Very high speed, high density electrical interconnect system with impedance control in the mating region
阅读说明：本技术 在配合区域中具有阻抗控制的非常高速、高密度电互连系统 (Very high speed, high density electrical interconnect system with impedance control in the mating region ) 是由 马克·W·盖尔卢斯 约翰·罗伯特·邓纳姆 小马克·B·卡蒂埃 小唐纳德·A·吉拉德 于 2015-11-12 设计创作，主要内容包括：一种具有分离屏蔽的信号导体对的模块化电连接器。连接器可以由模块组装,每个模块均包含周围具有部分传导性的或完全传导性的材料的成对信号导体。模块可以具有由传导材料和/或介电材料制成的突出部,该突出部被成形且被定位成当连接器被分离小于功能配合范围时减小根据传导元件的分离的沿着信号路径的阻抗的改变。(A modular electrical connector having separately shielded pairs of signal conductors. The connectors may be assembled from modules, each containing pairs of signal conductors with partially or fully conductive material therearound. The module may have a protrusion made of a conductive material and/or a dielectric material that is shaped and positioned to reduce a change in impedance along the signal path according to the separation of the conductive elements when the connectors are separated by less than the functional mating range.)
1. An organizer for an electrical connector comprising a plurality of contact tails for attachment to a printed circuit board, the organizer comprising:
an insulated main body;
a plurality of openings through the body sized and positioned to pass the plurality of contact tails therethrough; and
conductive plating on a portion of the body including at least a portion of two of the plurality of openings.
2. The organizer of claim 1, wherein:
the plated portion of the body is electrically lossy.
3. The organizer of claim 1, wherein:
the plurality of openings are sized and positioned to receive pairs of signal and reference conductors of the electrical connector, and
at least a portion of two of the plurality of openings includes at least a portion of the plurality of openings positioned and dimensioned to pass a contact tail from the reference conductor therethrough.
4. The organizer of claim 3, wherein:
the plurality of openings include an opening positioned and dimensioned such that contact tails from the signal conductors do not pass therethrough, wherein the opening is electrically separated from the plated portion.
5. An electrical connector, comprising:
a board mounting face including a plurality of contact tails extending therefrom;
an organizer, comprising:
including portions of plated plastic, and
a plurality of openings, wherein the plurality of contact tails pass through the openings.
6. The electrical connector of claim 5, comprising:
a plurality of signal conductors including a first portion of the plurality of contact tails; and
a plurality of reference conductors including a second portion of the plurality of contact tails, wherein,
a first portion of the plurality of contact tails passes through an insulating portion of the organizer, and
a second portion of the plurality of contact tails passes through a plated plastic portion of the organizer.
7. The electrical connector of claim 5,
the organizer includes an insulating portion and a conducting or lossy portion.
8. The electrical connector of claim 7,
the plated plastic portion is the conductive or lossy portion.
9. The electrical connector of claim 8, comprising:
a plurality of signal conductors including a first portion of the plurality of contact tails; and
a plurality of reference conductors including a second portion of the plurality of contact tails, wherein,
a first portion of the plurality of contact tails passing through the insulating portion, an
A second portion of the plurality of contact tails passes through the conductive or lossy portion.
10. The electrical connector of claim 5,
the organizer is part of a housing of the electrical connector.
11. The electrical connector of claim 5, comprising:
a plurality of shields inside the connector that are electrically connected to the plated plastic portion of the organizer.
12. The electrical connector of claim 11,
a portion of the plurality of contact tails is integrated with the inner plurality of shields, and
a portion of the plurality of contact tails pass through a plated plastic portion of the organizer.
13. An electronic assembly comprising the electrical connector of claim 5 in combination with a printed circuit board, wherein,
the organizer is between the board mounting surface and the printed circuit board.
14. An electrical connector, comprising:
a plurality of wafers, each of the plurality of wafers comprising an insulating portion and a column of conductive elements comprising contact tails adapted for insertion into a printed circuit board, wherein the plurality of wafers are arranged to provide a two-dimensional array of the contact tails, an
A component, comprising:
a body of plastic;
a plurality of openings through the body, wherein the contact tails in the two-dimensional array extend through the openings, an
A plating on a portion of the body, wherein the plating is electrically connected with contact tails in a first portion of the plurality of openings.
15. The electrical connector of claim 14, in combination with a printed circuit board, wherein,
the electrical connector is mounted to a surface of the printed circuit board; and is
The component occupies a space between the electrical connector and a surface of the printed circuit board.
16. The electrical connector of claim 15, wherein the component includes a flat surface for mounting against the printed circuit board and an opposing surface having a profile adapted to match a profile of the plurality of wafers.
17. The electrical connector of claim 15, wherein the portion having plating is aligned with a reference pad on a surface of the printed circuit board.
18. The electrical connector of claim 14,
each of the plurality of wafers comprises an electromagnetic shielding material;
for each wafer, the insulating portion separates at least one conductive element from the electromagnetic shielding material; and
the shielding material separates adjacent wafers of the plurality of modules.
19. The electrical connector of claim 18,
the plated portion of the component is electrically connected to the electromagnetic shielding material.
20. The electrical connector of claim 18,
the plated portion of the component is conductive plating.
Background
The present application relates generally to interconnect systems for interconnecting electronic components, such as interconnect systems including electrical connectors.
Electrical connectors are used in many electronic systems. It is generally easier and more cost effective to manufacture the system as a separate electronic component, such as a printed circuit board ("PCB"), that can be connected together with an electrical connector. A known arrangement for connecting several printed circuit boards is to have one printed circuit board act as a backplane. Other printed circuit boards, referred to as "daughter boards" or "daughter cards," may be connected through the backplane.
A known backplane is a printed circuit board on which a number of connectors can be mounted. Conductive traces in the backplane may be electrically connected to signal conductors in the connectors so that signals may be routed between the connectors. The daughter card may also be fitted with a connector. Connectors mounted on the daughter card may be inserted into connectors mounted on the backplane. In this manner, signals may be routed between daughter cards through the backplane. Daughter cards may be inserted into the backplane at right angles. Accordingly, connectors for these applications may include right angle bends and are also commonly referred to as "right angle connectors".
The connector may also be used in other configurations for interconnecting printed circuit boards and for interconnecting other types of devices, such as cables, to printed circuit boards. Sometimes, one or more smaller printed circuit boards may be connected to another larger printed circuit board. In such a configuration, the larger printed circuit board may be referred to as a "motherboard" and the printed circuit board connected to the motherboard may be referred to as a daughterboard. Further, plates of the same size or similar sizes may sometimes be aligned in parallel. Connectors used for these applications are commonly referred to as "stacked connectors" or "mezzanine connectors".
Regardless of the exact application, electrical connector designs have been adapted to reflect trends in the electronics industry. Electronic systems are generally getting smaller, faster and functionally more complex. Because of these changes, the number of circuits in a given area of an electronic system and the frequency at which the circuits operate have increased significantly in recent years. Current systems transfer more data between printed circuit boards and require electrical connectors that can electrically process more data at higher speeds than even connectors a few years ago.
In high density high speed connectors, the electrical conductors may be so close to each other that there may be electrical interference between adjacent signal conductors. To reduce interference and to otherwise provide desired electrical performance, shielding members are typically placed between or around adjacent signal conductors. The shield prevents signals carried on one conductor from "cross-talk" on the other conductor. The shielding may also affect the impedance of each conductor, which may further contribute to the desired electrical performance.
Examples of shielding can be found in U.S. patent nos. 4,632,476 and 4,806,107, which show connector designs that use shielding between columns of signal contacts. These patents describe connectors in which the shield extends parallel to the signal contacts through the daughterboard connector and the backplane connector. The cantilevered beam serves to make electrical contact between the shield and the backplane connector. Similar arrangements are shown in us patent nos. 5,433,617, 5,429,521, 5,429,520 and 5,433,618, although the electrical connection between the backplate and the shield is made using spring type contacts. A shield having a twist beam contact is used in the connector described in U.S. patent No. 6,299,438. Other shielding is shown in U.S. pre-authorization publication 2013-.
Other connectors have shield plates in the daughter board connector only. Examples of such connector designs can be found in U.S. patent nos. 4,846,727, 4,975,084, 5,496,183 and 5,066,236. Another connector with shielding only in the daughter board connector is shown in us patent 5,484,310. U.S. patent No. 7,985,097 is another example of a shielded connector.
Other techniques may be used to control the performance of the connector. For example, differential transmit signals may also reduce crosstalk. Differential signals are carried on paired conductive paths called "differential pairs". The voltage difference between the conductive paths represents a signal. Typically, a differential pair is designed with preferential coupling between the conductive paths of the pair. For example, the two conductive paths of a differential pair may be arranged to extend closer to each other than adjacent signal paths in the connector. No shielding is required between the conductive paths of the pair, but shielding may be used between differential pairs. Electrical connectors may be designed for differential signals as well as for single-ended signals. Examples of differential electrical connectors are shown in U.S. patent nos. 6,293,827, 6,503,103, 6,776,659, 7,163,421 and 7,794,278.
Another modification to connectors that accommodate changing requirements is to make the connectors larger in some applications. Increasing the size of the connector may result in tighter manufacturing tolerances. For example, the allowable mismatch between the conductors in one half of the connector and the receptacles in the other half may be constant regardless of the size of the connector. However, as the connector grows, the constant mismatch or tolerance may become a percentage reduction in the overall length of the connector. Thus, for larger connectors, manufacturing tolerances may be tighter, which may increase manufacturing costs. One way to avoid this problem is to use connectors constructed from modules to extend the length of the connectors. The Teradyne connection system of Nashua, N.H. was pioneered in the United states and is called
Another modular connector system is shown in U.S. patent nos. 5,066,236 and 5,496,183. Those patents describe "module terminals" that each have a single column of signal contacts. The module terminals are fixed in the plastic housing module. The plastic housing module is held together with a piece of metal shielding member. Shields may also be placed between the module terminals.
Disclosure of Invention
Embodiments of a high speed, high density interconnect system are described. Very high speed performance may be achieved by the shape and/or location of the conductive and/or dielectric portions of one connector that are positioned in impedance affecting relation with respect to the signal conductors of the mating connector across some or all of the functional mating range of the interconnection system.
In some embodiments, there is provided an interconnect system comprising: a plurality of signal conductors, each of the plurality of signal conductors including a contact tail adapted to be attached to a printed circuit board, a mating contact portion, and an intermediate portion electrically coupling the contact tail and the mating contact portion; and a housing portion holding at least one of the plurality of signal conductors, the housing portion including a mating area, wherein a first mating contact portion of the at least one signal conductor is disposed in the mating area of the housing portion; the housing portion includes a mating interface surface having an opening therein, wherein the opening is sized and positioned to receive a second mating contact from a mating component for mating with the first mating contact, and the mating area of the housing portion includes at least one protruding member extending beyond the mating interface surface and beyond a distal end of the first mating contact of the at least one signal conductor in the mating direction.
In some embodiments, there is provided an interconnect system comprising: a plurality of signal conductors, each of the plurality of signal conductors including a contact tail adapted to be attached to a printed circuit board, a mating contact portion, and an intermediate portion electrically coupling the contact tail and the mating contact portion; and at least one reference conductor surrounding the mating contact portion of at least one of the plurality of signal conductors on at least two sides; wherein the at least one reference conductor extends beyond a distal end of the mating contact portion of the at least one signal conductor in the mating direction such that the at least one reference conductor has a first region adjacent the mating contact portion and a second region extending beyond the distal end of the mating contact portion, and the at least one reference conductor has a first separation from the mating contact portion in the first region and a second separation from the mating contact portion in the second region.
In some embodiments, there is provided an interconnect system comprising: a first component comprising a first plurality of conductive elements held by a first dielectric housing and a second component comprising a second plurality of conductive elements held by a second dielectric housing, the interconnect system comprising a separable interface between the first and second plurality of conductive elements, wherein the first plurality of conductive elements are configured to provide a first signal path within the first component, the first signal path having a first impedance; the second plurality of conductive elements is configured to provide a second signal path within the second component, the second signal path having a first impedance; and the first plurality of conductive elements, the second plurality of conductive elements, the first dielectric housing, and the second dielectric housing are configured to provide a mating region having a length that varies with respect to separation between the first component and the second component, and when the first plurality of conductive elements are mated with the second plurality of conductive elements, the impedance varies across the mating region to a turning point having a second characteristic impedance such that variations in impedance from a first impedance at the first signal path within the first component to the second impedance at the turning point and from the second impedance at the turning point to the first impedance at the second signal path within the second component are distributed across the mating region.
In some embodiments, there is provided an interconnect system comprising: a first component and a second component, the first component including a first plurality of conductive elements held by a first housing, the second component including a second plurality of conductive elements held by a second housing, the interconnect system including a separable interface between the first and second plurality of conductive elements, wherein the first plurality of conductive elements, the second plurality of conductive elements, the first housing, and the second housing are configured to provide a mating region having a length that varies with respect to separation between the first and second components; the first plurality of conductive elements includes signal conductors, each signal conductor including: an intermediate portion disposed within the first housing; a mating portion extending from the first housing; and a transition portion between the intermediate portion and the mating portion, wherein the intermediate portion has a first width and the mating portion has a second width, the second width being greater than the first width; and the second plurality of conductive elements includes signal conductors and reference conductors, each reference conductor including: an intermediate portion disposed within the second housing; a fitting portion extending from the second housing; and a transition portion between the intermediate portion and the mating portion, wherein the intermediate portion has a first separation from adjacent ones of the signal conductors of the second plurality of conductive elements and the mating portion has a second separation from adjacent ones of the signal conductors of the first plurality of conductive elements.
In some embodiments, there is provided an interconnect system comprising: a first component and a second component, the first component comprising a first plurality of conductive elements held by a first housing, the second component comprising a second plurality of conductive elements held by a second housing, the interconnect system comprising a separable interface between the first plurality of conductive elements and the second plurality of conductive elements, wherein the first plurality of conductive elements comprises signal conductors and reference conductors and the second plurality of conductive elements comprises signal conductors and reference conductors; the first plurality of conductive elements, the second plurality of conductive elements, the first housing, and the second housing are configured to provide a mating region having a length that varies with respect to separation between the first component and the second component, and the interconnection system includes a plurality of dielectric members in the mating region positioned to separate a reference conductor and an adjacent signal conductor for at least a portion of the signal conductor, each dielectric member being shaped to provide a volume of dielectric material between the reference conductor and the adjacent signal conductor, the volume of dielectric material varying along the length of the mating region when the first component and the second component are separated.
The foregoing is a non-limiting summary of the invention defined by the appended claims.
Drawings
The drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. In the drawings:
FIG. 1 is an isometric view of an illustrative electrical interconnection system, according to some embodiments;
FIG. 2 is an isometric view of the backplane connector of FIG. 1, partially cut away;
FIG. 3 is an isometric view of a pin assembly of the backplane connector of FIG. 2;
fig. 4 is an exploded view of the pin assembly of fig. 3;
fig. 5 is an isometric view of a signal conductor of the pin assembly of fig. 3;
fig. 6 is a partially exploded isometric view of the daughtercard connector of fig. 1;
fig. 7 is an isometric view of a wafer assembly of the daughter card connector of fig. 6;
FIG. 8 is an isometric view of a wafer module of the wafer assembly of FIG. 7;
FIG. 9 is an isometric view of a portion of the insulating housing of the wafer assembly of FIG. 7;
FIG. 10 is a partially exploded isometric view of a wafer module of the wafer assembly of FIG. 7;
FIG. 11 is a partially exploded isometric view of a portion of a wafer module of the wafer assembly of FIG. 7;
FIG. 12 is a partially exploded isometric view of a portion of a wafer module of the wafer assembly of FIG. 7;
FIG. 13 is an isometric view of a pair of conductive elements of a wafer module of the wafer assembly of FIG. 7;
FIG. 14A is a side view of the pair of conductive elements of FIG. 13;
FIG. 14B is an end view of the pair of conductive elements of FIG. 13 taken along line B-B of FIG. 14A;
fig. 15A is a cross-sectional view of the wafer module shown in fig. 8 mated with the pin assembly shown in fig. 3, wherein the insulative portions of the pin assembly are cut away and there is no separation between the mating components;
fig. 15B is a cross-sectional view of the wafer module shown in fig. 8 mated with the pin assembly shown in fig. 3, wherein the shield is cut away and there is no separation between the mating components;
fig. 15C is a cross-sectional view of the wafer module shown in fig. 8 mated with the pin assembly shown in fig. 3, with the shield cut away and with separation between the mating components;
FIGS. 16A and 16B are cross-sectional views through the face of the wafer module shown in FIG. 8 mated with the pin assembly shown in FIG. 3, with no separation and separation between the mating parts, respectively;
17A-17D are graphs showing impedance as a function of distance through mating regions of two electrical connectors having non-overlapping dielectric portions at various amounts of separation;
figures 18A-18D are graphs showing impedance as a function of distance through mating regions of two electrical connectors with overlapping dielectric portions at various amounts of separation;
figures 19A-19C are schematic diagrams of mating regions of two electrical connectors having overlapping dielectric portions at various amounts of separation;
fig. 20A shows a simulated Time Domain Reflectometry (TDR) graph of a reference two-piece connector with the connector parts fully pressed together and separated by the functional mating range of the connector;
figure 20B shows a simulated TDR plot for the reference two-piece connector of figure 20A modified to include a tapered dielectric portion as shown in figures 19A-19C with the connector components fully pressed together and separated by the functional mating range of the connector;
fig. 20C shows a simulated TDR plot for the reference two-piece connector of fig. 20A modified to include conductive elements having the positions and widths as shown in fig. 16A and 16B with the connector parts fully pressed together and separated by the functional mating range of the connector;
figure 20D shows a simulated TDR plot for the reference two-piece connector of figure 20A modified to include both tapered dielectric parts as in figure 20B and conductive elements having positions and widths as in figure 20C when the connector parts are fully pressed together and separated by the functional mating range of the connector;
21A and 21B illustrate an alternative embodiment of a portion of a module of a two-piece, high speed, high density connector with the components fully mated; and
fig. 21C shows the connector of fig. 21A and 21B with the connector parts separated.
Detailed Description
The inventors have recognized and appreciated that the following designs may be used to improve the performance of high density interconnect systems, particularly those that carry the very high frequency signals necessary to support high data rates: this design reduces the effects of impedance discontinuities associated with variable spacing of separable components forming the mating interface. Such impedance discontinuities may create signal reflections that increase near-end crosstalk, attenuate signals passing through the interconnect, cause electromagnetic radiation that raises far-end crosstalk, or otherwise degrade signal integrity.
Separable electrical connectors may be used herein as an example of an interconnection system. The mating interface of some electrical connectors is designed such that the impedance of the signal conductors passing through the mating region matches the impedance of the intermediate portions of those signal conductors within the connector when the connectors are in the designed mated position. For low density interconnects such as coaxial connectors having a single signal conductor, the mating connector may be constructed and operated so that the designed mating position is reliably achieved. With such low density connectors, there may be greater design flexibility in selecting the shape and positioning or materials of the components to avoid impedance discontinuities.
However, for high density interconnects with multiple signal conductors, it is difficult to achieve the designed mating locations for all signal conductors simultaneously. In addition, the constraints imposed by meeting mechanical requirements to precisely locate multiple signal conductors with proper grounding and shielding in a small volume exclude many design techniques that may be used in a connector or cable that connects one or a small number of signal conductors. For example, a high-density connector may have an array of signal conductors spread out over a connector length of 6 inches or more. Such connectors may have widths on the order of inches or more, assuming as many as several hundred signal conductors are to be mated at the separable interface. Normal manufacturing tolerances of the connectors may preclude all signal conductors that fit in the designed mating positions over such a wide area, as when some portions of one connector are pressed against the mating connector, other portions of the connectors may be separated.
The force required to press the connectors together may also result in a change in separation between the connectors such that all portions of the connectors are not in the designed mating position. The force required to push the connectors together increases in proportion to the number of mated signal conductors. For high density connectors with multiple signal conductors, the force may be on the order of tens of pounds or more. The interconnect system may be designed to rely on human action to press the components together in a manner that produces the desired mating force. However, because of the variability in the manner in which the operator assembles the system or many other possible factors, the required force may not always be generated when mating the connectors, such that the connectors are not actually pressed together completely.
Further contributing to the variability of connector separation, the level of force required to force the connectors together completely may also create a bend in the substrate, such as a printed circuit board, to which the connectors are attached. For example, the printed circuit board may be bent more at the center than at the ends, and the portion of the connector mounted near the middle of the printed circuit board may be separated more than the portion of the connector near the sides of the printed circuit board.
To accommodate components that mate in mating positions other than as designed, many high density connectors are designed with a "functional mating range" of about 2mm to 5 mm. "functional mating range" refers to the amount by which a conductive element is designed to slide over a mating conductive element to reach a designed mating position from: at this point, the conductive elements engage with sufficient normal force to provide a reliable connection. In many embodiments, the connectors are fully pressed together in the designed mated position, and the fully pressed together position is used as an example of a mated position designed herein.
Because sliding the contacts relative to each other may remove oxides or contaminants on the mating contacts, certain portions of the functional mating range provide "wiping," which is desirable because the conductive elements in the sliding contact may remove contaminants from the mating contacts and establish a more reliable connection. However, the functional mating range in high density connectors is typically greater than that required for "wiping". In high density connectors, the functional mating range provides the additional advantage of enabling mating signal conductors to be in electrical contact even when the connector components are separated by a distance of up to the "functional mating range" amount.
The inventors have recognized and appreciated the problem of designing connectors with a large functional mating range, particularly very high speed, high density connectors. Traditionally, connectors designed to accommodate mating at any point over a range of positions provide signal paths with impedance variations, particularly when operating at high frequencies, whether these variations are relative to a nominal design value or along the length of the signal conductor or both.
If the mating connectors are separated by an amount less than the "functional mating range" supported by the connectors, the conductive elements of the mating connectors should make the required electrical contact at some point in the mating region. However, when mated at this point, the signal conductors may not have the same relative position to the other portions of the connector such that the signal conductors are in a fully mated position, which may affect impedance.
For example, the spacing between signal conductors in one connector and certain reference conductors or dielectric materials in a mating electrical connector can affect the impedance of the signal conductors. When there is a change in the spacing between the connectors, there may also be a change in the spacing between the signal conductors in one connector and these other structures in the impedance-affected location. Thus, the impedance may vary depending on the separation between the mating connectors.
When the connectors are separated, a portion of the signal conductors may not be surrounded by a material having an effective dielectric constant that is the same as the effective dielectric constant when the connectors are fully pressed together. Also, the separation between a signal conductor and an adjacent ground conductor may be different than when the connectors are fully pressed together. Thus, when the connectors are separated, while still close enough together to be within functional mating range, the impedance of the signal conductors within the mating area may differ from the designed impedance, and the resulting impedance may depend on the separation between the components.
The impedance in the mating region may be caused by a signal path geometry in which a portion of the interconnect system is positioned according to design while other portions are displaced from their designed positions. One such difference results from the different effective dielectric constants of the materials surrounding the signal conductors when the two components are fully pressed together relative to when there is separation between the components.
For example, a portion of a signal conductor may pass through a region in which the signal conductor is surrounded by a dielectric structure that is part of the same connector, such that the relative positions of the structures and the signal conductor are preserved regardless of the relative separation between the two connectors. When a dielectric material is located between a signal conductor and an adjacent reference conductor, the dielectric may affect the impedance. For example, a fixed relationship of the signal conductor, the reference conductor, and the dielectric may occur for intermediate portions of the signal conductor in a connector module in which the signal conductor is embedded in the dielectric to which the reference conductor is attached.
However, in the mating region, at least a portion of the conductive element must be exposed to make an electrical connection with a mating contact in the mating module. These structures may not be surrounded by dielectric members that form part of the same module as the signal conductors. When the two mating connectors are fully pressed together, the extended mating contact portion of one connector may be inserted into the mating contact portion of the other connector. In this configuration, the impedance of the signal path through the mating contact may be affected by the relative positioning of the signal conductor in one connector and the adjacent reference conductor or dielectric material from the mating connector.
In the nominal mating position, the extension may be inserted into the mating contact of the mating connector. In some embodiments, the mating connector may have a mating contact portion that functions as a receptacle. For any portion of the extended contact within the receptacle, the impedance of the signal path may be defined by the positioning of the receptacle relative to impedance-affecting structures in the mating connector, such as dielectric materials and reference conductors. These relationships may be designed to provide a desired impedance that, because it is determined by the relative position of the components within one connector, may be independent of the separation between mating connectors.
In some embodiments, the receptacle may be retained within a dielectric housing. Thus, the extension of the mating contact from the first connector may pass through the dielectric housing of the second connector before reaching the receptacle. In this region, the dielectric constant of the mating connector and the position of the reference conductor may be set such that the impedance has a desired value when the connectors are in the fully mated position.
In conventional connector designs, when there is separation between mating connectors, a portion of the mating contact portion of one connector that relies on structures in the mating connector to obtain a desired impedance is not at a designed position relative to these impedance influencing structures in the mating connector. Therefore, the separation between the connectors may cause the impedance in this region to be different from the designed impedance. The impedance may vary based on the amount of separation, thereby introducing greater variability.
For example, two connectors may have mating interface surfaces that mate together when the connectors are fully mated. The mating contact portion extending from one connector may have an impedance that varies along its length, with different impedances in different regions relative to those of the mating interface surfaces. The impedance of the signal path within the connector up to the mating interface surface of the connector may be controlled to have a nominal value based on the value of the design parameter within the connector. The mating interface of the connector may be designed such that when the dielectric portions are mated to each other, the impedance has a value such as 50 ohms, 85 ohms, or 100 ohms, or other suitable value, to match the impedance in other portions of the interconnect system. Likewise, the impedance of the signal path for a portion of the extended contact that extends through the mating interface surface of the mating connector may be controlled to have a nominal value that is based on the value of the design parameter within the mating connector.
However, any portion of the signal path between the two mating interface surfaces may have an impedance that is different than the nominal value. Such a portion of the signal path may exist due to separation between connectors that deviates from the designed separation for a fully mated connector. In this region, there may be no dielectric member or reference conductor placed in an impedance-affected position relative to the signal conductor. Typically, the material surrounding the mating contact is air. For example, air has a dielectric constant close to 1 compared to the insulator used to form the connector housing, which may have a relative dielectric constant in the range of 2 to 4. Thus, a signal conductor designed to have a nominal impedance when passing through an insulative housing will have a different impedance when passing through air, meaning that the signal conductor may have an impedance between mating interface surfaces that is different than the impedance within either connector housing.
Other design parameters may result in different impedances along the signal path in the region between the mating interface surfaces than within the connector. For example, a reference conductor positioned within the connector housing to provide a nominal impedance may have a different spacing relative to signal conductors within the region between the mating interface surfaces than within the connector housing. Because the impedance of a signal conductor may depend on the separation between the signal conductor and an adjacent reference conductor, a different pitch in one region than another may result in a change in impedance along the signal path from one region to another. For conventional high speed, high density connectors in which the reference conductors are secured to the connector, such spacing (and thus impedance) between the signal conductors and the reference conductors in the region between the mating interface surfaces is different when the connectors are fully mated than when the connectors are separated.
The fact that the impedance in the mating region is affected by the separation between the components means that, particularly for high speed connectors that have been designed to have uniform impedance in the middle and through the mating region, there will be a variation in impedance along the length of each signal conductor when the components of the interconnection system are not in their designed mated position. The impedance in at least a portion of the mating region will be different than the impedance in the intermediate portion, where the impedance is determined by the structure within each connector, independent of the amount of separation between the components.
The effect of the impedance change may depend on the amount of separation between the components or the operating frequency range of the connector. Such a change in impedance may have no discernable performance impact for small separations or for low frequency signals. At low frequencies, separation, even if equal to the full functional mating range of the connector, can result in very small differences in impedance relative to the intermediate portion of the signal conductor within the connector housing. Furthermore, at lower frequencies, such changes in impedance may be effectively averaged along the length of the signal path through the interconnect system, such that the changes in impedance have little effect.
However, at higher frequencies, the change in impedance associated with the separation of the connector may be more pronounced to the extent that connector performance is limited. Such an effect may be caused because the difference in impedance caused by the separation between the intermediate portions of the signal conductors and the mating region is large at higher frequencies. Furthermore, at higher frequencies, changes in impedance due to separation of components present local impedance discontinuities, rather than changes that are averaged over the length of the signal conductor. For example, in a high speed interconnect system, the connectors may be designed such that a fully mated connector may provide an impedance in the mating region that differs from the impedance in the middle by 3 ohms or less at higher ranges of the operating frequency of the connector. However, when the mating connectors are separated by up to the functional mating range distance, the impedance difference between a portion of the signal conductors and the intermediate portions of the signal conductors in the mating region may differ by an expected difference of two, three, or more times. Depending on the frequency range of interest, this difference between the actual impedance of the signal conductor and the designed impedance may cause signal integrity problems.
The frequency range of interest may depend on the operating parameters of the system in which such a connector is used, but may typically have an upper limit of between about 15GHz and 50GHz, for example 25GHz, 30GHz or 40GHz, although higher or lower frequencies may be of interest in some applications. Some connector designs may have a frequency range of interest that covers only a portion of this range, such as 1GHz to 10GHz or 3GHz to 15GHz or 5GHz to 35 GHz. At these higher frequencies, the effect of the change in impedance is more pronounced.
The operating frequency range of the interconnect system may be determined based on a range of frequencies that may pass through the interconnect with acceptable signal integrity. Signal integrity can be measured according to a number of criteria depending on the application for which the interconnect system is designed. Some of these standards may involve propagation of signals along single-ended signal paths, differential signal paths, hollow waveguides, or any other type of signal path. Two examples of such criteria are attenuation of the signal along the signal path or reflection of the signal from the signal path.
Other criteria may involve the interaction of multiple different signal paths. Such criteria may include, for example, near-end crosstalk, which is defined as a portion of a signal injected on one signal path at one end of the interconnect system that is measurable at any other signal path on the same end of the interconnect system. Another such criterion may be far-end crosstalk, which is defined as a portion of a signal injected on one signal path at one end of the interconnect system that is measurable at any other signal path on the other end of the interconnect system.
As a specific example, it may be desirable for the signal path attenuation to be no greater than 3dB power loss, the reflected power ratio to be no greater than-20 dB, and for the individual signal paths to contribute no greater than-50 dB to signal path crosstalk. Because these characteristics are frequency dependent, the operating range of the interconnect system is defined as the range of frequencies that meet a specified standard.
Accordingly, the present inventors have recognized and appreciated that it would be desirable to use techniques in a separable interface of a high speed, high density interconnect system to reduce the effects of variations in impedance due to variable separation of the components forming the interface. Such techniques may provide an impedance in the mating region that is independent of the separation between the separable components. Alternatively or additionally, such techniques may provide smoothly varying impedances across the mating region regardless of separation between separable components to avoid discontinuities in the magnitude that affect performance.
A design that reduces or eliminates impedance discontinuities or the effects of such discontinuities in the mating area, regardless of separation between components, may be achieved by selecting the shape and/or location of one or more conductive elements and/or dielectric elements. According to some techniques, impedance control may be provided by a member protruding from one connector, partially or completely, by separating the spaces of the mating connector. Thus, these members may have dimensions on the order of the functional mating range of the connector, for example 1mm to 3mm, or in some embodiments at least 2 mm. The protruding members may be dielectric and/or conductive. Thus, when the connectors are misaligned by a distance up to the functional mating range, these components will be positioned within the space between the connectors. The protruding member of one connector may protrude into the mating connector when the connectors are separated by less than a functional mating range. However, it should be understood that the protruding member may extend beyond the functional mating range such that the protruding member will protrude into the mating connector even if the connectors are separated from the functional mating range.
The protruding member may be positioned to reduce or substantially eliminate variations in impedance associated with variable separation of the connectors. Such a result may be achieved by having the projecting members in an impedance affecting relationship with the signal conductors in the mating region between the connectors when the connectors are separated. The shape and location of the protruding member may be such that the impedance of the signal conductors in the mating region provides a desired impedance regardless of the separation between the connectors. The connectors may be designed such that the protruding member does not affect the impedance in either connector regardless of the separation between the connectors.
For example, the protruding member may be conductive and may be configured as a reference conductor. In some embodiments, the conductive members may be configured to provide a nominal impedance within the connector to which the conductive members are attached regardless of separation between the connectors, but with little or no effect on the impedance in the other connectors. Such a result may be achieved by having the protruding member adjacent to a reference conductor in the connector such that there is no significant difference in distance between the signal conductor and the nearest reference conductor in the connector regardless of the amount of separation between the connectors.
Rather, the protruding members may be shaped and positioned to affect impedance along the signal path between the connectors. For example, in the region between the mating connectors when separated, the projecting members may be shaped and positioned to provide a spacing between the signal and reference conductors that, in combination with other parameters, provides a nominal impedance in that region. Such other parameters may include the thickness or shape of the signal conductor and/or the dielectric constant of the material in the region.
The protruding member may alternatively or additionally be dielectric and may for example be formed of a dielectric material of the type forming the connector housing. The dielectric protruding member may be shaped and positioned to reduce the effects of these variations by distributing impedance variations across the mating interface area of the connector that may result from separation of the connector. For example, when the connectors are fully mated, the dielectric protruding member from one connector may extend into an impedance influencing position with respect to the signal conductors in the mating connector. When partially unmatched, the dielectric protruding member does not extend all the way into the mating connector, thereby occupying a smaller impedance-affecting location and leaving an area with voids. Because the voids may be filled with air, separation means that more air is in an impedance-affecting position with respect to the signal conductors within the connector, thereby lowering the effective dielectric constant and affecting the impedance in that region.
If the dielectric projecting member cannot extend fully into the connectors because of a separation between the connectors, the dielectric projecting member instead fills at least a portion of the space between the two connectors, replacing air that may otherwise be present in the separation with a dielectric member. Thus, the protruding member increases the effective dielectric constant in the space between the connectors relative to the case where the space is completely filled with air. Because the dielectric constant is closer to the case where the complete signal conductor is within the connector housing, such as occurs when there is no separation between connectors, the magnitude of any change in impedance due to separation is less than if the entire space were filled with air.
In addition, the effect of separation between connectors spreads over longer distances. The change in the amount of dielectric material in the impedance-affecting location affects both the impedance along the signal path in the space between the connectors and the impedance along the signal path within one of the connectors. By distributing the change in impedance across a greater distance along the signal path, the abrupt change in impedance change at any given location may be smaller, and the effect of the change may likewise be smaller.
These techniques may be used alone or in any suitable combination. Thus, in some embodiments, the signal conductor pair may be surrounded by or adjacent to the reference conductor on one or more sides. The shape of some or all of the reference conductors, including the separation of the reference conductors from the axis of the signal conductors, may vary over the signal path through the mating connector. The shape of the signal conductors, including the width of the signal conductors, may also vary. Likewise, the amount of insulating material relative to the amount of air adjacent the signal conductors may also vary across the mating area. The values of these design parameters at different locations along the length of the mating region may be selected, individually or in combination, to provide an impedance along the signal conductors within the mating region that does not vary according to separation of the mating components or in which such variation is distributed to reduce impedance discontinuities.
In some embodiments, the shape of some or all of the reference conductors, signal conductors and insulation may vary over the mating region so as to define sub-regions. The length of at least some of the sub-regions may depend on the separation between the components, and the components may be shaped to provide a smooth transition between the sub-regions. A first such sub-region may be present within the first component. The second sub-region may be present within the second component. The second sub-region may comprise a portion of the mating interface in which the signal conductors having resiliency are surrounded by sufficient space to flex as required to generate the contractive force. The third sub-region may be between the first and second sub-regions. The length of the third sub-region may depend on the separation between the components.
In the first sub-region, the reference conductor may be separated from the axis of the signal conductor (referred to herein as the "signal conductor axis") by a first distance. The distance may be adapted to provide a desired impedance given the average dielectric constant of the material and the shape of the signal conductor in the first sub-area. In a second sub-region having air surrounding the signal conductor in the above example, the reference conductor may be separated from the signal conductor axis by a second distance. The second distance may be adapted to provide a desired impedance given the average dielectric constant of the material and the shape of the signal conductor in the second sub-region.
In the third sub-region, the separation between the reference conductor and the signal conductor axis may transition from a first distance adjacent the first sub-region to a second distance adjacent the second sub-region. The width of the signal conductor extending from the first component may also transition from a first width in the first sub-region to a second width in the second sub-region. Such transitions in signal conductor width may be coordinated with changes in separation between the reference conductor and the signal conductor axis and/or changes in the effective dielectric constant of the material adjacent the signal conductor to reduce or eliminate changes in impedance.
Furthermore, the dielectric member within the mating region may be designed to provide a smooth transition to the impedance. For example, in some embodiments, the dielectric member may be designed such that the effective permittivity of the material surrounding the signal conductors in the mating region provides the same impedance as the intermediate portion when the connector is in the nominal mating position. The effective dielectric constant may be provided by the overlap of dielectric members from two mating connectors. The members may be shaped such that the amount of overlap smoothly decreases as the separation between the connectors increases. In this manner, any impedance discontinuities that may otherwise be created by the mated connectors when in a position other than the nominal mating orientation may be reduced.
Described herein are designs of electrical connectors that improve signal integrity of high frequency signals, such as at frequencies in the GHz range including up to about 25GHz or up to about 40GHz or higher, while maintaining high density, e.g., where the spacing between adjacent mating contacts is on the order of 2mm or less, including, e.g., the center-to-center spacing between adjacent contacts in a column of between 0.75mm and 1.85mm or between 1mm and 1.75 mm. The spacing between the columns of mating contacts may be similar, although the spacing between all of the mating contacts in the connector is not required to be the same.
Fig. 1 illustrates an electrical interconnection system in a form that may be used in an electronic system. In this example, the electrical interconnect system includes right angle connectors and may be used, for example, to electrically connect a daughter card to a backplane. Fig. 1 shows two mating connectors. In this example,
Each of the connectors also has a mating interface at which the connector can be mated with or separated from another connector.
Each of the conductive elements includes an intermediate portion connecting the contact tail portion to the mating contact portion. The intermediate portion may be housed within a connector housing, at least a portion of which may be dielectric, to provide electrical isolation between the conductive elements. Additionally, the connector housing may include a conductive or lossy portion, which in some embodiments may provide a conductive or partially conductive path between some of the conductive elements. In some embodiments, the conductive portion may provide shielding. The lossy portion may also provide shielding in some cases, and/or may provide desired electrical performance within the connector.
In various embodiments, the dielectric member may be molded or over-molded (over-mold) from a dielectric material such as plastic or nylon. Examples of suitable materials include, but are not limited to, Liquid Crystal Polymer (LCP), polyphenylene sulfide (PPS), high temperature nylon, or polypropylene (PPO). Other suitable materials may be used, as the aspects of the present disclosure are not limited thereto.
All of the above materials are suitable for use as adhesive materials in the manufacture of connectors. According to some embodiments, one or more fillers may be included in some or all of the binder materials. As a non-limiting example, thermoplastic PPS filled with 30% of the volume with glass fibers may be used to form the entire connector housing or dielectric portion of the housing.
Alternatively or additionally, a portion of the housing may be formed from a conductive material such as machined metal or pressed metal powder. In some embodiments, a portion of the housing may be formed of metal or other conductive material, with a dielectric member separating the signal conductor from the conductive portion. In the illustrated embodiment, for example, the housing of the
The housing of
Other components that may form part of the connector housing may provide mechanical integrity to the
In some embodiments, each wafer may hold a column of conductive elements that form signal conductors. These signal conductors may be shaped and spaced to form single-ended signal conductors. However, in the embodiment shown in fig. 1, the signal conductors are shaped and spaced in pairs to provide differential signal conductors. Each of the columns may include or be defined by a conductive element that serves as a ground conductor. It will be appreciated that the ground conductor need not be connected to earth ground, but rather is shaped to carry a reference potential, which may include earth ground, a DC voltage, or other suitable reference potential. The "ground" or "reference" conductor may have a different shape than the signal conductor, which is configured to provide suitable signal transmission characteristics for high frequency signals.
The conductive elements may be made of metal or any other material that is conductive and provides suitable mechanical properties for the conductive elements in the electrical connector. Phosphor bronze, beryllium copper, and other copper alloys are non-limiting examples of materials that may be used. The conductive element may be formed from such material in any suitable manner, including by stamping and/or forming.
The spacing between adjacent columns of conductors is not critical. However, higher densities can be achieved by placing the conductors closer together. As a non-limiting example, the conductors may be stamped from a 0.4mm thick copper alloy, and the conductors in each column may be separated by 2.25mm, and the columns of conductors may be separated by 2 mm. However, in other embodiments, smaller dimensions may be used to provide higher densities, for example, thicknesses between 0.2mm and 0.4mm or spacings between conductors between or in columns of 0.7mm to 1.85 mm. Further, each column may include four pairs of signal conductors, such that it achieves a density of 60 or more pairs per linear inch for the interconnect system shown in fig. 1. However, it should be understood that higher density connectors may be achieved using more pairs per column, tighter spacing between pairs within a column, and/or smaller distances between columns.
The wafer may be formed in any suitable manner. In some embodiments, the wafer may be formed by stamping the columns of conductive elements from a sheet of metal and overmolding a dielectric portion over the middle portions of the conductive elements. In other embodiments, the wafers may be assembled from modules, each of which includes a single-ended signal conductor, a single pair of differential signal conductors, or any suitable number of single-ended or differential pairs.
The inventors have recognized and appreciated that assembling the wafer from modules may help reduce "tilt" in signal pairs at higher frequencies, such as frequencies between about 25GHz to 40GHz or higher. In this context, skew refers to the electrical propagation time difference between signals in a pair operating as a differential signal. For example, a reduced tilt modular construction is devised in co-pending U.S. application publication No. 2015/0236452, which is incorporated herein by reference.
In accordance with the techniques described in this co-pending application, in some embodiments, the connectors may be formed from modules that each carry a signal pair. The modules may be individually shielded, for example by attaching shielding members to the modules and/or inserting the modules into organizers or other structures that may provide electrical shielding between ground structures and/or pairs around signal-carrying conductive elements.
In some embodiments, the signal conductor pairs within each module may be broadside coupled over a substantial portion of their length. Broadside coupling enables the signal conductors in a pair to have the same physical length. To facilitate routing of signal traces within a connector footprint of a printed circuit board to which the connector is attached and/or to form a mating interface of the connector, the signal conductors may be aligned in edge-to-edge coupling in one or both of these regions. Thus, the signal conductor may comprise a transition region where the coupling changes from edge to broad side, and vice versa. As described below, these transition regions may be designed to prevent mode conversion or suppress undesirable propagation modes that may interfere with the signal integrity of the interconnect system.
The modules may be assembled into wafers or other connector structures. In some embodiments, different modules may be formed for each row position (where the pairs are to be assembled into right angle connectors). These modules can be used together to build a connector with the required number of rows. For example, a module that forms one shape may be directed to a pair to be positioned at the shortest row of connectors, sometimes referred to as the a-b row. A separate module may be formed for the conductive elements in the next longest row, sometimes referred to as the c-d row. The inner portion of the module having rows c-d may be designed to fit the outer portion of the module having rows a-b.
The pattern may be repeated for any number of pairs. Each module may be shaped for use with modules carrying pairs for shorter and/or longer rows. To manufacture a connector of any suitable size, a connector manufacturer may assemble a number of modules into a wafer to provide a desired number of pairs in the wafer. In this manner, a connector manufacturer may introduce a connector family for a widely used connector size such as 2 pairs. As customer requirements change, connector manufacturers may obtain tools for each additional pair, or for modules containing multiple pairs, grouped pairs, to produce larger size connectors. The tool used to produce modules for smaller connectors can be used to produce even shorter rows of modules for larger connectors. Such a modular connector is shown in fig. 8.
Fig. 2 provides further detail of the construction of the interconnection system of fig. 1, and fig. 2 shows a
In the illustrated embodiment,
In the illustrated embodiment, four rows and eight columns of
In the embodiment shown in fig. 2, each of the
In some embodiments, the housing 222 may contain both conductive and lossy portions. For example, the shroud, including the walls 226 and
Lossy or conductive members may be positioned adjacent to rows 230A, 230B, 230C, and 230D of
In some embodiments, other lossy or conductive members may extend into the mating interface 220 perpendicular to the
Fig. 3 shows
Conductive elements that serve as
Fig. 4 shows an exploded view of
As can be seen, the surface 428 is substantially uninterrupted. Attachment features such as tabs 432 may be formed in surface 428. Such tabs may engage openings (not visible in the view shown in fig. 4) in
In the embodiment shown, flexible member 322 is not cut from a planar portion of
Fig. 4 also reveals a
According to some embodiments, some or all of the adjacent surfaces in the mating connector may be tapered. Thus, although not shown in fig. 4, the surfaces of the insulative portions of the
As described in more detail below, the tapered surfaces in the mating interface may avoid abrupt changes in impedance as a function of connector separation. Thus, other surfaces designed to be adjacent to the mating connector may also be similarly tapered. Fig. 4 shows such a
Fig. 5 shows further details of
In the illustrated embodiment, the
In the illustrated embodiment, the
The mating contact portion may be any suitable shape, but in the illustrated embodiment, the mating contact portion is cylindrical. The cylindrical portion may be formed by rolling a portion of a metal sheet into a tube or in any other suitable manner. Such a shape may be produced, for example, by stamping the shape from a sheet of metal that includes an intermediate portion. A portion of the material may be rolled into a tube to provide the mating contact. Alternatively or additionally, the wire or other cylindrical element may be flattened to form the intermediate portion, leaving the mating contact portion cylindrical. One or more openings (not numbered) may be formed in the signal conductors. Such openings may ensure that the signal conductors are securely engaged with the
Turning to fig. 6, further details of the
The conductive elements within wafer 700A may include mating contact portions and contact tail portions. Contact tails 610 are shown extending from a surface of
In some embodiments, the conductive portion may be flexible, for example, may be produced from a conductive elastomer or other materials known in the art for forming gaskets. The flexible material may be thicker than the insulating portion of member 630. Such flexible material may be positioned to align with pads on a surface of a daughter card to which
The conductive or lossy portion of member 630 may be positioned to electrically connect with a reference conductor within
The mating contact portion of the wafer 700A is held in the front housing portion 640. The front housing portion may be made of any suitable material, which may be insulating, lossy or conductive, or may include any suitable combination or such materials. For example, the front housing section may be molded from a filled lossy material or may be formed from a conductive material using similar materials and techniques to those described above for the housing wall 226. As shown in fig. 6, the wafer is assembled from modules 810A, 810B, 810C, and 810D (fig. 8) each having pairs of signal conductors surrounded by reference conductors. In the illustrated embodiment, the front housing section 640 has a plurality of channels, each channel being positioned to accommodate such a pair of signal conductors and associated reference conductors. However, it should be understood that each module may contain a single signal conductor or more than two signal conductors.
Fig. 7 shows a wafer 700. A plurality of such wafers may be aligned side-by-side and held together with one or more support members, or in any other suitable manner to form a daughtercard connector. In the illustrated embodiment, the wafer 700 is formed from a plurality of modules 810A, 810B, 810C, and 810D. The modules are aligned to form a row of mating contacts along one edge of the wafer 700 and a row of contact tails along the other edge of the wafer 700. In embodiments where the wafer is designed for right angle connectors, as shown in fig. 7, those edges are vertical.
In the illustrated embodiment, each of the modules includes a reference conductor at least partially surrounding a signal conductor. The reference conductors may similarly have mating contact portions and contact tail portions.
The modules may be held together in any suitable manner. For example, the module may be held within a housing, which in the embodiment shown is formed with members 900A and 900B. The members 900A and 900B may be formed separately and then secured together, capturing the modules 810A,. 810D therebetween. The members 900A and 900B may be held together in any suitable manner (e.g., by attachment members forming an interference fit or snap fit). Alternatively or additionally, adhesives, welding, or other attachment techniques may be used.
The members 900A and 900B may be formed of any suitable material. The material may be an insulating material. Alternatively or additionally, the material may be or may include a lossy or conductive portion. The members 900A and 900B may be formed, for example, by molding such material into a desired shape. Alternatively, the components 900A and 900B may be formed in place around the modules 810A,. 810D, e.g., via an insert molding operation. In such an embodiment, members 900A and 900B need not be separately formed. Rather, the housing portion for retaining the modules 810A.., 810D may be formed in one operation.
Fig. 8 shows modules 810A, 810D without components 900A and 900B. In this view, the reference conductor is visible. A signal conductor (not visible in fig. 8) is enclosed within the reference conductor, forming a waveguide structure. Each waveguide structure includes a contact tail region 820, a middle region 830, and a
Although the reference conductor may substantially surround each pair, it is not required that the housing have no openings. In the embodiment shown, the reference conductor may be shaped to leave an opening 832. These openings may be in the narrower walls of the housing. Such openings may suppress undesired energy propagation modes. In embodiments where members 900A and 900B are formed by overmolding lossy material over the module, the lossy material may be allowed to fill openings 832, which may further inhibit the propagation of undesirable signal propagation modes that may degrade signal integrity.
Fig. 9 shows a
The members 900A and 900B may be molded from or include lossy material. Any suitable lossy material may be used for these and other structures that are "lossy". Materials that conduct but conduct with some loss or that absorb electromagnetic energy in the frequency range of interest by other physical mechanisms are collectively referred to herein as "lossy" materials. The electrically lossy material may be formed of a lossy dielectric material and/or a poorly conducting material and/or a lossy magnetic material. The magnetically lossy material can be formed, for example, from materials conventionally considered to be ferromagnetic materials, such as materials having a magnetic loss tangent greater than about 0.05 over the frequency range of interest. The "magnetic loss tangent" is the ratio of the imaginary part to the real part of the complex electrical permeability of a material. Actual lossy magnetic materials or mixtures containing lossy magnetic materials may also exhibit useful dielectric loss amounts or conduction loss effects over a portion of the frequency range of interest. Electrically lossy materials can be formed from materials that are conventionally considered dielectric materials, such as materials having an electrical loss tangent greater than about 0.05 over the frequency range of interest. "electrical loss tangent" is the ratio of the imaginary to the real part of the complex dielectric constant of a material. Electrically lossy materials can also be formed from materials that are generally considered conductors but are relatively poor conductors in the frequency range of interest, containing the following conductive particles or regions: the conductive particles or regions are sufficiently dispersed that they do not provide high conductivity or are otherwise prepared to have properties that result in relatively poor bulk conductivity in the frequency range of interest as compared to good conductors such as copper. Electrically lossy materials typically have a bulk conductivity of from about 1 siemens/m to about 100,000 siemens/m and preferably from about 1 siemens/m to about 10,000 siemens/m. In some embodiments, a material having a bulk conductivity between about 10 siemens/meter and about 200 siemens/meter may be used. As a specific example, a material having a conductivity of about 50 siemens/meter may be used. However, it should be understood that the conductivity of the material may be selected empirically or by electrical simulation using known simulation tools to determine a suitable conductivity that provides suitably low crosstalk and suitably low signal path attenuation or insertion loss.
The electrically lossy material can be a partially conductive material, such as a material having a surface resistivity between 1 Ω/square and 100,000 Ω/square. In some embodiments, the electrically lossy material has a surface resistivity between 10 Ω/square and 1000 Ω/square. As a specific example, the surface resistivity of the material may be between about 20 Ω/square and 80 Ω/square.
In some embodiments, the electrically lossy material is formed by adding a filler containing conductive particles to a binder. In such embodiments, the lossy member can be formed by molding or otherwise shaping the binder with filler into a desired form. Examples of conductive particles that may be used as fillers to form electrically lossy materials include carbon or graphite formed into fibers, flakes, nanoparticles, or other types of particles. Metals in the form of powders, flakes, fibers or other particles may also be used to provide suitable electrically lossy characteristics. Alternatively, a combination of fillers may be used. For example, metal-plated carbon particles may be used. Silver and nickel are suitable metals for electroplating of the fibers. The coated particles may be used alone or in combination with other fillers such as carbon flakes. The binder or matrix may be any material that will set, cure, or otherwise be used to position the filler material. In some embodiments, the adhesive may be a thermoplastic material conventionally used in the manufacture of electrical connectors to mold electrically lossy material into a desired shape and position as part of the manufacture of the electrical connector. Examples of such materials include Liquid Crystal Polymers (LCP) and nylon. However, many alternative forms of binder material may be used. A curable material such as epoxy may be used as the adhesive. Alternatively, a material such as a thermosetting resin or an adhesive may be used.
Further, while the above-described binder material may produce an electrically lossy material by forming a binder around a filler of conductive particles, the invention is not so limited. For example, the conductive particles may be impregnated into the formed matrix material, or may be coated on the formed matrix material, for example, by applying a conductive coating onto a plastic or metal part. The term "binder" as used herein includes a material that encapsulates the filler, which is impregnated with the filler or otherwise serves as a substrate to hold the filler.
Preferably, the filler will be present in a sufficient volume percentage to enable a conductive path to be created from particle to particle. For example, when metal fibers are used, the fibers may be present in about 3% to 40% by volume. The amount of filler can affect the conductive properties of the material.
The filled material is commercially available, for example under the trade name Celanese
Various forms of reinforcing fibers, either in woven or non-woven form, coated or uncoated, may be used. Non-woven carbon fibers are one suitable material. Other suitable materials may be used, such as custom blends sold by the RTP company, as the present invention is not so limited.
In some embodiments, the lossy member can be manufactured by stamping a preform or a sheet of lossy material. For example, the insert may be formed by stamping a preform as described above using an appropriate pattern of openings. However, other materials may be used instead of or in addition to such preforms. For example, a sheet of ferromagnetic material may be used.
However, lossy members may be formed in other ways. In some embodiments, the lossy member may be formed by interleaving layers of conductive material, such as metal foil, and lossy material. The layers may be rigidly attached to each other, for example, by using epoxy or other adhesive, or may be held together in any other suitable manner. The layers may have a desired shape before being secured to each other, or may be stamped or otherwise formed after they are held together.
Fig. 10 shows further details of the construction of the
In the illustrated embodiment, the
The exploded view of fig. 10 reveals that the
The impedance of the signal conductors in
If the
Sub-area 340 (fig. 3) may exist within
The impedance in
When the
In the embodiment shown in fig. 3 and 10, the
As described in more detail below, these components may also be sized and may have material properties that provide impedance control based on the separation of the
In the illustrated embodiment, this impedance control is provided in part by protruding
Impedance control may also be provided by the shape or position of the conductive element. Impedance control is also provided by the
Turning to fig. 11, further details of exemplary components of
Caps 1112 and 1114 may be attached to opposite sides of central member 1110. Covers 1112 and 1114 may help to retain
In the illustrated embodiment, the slots 1212A and 1212B are configured to hold pairs of signal conductors for edge coupling at the contact tails and the mating contacts. In a substantial part of the middle of the signal conductor, the pair is kept for broadside coupling. To transition between edge coupling at the ends of the signal conductor to broadside coupling in the middle, transition regions may be included in the signal conductor. The slot in the central member 1110 may be shaped to provide this transition region. Protrusions 1122, 1124, 1126 and 1128 on covers 1112 and 1114 may press the conductive elements against central portion 1110 in these transition regions.
Fig. 12 shows further details of the
The
In the illustrated embodiment, the mating contact portion is tubular. Such a shape may be formed by stamping the conductive element from a sheet of metal and then forming to roll the mating contact into a tubular shape. The circumference of the tube may be large enough to receive pins from a mating pin module, but may conform to the pins. The tube may be divided into two or more sections forming a flexible beam. Two such beams are shown in fig. 12. A boss or other protrusion may be formed on the distal portion of the beam, creating a contact surface. These contact surfaces may be coated with gold or other conductive ductile material to enhance the reliability of the electrical contact.
When the
Fig. 13 illustrates in more detail the positioning of the
In contrast, the middle portions 1314A and 1314B are aligned with the wider sides facing each other. The middle portions are aligned in the direction of the rows 1342. In the example of fig. 13, conductive elements for a right angle connector are shown as reflected by the right angle between column 1340 (which represents the point of attachment to a daughter card) and column 1344 (which represents the location of mating pins attached to a backplane connector).
In conventional right angle connectors in which edge-coupled pairs are used within the wafer, the conductive elements in the outside rows at the daughter cards are longer within each pair. In fig. 13,
Further, in fig. 13, another technique for avoiding skew is introduced. While contact tail 1330B for
Fig. 14A and 14B illustrate edge coupling and broadside coupling within the same pair of signal conductors. Fig. 14A is a side view looking in the direction of row 1342. Fig. 14B is an end view looking in the direction of column 1344. Fig. 14A and 14B illustrate the transition between edge-coupled mating contact portions and contact tail portions and broadside-coupled intermediate portions.
Additional details of the mating contacts (e.g., 1318A and 1318B) are also visible. The tubular portion of mating contact 1318A is visible in the view shown in fig. 14A, while the tubular portion of
Turning to fig. 15A-15C, further details of the manner in which impedance may be controlled despite deviations in the mating position of the mating connector from the nominal mating position are shown. In fig. 15A-15C, some connector components are omitted or partially cut away to reveal various techniques for providing impedance control across the functional mating range of the connector. In this embodiment, the shape of both the conductive element and the dielectric member affects the impedance in the mating region.
Fig. 15A illustrates the mating interface area when
Fig. 15A shows the
Fig. 16A shows a cross-section through the mating module in the direction shown by line 16-16 in fig. 15A. In fig. 16A, the
The
Fig. 15B shows the mating contacts of
Other parameters may also affect the impedance in this region, including the thickness of the
In
However, as shown by a comparison of fig. 15B and 15C and a comparison of fig. 16A and 16B, in region 1542, the value of a parameter that may affect impedance on a signal conductor may depend on the position of
For example, because the
Fig. 15B shows the
As shown in fig. 15C, sub-region 1562 appears when
The length of this sub-region 1562 may depend on the separation between the
While potentially increasing impedance over such large distances may be contrary to the desire to provide the following connectors, the
Furthermore, in the illustrated embodiment,
However, as the separation between the
Fig. 17A to 17D to 18A to 18D schematically show how the shape and position of the extended insulating portion can reduce the influence of the change in impedance caused by the separation of the connectors when mated. A comparison of fig. 17A-17D-18A-18D in conjunction with fig. 19A-19C illustrates how the positioning of the dielectric material may reduce the magnitude and/or effect of the impedance change across the mating region according to the separation of the mating modules. Fig. 17A to 17D show connectors without dielectric portions in one connector block from the impedance-affecting position in the mating block. Connector modules 1710 and 1720 schematically illustrate flat, opposing mating interface surfaces. It should be understood, however, that the mating face of the connector may not be flat as shown in fig. 17A to 17D. For example, the mating face of the connector may include a gathering feature that helps guide the mating contact from the mating connector into the cavity of the connector. Alternatively or additionally, the connectors may include alignment features or polarization features that help align mating connectors or ensure that only connectors designed for mating may mate. Furthermore, it should be appreciated that the connector module will include conductive elements that are not shown for simplicity.
Fig. 17A shows modules 1710 and 1720 abutting each other. The signal paths through modules 1710 and 1720 may be designed to have substantially uniform impedance through the mating area shown in fig. 17A because the relative positioning of the dielectric material, reference conductors, and signal conductors is fixed within each module. Each of modules 1710 and 1720 may be designed to have the same nominal impedance such that the impedance of the signal path through modules 1710 and 1720 may be represented by curve 1730A.
Curve 1730A shows the impedance as a function of distance X through the mating area of the connector. Curve 1730A is an ideal impedance curve that does not account for the effects of impedance discontinuities or other impedance artifacts associated with the flexible member (which provides for the fit between the conductive elements in modules 1710 and 1720). However, curve 1730A shows uniform impedance through modules 1710 and 1720.
Fig. 17B shows the same blocks 1710 and 1720 when slightly mismatched. The modules are separated by less than the functional mating range so that electrical contact can still be made between the conductive elements in the modules so that a signal path can exist through both modules. Curve 1730B is also an ideal curve of such impedance across the mating area of the connector, highlighting the change in impedance caused by the separation of the connectors.
The curve 1730B shows an impedance at each end that is approximately equal to the uniform impedance of the curve 1730A. This impedance reflects that within each of the modules, the impedance of the signal path is determined by the values of the structural parameters, such as the width and thickness of the signal conductor and the separation between the signal conductor and the nearest reference conductor in the same module. Other parameters include the effective dielectric constant of the materials separating the signal and reference conductors. For signal conductors carrying differential signals, the parameters may also include the separation between the signal conductors of the pair and the effective dielectric constant between the signal conductors of the pair. The values of these parameters are not dependent on the separation of the connector modules so that the impedance through these portions of the connector is the same regardless of the separation.
However, the separation between the modules does create a sub-region in which the relative permittivity is not determined by the permittivity of the material of the connector but by the permittivity of the air filling the space 1722B between the modules 1710 and 1720. When the separation is less than the functional mating range of the connector, there will still be an electrical connection between the conductive elements in modules 1710 and 1720 such that a signal path is formed through space 1722B. Because the relative permittivity in this region is lower than within modules 1710 and 1720, the impedance is higher, as shown by sharp peak 1732B in curve 1730B. For very high frequency signals, spikes 1732B may affect signal integrity.
Fig. 17C shows modules 1710 and 1720 having a larger space 1722C. As can be seen from curve 1730C, this spike is the same magnitude as spike 1732B. However, there is a higher impedance over a larger distance in the mating region.
This pattern continues in fig. 17D. The larger space 1722D results in an impedance spike 1732D in curve 1730D of the same magnitude as spike 1732B but at a larger distance. The peak in impedance may exist at a distance as great as the functional mating range of the connector and the connector should still meet the connector specification.
However, the inventors have recognized and appreciated that the impact of an impedance spike on signal integrity may depend on the distance over which the impedance spike is present. Further, the magnitude of the impedance spike may depend on the frequency of the signal through the connector. Higher frequencies may result in a larger change in the magnitude of the impedance. Thus, the impedance spikes shown in fig. 17B-17D may cause damage to very high frequency connectors.
Fig. 18A-18D illustrate how positioning the dielectric portion from one module in an impedance-affecting position relative to a mating module can reduce either the magnitude or the effect of the impedance change associated with the separation of the connector modules. As shown in fig. 18A-18D,
Fig. 18B shows a space 1822B between
As shown in fig. 18B, the impedance at each end of the curve is at the same level as the baseline shown in curve 1830A. The impedance corresponds to an amount of dielectric material adjacent the signal conductor that occupies space adjacent the signal conductor. However, because of space 1822B, although
Space 1822B is on the same order of magnitude as space 1722B. However, by comparing fig. 18B and fig. 17B, it can be seen that the influence of the space is small in fig. 18B. First, the dielectric portion of at least one of
Similar patterns can be seen in fig. 18C and 18D. Space 1822C is larger than 1822B, resulting in a larger impedance at platform 1832C than at 1832B. However, because the
In fig. 18D,
As shown by fig. 18A to 18D, the overlapping insulation portions in the impedance-affected position can reduce the effect of separation between the connectors. While the tapered shape of the modules shown in fig. 18A-18D facilitates a gradual transition, the modules are not required to have overlapping dielectric portions that are tapered or tapered over their entire length to achieve benefits. The benefits schematically illustrated in fig. 18A-18D may also be achieved using protrusions such as
Fig. 19A to 19C schematically show the configuration of the dielectric portions adjacent to the
Although
In the illustrated embodiment, the protruding
The configuration of the reference conductor may also provide a desired impedance profile (profile) depending on the separation of the
Fig. 16A shows a
In the nominal mated position of
In
In
The dimensions are different in
The dimensions established for the
As shown in fig. 16B, the distance S3 is determined by the
Turning now to fig. 20A-20D, computer simulation illustrations are shown for illustrating the impact of appropriate selection of parameters associated with the reference and ground conductors and selection of parameters associated with the dielectric material. These figures are Time Domain Reflectometry (TDR) graphs. The TDR transmits a pulse along a signal path and measures the time at which energy reflected by the pulse at different points along the signal path is received back at the transmitter. Because the reflection is caused by a change in impedance, the amount of energy reflected represents the magnitude of the change in impedance. The time at which the reflected energy is received is indicative of the distance along the signal path to the location at which the particular impedance change occurred. Thus, plotting the received energy as a function of time, as shown in fig. 20A-20D, exhibits impedance as a function of distance along the signal path. The received signal may be filtered such that the graph represents the impedance at a particular frequency. In this example, the frequency is suitable for very high frequency signals, such as 60 Ghz.
In the simulation shown in fig. 20A, trace 2010A represents the impedance along the signal path when the connectors are fully pressed together. Trace 2012A represents the impedance when the connector is separated from its functional mating range. In fig. 20A, the functional fit range is 2 mm. Each trace shows some variation in impedance across the mating interface region. For example, the impedance drops by about 7 ohms in trace 2010A, representing the effect of mating contacts, such as mating contact 1318A and
Fig. 20B-20D show the same type of TDR plots with the connector model of fig. 20A adjusted to include an impedance compensation technique. In fig. 20B, the impedance compensation technique includes a dielectric member protruding from one connector to a mating connector. This technique may be implemented by, for example, the
Fig. 20C is a TDR plot when the baseline model of fig. 20A is modified to include a conductive element such as that shown in fig. 16B, where the signal conductor thickness and signal conductor-to-reference conductor spacing are set to compensate for the difference in dielectric constant and conductor spacing in
Trace 2010C in fig. 20C shows the impedance along the signal path when the connectors are fully pressed together. Thus, trace 2010C appears similar to trace 2010A. Trace 2012C represents the same distance that the connector mismatch uses in making traces 2012A and 2012B. Trace 2012C similarly shows an increased impedance associated with different ones of the signal and reference conductors in the mismatched positions relative to the fully mated position. The increase in impedance on trace 2012C is less than the increase in impedance on trace 2012A, revealing the effect of the
FIG. 20D is a TDR plot when the baseline model of FIG. 20A is modified to include both a modification of the dielectric structure as represented in FIG. 20B and a modification of the structure of the conductive element as in FIG. 20C. Fig. 20B and 20C show that these techniques can be advantageously used alone. Fig. 20D illustrates that these techniques may be advantageously used together.
Trace 2010D in fig. 20D shows the impedance along the signal path when the connectors are fully pressed together. Thus, trace 2010D appears similar to trace 2010A.
The models used in generating fig. 20A-20D show the performance improvement. Although the 50% improvement in impedance variability is significant, particularly for very high speed connectors, these examples are not intended to illustrate the limitation on the performance improvement that can be achieved. Applying the design techniques presented herein in combination with other optimization practices may provide even greater reduction in impedance variation. In some embodiments, for example, the maximum impedance difference between fully mated to a position where the connectors are mismatched to the end of the functional mating range may be greater than 50%, such as greater than 60%, 70%, or 75%. In some embodiments, the impedance difference may be in a range of, for example, 50% to 75% or 60% to 80%.
Further, the design techniques as described herein may result in a connector that provides predictable impedance for a signal path through the connector in operation. A designer of an electronic system may design other portions of the system based on the nominal impedance of the connector. Deviations from this nominal impedance that occur in operation because the connectors are not fully mated can affect the performance of the entire electronic system. Accordingly, it is desirable for the connector to provide an impedance that deviates as little as possible under specified operating conditions. In some embodiments, the impedance deviation across the mating region in a fully mated or partially unmatched configuration may be 3 ohms or less at frequencies up to 60GHz in some embodiments. In other embodiments, the variation may be 4 ohms or less or may be 2 ohms or less. In other embodiments, the deviation from the nominal impedance across the mating region may be in the range of 1 ohm to 4 ohms or 1 ohm to 3 ohms.
Additional benefits may also be produced by providing a gradual change in impedance. Gradual changes may have less impact on signal integrity than abrupt changes of similar magnitude. For example, using the techniques described herein, the effect of impedance spikes may be reduced, in some embodiments, without a section where the impedance changes by more than 1 ohm in the 0.5mm mating region. In other embodiments, the variation may be 2 ohms or less or 0.5 ohms or less. In other embodiments, the impedance change may be in the range of 0.5 to 2 ohms or 0.1 to 1 ohms.
It should be understood that other structures providing impedance control may be designed in accordance with the principles described herein. Fig. 21A-21C show alternative designs for the conductive element that also provide impedance control. In this embodiment, the mating contact portion of the signal conductor is a cylindrical tube. One connector has a smaller diameter tube than the other connector so that the smaller tube fits within the larger tube. Electrical contact between the tubes is ensured by an outward projection on the smaller tube and/or an inward projection on the larger tube. These projections may extend by an amount greater than the difference in diameter between the larger and smaller tubes. By splitting one or both of the tubes, flexibility can be created at the mating contact to provide sufficient mating contact force. If the outer larger tube is split, its diameter may increase slightly as the smaller tube is inserted, creating a spring force that provides the desired mating contact force. Alternatively or additionally, if the inner smaller tube is split, its diameter may be compressed as it is inserted into the larger tube, creating the required spring force.
Fig. 21A-21C illustrate in cross-section mating interfaces of pairs of signal conductors having mating contact portions shaped as tubes. Fig. 21B shows the pair with the tubes shown side-by-side in the nominal mating position which, in the embodiment shown, causes the connectors to be fully pressed together. Fig. 21A is viewed from line a-a in fig. 21B, such that only the mating contact portion of one of the signal conductors of the pair is visible. Fig. 21C shows the same view as fig. 21A, but with the connectors separated to function fit ranges.
In the illustrated embodiment,
The pairs of signal conductors in each connector are adjacent to the reference conductor. In some embodiments, each pair is surrounded by a reference conductor or a combination of reference conductors. The pairs of
To provide a fit between the conductive elements in the mating connector,
Other techniques for providing flexibility may alternatively or additionally be used. For example, a portion of the reference conductor may be separate from the body of the reference conductor to be similarly flexible. In the embodiment shown,
Regardless of the manner in which the tabs are flexible, fig. 21A and 21C illustrate
Similarly, if the connectors are close enough to be within a functional mating range, the tubes forming the mating contact portions for the signal conductors of one connector will enter the tubes forming the mating contact portions for the signal conductors in the other connector. For example,
In the embodiment shown, each of
This configuration of the mating contacts and reference conductors provides a mating interface in which the impedance is largely independent of the separation distance between the mating connectors. For example, in the configuration shown in fig. 21A, in
When the connectors are mated and
When
In
The
In the illustrated embodiment, such as in fig. 21C, the impedance in
While details of particular configurations of the conductive elements, the housing, and the shield member are described above, it should be understood that these details are provided for illustrative purposes only, as the concepts disclosed herein can be otherwise implemented. In this regard, the various connector designs described herein may be used in any suitable combination, as the aspects of the present disclosure are not limited to the particular combination shown in the figures.
Having thus described several embodiments, it is to be appreciated various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be within the spirit and scope of the invention. Accordingly, the foregoing description and drawings are by way of example only.
Various changes may be made to the illustrative structures shown and described herein. For example, examples of techniques for improving signal quality at a mating interface of an electrical interconnection system are described. These techniques may be used alone or in any suitable combination. Further, the size of the connector may be increased or decreased from the size shown. Furthermore, materials other than those explicitly mentioned may be used to construct the connector. As another example, a connector with four differential signal pairs in a column is used for illustrative purposes only. Any desired number of signal conductors may be used in the connector.
Many types of components in an interconnect system that form a separable interface may present problems associated with impedance variations across the mating interface area or deviations from nominal or design values as a function of separation of the mating components. Separable connectors used to connect daughter cards to a backplane, such as in electronic systems, may be used as an example where this problem may arise. It should be understood, however, that the use of connectors is exemplary and not limiting of the invention. Similar techniques may be used with sockets that may be mounted to a printed circuit board and form a separable interface to a component such as a semiconductor chip. Alternatively or additionally, these techniques may be applied where connectors, sockets, or other components are attached to the printed circuit board. While these components are not intended to be separated from the printed circuit board during normal operation of the electronic system, separation of the components during operation is affected by the relative positioning of the components as they are manufactured as separate components and then combined together at the interface.
Manufacturing techniques may also be varied. For example, an embodiment is described in which
Further, the change in the impedance between the fully mated position and the partially separated position of the two mating parts has been described. In some cases, the fully mated position has the housing abutting one component of the housing of the mating component. It should be understood that the principles described herein are applicable regardless of the design separation between components in the designed mated position. For example, the connector components may be designed to have a mating position in which the components are separated by 2 mm. If the separation is more or less, without the techniques as described herein, the impedance may be different from the impedance of the designed mating location, resulting in an impedance discontinuity that affects performance.
As another example, a connector formed from modules, each of which contains a pair of signal conductors, is described. Each module does not necessarily contain exactly one pair, or the number of signal pairs in all modules in a connector is not necessarily the same. For example, 2 or 3 pairs of modules may be formed. Further, in some embodiments, core modules having two, three, four, five, six, or more number of rows in a single-ended or differential pair configuration may be formed. Each wafer or each connector in embodiments where the connectors are wafer rounded may include such a core module. To manufacture a connector having more rows than included in the base module, additional modules (e.g., each having a smaller number of pairs, such as a single pair per module) may be coupled to the core module.
Further, while many of the inventive aspects are shown and described with reference to a daughterboard connector having a right angle configuration, it should be understood that aspects of the present disclosure are not so limited, as any of the inventive concepts may be utilized with other types of electrical connectors, such as backplane connectors, cable connectors, stack connectors, mezzanine connectors, I/O connectors, chip sockets, and the like, either alone or in combination with one or more other inventive concepts.
In some embodiments, the contact tails are shown as press-fit "eye of the needle" flexible portions designed to fit within the through holes of the printed circuit board. However, other configurations may also be used, such as surface mount elements, spring contacts, solderable pins, etc., as aspects of the present disclosure are not limited to using any particular mechanism for attaching a connector to a printed circuit board.
The disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description and/or illustrated in the drawings. Various embodiments are provided for purposes of illustration only and the concepts described herein can be practiced or carried out in other ways. Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," "having," "containing," or "involving," and variations thereof herein, is meant to encompass the items listed thereafter (or equivalents thereof) and/or as additional items.