phototherapy polymer pad of a ribbon design.
Figure 95C is a perspective exploded view of a phototherapy polymer pad of a ribbon design.
Figure 95D is a bottom perspective view of a phototherapy polymer pad of a tape design.
Figure 95E includes top and bottom caps in a phototherapy polymer liner of a ribbon design.
Figure 95F shows various views of a distributed rigid-flex printed circuit board in a phototherapeutic polymer cushion in a ribbon design.
Fig. 96 shows a process flow for assembling a phototherapy polymer pad in tape form.
Figure 97 includes a perspective view of a phototherapy polymer pad in tape form.
Fig. 98 includes a photograph of a distributed rigid-flex printed circuit board with a phototherapy polymer pad in tape form.
Fig. 99 is a perspective view of a phototherapy polymer pad and associated cables in tape form.
Diagram 100 includes a top view of metal layers in a distributed rigid-flex printed circuit board design.
Fig. 101A includes a perspective view of a reconfigurable phototherapy polymer pad.
Fig. 101B includes top, bottom, and side views of a reconfigurable phototherapy polymer pad.
Fig. 102 is a perspective view and an exploded view of a reconfigurable phototherapy polymer pad design.
Fig. 103A includes various perspective views of a distributed rigid-flex printed circuit board in a reconfigurable phototherapy polymer pad design.
Fig. 103B includes various edge views of a distributed rigid-flex printed circuit board in a reconfigurable phototherapy polymer pad design.
Fig. 104 includes top and bottom covers in a reconfigurable phototherapy polymer pad design.
Figure 105 includes a polymeric adjustable band for a reconfigurable phototherapy polymeric cushion design.
Figure 106A includes a top view photograph of a distributed rigid-flex printed circuit board of a reconfigurable phototherapy polymer pad design.
Fig. 106B includes a bottom view of a distributed rigid-flex printed circuit board of a reconfigurable phototherapy polymer pad design.
Fig. 107 includes a photograph of the reconfigurable phototherapy polymer pad in perspective view.
Fig. 108 includes a perspective photograph of a reconfigurable phototherapy polymer pad and associated cables.
Fig. 109 includes various perspective views of a cranial phototherapy polymer liner cap.
Figure 110 includes various perspective views of a mask phototherapy polymer pad cover.
Figure 111 includes various perspective views of a knee-protecting cup-shaped phototherapy polymer pad cover.
Detailed Description
As previously mentioned, implementing electronic circuits and systems generally involves mounting and interconnecting electronic components on a printed circuit board or boards. Such printed circuit boards include rigid printed circuit boards that cannot be bent or altered in shape, flexible printed circuit boards that can be flexed or twisted, or combinations thereof. In medical devices such as LED light pads for light therapy or for use in sports applications such as wearable electronics or "wearable devices", all of the above techniques have a number of drawbacks. If the rigid printed circuit board is bent, the rigid printed circuit board may be broken or cracked, and after repeated bending cycles, components mounted on the flexible printed circuit board may be cracked and fall off from the solder, and the hybrid rigid-flexible printed circuit board may tear or tear the position where the flexible printed circuit board is connected to the rigid printed circuit board. Other methods of connecting rigid printed circuit boards using wires or connectors can also lead to partial or complete electrical failure of the electronic system after repeated flexing of the printed circuit boards and their interconnections. In many cases, even a single wire, breakage of a printed circuit board trace or solder joint, or moisture corrosion, can prevent or completely disable the operation of the circuit.
In the present invention, a novel and inventive printed circuit board technology that is resistant to damage and use, including its design and manufacturing methods, is disclosed. The new printed circuit board technology and corresponding system design approach provide many advantages not provided by today's designs or printed circuit boards, including a combination of the following functions:
realizing three-dimensional flexible electronic devices capable of withstanding a large number of bending cycles without degradation or system failure
Three-dimensionally flexible electronic devices that can be made flexible or fit any shape or size, fixed or movable, and are suitable for sports use as wearable electronic devices and for conformal medical devices (such as surveillance or phototherapy).
Realize a series of rigid printed circuit boards, capable of forming any 3D shape, and electrically interconnected without wires, cables or connectors.
Redundant connection of the rigid printed circuit board array, resulting in a possible disconnection of one or more electrical interconnections, i.e. as an open fault, without causing an electronic circuit fault or a system fault.
To achieve a flexible electronic device to prevent mechanical damage from bending, twisting or tearing.
Flexible electronics that are not sensitive to moisture or corrosion damage are achieved.
In accordance with the above objects, a 3D flexible printed circuit board with redundant interconnects is disclosed.
Redundant distributed networks-if the grid is distributed over multiple printed circuit boards containing different components, circuits and functions, interconnection failures between components can compromise not only two interconnected printed circuit boards, but possibly the entire system. In the prior art rigid-flexible printed circuit boards shown in fig. 11A and 11B, it is apparent that each of the flexible and rigid printed circuit boards is unique. In the design of reliable and highly reliable systems, unique circuits are not "good" because they represent the risk of a single point of failure.
For example, in fig. 13A, rigid printed circuit boards 190A, 190B, and 190C are unique and uniquely incorporate
To mitigate single point failures, redundant arrays of identical signals and circuits may be distributed across a printed circuit board grid. One such
In purely redundant embodiments, all circuit blocks C1,1To C3,3Are the same. In another embodiment, the circuit blocks are largely identical, but some limited number of circuits are unique, e.g., power and control. The division of an electronic system into a plurality of sub-circuits for redundant operation in accordance with the present invention is discussed later in this application.
In addition to redundant circuits, power and signals are also distributed in a redundant manner for the disclosed
Because the
FIG. 16E shows an identification circuit C1,2And C1,3An alternate representation of the
In the case of two interrupts 220A and 220B shown in FIG. 16H, the signal propagates through
In the case of the interrupts 220A and 220C shown in FIG. 16L, the redundant connections can also maintain signal connections in which signals are routed through the circuit C via the
Fig. 16P shows that interrupts 220A and 220D disconnect the same network of
With the redundant signal distribution described above, signals can flow in either direction (i.e., bi-directionally) through the conductive interconnections between the multiple rigid printed circuit board circuits. For this reason, all communication interconnections shown in the previous figures are schematically represented by arrows pointing in both directions, i.e. bi-directional. These signals may be evenly distributed throughout the circuit grid. If the circuit elements are also uniform, their use of the input signal is the same. Otherwise, circuits that do not utilize a particular signal may ignore it. Importantly, whether or not a given circuit uses input signals, in redundant signal distribution, each circuit and rigid printed circuit board must pass its input signals to all of its neighbors-otherwise the redundancy of the network is reduced. This implementation of signal replication in redundant circuits will be discussed later in this disclosure.
Redundant power distribution is different from redundant signal distribution. Although the redundant signal distribution is generally uniform and bi-directional, there is no predefined signal flow direction between circuit elements and the power distribution is generally directional, flowing from the power source to the electrical load rather than in reverse. The power supply of the system is a circuit or a rigid printed circuit board containing the power supply, which may for example comprise the power supply
Connector to an external power supply
Supply or voltage regulator circuit
Batteries
Capacitors or supercapacitors
Charger circuits connected to the power supply by cables or connectors, e.g. USB
Wireless charger circuit
·
In the case of a power supply that is portable, the battery, capacitor or local energy storage element must be charged through a connector or wirelessly by radio or magnetic coupling. Regardless of the power supply, throughout the circuit grid, power flows in only one direction — from the power supply (i.e., the rigid printed circuit board containing the power supply circuitry) to the other circuitry. Thus, unlike a signal that may flow bi-directionally, power flows "uni-directionally" from the power source to the electrical load, in which case the circuit is supplying power.
Thus, the
The alternative schematic representation of
including
Including intermediate circuits C as shown in FIG. 17G 2,2,C2,1,C3,1,C3,2,C3,3And
Including intermediate circuits C as shown in FIG. 17H1,1,C2,1,C3,1,C3,2,C3,3And C2,3Of the power bus228A, 228B, 229A, 229B, 227C, and 226C.
Including intermediate circuits C as shown in FIG. 17I1,1,C2,1,C2,2,C3,2,C3,3And
If both
the
The
The
The
In the event interrupt 230A interrupts
The methods of redundant signal routing and power buses in a distributed system disclosed herein are suitable for a wide range of applications. One such example is their use in phototherapy in medical applications. In the
As shown, the mounting includes a circuit C1,2The
Circuit C implemented in rigid printed
In contrast, a redundant phototherapy device 268 is shown in fig. 18B. The circuit operation is the same as the
In another embodiment of the present invention, the interconnection between the rigid printed circuit board 276 and the rigid printed circuit board 277A is accomplished using a merged rigid flexible printed circuit board technology whereby a grid of flexible printed circuit boards interconnecting the various rigid printed circuit board islands is fabricated together into a single printed circuit board, including grid pattern flexible printed circuit board and rigid printed circuit board islands. This application will discuss rigid-flex printed circuit board fabrication later to facilitate redundant interconnection.
FIG. 18C compares non-redundant and redundant systems under normal operating conditions and after failure. When an
Thus, while many other paths may exist to support conduction, only the number of connections directly connected to the rigid printed circuit board B is important in order to ensure operation of the rigid printed circuit board B. Fig. 18D illustrates that while multiple parallel conductive paths 287 may improve the statistical chance that the entire circuit experiences damage, the additional paths do not improve the survival rate of the connectivity to the particular printed circuit board (in this case, printed circuit board B). For example, the
Redundant circuit topology-the redundancy of each component circuit in a redundant system depends on its connectivity to other component circuits in the network. FIG. 19 shows a view for a representation as element C r,cOf any given
For example, if
According to the above equation with only one connection, i.e. where z is 1, then a redundancy factor RF of 0 means that there is no connection redundancy and a single failure point will certainly lead to a system failure or an electrical failure. In the case where
As described above, each circuit in an untrusted system has its own unique redundancy factor. Higher redundancy circuits are less prone to interconnect failure and therefore more reliable than circuits with lower RF ratings. However, the lowest redundancy factor circuit sets the redundancy factor of the system. The impact of a circuit fault on the overall system depends on the importance of the circuit. If the circuitry is not important, the failure will cause the overall system to degrade, for example, performance may degrade, or certain areas of the distributed system may cease to operate, but the entire system will continue to operate. For example, a non-critical failure in a medical device may include a LED string where a portion of the biosensor fails to report biological information in a particular area being monitored or the phototherapy polymer pad fails to illuminate.
In contrast, a failure of a critical system may involve a central microcontroller, signal processing IC, or power supply disconnected from the system, resulting in a complete system failure. The distributed system manufactured in accordance with the present invention thus includes a redundant electrical topology in which critical circuitry is located only on printed circuit boards having a high redundancy factor. In contrast, according to the disclosed design approach, a printed circuit board with a low RF rating will be used for only non-critical functions of limited importance or for implementing functions that are limited to only a small area being monitored or processed.
Various designs must be considered in order to determine the dependence of the redundancy factor of the circuit on the connections and locations in the distributed network.
Fig. 20 compares two examples of systems containing only two rigid printed circuit boards. In the top diagram, circuit C is included1,2The rigid printed circuit board 301 is connected to the circuit C by a single
For consistency of nomenclature, fig. 29A shows a rigid printed circuit board, where two
Following the above naming convention, FIG. 21A compares two examples of a system comprising three rigid printed circuit boards. In the top diagram, circuit C is included1,2Is electrically connected to the rigid printed
In a similar manner, a topological representation showing electrical connections to a circuit may include various power, ground, and signal lines depicted herein as lines of various thicknesses. Since no particular printed circuit board layout is depicted, the illustration is a topological structure, and it should be understood that each connection into a circuit is connected to every other corresponding voltage or signal line connected to the same circuit. For example, a circuit C as shown in FIG. 23C 2,2In (2), four flexible connectors each include four narrow conductors and two thick conductors. Inside the circuit, the connectors are interconnected as "same type" signals or voltages, i.e., each ground line is connected to all other ground lines, wherein each + V power line is connected to all other + V lines, wherein each signal a line is connected to its respective signal a line, signal B line is connected to other signal B lines, and so on. Since the topological layout is not a specific physical layout, the fact that the ground can be illustrated as connected in is in circuit C2,2When connected to circuit C2,1When entering into the circuit C2,3Is on the right, does not mean that the ground is connected to something other than ground, in every circuitThe ground is only connected without regard to its depiction in the electrical topology. Specific physical printed circuit board layouts (such as shown later in fig. 60A-60E) and methods of facilitating these interconnections within a circuit, such as shown in fig. 65A-65C fig. 67 shows that a particular electrical topology can be implemented with a wide variety of physical implementations.
Furthermore, because each signal line, ground or power line, is connected to their respective identical line throughout the topology network, the multiple paths available for a given line or signal may ostensibly be considered "parallel" electrical connections, and the parallel connections may be considered "redundant" connections if present, i.e., they carry and share current at the same time.
Because these connections are electrically parallel, in normal operation, current between the two circuits is carried simultaneously through some combination of all possible parallel connections present between the circuits. In an ideal parallel connection, theoretically, the conductivities of the connections are identical and the currents are evenly distributed, i.e. balanced, in the various paths. However, if the resistance of one path is slightly different from the resistance of another path, the current will automatically redistribute among the paths (similar to the way river water flows to the ocean by flowing through many different rivers). Thus, in a real physical system, the change in current pattern distributed between the conductors is unimportant and does not affect system operation or performance. In essence, when carrying current between and across multiple connections in a distributed network, the exact distribution of current between the flexible interconnects is not important, and for all surface purposes the circuit can be considered identical to an idealized parallel connection, even if they are not perfectly matched.
Since the various conductive paths are used simultaneously, the connection represents an "electrically redundant" connection. If one or more interconnects fail, i.e., become open, the current will naturally redistribute to the available circuit paths without any significant effect on the operation of the system. Even if only one connection per connection fails, i.e. the redundant connection is broken, the connection between the circuits is preserved as long as at least one connection persists, and the system operation remains unaffected.
As a differential nuance, the meaning of redundancy in system reliability describes multiple components, elements or connections being used simultaneously. This definition is in contrast to backup or standby, where another component, element or connection is available but not in use at the time. When a primary element fails, some action must be taken to activate the standby element, often resulting in a delay in the process. For example, when a tire of an automobile is blown out, the automobile is deactivated until the spare parts can be removed from the trunk, the damaged tire removed and the spare tire installed. On large truck or semi-trailer trailers, four tires are running on each axle at all times. If a tire has a flat truck, it can continue to run unobstructed.
In electronic devices, redundant systems or connections are immediately available, whereas a standby system may cause temporary system failures and permanent memory loss before the standby is activated. For example, an emergency backup generator requires time to increase and stabilize. If a power failure occurs, the load power is interrupted until the generator is brought online. For example, in a hospital, if such electrical failures occur during a serious medical procedure, they may pose a serious risk to the patient even due to a brief power failure.
The disclosed redundant distributed system thus has advantages over solutions involving spare parts or replaceable elements. Consider, for example, criticality of wearable soft electronics used in cardiac pacemaker applications, or regulating neural pathways in the brain of patients with seizures. If a power failure occurs at the wrong time, even briefly, such as when driving a car, a temporary interruption of operation may have dire consequences. In such extremely reliable applications, redundant connections are of critical importance. Even in less critical applications, there is no reason to not employ redundancy design methods and apparatus in distributed electronic systems, since the performance or cost of using redundancy methods as disclosed herein is not adversely affected or compromised.
An alternative three printed circuit board topology is shown in FIG. 21B, includingCircuit C with three
Fig. 22A shows a topological example of a system including four rigid printed circuit boards. Each rigid printed
Another topology shown in fig. 22C includes four rigid printed
An alternative interconnect topology that is identical to the previous example is shown in fig. 22D. In this way, the
Fig. 23A shows a topological example of a system including five rigid printed circuit boards. Except for the central circuit C2,2In addition, each rigid printed
An increase in area efficiency can be achieved with the topology shown in fig. 23B. Based on a 2 × 3 matrix, the first row contains two circuits C1,1And C1,3And the second row contains three circuits, circuit C2,1,C2,2And C2,3. Circuit C2,2Connected to the first row of printed circuit boards using
Five further printed circuit board topologies based on a 3 × 3 matrix are shown in FIG. 23C, where a printed
By inserting printed
Fig. 25A shows a topological example of a system including nine rigid printed circuit boards arranged in a 3 × 3 grid. As shown, the grid includes three types of printed circuit boards:
a circuit C with a redundant RF-3 generated by a central printed
Contact of the center edge printed
Contact two corner printed
Overall system redundancy is higher for
For a corresponding redundancy factor of
By adding the
Fig. 26A shows a topological example of a system including twelve rigid printed circuit boards arranged in a 3 × 4 grid. As shown, the grid includes three types of printed circuit boards:
a circuit C with a redundant RF-3 generated by a central printed
Contact of the center edge printed
Corner printed
The total system redundancy LRF is 1, limited by the corner pcb, and the average redundancy is 1.83.
For a corresponding redundancy factor of
To simplify the schematic of a more complex topology network, the details of the
By adding a
By including the diagonal connector of the soft 299B as shown in FIG. 26D and included in the circuit C1,1And C2,2,C3,4And C2,2,C1,4And C2,3,C3,4And C2,3Thus, all edge and corner circuits are improved to
Fig. 27A shows a topological example of a system including 20 hard printed circuit boards arranged in a 4x5 grid. As shown, the grid includes three types of printed circuit boards:
the center printed
Contact three center edge printed
The corner PCB 230 contacts two
The total system redundancy LRF is 1, limited by the corner pcb, and the average ARF is 2.1.
For a corresponding redundancy factor of RF-3, any central circuit is suitable for integrating critical functions and circuits.
By adding the
By in circuit C1,1And C2,2,C4,1And C3,2,C1,5And C2,4A diagonal connector including a soft 299B as shown in FIG. 27C, implementing an alternative embodiment of the same 4 × 5 network, and C3,4And C4,5. Thus, all edge and corner circuits are improved to be redundant with
As shown in fig. 27D, the use of
In some cases, such as where critical components or connectors or microcontrollers are integrated into distributed circuitry, it is particularly valuable to provide extraordinary redundancy for printed circuit boards containing critical circuitry. This is the case in fig. 27E, where the surrounding circuit C is added 2,3The total number of connections to the printed
To uniformly improve the reliability of more circuits in the matrix, an "x-shaped"
Thus, despite the high component circuit reliability of the overall system, the weakest elements in the system remain corner pieces. In accordance with the present invention, the reliability of the overall electrical system is improved by minimizing the impact of these corner circuits,
as shown in fig. 27G, add edge connections on the corner circuits,
at corner circuit C1,1,C1,5,C4,1And C4,5Or to implement only non-critical functions
Completely eliminating any circuit function on the corner printed circuit board, i.e. converting it to a purely passive circuit or interconnect, as shown in fig. 27H.
As shown in fig. 27G, in addition to the
Corner printed
The top and bottom edge printed
The center side printed
Includes a circuit C2,2,C2,3,C2,4And C3,2,C3,3,C3,4All with an internal printed
Such a topology is particularly robust for use in systems requiring many critical circuits, with
Alternatively, as shown in fig. 27H, the four corner circuits including the printed
In addition to eliminating corners, another way to add redundancy to the system shown in figure 27I is to use horizontal and
To summarize the previous case, the redundant interconnections of the disclosed circuit may be represented as a rectangular grid with the soft 299 connections shown in FIG. 28A, including having circuit C 2,1To Cm,nM rows and n columns. The
Corner circuit C without end cap connection1,1,Cl,n,Cm,lAnd Cm,nA redundancy RF of 1 is present and all center edge circuits are present with RF of 2, including the side center circuits in
Adding the
The generalized enhanced interconnect topology shown in figure 28C incorporates elements of a rectangular grid of circuits including soft 299 interconnects as well as end caps including soft 299A and diagonal interconnects including soft 299B. In this combination, the corner circuit C1,1And Cm,nThe reliability of (2) is increased to
The RF uniformity problem in distributed circuits is best addressed by using the aforementioned X-shaped connecting
As previously described, the redundancy of each circuit element can count the number of flexible printed circuit boards connected to a rigid printed circuit board. Fig. 29A and 29B summarize these various combinations. As shown, fig. 29A shows printed
System reliability-as described above, redundancy improves the reliability of the system and facilitates immunity from damage or loss caused by repeated bending cycles of a distributed flexible printed circuit board as disclosed in accordance with the present invention. In the following discussion of system reliability, or conversely, the possibility of component and system failure, the variable "p" is used to represent statistical probability, the notation pf is used to represent failure probability, and the subscripts "i", "r", and "s" are used to identify the flexible interconnect, the rigid printed circuit board, and the entire system, respectivelyProvided is a system. For example, using this notation, the term pfiMeaning the failure probability of an interconnect failure, and the term pfsIndicating the probability of system failure. The probability of a system failing, its inverse of the probability of failure, is given by the relationship (100% -p)fs) It is given.
In the case of
In the redundant system disclosed herein with RF ═ 1, two failures must occur to cause system failure. Considering normal use, i.e. ignoring the possibility of catastrophic mechanical damage (e.g. a horse stepping on a phototherapeutic polymer pad), only two circuits and two interconnected RF ═ 1 systems are shown in the topology of fig. 20, and assuming that the possibility of an independent failure event system failure is a multiplicative probability of two failures, i.e. the probability of a failure of an independent failure event system is a multiplicative probability of two failures
pfs=pfi·pfi=(pfi)2
The same result occurs for a system comprising three printed circuit boards, as shown in the RF-1 redundant topology of fig. 21A. As shown, any two
In systems with a greater number of circuits, the failure rate of all systems with different redundancies is lower, because the probability of two consecutive failures occurring in different parts of the circuit is higher and does not lead to system failure. For example, as shown in FIG. 23A In a system including a plurality of
As shown, the network includes 1 four-connection printed
pfs=pfi·pfi/11=[(pfi)2/11]
The same concept can be scaled to an example with a large number of circuits, but still exhibiting RF-1 with the lowest reliability connection. For example, there are 17 connections in the topology shown in fig. 26B. The failure rate of the RF-1 component is given by
pfs=pfi·pfi/16=[(pfi)2/16]
For
pfs=pfi·(pfi/16)·(pfi/15)=[(pfi)3/240]
Extended concept to overcome the possibility that
pfs=pfi·(pfi/16)·(pfi/15)·(pfi/14)=[(pfi)4/3,360]
For the system described with a topology comprising 12 circuits and 17 flex connections, as various flex failure rates p fiThe probability of system failure of the function of (a) is described in the table below. The term ppm refers to parts per million and ppb refers to parts per billion. Fig. 30A shows curves 350,251, 352 and 353 for an electrical system fault p with a redundancy factor RF of 0, RF of 1, RF of 2 and RF of 3fsAs a mechanical failure rate p of said networkfiThe probability of the function of (a). Note that although there is no circuit with RF-0, the failure rate of RF-0 is not the same as if the circuits were connected in series (e.g., using a serpentine interconnect pattern.
0
4
6
2
Pfi
RF=0
RF=1
RF=2
RF=3
5%
5%
0.02%
0.52ppm
1.9ppb
10%
10%
0.06%
4.2ppm
30ppb
20%
20%
0.25%
33ppm
480ppb
40%
40%
1.00%
270ppm
7.6ppm
60%
60%
2.25%
900ppm
39ppm
80%
80%
4.00%
0.21%
120ppm
98%
98%
6.00%
0.39%
270ppm
To compare the electrical failure rate of the redundant system to the mechanical failure rate of the flexure, a ratio of the mechanical failure rate to the electrical failure rate may be used, as set forth in the table below.
Machine with a movable working part
RF=0
RF=1
RF=2
RF=3
5%
1X
320X
96,000X
26,880,000X
10%
1X
160X
24,000X
3,360,000X
20%
1X
80X
6,000X
420,000X
40%
1X
40X
1,500X
52,500X
60%
1X
27X
667X
15,556X
80%
1X
20X
375X
6,563X
98%
1X
16X
250X
3,570X
The table above shows that even with a mechanical failure rate of 60% for the flexible circuit, the statistical likelihood of failure of the RF-1 redundant topology is 1/27 for a 60% failure rate without redundancy. For the RF-3 redundant system, the electrical failure rate is 1/667 for the mechanical failure rate at RF-2 and 1/15556 for the normal value.
While the benefits of redundancy are general, the exact statistical data depends on the number of circuit elements and interconnects. For example, there are 20 circuits and 31 soft connections in the topology shown in FIG. 27A. The failure rate of an
pfs=pfi·pfi/30=[(pfi)2/30]
In the
pfs=pfi·(pfi/30)·(pfi/29)=[(pfi)3/870]
Extended concept to overcome the possibility that
pfs=pfi·(pfi/30)·(pfi/29)·(pfi/28)=[(pfi)4/24,360]
For the described system with topology comprising 20 circuits and 31 soft connections, 4 circuits with
0
4
10
6
Pfi
RF=0
RF=1
RF=2
RF=3
5%
5%
0.01%
0.14 ppm
0.26ppb
10%
10%
0.03%
1.1ppm
4.1ppb
20%
20%
0.13%
9.2ppm
66ppb
40%
40%
0.53%
74ppm
1.1ppm
60%
60%
1.20%
250ppm
5.3ppm
80%
80%
2.13%
590ppm
17ppm
98%
98%
3.20%
0.108%
380ppm
In fig. 30B, a curve 350,251 indicates an electrical system fault p when the redundancy factor RF is 0, RF is 1, RF is 2, and RF is 3fsAs a mechanical failure rate p of said networkfi352 and 353. Note that although there is no circuit with an RF of 0, the failure rate of
Machine with a movable working part
RF=0
RF=1
RF=2
RF=3
5%
1X
600X
348,000X
194,880,000X
10%
1X
300X
87,000X
24,360,000X
20%
1X
150X
21,750X
3,045,000X
40%
1X
75X
5,438X
380,625X
60%
1X
50X
2,417X
112,778X
80%
1X
38X
1,359X
47,578X
98%
1X
31X
906X
25,882X
The table above shows that even though the mechanical failure rate of the flex circuit is 60%, the statistical chance of a RF-1 redundant topology failure is 1/50 with a 60% failure rate without redundancy. For the RF-3 redundant system, the electrical failure rate is 1/2,417 and the normal 1/112,778th of the mechanical failure rate at RF-2. This failure rate is even lower than in the previous example. Generally, with redundancy, the greater the number of redundant circuits and interconnects-the higher the system redundancy, the lower the electrical failure rate of the system.
Knowing how the statistical failure rate of the system affects the service life depends on the shape of the cumulative failure loss curve. As shown in fig. 31, an electrical system without electrical redundancy, i.e.,
During the normal service life phase 370, the failure occurs at a very low but non-zero rate of one cumulative failure of one billion interconnects up to a certain number of flex cycles corresponding to
After the onset of the wear failure, the failure rate depends on the manufacture of the product. Cumulative faults typically occur in an exponential fashion, resulting in a straight line on a log or semi-log paper. In the failure curve 372A, failure occurs rapidly once it occurs, representing a "rapid wear" mechanism, such as embrittlement of the plastic. The slower failure rates represented by the lines 372B, 372C and 372D of decreasing slope depict failures that occur gradually, e.g., gradual corrosion of the conductor, delamination of the conductor, solder lifting, etc.
The benefit of redundancy versus operating life is illustrated in the logarithmic graph of fig. 32, where after a number of bending cycles associated with a
For example, life testing of non-redundant printed circuit boards shows failure after thousands of cycles, but depending on the specific design, the disclosed redundant printed circuit board design method with RF ═ 1 failure is confirmed only after 30,000 or 50,000 cycles.
Hierarchical redundancy-the partitioning of an electronic system into component circuits determines the overall reliability of the system. According to the invention, the redundancy required to divide the system into a plurality of parts (i.e. "divide" the system) and then implement each particular function on a particular rigid printed circuit board in the matrix of printed circuit boards depends on the importance of the function and its function. Thus, the system can be divided into a number of important levels from critical circuit function to ancillary circuit function. In practice, the circuit functionality of the system may be broken down into a limited manageable number of levels of importance, for example, four levels, as shown in FIG. 33. The definition of these levels can be taken into account by the degree of system damage that would result if a particular function failed, as represented by the following levels of importance (in the column symbolically represented by "!!":
key level: a "critical" level of circuit functionality refers to a circuit functionality whose failure adversely affects the operation of most or every circuit in the system, may disable the system altogether, or may lead to a safety hazard. Power loss is an example of a critical circuit function.
Importance level: an "important" level of circuit functionality is one whose failure can negatively impact critical global functional characteristics of the system. Its ability to communicate with other systems, its ability to detect important information or perform important tasks or operations.
Basic level: a "basic" level of circuit functionality is one in which a failure of one or more parts of the system can adversely affect the function of the circuit, but leave other parts of the system undamaged, for example, causing some sensors or LEDs in certain limited parts of the circuit to fail, but not disable the entire system.
Assistance level: an "auxiliary" level of circuit functionality is one whose failure would render the system inconvenient to operate, for example, by indicating a light failure, or making it more difficult for the system to recall historical data or trace data, but the actual operation of the system functionality is not affected, either globally or locally.
Examples of critical stage circuit functions include primary external connectors for connecting an external power source or controlling to a distributed electronic system, including protection against electrostatic discharge (ESD), overvoltage, overcurrent, overtemperature, or performing other safety functions. Other key level functions include any primary power source, such as a battery and its associated battery charger, as well as linear and switching regulators. Other key functions include logic, Digital Signal Processors (DSPs), Analog Signal Processors (ASPs), clock circuits, data converters including D/a and a/D converters, microcontrollers and their associated firmware or operating system, such as BIOS (basic input/output system) stored in non-volatile memory (NVM), such as flash or EEPROM. Other key circuits include analog circuits such as oscillators, amplifiers, filters, comparators; digital circuits such as logic gates, flip-flops, counters, digital Phase Locked Loops (PLLs); RF communication circuits, such as radios, WiFi, bluetooth, 3G, 4G; and an interface circuit such as USB.
Examples of important level circuit functions include unique or single instance circuits such as sensors, drivers, LEDs, transmitters, read-write data and scratch pad memory, auxiliary external connectors, and antennas for RF links. Examples of basic level circuit functions include sensor arrays, driver arrays, LED arrays, point-of-load (POL) regulators, local functions, storage capacitors, and interconnect links. Examples of auxiliary level circuit functions include auxiliary sensors, monitors, usage tracking functions, indicator lights, convenience functions and a third connector for connection convenience only.
The design methodology for tuning an electronic application to a distributed system with hierarchical redundancy depends on the application of the product. For consumer applications such as wearable biometric health monitors, minimal redundancy may be employed, primarily to reduce product return costs. By avoiding field failures through a hierarchical redundancy design, manufacturers can avoid warranty costs and maintain a better reputation as high quality consumer device manufacturers. Such a design may therefore employ minimal redundancy, as shown in the column labeled "minimal" in the table of FIG. 33. In this design, the critical circuit functions utilize redundancy RF ≧ 2, while the critical circuit functions utilize redundancy RF ≧ 1. There is no redundancy in the basic and auxiliary circuit functions, i.e.,
In medical or military "high reliability" applications, reliability is of paramount importance, possibly life-critical, and thus excellent reliability is required. The recommended design method for the "superior" reliability system shown uses the highest reliability of the critical circuit functions, ideally RF ≧ 7 and RF ≧ 5, while the important function uses RF ≧ 4, the primary function uses RF ≧ 3 and the auxiliary function circuit function uses RF ≧ 2.
Between consumers and high reliability applications, a good reliability design method adopts a compromise design concept, the design redundancy RF of the key circuit function is more than or equal to 3, the RF of the important circuit function is more than or equal to 2, the RF of the important circuit function is more than or equal to 1, and the auxiliary RF is 1. This good design approach is suitable for professional or professional consumers, such as LED phototherapy polymer pads for human hydrotherapy centers, veterinary clinics for small animals, portable devices for treating horses and camels in stables, and other portable applications such as "consumer" devices for professional use. For on-site treatment of accidents or monitoring performed by medical personnel.
Examples of various circuit functions and their corresponding hierarchical redundancy are shown in the following schematic diagrams, including critical, important, primary, and secondary circuit functions.
Key Circuit function-
FIG. 34C shows a
Fig. 34D shows a high voltage input dual output PSC circuit 400E with high voltage and buck voltage drop regulator outputs. The high voltage power input of
Fig. 34E shows a dual
Fig. 34F shows a battery and
The foregoing circuitry and protected system connections relate to the primary power provided to the disclosed distributed systems defined as the key components required for the operation of any electronic system or device. Other key circuit functions relate to digital control of the system, key analog and digital circuits to perform control, signal processing, Radio Frequency (RF) such as 4G, WiFi, WiMax, bluetooth communications, and wired or bus communications (e.g., radio). USB, Ethernet, IEEE1394, HDMI, and others.
FIG. 35A shows one such critical control function, "digital program control," 430A, in which the microcontroller unit MCU440 executes software or firmware computer code stored in its on-chip memory or other memory 441, the memory 441 typically comprising flash or EEPROM, and using I with the rest of the system, e.g., through
The central control firmware operating within MCU 440 may also distribute this same clock signal or more likely a lower frequency clock signal generated by digitally dividing the frequency of clock 442 into other circuits in the system using a counter. This shared clock signal labeled "clock out" is transmitted over
In addition to utilizing a programmable software-based microcontroller, control of the electronic system may be performed by dedicated analog or digital circuits as shown in FIG. 35B, including analog signal processing circuits ASP and filters 446, by programmable or hardwired logic and digital signal processing DSP circuit "signal processing"
In some potential applications of a distributed electronic system, rather than performing signal processing, analog and digital signal processing may be replaced by a dedicated analog, digital or mixed-signal IC as shown in fig. 35C, including an analog IC448 incorporating functionality including analog circuitry, signal multiplexing and mixed-signal. Logic and
Finally, radio frequency "RF communication"
Important circuit functions-important circuit functions are circuits that perform the required operations, such as sensing, LED driving, monitoring, data acquisition, etc. These important circuit functions basically define the function and use of the product. One such important circuit is the
Temperature detection using semiconductor diodes or thermistors
Magnetic detection using Hall Effect sensors
Detection of chemical or biological organisms using visible or infrared light
Tension detection using micromachines or nanomachines
Thermography using an infrared detector
Chemical pH sensor
Potential detection of electroencephalogram, electrocardiogram, muscle contraction, etc
For discrete sensors, the output signal represents the real-time data of the sensor as a digital or analog value, rather than a data bus compatible information or bi-directional data stream. A higher functionality of the alternative power sensor is the
Other important circuit functions include the driver of the energy emitting device. The energy emitting devices can be used in the development of medical treatments, imaging, biometrics and disease detection, including
LED and laser (optical, ultraviolet and infrared energy)
Microcurrent (electric)
Radio frequency/microwave emitter (long wave electromagnetic)
Ultrasonic (vibration/sound energy)
Heat (vibration/heat energy)
The energy emitting means may comprise a single point source or a plurality of sources distributed over a large area. In therapy, the target area is intentionally subjected to energy that stimulates a biochemical or biophotonic response, e.g., phototherapy, to stimulate enhanced activity of chemical substances present or introduced into the organ or tissue, e.g., photodynamic therapy or to stimulate muscle activity, e.g., microcurrent or hyperthermia. When used in conjunction with the above sensors, sensitive detection of blood oxygen and detection of certain proteins, antigens and microorganisms becomes possible.
One example of an important circuit function including LED driver 460C is shown in fig. 36B, which includes series-connected LED strings 471A through 471N, current control device 470 and transistor 464C for pulsing the LEDs at a controlled frequency and duty cycle. The power to the LED string is provided through redundant connection + HV465 and
Programmable LED driver 460D shown in FIG. 36C shows capable of I2C-
Another important circuit function is the "scratch pad"
Another example of an important circuit function is the
Basic circuit function-in the disclosed distributed system, a "basic" function means not the only electronic circuit, and may in fact be repeated in multiple instances within a single system. For example, LED phototherapy polymer pads used for phototherapy comprise a number of tiles or strings of LEDs covering a large area. An open circuit failure in any single LED string will render the LED inoperable in a small area, thereby "blackening" that portion, but not preventing operation of the overall product. Interconnection faults of basic circuit functions are therefore not system-wide, but rather "local" behavior affects only a part of the distributed system.
Two basic circuit functions that are usually repeated over a large area of a distributed system are sensor arrays or energy emitting devices such as LEDs. The sensor array element 490A and the smart sensor array element 490B shown in fig. 37A are two examples of basic circuit functions, substantially the same as their
For example, in a sensor array comprising a matrix of 32 sensor circuit elements, each sensor element comprises a "32 in 1" circuit element. These elements may be identified, for example sequentially, using a serial number. 1 st element of 32 elements, 5 th element of 32 elements, 29 th element of 32 elements, or by using the unique C described abover,cA row and column matrix number representing a rectilinear grid pattern, wherein C 1,2The identification being in the 1 st and 2 nd column circuits of the matrix, C4,4Identify the sensor located in the 4 th row and 4 th column circuitry of the matrix, etc. As these sensor elements repeat any one of the grids in many "instances" of the distributed system without compromising the operation of the entire system.
An example of such a sensor matrix distributed in a grid pattern is shown in fig. 37B, where
Similarly, the third and fourth rows C3,1To C3,4And C4,1To C4,4Sensor element 498 is coupled to
The connectivity of the
Although the distributed
Considering the same system example, fig. 37D shows the corresponding power distribution network. From a power perspective, either the sensor or the sensor interface circuit, each circuit function is only one electrical load 390. By distributing power over the power bus 389 on each connector including the
System level redundancy summary shown in the table below. The redundancy factor for a circuit function meets the criteria of a "good" redundancy design approach, except for critical circuit functions that are not present in the design.
The implementation of the sensor element depends on the nature of the variable being sensed or monitored. Although any physical parameter may be monitored, for purposes of illustration and not limitation, various temperature sensing sensors are described below. Fig. 38A illustrates an example of an over-temperature detection circuit for preventing overheating, which is an important feature in medical devices and consumer electronics.
As shown, the reference voltage V is fixedref521A is connected to the positive input of the comparator and the
Diode voltage V with the cause of overheating eliminatedf(T)520 rises until it crosses the voltage (V) at temperature T2 ref+ Δ V) 521B. At T2, the output voltage V of
In the system, as shown in fig. 38B, the
As an alternative to the wired-OR method, another method of monitoring the likelihood of an overheat condition within a distributed system is to parallel a plurality of forward biased diodes, as shown in FIG. 38C. In this approach, each of the temperature sensing diodes 502D, 502E, 502F, and 502G, and others (not shown), are located on a different printed circuit board that includes the sensors 500D, 500E, 500F, 550G, and others (not shown). Each forward biased diode carries a portion of current 501Z. The voltage across the parallel combination of diodes is equal to the lowest voltage of the diodes, i.e. voltage Vfd(T),Vfe(T),Vff(T),Vfg(T) or other voltage (not shown). This lowest voltage is compared to a fixed reference 503Z by comparator 504Z and passes I2The C-
Although the temperature detection circuit measures analog parameters such as the voltage across a forward biased PN semiconductor diode, the potential of a thermoelectric device such as a thermistor or a peltier junction, the analog temperature information can be converted to a simple "digital" yes/no evaluation using a comparator-is the circuit too hot? The purpose of the over-temperature detection circuit is to evaluate whether an over-temperature condition has occurred or is about to occur through its circuit of the same name. If so, measures may be taken to shut down all or part of the circuit to reduce power consumption until it returns to safe operation. If the over-temperature condition involves shutting down the circuit, the protection function may be referred to as an over-temperature shutdown or OTSD circuit. In other variations of the circuit, two comparators are used-one for detecting an over-temperature condition and the other for detecting that the system is hot but not yet over-heated, i.e., providing a warning of a potential problem.
Alternatively, if quantitative temperature monitoring is desired, such as in a thermometer function, analog measurement of the temperature sensor can be achieved by using an analog-to-digital (A/D) as shown in FIG. 39AThe converter. For example, a voltage V across a temperature sensor, such as a forward biased PN junction 502, operated at a fixed bias by a
Due to I2The C-
For quantitative monitoring of large area sensors several methods can be used
Parallel sensors, detecting and digitizing only the lowest voltage sensor components, converting them to serial data, and then transmitting the data over a serial bus to a central control circuit or microprocessor, as shown in fig. 39B.
Multiplexing the analog data of each sensor, digitizing and converting the voltage data of each sensor into serial data, and then transmitting the data to a central control circuit or microprocessor through a serial bus, as shown in fig. 39C.
Digitizing and converting the data of each sensor into serial data, and then transmitting the data of each sensor to a central control circuit or microprocessor through a serial bus, as shown in fig. 39D.
Referring to FIG. 39B, parallel temperature transfer including forward biased PN diodes such as 502I, 502J, 502K, 502L and others (not shown) driven by a shared current source 502ISensors 500I, 500J, 500K, 500L and others (not shown) generate Vfi(T),Vfj(T),Vfk(T),Vfl(T) or other (not shown) single analog value of the voltage substantially comprising the lowest voltage diode. This lowest voltage value is digitized by A/
In fig. 39C,
Another approach is to duplicate the
In a manner similar to a sensor, a distributed driver for an energy emitting device, such as an LED, may include "important" circuit functions that occur exclusively in a single instance in the system, or may include "basic" functions of constituent "elements" in an array, or a matrix. Each circuit element represents "one or more" identical components that are typically repeated in a regular pattern, or a periodic repetition fixed on a substrate or grid of a printed circuit board. In a distributed system comprising "n" clones with the same basic circuit function, each driver circuit may be referred to as an "n in 1" circuit element. An example of a unique driver program includes an LED driver for performing optical chemical analysis such as blood oxygen detection. In contrast, basic circuit function LED drivers include a matrix of LED elements for illuminating large areas, for example in a phototherapy polymer pad used as part of a phototherapy system.
Including the LEDs, the circuitry for
Since the basic circuit functions of the distributed LEDs require only a limited redundancy factor RF ≧ 1, signal level communication with the LED driver does not take full advantage of the available redundancy. As shown in fig. 40B, the LED signal bus 580 includes a single line per row of printed circuit boards, i.e., in rows 1-4, but only includes connections in two columns, specifically in
To facilitate digital bus communication to control the LEDs, I can be included2
A limitation of this LED driver design approach is that the LEDs in each LED driver are limited to the same printed circuit board as their driving electronics, i.e. the LEDs, current sources and transistors are limited to the same rigid printed circuit board in order to maintain the desired level of redundancy. Separating the LEDs from one printed circuit board and distributing them over multiple printed circuit boards automatically reduces redundancy. This problem is illustrated in FIG. 40D, where
This problem can be solved by providing redundant paths for the LEDs. One such method is shown in FIG. 40E, except for circuit C1,1And C2,1In addition to the
An excellent redundancy design method is shown in FIG. 40F, where circuit C is removed in
Another example of a point-of-load voltage regulator 581 having a basic stage circuit function of RF ≧ 1 for driving the local electrical load 582 and the local
Another important element used in redundant circuits is the role of the rigid printed circuit board as a circuit interconnect. As shown in fig. 44, these interconnect links may include L-shaped
The function of the auxiliary circuit-is mainly to provide information and to facilitate the use of the device. Failure of the auxiliary circuit function does not affect the operation of the device.
Hierarchical redundant distributed electronic systems-combining critical, important, primary and secondary levels of functionality in a hierarchical redundant distributed electronic system fabricated in accordance with the present invention, 3D flexible large area or wearable devices with high interconnect reliability can be achieved.
An example of a layered design is shown in FIG. 45, which incorporates a
Circuit C2,3Power PSC 400A containing protected system connections, battery charger and battery
Circuit C3,3-
Circuit C4,1
For circuit C1,4,C2,1And C4,1Of a T-shaped link
Electrical loading of the remaining circuit elements
The power distribution system includes two power buses. Specifically,
The supply of power to various electrical loads depends on the importance of the power supply circuit. Circuit C3,2,C3,4And C4,3The critical electrical load in (1) receives power using a
As can be seen from the above table, the redundant RF of each key function is equal to or greater than 3, the redundant RF of each important function is equal to or greater than 3, and the RF of each basic function is equal to or greater than 1. Thus, the design approach embodies a "good" redundancy level for the distributed system.
Redundant signal communication and protocol-the communication protocol for sending signals between the various printed circuit boards and circuits depends on the nature of the product or system and the operating frequency of the system. Since many applications of distributed systems involve biometric monitoring or medical applications that operate at natural frequencies or at lower frequencies (i.e., below 20kHz) in the audio spectrum, the speed required for communication between circuits in the distributed system is relatively slow due to electronic standards. Communication data rates in the range of hundreds of kilohertz, similar to 12The frequency of the L standardized bus protocol is generally suitable for analog and digital signal distribution in distributed systems. The main considerations specific to distributed systems are how the distributed network affects timing, waveform shape, and synchronization of the same signal (i.e., redundant signal paths) across quasi-parallel routes, rather than speed issues. The flow section discusses the impact of implementing electronic systems on large area and how to solve problems that arise in practical redundant physical systems. In the case of other situations, it is possible to, For synchronization purposes, a common clock frequency must be allocated throughout the distributed system. Clock reconstruction is also discussed in this section, but as a separate subject.
FIG. 48 shows three separate signals Φ as labeled as
Unfortunately, as shown in fig. 49, this ideal situation is unlikely, and each waveform may change over time, i.e., delay or change shape, i.e., distortion caused by the propagating signal-carrying electrical network. As shown,
As shown in FIG. 50A, when the three signals reach their destination circuits, hard-wiring the three
One simple way to remove unwanted noise and distortion from signal propagation is to use a low pass filter as the input to any circuit as shown in FIG. 50B, where the carried signal Φ carriesX
Another problem with the
Another way to avoid the phase delay problem of redundant circuit connections is to use only one of the input signals selected using
This problem is solved by the function of the
FIG. 50E illustrates another means for filtering a noisy input signal resulting from a hard-wired connection of multiple redundant inputs. As shown, link 601 employs a sample and hold circuit 620 to provide a signal having a significantly higher level than the signal ΦXFrequency of (2)At regular intervals, i.e. phi, set by the
Managing the phase delay of digital signal communications in a distributed system is much easier than processing analog signals. The main effect of sending digital pulses through redundant paths is that any propagation delay causes a phase shift of the signal, as shown in fig. 51A, where in this case the digital signal Φ is representedA,ΦBAnd phiCThe
To prevent contention between logic gates, a Boolean logic OR
FIG. 51B illustrates that the output of OR
Redundant clock communication and protocol-the distribution and processing of clock signals in redundant systems requires selection of the best available clock signal to synchronize any given circuit, in a manner similar to the processing of a set of redundant input signals to avoid analog distortion and digital data contention. Rather than suggesting two particular approaches to achieving the highest level of clock consistency in a redundant electronic system, according to the present disclosure, multiple clock signals are analyzed to reconstruct the clock signals and identify the best source. These two methods are as follows:
in the presence of I2In the case of C-etc. clock serial bus communication, the shift register used to load the data should use the clock signal present on the same flexible interconnect as its associated data bus. In other words, during a data bus read operation, a clock signal paired with a particular serial data bus should be used to clock the data because the signal matches the data bus in propagation delay.
For system clock synchronization, the first clock signal used for the clock input to a given circuit and the printed circuit board should be used for system synchronization. Delayed clock signals arriving at other clock input lines during the same clock cycle should be ignored until the next cycle begins.
One means of ignoring late signals is shown in the redundant clock generator circuit of FIG. 52, where the input clock signals on buses 630A, 630B and 630C
Andthe combination by the boolean logic or gate 636 to produce a single waveform 639 varies in duration in a manner similar to that shown in fig. 51A. To generate a consistent clock signal, the leading edge of the pulse triggers one shot 637, one triggered circuit generates a digital pulse 640 having a predefined duration, and ignores any additional inputs for a defined period of time, i.e., it does not trigger a re-trigger but its logic high output state. In this way, the cleaning clock pulse for the drive circuit is derived from a plurality of redundant signals. Even in different circuits 635A, 635B, and 635C, the resulting clock signals will have the same duration, but the leading clock edges forRedundant serial bus communication and protocol-another way to facilitate communication through a distributed system is to use a serial bus. In contrast to analog and digital data, where the system clock is time sequenced and transmitted to each circuit, even without the need for a circuit to access the data, a data packet transmitted over the serial bus may contain important information indicating whether the receiving circuit is to process, an incoming data packet or ignore it, whether such information is related to a particular type of circuit function, e.g., sensor data, and whether two incoming packets have the same sender and content, i.e., whether the packets represent unique or redundant information. Time information may also be used to ensure proper ordering of the data packets.
As shown in the example network of fig. 53A, data bus communications involve two distinct functions, namely reading or receiving incoming packets from the bus and writing or sending data onto the bus. These serial buses may enable point-to-point communication between only two devices (e.g., USB), or may be connected to a shared common bus. When a data bus, such as
Electrically, a serial bus may comprise a single set of signals sent simultaneously to each device in a network or system, or may alternatively be sent only in point-to-point communication between two circuits, then copied and sent to a serial network. In the case of a shared electrical bus, operating as a receiver, one function of the serial interface circuit is to receive each incoming message or data packet, temporarily store it, determine whether it is one of the intended recipients of the data packet, and then pass the data content of the data packet onto a local circuit on the same printed circuit board for use, otherwise discard it-in other words, first accept the message and then determine whether it should be used. Since the received data packet is already sent to each network connection circuit anyway, each receive bus transceiver is not responsible for forwarding messages over the serial bus.
In point-to-point serial communications, each circuit receiving a packet assumes the responsibility of forwarding the same copy of the received packet to a neighbor in the data network, and at the same time decides whether the received data is also intended for its particular circuit. In this case, there is no common electrical connection or conductor shared by multiple circuits. Instead, each transceiver is electrically operated as a receiver and signal repeater, whereby message forwarding occurs regardless of whether the received data packet is intended for a particular circuit or printed circuit board.
Thus, the interconnected devices still function as if they all share a common serial data bus and interconnect, regardless of whether the serial bus is electrically connected to each device by being commonly connected to a common set of conductors (i.e., a physical bus layer) or otherwise. The principle of the data bus operating as a unified data link can best be understood by considering the 7-layer OSI model (https:// en. wikipedia. org/wiki/OSI _ model), without actually sharing a common electrical connection. In this model, the physical or PHI "
For example, in a serial bus that includes a shared electrical connection to each network connection circuit,
Ignoring the subtleties of the
Some serial buses also employ a master-slave architecture, where one particular circuit is the control that manages serial bus communications, while in others the relationship between parties is a peer relationship with the first transmission control bus until they are released to send data for other "callers". Fig. 53A illustrates an example of a master-slave serial architecture, where the serial bus transceiver 660A illustrates an example master serial bus controller that includes master transmit 663A, master receive 664A, and handshake 662 functions. In contrast, serial bus transceivers 660B and 660C illustrate slave serial bus controllers that include slave transmit 663B and 663C, slave receive 664B and 664C, and handshake 662 functionality. In such an architecture, master transceiver 660A controls serial communication and provides operational instructions to circuits connected to slave transceivers 660B, 660C and other circuits (not shown). The slave device, in turn, may send back measurement or status data to the controller.
The serial bus communication protocol avoids the problem of multiple circuits simultaneously attempting to transmit information over a shared bus, a condition known as "bus contention". The means by which serial data bus communications avoid bus contention is referred to as "handshaking," i.e., protocol-specific communications negotiated between devices connected to the serial bus, including a hardware or firmware implementation 662 schematically represented as "handshaking.
There are many serial communication technologies, each with its own specific algorithms and communication protocols. There are various PHY (layer 1) implementations of serial buses including common electrical connections, including I2C, SMB and AS2C buses. Point-to-point serial bus protocols including PHY (layer 1) implementations of a serial bus that require a hub or repeater to propagate serial data messages over a network include SCSI, ethernet, IEEE1394 (firewire), MIDI, and USB. Typically, use is made of a material such as I2Inter-wire communication "without a hub" in a universal electrically connected distributed system such as C involves less overhead and lower cost than more complex point-to-point serial bus serial communication methods. As a communication method, serial bus communication including the above-mentioned international standard protocol is well known to those skilled in the art. Thus, the basic serial bus operation will not be detailed herein unless it relates to adapting the serial bus operation when reliably performing communication in a distributed system with redundant interconnects.
Adapting serial communications in distributed electronic devices through redundant communications, whether implemented through a shared bus or a point-to-point PHY (layer 1) implementation, presents a number of unique challenges for redundant communications. The serial bus interface implementation shown below is intended to illustrate, by way of example and not limitation, the adaptability of serial communication in redundant communication methods and protocols. Specifically, before receiving multiple data packets and knowing whether to utilize or ignore incoming data, the receiving bus interface must interpret and solve the following problems with incoming data packets (i.e., incoming messages), namely:
is the received incoming message represent a different and unique data packet from multiple senders, or from a common sender?
If sent from a common sender, whether the incoming message represents a unique message sent in a different time order, or any slight differences in the sending time due to delays in data serialization?
Is serial communication delay allowed, should a message be sent from the same sender at the same time, i.e. if an incoming message represents a redundant data packet, which data packet should be selected for use by the receiving circuit?
Dynamic resolution of these problems as data arrives at any given circuit is important to achieve reliable operation of a distributed system with redundant interconnects. Since multiple messages may arrive at the redundant bus input of a given circuit at the same time or overlap without warning, it is not possible to multiplex a single serial interface circuit to capture incoming messages including address and data content. Input data at the input of a given circuit is easily lost and lost during multiplexing. Instead, each serial interface transceiver must be ready to receive multiple incoming messages "simultaneously," even before it has time to interpret how the data is processed.
One way to accomplish this task is to include a separate serial bus transceiver for each serial bus connection on a given circuit and rigid printed circuit board. Such an approach requires two to eight serial interfaces per printed circuit board, which can be expensive both in real estate on the board and in material cost manufacturing, i.e., high BOM cost. There is no need to implement multiple unique serial interfaces on each circuit and printed circuit board in a distributed system, but rather a buffer is used to capture incoming data in real time and shared with a single multiplexed serial interface to analyze and interpret the data. In this way, the buffer implemented as part of the redundant bus interface captures data regardless of when it reaches its speed and how fast it is, and the serial interface circuit has time to analyze it and decide on the course of action before a new message arrives.
Fig. 53B illustrates the use of redundant serial interfaces, where three conventional
One implementation of a
The
As shown in fig. 54B, writing data to the redundant serial bus involves transferring the data into the data register 653 under the control of the
One possible data format for a redundant serial data packet is shown in fig. 54C, which identifies the destination address 670 of the data packet, the source address 671 of the circuitry used to generate the data packet, the time 672 at which the data packet was created, and the content 674 of the data packet, i.e., its payload. In the OSI model, an address can be considered a medium access control or MAC address corresponding to OSI layer 2 (link layer). Instance #673 is an optional field for marking redundant data packets.
When a new data packet is received by the redundant bus interface, the interface may filter incoming packets from a given data source using data from a field containing time 672, instance #673, or other unique packet data embedded in the payload 574 to identify redundancy. Redundant data packets may be reliably employed in this manner to ensure command and control redundancy for the distributed system, providing redundancy beyond that of the redundant electrical interconnects.
Redundant mechanical design-the mechanical design of a distributed electronic system made in accordance with the present invention must meet a number of design goals, namely:
Covering the area required for the dispensing assembly, including sensors, LEDs or other energy emitting devices.
Provide sufficient area to integrate control circuitry and power into the system.
Providing redundant power and signal distribution throughout the system.
Facilitating the ability of the 3D flexible printed circuit or other flexible substrate to conform to any desired shape, especially in the case of wearable and medical devices, the system must be flexible to conform to the shape of a human or animal body or body part.
Avoiding breakage or mechanical failure of electrical connections of circuit board mounted components during repeated bending cycles, including components that prevent solder cracking, wire lifting, wire breakage, lead breakage, solder ball cracking and printed circuit board dropout, in part by reducing stress and distortion of printed circuit boards on which semiconductors and other components are mounted.
Facilitating a soft connection that can withstand thousands of bend cycles without failure, including avoiding flex damage, flex tear, and tear at flex-to-rigid printed circuit board interfaces.
The possibility of preventing moisture, sweat, blood or chemicals from damaging components and printed circuit board traces, including but not limited to moisture-induced electrical shorts, corrosion, filament formation, salt and ionic compound shorts.
In a manner similar to the electrical redundancy previously described, mechanical redundancy involves designing redundant arrays to minimize the risk of mechanical damage to the rigid-flex printed circuit board. The mechanical strength of the rigid printed circuit boards in the redundant distributed system depends on the position of the rigid printed circuit boards in the matrix and the number of their associated connections. One way to measure the strength of redundant mechanical designs is to classify each flexible printed circuit board as an unsupported degree of freedom or DOF. For example, as shown in fig. 55A of the corner printed
The second degree of freedom includes Y-direction stress 770Y, which may result in
For a non-corner edge printed circuit board, the three connector printed circuit boards 703B shown in fig. 56A are subjected to stress 770Y mainly only in the Y direction, resulting in DOF of 1. While the bending force can be applied in two directions, the array of soft interconnect rigid printed circuit boards provides mechanical support to the structure, distributing the force over a large area and making it impossible for any central element to tear. This property is similar to a sheet of plastic or christmas wrapping paper in that the tear does not start in the center, but always starts at the edges and then spreads on the paper. In such a process, the propagation of the tear transforms the central portion into an edge, i.e. the material adjacent to the tear acts as an edge and cannot resist the tearing forces and the central portion before the tear starts and propagates from the edge or corner.
In short, for the range of forces that occur during normal use of the 3D pad, the tearing force may tear vertical edges, horizontal edges or corners of the soft material in the rigid-flex printed circuit board. Therefore, the horizontally oriented T-shaped rigid-flexible printed circuit board element can be torn only vertically, the vertically oriented T-shaped rigid-flexible printed circuit board element can be torn only horizontally, and the corner fitting can be torn along two axes, i.e., two degrees of freedom. Additional support for the corner fitting can be enhanced by adding a diagonal soft connection, but the corners are still subject to tearing in the x and y directions. Since such edge members have 1 degree of freedom, corners are inevitably limited by 2 degrees of freedom. The inner part with a + connection (or more) is not limited by any degree of freedom, as the confusion holds all the content together, i.e. DOF is 0.
As shown in fig. 56B, the strength of the edge pcb may be improved by adding diagonal 299B, whereby 5-connection pcb 705 reduces Y-
FIG. 58 shows an overall damage resistance force diagram for a distributed system of various redundant designs. For corner elements with
Fig. 59 shows the elements of overall damage resistance versus bending strength, where the bending or bending strength ranges from stiff and inflexible to easy bending. The graph of tear resistance 691 shows high tear resistance at low bending strength, which means that a more rigid flexible connector is less prone to tearing. At high bending strength, meaning the use of highly flexible, soft connectors, the tear resistance is significantly reduced. Conversely, the bending strength resists the curve of the flex crack 692, i.e., the resistance to cracking of the flex connection, indicating that stiffer (less flexible) flex connectors are more susceptible to failure to crack. The overall curve of bending strength 693 versus bending strength illustrates a compromise of two competing mechanisms, with the best strength occurring at a moderately soft level, being less flexible and less stiff.
Redundant geometry design-the design of fig. 60A shows a square rigid printed circuit board on a
Another
Fig. 60B shows a variation of a square rigid printed circuit board on a square grid design 751, which includes a corner triple flex connection printed
Fig. 60C shows two variations in the basket weave pattern throughout which provides excellent mechanical support. The basket weave pattern includes
Fig. 60D shows that the rigid printed circuit board need not be uniform in size throughout the printed circuit board matrix, as long as the size of the printed circuit board surrounding the enlarged printed circuit board can be compensated for by adding smaller printed circuit boards around it. For example, in the
The right hand side of the diagram in fig. 60D illustrates another printed
In all of the above-described geometric printed circuit board designs, it should be understood that the term "printed circuit board" has a variety of meanings depending on the context in which it is used. First, the entire matrix including the interconnection of the rigid printed circuit board portion and the flexible printed circuit board is consolidated into a rigid printed circuit board element, which comprises a single heterogeneous printed circuit board, i.e., a rigid-flex printed circuit board. In other discussions, the term printed circuit board is used to refer only to the rigid portion of the non-uniform soft rigid printed circuit board, not to the entire substrate. In a similar context, the terms "flex" or "flex connector" are intended to refer to those portions of a heterogeneous printed circuit board that are not rigid. Thus, depending on the context of the discussion, the term printed circuit board does not refer to the entire non-uniform rigid-flex printed circuit board or rigid printed circuit board portion thereof.
Another important point in the mechanical design of the distributed printed circuit board disclosed herein is that the term rigid printed circuit board is not limited to the prior art definition of rigid printed circuit boards as rigid boards comprising FR4, glass or phenolic materials, but may comprise printed circuit board materials that are more rigid and "soft" lower than the soft parts of the printed circuit board. For example, the rigid portion of a soft rigid bonded printed circuit board may include areas with thicker polyimide or polyimide layers containing chemical compositions that provide reduced flexibility and bending than those used in the flex portion of the printed circuit board, as compared to using glass or phenolic materials. This interpretation of stiff-flex is represented herein as a printed circuit board with a soft and less flexible island mix, which is introduced herein as a "quasi soft hard flex" printed circuit board or QRF printed circuit board. The soft and hard bonding and the manufacture of the newly disclosed QRF printed circuit board will be discussed later in this disclosure and will not be detailed here.
Printed circuit board architecture-in addition to the plan view of its geometric design, the mechanical construction of a distributed printed circuit board with redundant interconnects can be illustrated by cross-sectional views of the printed circuit board in various locations or "cut lines," with specific cross-sections showing particular paths. Fig. 61 shows an example showing a rigid-flex printed circuit board with unprotected copper interconnects. As shown, the flexible printed circuit board includes
One limitation of the design shown is that all copper layers are exposed to the risk of moisture and corrosion. If the entire system, including the printed circuit board and all components mounted thereon, is encapsulated in a coating, e.g., plastic, silicone, polymer coating, etc., then protection of the metal layer is not necessary. However, if there is an environmental risk to moisture, chemicals, salt, perspiration and other fluids, the metal layer needs to be coated or encapsulated by another protective layer of electrically insulating material. A protected version of a rigid-flex-like printed circuit board is shown in fig. 62, where
In the disclosed system, electrical interconnections between rigid printed circuit boards and various metal layers within a flexible printed circuit board within a given rigid printed circuit board may be accomplished without the need for wires, connectors or solder joints using conductive vias. These conductive vias include conductive pillars of metal or other low resistance material formed perpendicular to the various metal layers, and may penetrate through two or more metal layers to facilitate multilayer connectivity and non-planar electrical topology, i.e., electrical shorts where conductors must cross each other without becoming electrical. For example, fig. 63 shows one possible cross-section of a flexible printed circuit board in which conductive lines including
In many cases, one wire must cross over another wire without shorting the two wires. These "cross under" connections require at least two metal layers to cross under. Fig. 64 shows a cross section under a cross realized in a flexible printed circuit board or a flexible printed circuit board portion of the flexible printed circuit board. As shown, for
An example using multiple cross-connects is shown in fig. 65A, where a T-link in a flexible printed circuit board, where the + V connection including
This use of cross-connections in a T-shaped flexible printed circuit board link may extend to + connections in the manner shown in fig. 65B, where the + V power distribution on
Redundant interconnect methods can also be used to bend printed circuit board crossovers without electrical connections. For example, in fig. 65C,
The cross under approach shown may also be applicable to rigid printed circuit boards, and becomes particularly versatile when applied to rigid printed circuit board portions of rigid printed circuit boards implemented in the present disclosure. As shown in fig. 66A, a cross-section of the rigid portion of the rigid-flex printed circuit board may employ
An example of the use of cross-supports in a rigid printed circuit board is shown in the power and signal distribution bus of fig. 67. In this case, the bus, a parallel set of
To save space, lines may be stacked as shown in the top and side views of fig. 68, where line 841D includes
Additional layers may be added to provide support for the flexible connector. For example, fig. 69A shows a three-layer conductive layer flexible material including
The
The cross section B-B' shown in fig. 69C shows how the mechanical connection of the rigid printed circuit board 850 to the
For the purposes of this disclosure, the term basket weave pattern may be considered as one example of a geometric pattern of a mesh, specifically, having elements spaced at regular intervals (i.e., having a regular periodicity), and generally including elements that are perpendicular and parallel to the edges of the soft link. As one possible example, the term mesh has a broader meaning describing any pattern or mesh, including diagonally oriented elements forming a regularly or irregularly spaced mesh, and including a basket weave pattern. Other patterns may include fishbone or herring bone shapes, with meshes having elements that are not evenly spaced logarithmically or using other geometric schedules, e.g., the spacing of the elements increases with increasing density to some maximum density (minimum spacing) and then decreases in density in the opposite direction of the same schedule.
Thus, the broad meaning of grid refers to any repeating structure or geometric pattern, uniform or only semi-regular, for reinforcing flexible printed circuit boards and their connections to rigid printed circuit boards. Mechanically, the use of conductive grid connections (including basket weave patterns) between flexible and rigid printed circuit boards naturally increases bending and tear strength, as it can propagate damaging forces to multiple elements. These relatively ductile conductive elements are within the limits of being able to bend and deform without breaking. The principle of this lattice design is the two-dimensional (planar) analog of the molecular structure of polymer, wood or glass fibers or carbon reinforcement-a material that exhibits higher breaking strength than solid materials (in some cases even stronger than steel). The distributed force principle is not only used for the design of the grid, but also for the design of the connection of the flexible printed circuit board and the rigid printed circuit board. Thus, the grid to rigid printed circuit board connection is not held by a single point, but is distributed over a line or conductive strip containing a plurality of through holes to securely anchor the mechanical connection.
The elements used to form the mesh or basket fabric stress relief may comprise a metal layer such as copper, or may comprise any strong material that is flexible. While the theoretical upper web may comprise a patterned non-conductive material, most flexible materials comprise a metal or semi-metal. An additional benefit of using metal to form the mesh is that this layer can also be used to transfer signals (or power) between rigid printed circuit boards according to the redundant interconnect design methods disclosed herein.
The web-based connection technique can be applied to any interconnect layer within a flexible printed circuit board, whether in the first metal layer, the second metal layer, or in the third metal layer in a three-layer metal flex printed circuit board. The grid is fabricated without any additional or special processing steps, but using a development etch process for defining, patterning and etching the metal in that particular interconnect layer. In this manner, the metal layer used to form the grid is deposited or laminated onto another flexible printed circuit board sandwich. The layer is then coated with a developing etch resist or a dry developing etch resist and patterned using a mask that defines electrical interconnects and a mechanically reinforcing mesh structure. The metal is etched to form a defined pattern and then coated with a protective insulating layer. Note that during the metal etch process step, if the metal to be etched is covered by an insulator (e.g., as part of a previous lamination manufacturing process sequence), the protective layer must be etched and removed before etching the underlying metal.
This structure may be added to add additional metal layers on the flex pcb 851 or rigid pcb 850 portions of the rigid-flex pcb. In one example shown in FIG. 69E, an
Distributed rigid-flex printed circuit board manufacturing-the manufacture of rigid-flex printed circuit boards for distributed systems is significantly different from prior art flexible printed circuit boards and traditional rigid flexible printed circuit boards shown in the background section of this application. In the prior art, the flexible printed circuit board is not designed for repeated bending and twisting. As a result, flexible printed circuit boards are subject to tearing, cracking, interconnect disconnection, and components falling off the printed circuit board. Due to the localized stresses, the prior art rigid-flex printed circuit boards experience additional flex failures at the flex-rigid interface. Based on our own experimental data, repeated flex testing on rigid-flex bonded printed circuit boards manufactured by contract manufacturers using traditional rigid-flex bonding manufacturing methods has been found to fail in flex testing for several weeks, with some printed circuit boards being bent for only three day cycles. This rapid wear failure is problematic and completely unusable for products requiring repeated flexing in medical and wearable applications. In contrast, the disclosed distributed rigid-flex printed circuit boards, which were subjected to bending cycles of 30,000 to 70,000 without failure or performance degradation, were subjected to bending tests for a period of several months. Under normal commercial use conditions, the number of bending cycles corresponds to five to ten years of usage.
In addition to reliability considerations, manufacturability is another important consideration for product quality. The combined soft and rigid manufacturing processes available today are not directly suitable for covering large area printed circuit boards, e.g. printed circuit boards with a length and/or width of several hundred millimeters, but are limited to small printed circuit boards, typically the size and smaller of a mobile phone. Rigid printed circuit boards are manufactured in large areas, such as on computer motherboards, but are manufactured on rigid substrates and cannot be bent or flexed without breaking or cracking. As a trace of early printed circuit board manufacturing techniques and low cost factories built in the fifties and sixties of the twentieth century, today's printed circuit board manufacturing relies on uniform material deposition and undistorted optical patterns to maintain consistency and product quality.
This original method is not effective in manufacturing printed circuit boards occupying large areas. For example, large panel LCD mother glass manufacturers for HDTV face similar challenges, requiring hundreds of millions of dollars in investment to achieve good uniformity across LCD panels. Due to economic limitations of low gross rates of printed circuit board manufacturers, it is justified that no such printed circuit board factory investments exist. As a result, commercial printed circuit board manufacturing has been downgraded to "low technology" manufacturing methods and capabilities. Given these manufacturing limitations, today's printed circuit board factories using conventional processes and manufacturing methods cannot manufacture products comprising an array of uniformly constructed rigid printed circuit boards distributed over a large flexible interconnect grid, i.e., distributed electronic systems implemented in rigid-flex bonded systems.
Without requiring a significant capital investment, the distributed rigid-flex bonded structure fabrication sequence disclosed herein minimizes adverse large area effects by minimizing sensitivity to process parameters, e.g., using a laser tuned to a wavelength that is absorbed only by the cut material, and by constraining fabrication to a smaller area, repeating the process to cover the entire printed circuit board area. These methods include fabrication using moving heads and newly available 3D printers, as well as moving belt processes, and "step and repeat" optical patterning and deposition methods. The redundant design approach complements the robust distributed hard-soft combining manufacturing disclosed herein, collectively facilitating high quality manufacturing of highly reliable products based on hard-soft combining distributed electronic systems and circuits.
Fig. 70 shows a general process flow for distributed rigid-flex printed circuit board manufacturing. The process flow is illustrative but not limiting of the disclosed process framework in which unique manufacturing requirements and challenges of distributed soft and hard bonded printed circuit boards are identified and addressed. In the illustrated flow, the flexible printed circuit board forms a distributed grid of interconnected rigid printed circuit board "islands" in which the flexible layer passes through each rigid printed circuit board island as a central layer, i.e., the flexible layer is sandwiched within the rigid printed circuit board outer layers. As such, the flexible printed circuit board first utilizes the steps of "flexible printed circuit board formation" (step 990) and optional "blind via formation" (step 991), followed by rigid printed circuit board attachment (step 992), where a top rigid printed circuit board is attached to one and then a bottom rigid printed circuit board is attached to the other side of the flexible printed circuit board.
The process flow shown produces a three-layer printed circuit board interlayer, i.e., a rigid-rigid or RFR interlayer. Each hard and each soft layer may comprise one, two or more conductive layers. The cross-section shown shows a bimetallic flex printed circuit board sandwiched by two single metal layer rigid printed circuit boards, resulting in the example RFR sandwich printed circuit board shown in fig. 82E. However, the process may be modified to create any number of soft and hard bonded printed circuit board sandwiches, each printed circuit board containing multiple metal layers. For example, each rigid printed circuit board may utilize from one to six metal layers limited in total to thickness considerations.
If "thick" metal is desired, the thick metal should preferably constitute the last "outermost" metal layer, i.e. the topmost metal layer of the top rigid printed circuit board or the bottommost metal layer of the bottom printed circuit board, or both, for manufacturability purposes. Thick metal is advantageous for ground and power, but signal routing is generally not required. The flexible printed circuit board may also include a plurality of layers, for example, from one layer to four layers. But unlike rigid printed circuit boards, where only cost and thickness determine the number of embedded metal layers, in flexible printed circuit boards, each additional metal layer reduces the flexibility of the flexible layer, increasing the risk of interconnect failure due to cracking or breaking.
The flexible printed circuit board is sandwiched between two rigid printed circuit boards as described in the RFR sandwich. Although the "R-F" sandwich can be formed using a single rigid printed circuit board attached to one side of the flex, without securing the flex on both sides, the mechanical strength of the flex-rigid bond connectors can be reduced. Other variations of the process flow may involve repeating the steps of forming multiple soft interconnect layers, for example, to form an RFRFR sandwich structure that includes two soft interconnect layers interspersed between three rigid printed circuit board layers. While such an option may be advantageous in highly redundant systems and military applications, in common flexible electronic devices used in wearable and medical products, for example, super redundancy may be expensive and unreasonable. After the rigid printed circuit board is attached (step 992), the rigid printed circuit board metal layers are patterned using photo development etching and metal etching as shown in the step entitled "metal patterning" (step 993). Thereafter, an electrical connection is made from the top rigid printed circuit board metal to the soft layer (i.e., "top via") using a "via structure" (step 994) to create an electrical connection from the bottom rigid printed circuit board metal to the soft layer, i.e., "bottom via", or a via, i.e., "via", is formed through the RFR sandwich. In "thick metal formation" (step 995), metal is plated onto the exposed metal, which both fills the exposed vias and increases the thickness of the outermost metal layer. Alternatively, the via holes may be filled in advance in the via hole forming step (step 994). In another embodiment, the order of thick metal formation (step 995) and via formation (step 994) is reversed.
After the metal interconnection is completed and the via is formed and filled, the rigid printed circuit board may be removed from those portions of the rigid-flex printed circuit board where only the flexible connections are located in the flexible portion of the rigid-flex printed circuit board. This removal process, as shown by the step entitled "rigid printed circuit board removal" (step 996), is critical to producing a reliable distributed rigid-flex printed circuit board. If performed improperly, removal of the rigid printed circuit board layer may damage the underlying soft layer, resulting in product loss or premature flex failure during normal use. A final "soft patterning" step 997 is performed to remove unwanted portions of the soft insulator to maximize the soft-hard combination printed circuit board flexibility and interconnect softness. Each of these manufacturing steps is further detailed in the following description and corresponding figures.
The steps of flexible printed circuit board formation (step 990) and blind via formation (step 991) are described in further detail in fig. 71, which depicts details of one possible process flow entitled "flexible manufacturing". As shown, the curved pcb formation (step 990) includes bending (
Fig. 72A shows flexible printed circuit board formation (step 990) including laminating the flexible insulating
The adhesive layer 808A, also referred to as an adhesive, may include epoxy, insulating potting compound, acrylic adhesive, polyimide adhesive, and other adhesives. The adhesive may be applied as a sheet, spray, gel or paste. Although the adhesive layer 808A is depicted as a separate layer, it may also be impregnated into the insulating
After lamination, the flexible printed circuit board is ready for metal patterning, metal routing and linking for signal, ground, power, cross-under and woven basket stress relief. As shown in fig. 72B, patterning of the
As previously mentioned, in conventional printed circuit board manufacturing, a copper layer is typically patterned to form circuitry by a "development etch" process, an image is transferred from a computer generated optical reticle or "reticle" to a development etch paste, developed, and then baked to develop the etch paste by performing a metal etch. The same development etching method can be applied to other materials than metal, for example, glass, coatings, plastics, etc. Although the disclosed "patterning" process shows a specific sequence of metal pattern definitions including conventional dry development etch development etching, the distributed rigid-flex printed circuit board fabricated according to the present invention is not limited to any one particular method, but (except for large area printed circuit boards s) is independent of the patterning method. Large area printed circuit boards face unique problems that are incompatible with conventional development etching. New and inventive solutions to these problems are subsequently disclosed in this disclosure. Regardless of the particular method of development etching employed, the development etch patterning process transfers the reticle pattern to the metal. The pattern defines the locations of metal connection sites, metal is required to form the multi-layer via connections, and wherein a conductive mesh will be formed to improve the mechanical strength of the flexible printed circuit board and its connection to the rigid printed circuit board.
Various permutations and combinations of the conventional and novel development etch methods are shown in fig. 83A. In the example shown,
Although photomasks are suitable for use with conventional printed circuit boards, the large area of distributed rigid-flex printed circuit boards makes photomask-based development etch imaging problematic. To overcome this limitation, the optical reticle is replaced with direct laser writing of photoresist layer 1003C using
After exposing the photoresist, the resist is "developed," causing the photoresist to be washed away in some areas and left in other areas, as defined by the exposed portions of the photoresist, which are the shadow of the reticle. After developing the photoresist, the organic photoresist layer mimics the pattern of the reticle it is exposed to, covering
The portions of
In the case of negative photoresists, any photoresist regions exposed to light cause exposed chemical bonds to crosslink during the development process, do not break, leave only the exposed portions of the photoresist, and wash away the photoresist in the shadow of the reticle. Since the photoresist 1003C remains only in the light exposed areas where it becomes photopolymerizable photoresist 1003E, all dark areas will cause the
Thus the reticle polarity, i.e., the dark features and clear portions of the reticle, or their direct write equivalent, must correspond to any developing etch paste employed in the masking operation. After exposure, the developed etch resist is "hard baked" at high temperatures to enhance its ability to withstand prolonged exposure to acid etch. Because the photoresist comprises organic compounds, it is relatively insensitive to exposure to acids, particularly after hard baking.
Development etching is not the only method of patterning printed circuit boards. As shown, patterning large area printed circuit boards can also be accomplished using screen printing or printing using a mask, as shown in fig. 83B. In the screen printing process, the
As a novel and novel embodiment of the present invention, a
The foregoing methods described and disclosed facilitate a number of means by which printed circuit board features may be defined. Typically, patterning by etching includes (i) depositing or laminating the layer to be patterned (ii) covering the material to be etched with a patterned etch-resistant mask formed by a reticle, laser direct write, screen printing or printing) etching the material, and (iv) removing the reticle. These methods are summarized above and, for the sake of brevity, will not be repeated in the soft and hard combination printed circuit board manufacturing sequence. It should be understood that for all process flows shown herein, although the method shown includes a reticle exposure of dry developed etch resist, any of the methods described are applicable to patterning and etching of rigid-flex printed circuit board features. It should also be appreciated that, without limitation, the patterning of large area printed circuit boards is particularly beneficial for use with the newly disclosed laser printed circuit board direct write and print technology.
Returning to the diagram depicted in FIG. 72C entitled "etch Top-curved Metal," the
In the center view shown in fig. 72C, the
To facilitate interconnection between the
In fig. 73C, the etched vias are filled or partially filled with metal or other conductive material. In the case of etched vias filled with
As shown in fig. 75A, the "soft top hard pcb" operation (step 992A) begins with the manufacture of a
The hard lamination process is then repeated for the bottom side of the rigid-flex printed circuit board as shown in fig. 75B.
The operation entitled "laminating the bottom rigid printed circuit board to the soft top" (step 992B) begins with the
The operation "pattern top metal" (step 993A) is shown in fig. 76A, where
Fig. 76C shows the resulting four-layer metal soft rigid printed circuit board compatible with a distributed electronic system. The metal thickness of all four
Having completed portion I of the soft and hard bonding structure, the printed circuit board is now ready for the fabrication of soft and hard bonding portion II, as detailed in the flow chart relating to the "via structure" (step 994) shown in fig. 77, including the "top via structure" (step 994A) in combination with the "via formation" (step 994B) or followed by the "bottom via formation" (step 994C), followed by the thick metal formation (step 995).
The top via serves to facilitate electrical connection between the
The vias function to facilitate electrical connection between the
In this step, the vias can be filled with metal or other conductive material, it is effective to form top, bottom and bottom vias, which are then all filled into a single electroplating operation, rather than one at a time. Via and via etching may also be shared, with the via definition formed first and partially etched, and then the top via defined and etched to its target depth. If the mask opening of the top via is open at the via location, the via will continue to etch during the top via etch process to reach its final target depth, i.e., penetrate the entire RFR interlayer.
The bottom via serves to facilitate electrical connection between the
The thick metal formation process involves plating copper on top of any exposed metal conductors and filling any unfilled vias. Fig. 81 shows a cross section of a distributed rigid-flex printed circuit board after thick metal plating. As shown, the metallization deposits a thick
The next step in the distributed rigid-flex structure manufacturing sequence is to remove the top and bottom rigid printed circuit boards in the rigid-flex printed circuit board portions that are used for flexing only, i.e., in the flexible portions of the printed circuit boards. Fig. 82A illustrates the use of a
Fig. 82E shows the distributed rigid-flex printed circuit board after
The final step prior to printed circuit board assembly is to remove the unused portion of the flexible printed circuit board using a
The use of a laser to remove hard printed circuit board material from selected portions of a hard-soft printed circuit board and to remove unwanted remaining portions of the soft material provides excellent process control that is not possible using mechanical methods such as sawing, cutting or grinding the material. Even so, any damage to the flexible layer that occurs during processing of the RFR interlayer, especially during removal of the stiff insulation layer, permanently damages the flex and greatly shortens its service life and its ability to survive repeated bending cycles. A method of reducing the risk of flex damage by introducing an interface layer between a stiff layer and a soft layer in an RFR interlayer. This modified process flow is shown in sequence starting with fig. 85A, where interface layers 849Y and 849Z comprising uncured organic, epoxy or polymer materials are deposited on the top and bottom of the capped flexible laminate. In fig. 85B, the interface layer is chemically or optically treated to harden
After the interfacial layer deposition, the hard insulating
Fig. 86A illustrates in simplified form the use of interface layers, including alternating regions of
Quasi-hardbound board manufacturing-an alternative to the disclosed distributed hardbound printed circuit boards and methods of manufacturing thereof is a new printed circuit board technology known as quasi-hardbound printed circuit boards or "QRF" printed circuit boards. Unlike rigid-flexible printed circuit boards constructed using stacked layers of metal, rigid and flexible insulating laminates, the disclosed QRF substrate includes a flexible printed circuit board that is locally reinforced with a soft, smaller layer of polymeric material or polyimide compound, deposited or printed onto the flexible printed circuit board from its bottom layer. In one example process sequence, fabrication begins with a flexible printed circuit board including a capped flexible laminate. As shown in fig. 89A, the flexible printed circuit board is then printed with an insulating material by a
By employing printing,
Similarly, as shown in fig. 89B, the thickest part of the insulator 1018C is printed on the bottom side of the quasi-rigid printed circuit board interlayer region, a thin insulator 1018D is printed to protect the bottom side of the flexible printed circuit board from etching, and the opening 1019B is free of insulator deposition. The exposed portions of the thin printed
In fig. 89C, the
Printed circuit board assembly and moisture protection-after the described rigid-flex printed circuit board is formed, the final step in manufacturing the distributed rigid-flex system involves surface mount assembly of the printed circuit board, followed by protection of the electronic system from mechanical damage, moisture and other environmental conditions.
As shown in the cross-section of the rigid flexible printed circuit board shown in fig. 90, electronic components are mounted by using surface mount components, and then an array of a plurality of rigid flexible printed circuit board islands interconnected by a shared flexible printed
In the example shown in fig. 90,
One possible means of support during bonding is shown in fig. 91, where a frame 1068 supports the rigid portion of the distributed rigid-flex printed circuit board using pins 1069. These pins prevent distortion and bending of the component during pick and place during the SMT process. The frame and pins may comprise metal or any strong material, such as a reinforced polymer of glass fibers. Additional pins may be added to support larger rigid printed circuit board sizes. The frame may be permanently included as part of the bonding apparatus or as part of a carrier that is attached to a rigid-flex printed circuit board.
By immersing the printed circuit board in the water-repellent emulsion 1071 in the bath 1070, moisture protection, i.e., water repellency, can be achieved by spraying a rigid printed circuit board with a coating or acrylic layer or as shown in fig. 92. Inset 1074 shows the inclusion of the optical sensor or
After protection from moisture, the distributed rigid flex printed circuit board is installed into a polymeric housing or
Practical application of 3D flexible distributed printed circuit board-rigid-flex-combined printed circuit board manufacturing, a combination of distributed printed circuit board design and electrical redundancy can be applied to a variety of wearable electronic and medical devices. The flexibility of the disclosed flexible printed circuit board design and manufacturing process provides great versatility for conforming the electronic device to the abnormal and curved surfaces of the human body, as well as being suitable for veterinary and equine medicine. Square, rectangular and hexagonal arrays of rigid or quasi-rigid printed circuit boards using redundant matrix interconnection through flexible interconnection and stress relief, supported shapes including flat, curved, circular, hemispherical flexible pads, including
Waist and broadside belts
Collar and headband
Cuffs, arm bands and wrist bands
Shape of hats and helmets
Mask
Reconfigurable arrays
The 3D flexible printed circuit board design method and geometry, manufacturing process, and redundant electronic system structure disclosed herein may be applied to various shapes. Practical applications of this technology are included herein for illustration, but are not limited to this versatility.
One such application is a collar or band shape that includes an elongated pad designed to surround the neck, waist, headband, cuff, wristband and armband. Fig. 95A shows top and bottom exterior views of a flexible strip phototherapy polymer pad including a
An enlarged view of a ribbon-shaped phototherapy polymer pad including a rigid-flex printed
Fig. 95E shows various views of the top and bottom polymeric covers, including a top
The assembly of the phototherapy polymer pad and corresponding perspective view shown in the flowchart of fig. 96 includes the installation of a USB support sheath in
A perspective photograph of the rigid-flexible printed
Fig. 99 shows the final tape-like phototherapy polymer pad and its associated cables. Fig. 100 shows four views of a rigid-flex printed circuit board used in a tape-like phototherapy polymer liner design, showing the
Fig. 101A shows top and bottom exterior views of three reconfigurable phototherapy polymer pads including a central phototherapy polymer pad 1115A and lateral phototherapy polymer pads 115B. In the phototherapy polymer pad as shown, the LEDs emit light through the
The reconfigurable phototherapy polymer pad includes
Fig. 104 shows various views of the top and bottom polymeric covers, including a top
A perspective photograph of a rigid-flex bonded printed circuit board is shown in fig. 106A, which includes a top view of rigid printed
Other suitable shapes for the phototherapy polymer pad or as a sensor array using a hexagonal rigid-flexible printed circuit board include the head cap of fig. 109, including an underside view 1160A and a top perspective view 1160B, the mask 1161 of fig. 110 and a cup-shaped phototherapy polymer pad for the knee, ankle, shoulder, elbow, etc., as shown in perspective views 1162A-1162D of fig. 111.
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