阅读说明：本技术 用于射频部件的多层冷却结构 (Multilayer cooling structure for radio frequency components ) 是由 安德烈·格雷德 丹尼尔·格鲁纳 安东·拉班克 于 2018-08-20 设计创作，主要内容包括：一种装置(100)包括：在第一位置处具有射频(RF)结构(108、114)的电路板(102),该RF结构由电路板的导电迹线形成；载热体(118)；以及将电路板(102)和载热体(118)彼此耦合的多层冷却结构(116),该多层冷却结构(116)包括在第一位置处邻近RF结构的第一叠层(120)以及位于第二位置处的第二叠层(122、132),第一叠层(120)包括邻近载热体(118)的介电层(126)以及将介电层(126)和电路板(102)彼此耦合的热界面材料(TIM)(124),介电层(126)的导热性和刚性比TIM(124)更高,第二叠层(122、132)包括邻近载热体(118)的金属层(134)以及将金属层(134)和电路板(102)彼此耦合的TIM(136)。(An apparatus (100) comprising: a circuit board (102) having a Radio Frequency (RF) structure (108, 114) at a first location, the RF structure being formed from conductive traces of the circuit board; a heat carrier (118); and a multi-layered cooling structure (116) coupling the circuit board (102) and the heat carrier (118) to each other, the multi-layered cooling structure (116) comprising a first stack (120) adjacent to the RF structure at a first location and a second stack (122, 132) at a second location, the first stack (120) comprising a dielectric layer (126) adjacent to the heat carrier (118) and a Thermal Interface Material (TIM) (124) coupling the dielectric layer (126) and the circuit board (102) to each other, the dielectric layer (126) having a higher thermal conductivity and rigidity than the TIM (124), the second stack (122, 132) comprising a metal layer (134) adjacent to the heat carrier (118) and a TIM (136) coupling the metal layer (134) and the circuit board (102) to each other.)

1. An apparatus, comprising:

a circuit board having a radio frequency structure at a first location, the radio frequency structure formed from conductive traces of the circuit board;

a heat transfer medium; and

a multi-layered cooling structure coupling the circuit board and the heat carrier to each other, the multi-layered cooling structure comprising a first stack adjacent the radio frequency structure at the first location and a second stack at the second location, the first stack comprising a dielectric layer adjacent the heat carrier and a thermal interface material coupling the dielectric layer and the circuit board to each other, the dielectric layer having a higher thermal conductivity and a higher rigidity than the thermal interface material, the second stack comprising a metal layer adjacent the heat carrier and the thermal interface material coupling the metal layer and the circuit board to each other.

2. The apparatus of claim 1, wherein the thermal interface material comprises at least one of a thermal pad, an adhesive, a bonding film, a matrix fiber aggregate, a solder, and a glue.

3. The apparatus of claim 1, wherein the radio frequency structure has a central opening, the apparatus further comprising at least one component on the circuit board aligned with the central opening.

4. The apparatus of claim 1, wherein the radio frequency structure comprises at least one of an inductor, a transformer, and a transmission line.

5. The apparatus of claim 1, wherein the circuit board has a first layer facing the multi-layer cooling structure and a second layer opposite the first layer.

6. The apparatus of claim 5, wherein the radio frequency structure is located at the first layer.

7. The apparatus of claim 1, wherein the dielectric layer comprises at least one of a ceramic material and a ferromagnetic ceramic material.

8. The apparatus of claim 1, wherein the dielectric layer and the metal layer have a common shape.

9. The apparatus of claim 1, wherein the dielectric layer and the metal layer have a common dimension.

10. The device of claim 1, further comprising a plating on a surface of the metal layer.

11. The apparatus of claim 10, wherein the plating comprises at least one of tin and gold.

12. The apparatus of claim 1, wherein the multi-layered cooling structure comprises more than two laminations located between the circuit board and the heat carrier.

13. The apparatus of claim 1, further comprising a power component mounted to the metal layer.

14. The apparatus of claim 13, further comprising a recess in the circuit board for receiving the power component.

15. An apparatus, comprising:

a printed circuit board having a radio frequency structure at a first location on a first surface, the printed circuit board having a second surface opposite the first surface, the radio frequency structure being formed from conductive traces of the printed circuit board and including at least one of an inductor, a transformer, and a transmission line;

a heat carrier including at least one of a radiator and a water-cooled plate; and

a multi-layered cooling structure coupling the printed circuit board and the heat carrier to each other, the multi-layered cooling structure comprising a first laminate adjacent the radio frequency structure at the first location and a second laminate at the second location, the first laminate comprising a dielectric pad coupled to the heat carrier and a thermal interface material coupling the dielectric pad and the printed circuit board to each other, the thermal interface material comprising at least one of a thermally conductive pad, an adhesive film, a matrix fiber aggregate, solder, and glue, the dielectric pad having a higher thermal conductivity and rigidity than the thermal interface material, the second laminate comprising a metal layer coupled to the heat carrier, the metal layer coupled to the first surface of the printed circuit board, the first laminate adjacent the second laminate.

Technical Field

This document relates generally to a multilayer cooling structure for radio frequency components.

Background

Some Radio Frequency (RF) power components or modules include planar power RF structures such as inductors, transformers, or transmission lines. During operation, such RF power components may generate a significant amount of heat. Thus, cooling of the RF power components may be required or desired.

Some RF components operate at frequencies in the microwave range (e.g., 300MHz to 300GHz) or higher. For such RF components, the heat sink may be bonded directly to a Printed Circuit Board (PCB) on which the RF components are implemented. In this case, it is acceptable for the metal heat sink to be in relatively close proximity to the RF components, since the RF components require a relatively low inductance of the inductive element and/or a relatively low impedance of the transmission line. This may not be the case for lower frequencies.

Disclosure of Invention

In a first aspect, an apparatus comprises: a circuit board having a Radio Frequency (RF) structure at a first location, the RF structure formed from conductive traces of the circuit board; a heat transfer medium; and a multi-layered cooling structure coupling the circuit board and the heat carrier to each other, the multi-layered cooling structure comprising a first stack adjacent to the RF structure at a first location and a second stack at a second location, the first stack comprising a dielectric layer adjacent to the heat carrier and a Thermal Interface Material (TIM) coupling the dielectric layer and the circuit board to each other, the dielectric layer having a higher thermal conductivity and rigidity than the TIM, the second stack comprising a metal layer adjacent to the heat carrier and the TIM coupling the metal layer and the circuit board to each other.

Implementations may include any or all of the following features. The TIM includes at least one of a thermally conductive pad, an adhesive, a bonding film, a matrix fiber aggregate, a solder, and a glue. The RF structure has a central opening, and the apparatus further includes at least one component on the circuit board aligned with the central opening. The RF structure includes at least one of an inductor, a transformer, and a transmission line. The circuit board has a first layer facing the multi-layer cooling structure and a second layer opposite to the first layer. The RF structure is located at the first layer. The dielectric layer includes at least one of a ceramic material and a ferromagnetic ceramic material. The dielectric layer and the metal layer have a common shape. The dielectric layer and the metal layer have a common dimension. The apparatus also includes a plating layer on a surface of the metal layer. The plating layer includes at least one of tin and gold. The multilayer cooling structure comprises more than two stacks located between the circuit board and the heat carrier. The apparatus also includes a power component mounted to the metal layer. The device also includes a recess in the circuit board for receiving the power component.

In a second aspect, an apparatus comprises: a printed circuit board having a Radio Frequency (RF) structure at a first location on a first surface, the printed circuit board having a second surface opposite the first surface, the RF structure being formed from conductive traces of the printed circuit board and including at least one of an inductor, a transformer, and a transmission line; a heat carrier including at least one of a radiator and a water-cooled plate; and a multi-layered cooling structure coupling the printed circuit board and the heat carrier to each other, the multi-layered cooling structure comprising a first stack adjacent the RF structure at a first location and a second stack at a second location, the first stack comprising a dielectric pad coupled to the heat carrier and a thermal interface material coupling the dielectric pad and the printed circuit board to each other, the thermal interface material comprising at least one of a thermally conductive pad, an adhesive, a bonding film, a matrix fiber aggregate, solder, and an adhesive, the dielectric pad having a higher thermal conductivity and rigidity than the thermal interface material, the second stack comprising a metal layer coupled to the heat carrier, the metal layer coupled to a first surface of the printed circuit board, the first stack adjacent the second stack.

Drawings

Fig. 1 shows an example of an apparatus.

Fig. 2 shows an example of a circuit board.

Fig. 3 shows an example of a frame.

Fig. 4 shows an example of a frame island.

Fig. 5 to 8 show examples of the assembly.

Fig. 9A to 9B show examples of devices having inductors.

Fig. 10A to 10B show examples of the apparatus having the transformer.

Fig. 11A to 11B show examples of devices having transmission lines.

Fig. 12 shows another example of the device in fig. 1.

Fig. 13A to 13C show examples of arrangements with circuit boards.

Detailed Description

Examples of cooling stacks that may be built between a heat sink and a circuit board (e.g., PCB) are described herein. Cooling of the planar RF structure may be provided in some embodiments. Forced cooling may be provided for planar RF power structures. Hybrid layer stacks may be provided to cool the planar RF power structure.

RF circuits having frequencies below the microwave range (e.g., in the range of about a fraction of MHz to about 100 MHz) may generally have higher inductance of the inductive components and/or impedance of the transmission line than higher frequency circuits. Examples of devices associated with such lower frequencies include, but are not limited to, generators for RF power delivery. For example, without limitation, RF power generators may be used in the following fields: manufacturing a semiconductor; manufacturing of LED displays or LCDs; thin film deposition, including for photovoltaic systems such as solar panels; plasma studies such as in cyclotrons; industrial or medical applications; and/or a laser power supply.

Due to the higher inductance and/or higher impedance in the sub-microwave RF generator, it is not possible or practical to bond electrically conductive heat sinks or other mechanical heat carriers directly to the PCB (these heat carriers are usually connected to ground potential). This close arrangement of the metal components significantly reduces the inductance or impedance due to the destructive superposition of the magnetic field of the RF components and the magnetic field of the eddy currents in the heat carrier. Furthermore, making the PCB thicker may not be an acceptable solution, as the thermal resistance is typically too high, so that cooling is insufficient.

A multi-layer cooling structure may be provided comprising a different but more thermally conductive material than the thermally conductive PCB material. In some embodiments, the circuit board may be bonded to a multi-layer cooling structure that includes a frame featuring one or more cutouts or cavities. For example, the multi-layer cooling structure may be mounted to a heat carrier. The cavity may be provided in a multilayer cooling structure requiring additional space with good thermal conductivity but electrical insulation. For example, the cavity may be disposed adjacent to an RF structure such as an inductive element or a transmission line. The cavity may be at least partially filled with one or more well-thermally conductive inlays (e.g., boards), and one or more thermal interface materials are filled between the circuit board and the inlays. The thermal interface material is flexible at least during the production process. For example, if an adhesive or laminate is used, the thermal interface layer is subsequently hardened after the height tolerances have been compensated for. A thermal interface material may also or alternatively be disposed between the inlay and a heat sink or other heat carrier. Such a stack may provide cooling of the RF structure without significant adverse effects on inductance and/or impedance. Another area of the circuit board, for example, where components without inductive properties are provided, can be cooled directly by means of another laminate formed by the frame. This can provide thermal diffusion and a reduction in thermal resistance. The thickness of the frame and/or other parts of such a stack may be chosen accordingly.

Fig. 1 shows an example of an apparatus 100. The device 100 may be part of an RF device according to any example described herein. The apparatus 100 includes a circuit board 102. In some embodiments, the circuit board 102 is a PCB. For example, the circuit board 102 may have conductive traces that form and/or connect the components of the device 100.

The circuit board 102 may include a top layer 104. The top layer 104 may include one or more components and/or conductive traces of the circuit board 102 that are schematically illustrated in the figures herein for illustrative purposes. In some embodiments, the components 106 may be considered "lumped" components. For example, the schematically illustrated component 106 may represent at least one capacitor and/or at least one resistor. Some components of the apparatus 100 may include RF structures and may operate with signals having one or more frequencies, such as sub-microwave frequencies. For example, a high power signal that has been amplified may be passed through passive components to match the load impedance for the power transistor and/or provide filtering. In some embodiments, the RF structure 108 may include or be part of an inductor, transformer, or transmission line. For example, the RF structure 108 may be formed from conductive traces (e.g., copper traces) of the circuit board 102. The top layer 104 may be formed at the core 110 of the circuit board 102. In some embodiments, the core 110 may include a PBC substrate.

The circuit board 102 may include a bottom layer 112 formed at the core 110. The bottom layer 112 may include one or more components and/or conductive traces of the circuit board 102. In some embodiments, the RF structure 114 may include or be part of an inductor, transformer, or transmission line. For example, the RF structure 114 may be formed from conductive traces (e.g., copper traces) of the circuit board 102. The terms "top" and "bottom" are used for illustrative purposes only with respect to the views provided.

RF structures 108 and/or 114 may be referred to as planar RF structures. The RF component may be considered a planar RF structure when formed by conductive traces of a circuit board (e.g., etching a metal layer located at the core 110). For example, the planar RF structure may include inductors, transformers, and/or transmission lines.

The apparatus 100 herein includes a multi-layer cooling structure (MSCS)116 for the circuit board 102. MSCS116 may be used to remove dissipated heat from circuit board 102 while helping components/structures of circuit board 102 have a desired and reproducible inductance and/or impedance. MSCS116 is positioned between circuit board 102 and heat carrier 118. In some embodiments, MSCS116 may be positioned adjacent (e.g., abutting) bottom layer 112. For example, MSCS116 may be positioned against RF structure 114. The heat carrier 118 may include structures capable of removing heat from the MSCS 116. For example, but not by way of limitation, the heat carrier 118 may include a heat sink (e.g., a metal structure), a water-cooled plate, and/or another heat transfer mechanical carrier.

MSCS116 may include more than two stacked layers that are used to facilitate thermal energy removal from circuit board 102 in a manner that is the same as or different from one another. Here, MSCS116 includes at least stack 120 and stack 122. Each stack of MSCS116 may include more than two layers. In some embodiments, laminate 120 includes Thermal Interface Material (TIM)124, inlay 126, and portion l28A as part of layer 128. The portion l28A here forms one end of the stack 120 and is positioned adjacent (e.g., abutting) the heat carrier 118. At the other end of the laminate 120, the TIM 124 is positioned adjacent to (e.g., abutting) the bottom layer 112 of the circuit board 102. For example, the TIM 124 may be positioned adjacent to the RF structure 114.

The TIM 124 may serve as a soft thermal interface that provides a thermal connection between the circuit board 102 and the inlay 126. The TIM 124 is electrically insulating. In some embodiments, the TIM 124 may include a thermal pad, an adhesive, a bonding film, a matrix fiber aggregate, a solder, and/or a glue. In some embodiments, the matrix fiber aggregate may be formed from fibers dispersed in a polymer matrix. For example, the matrix fiber aggregate may comprise pre-impregnated composite fibers or prepregs. The TIM 124 may be used to compensate for one or more deviations in the device 100. For example, the TIM 124 may compensate for mechanical tolerances (e.g., such as variations in one or more dimensions of the laminate 122) that are deemed to be within design parameters of the device 100. For another example, TIM 124 may fill the void between underlayer 112 and inlay 126.

Inlay 126 may be a relatively rigid piece of material with good thermal conductivity that provides electrical insulation. Inlay 126 may provide a thermally conductive, electrically insulating bridge between circuit board 102 and heat carrier 118. In some embodiments, inlay 126 has a higher thermal conductivity than TIM 124. Inlay 124 is more rigid than TIM 124. For example, inlay 126 may be selected to have a maximum size that fits within a cavity 130 formed between laminate 122 and another laminate 132, here on a side of laminate 120 opposite laminate 122. For example, the blank or sheet part may be sized to fill the cavity 130 as much as possible, and then the TIM 124 may compensate by filling some or all of the remaining space. The material of inlay 126 may be selected to provide a good compromise between the thermal conductivity of the material and the cost. The thickness of inlay 126 can be selected to provide a good compromise between overall thermal conductivity and effective compensation for mechanical tolerances.

Inlay 126 may be made of one or more materials that provide suitable thermal conductivity and electrical insulation. In some embodiments, inlay 126 may comprise a ferromagnetic ceramic material such as ferrite, such as Al₂O₃Or a ceramic material of A1N and/or another thermally conductive rigid material. Inlay 126 may have a thermal conductivity that is less than that of metal, but inlay 126 may be used to provide cooling to circuit board 102 without significantly degrading inductance and/or impedance.

Portion 128A (e.g., thermal paste) may be a portion of an entire layer (here, layer 128) that may span multiple or all of the stacks (here, stacks 120, 122, and 132) of MSCS 116. The portion 128A should provide good contact (e.g., to compensate for roughness) and good thermal conductivity between the other portions of the stack 120 on the one hand (here most directly the inlay 126) and the heat carrier 118 on the other hand. In some embodiments, another material may be used instead or in addition. For example, portion 128A (or the entire layer 128) may include a thermal pad, an adhesive, a bonding film, a matrix fiber aggregate, solder, and/or glue.

Stack 122 of MSCS116 may include frame 134. The frame 134 may be a thermally conductive structure coupled to the circuit board 102 that helps remove heat from portions of the circuit board 102 to the heat carrier 118. The frame 134 may be electrically conductive. The frame 134 may have one or more cavities or openings. For example, a cavity 130 may be provided by the frame 134 for accommodating the stack 120 between the stacks 122 and 132. The frame 134 may be made of a PCB substrate (including but not limited to clad metal plate, polymer foil, cloth, and/or paper) or metal (including but not limited to copper). The frame 134 may be provided in the stack 122 or in the stack 132 or both. The frame 134 may provide direct cooling of one or more areas of the circuit board 102 other than the RF structure 114. For example, the component 106 (located in either or both of the stacks 122 or 132) may be cooled by the frame 134. The frame 134 may facilitate heat spreading and reduce thermal resistance when providing cooling. For example, the thickness of the frame may be selected to provide sufficient heat diffusion.

The thickness of the frame 134 in the direction between the circuit board 102 and the heat carrier 118 may affect or define one or more other dimensions in the device 100. The frame 134 may be designed to hold the circuit board 102 (e.g., the RF structure 114 thereof) at an appropriate distance from the heat carrier 118. In some embodiments, inlay 126 is selected based at least in part on the thickness of frame 134 and the depth of cavity 130. For example, inlay 126 may be designed to have a thickness that is at least half the thickness of frame 134. In some embodiments, inlay 126 may have a maximum size that can be accommodated by cavity 130, and then may be (essentially) as thick as frame 134. In some embodiments, inlay 126 may be thicker than cavity 130 (i.e., thicker than frame 134). Thus, inlay 126 may be partially received by a cavity in a heat sink or other heat carrier. As previously exemplified, the TIM 124 may compensate for tolerance variations in the device 100, including but not limited to compensating for tolerance variations in the frame 134.

MSCS116 may include layer 136 positioned between bottom layer 112 and frame 134 (in stack 122 and/or stack 132) or between bottom layer 112 and TIM 124 (in stack 120), or both. In some embodiments, the layer 136 may couple the bottom layer 112 and the frame 134 to each other and provide thermal conductivity. For example, layer 136 may include an adhesive, a glue, and/or a thermally conductive paste.

The apparatus 100 is an example of an apparatus that includes a circuit board (e.g., circuit board 102) having an RF structure (e.g., RF structure 114 at a first location thereof (e.g., a location of layer 120 above bottom layer 112) formed from conductive traces of the circuit board. The device has a heat carrier (e.g., heat carrier 118) and a multi-layered cooling structure (e.g., MSCS116) coupling the circuit board and the heat carrier to each other. The MSCS includes a first stack (e.g., stack 120) adjacent the RF structure at a first location and a second stack (e.g., stack 122) at a second location (e.g., a location on bottom layer 112 facing stack 122). The first laminate includes an inlay (e.g., inlay 126) adjacent to the heat carrier and a thermal interface material (e.g., TIM 124) coupling the inlay and the circuit board to one another. Inlays have higher thermal conductivity and rigidity than thermal interface materials (e.g., inlays made of ceramic or ferrite as compared to TIMs made of soft thermal pads, adhesives, bonding films, prepregs, or glues).

Fig. 2 shows an example of a circuit board 200. Circuit board 200 may be used with one or more of the examples described herein. For example, circuit board 200 may be used as circuit board 102 (fig. 1). Circuit board 200 may be made of a clad metal substrate or composite material, to name two examples. Circuit board 200 may be a PCB having one or more conductive traces on either or both surfaces thereof. The circuit board 200 may have any suitable shape, including but not limited to rectangular.

Circuit board 200 may include one or more surface features that aid in the function of the component. In some embodiments, the circuit board 200 has one or more through-hole connections 202. For example, the via connections 202 may provide a connection from one side of the circuit board 200 (e.g., from the top layer 104 in fig. 1) to circuitry (e.g., RF structures) at an opposite side of the circuit board 200 (e.g., at the bottom layer 112 in fig. 1).

The circuit board 200 may include one or more openings. Here, the circuit board 200 has two recesses 204. In some embodiments, recess (es) 204 may be open to opposing surfaces of circuit board 200. The recess (es) 204 may be used to accommodate one or more components that are not mounted to the circuit board 200, for example, as will be described below.

Fig. 3 shows an example of a frame 300. Frame 300 may be used with one or more of the examples described herein. For example, frame 300 may be used as frame 134 (FIG. 1). The frame 300 may be made of metal (e.g., copper) or a PCB substrate, to name two examples. The frame 300 may have any suitable shape, including but not limited to rectangular.

The frame 300 may include one or more openings. Here, the frame 300 has two recesses 302 and two recesses 304. In some embodiments, recess (es) 302 may open to opposing surfaces of frame 300. The recess (es) 302 may be used to house an RF structure having a central opening, for example, as will be described below. In some embodiments, recess (es) 304 may open to opposing surfaces of frame 300. The recess (es) 304 may be used to accommodate RF structures without a central opening, for example, as will be described below.

Fig. 4 shows an example of a frame island 400. The frame island 400 may be used with one or more of the examples described herein. The frame island 400 may, for example, serve as an island that supports a portion of a circuit board (components thereon) when surrounded by an RF structure, for example, as will be described below. The frame island 400 may be made of metal (e.g., copper) or a PCB substrate, to name two examples. The frame island 400 may have any suitable shape, including but not limited to rectangular.

Fig. 5 to 9 show examples of the assembly. These components may illustrate various stages of assembly of a device (e.g., any of the devices described herein). In fig. 5, the circuit board 200 and the frame 300 are shown coupled to each other. This may correspond to the coupling of the circuit board 102 and the frame 134 to each other in fig. 1, for example. The portions of circuit board 200 that cover recesses 302 and 304 (fig. 3) of frame 300 may be provided with one or more RF structures, including but not limited to inductors, transformers, and/or transmission lines. For example, the RF structure(s) may be located at a surface of circuit board 200 facing recesses 302 and 304, or at a surface on the opposite side of circuit board 200, or both.

One or more components not mounted to circuit board 200 may be mounted to frame 300. Here, the member 500 is mounted to the frame 300. The recess 204 of the circuit board 200 may receive the component 500. For example, the member 500 may fill almost the entire recess 204. In some embodiments, the component 500 may be a power transistor, a power resistor, or the like that is directly cooled by the frame 300 (e.g., by a metallic material). For example, when component 500 is positioned directly onto frame 300, there is no thermal resistance of the circuit board between component 500 and the heat carrier. In addition, heat from component 500 does not travel directly towards a heat carrier (not shown), but may spread within frame 300. According to other characteristics of the embodiment, the frame 300 has a suitable thickness that can reduce the thermal resistance between the component 500 and the heat carrier. For example, if the thickness of the frame 300 is too great, heat may diffuse, but there may be additional thermal resistance from the material (e.g., copper) of the frame 300. However, if the thickness of the frame is too small, no significant heat diffusion will be provided.

The above examples illustrate that the apparatus may include a power transistor (e.g., component 500) mounted to a frame (e.g., frame 300), and the circuit board (e.g., circuit board 200) may include a recess (e.g., recess 204) that receives the power component (e.g., transistor).

Fig. 6 shows the frame 300 and the circuit board 200 from a different angle than in fig. 5, where the recesses 302 and 304 are now visible. The frame island 400 has been mounted into the recess 302 of the circuit board 200.

Fig. 7 shows RF structure 700 having been positioned onto circuit board 200 within at least one recess 302 of frame 300. Likewise, the RF structure 702 has been positioned onto the circuit board 200 within the at least one recess 304 of the frame 300. In some embodiments, the RF structure 700 may have a central opening 704 for receiving the frame island 400 and component(s) supported by the frame island 400 that are mounted to the circuit board 200. It is advantageous to support the circuit board by the islands 400, which avoids bending of the circuit board and damage to the components from the pressure of the compressed TIM.

Fig. 8 shows frame 300 coupled to circuit board 200 (partially visible through a recess in frame 300) by bolts 800. Another attachment means, such as an adhesive, may additionally or alternatively be used. The frame 300 may also be coupled to a heat carrier.

Fig. 9A and 9B illustrate an example of an apparatus 900 having an inductor 902. Device 900 and/or inductor 902 may be used with any of the examples described herein. For example, the RF structure 114 (fig. 1) may form a portion of the inductor 902. The jumper pin 903 shown in fig. 9A may be used for inductive tuning of the inductor 902. The apparatus 900 includes a frame 904 defining a cavity 906. For example, frame 134 (fig. 1) may form a portion of frame 904. Cavity 906 may have a similar or identical function as cavity 130 (fig. 1). The inductor 902 may be provided with one or more bridge portions to adjust the inductance. A gap 908 between the outer perimeter of inductor 902 and the inner surface of frame 904 may be selected such that the material (e.g., metal) of frame 904 does not unduly affect the inductance of inductor 902. Here inductor 902 has a central opening 910. In some embodiments, such as described below, the central opening 910 may be used to house one or more components (not shown) of the device 900. The inductor 902 may be located at a layer of a circuit board (not shown) facing a heat carrier (not shown). For example, the inductor 902 may be positioned at the bottom layer 112 (fig. 1). Through-hole connections 912 may be provided between different layers of the circuit board. For example, the via connection 912 may be positioned between the top layer 104 (fig. 1) and the bottom layer 112 (fig. 1). A heat carrier (not shown) may be provided at a side of frame 904 opposite inductor 902.

Fig. 10A and 10B show an example of an apparatus 1000 with a transformer 1002. Apparatus 1000 and/or transformer 1002 may be used with any of the examples described herein. For example, the RF structure 114 (fig. 1) may form a portion of the transformer 1002 (e.g., a primary or secondary winding thereof). The apparatus 1000 includes a frame 1004 that defines a cavity 1006. For example, the frame 134 (fig. 1) may form a portion of the frame 1004. Cavity 1006 may have a similar or identical function as cavity 130 (fig. 1). The gap 1008 between the outer perimeter of the transformer 1002 and the inner surface of the frame 1004 may be selected such that the material (e.g., metal) of the frame 1004 does not unduly affect the inductance of the transformer 1002. Here the transformer 1002 has a central opening 1010. In some embodiments, the central opening 1010 may be used to house one or more components 1012 of the device 1000. In some implementations, component(s) 1012 may be components other than inductors, transformers, or transmission lines. For example, component(s) 1012 may be resistors and/or capacitors. The component(s) 1012 may be supported by the frame island 400 (fig. 4) to avoid damage due to PCB bending. The component(s) 1012 may be mounted to a surface of the circuit board remote from the heat carrier (e.g., the top layer 104 in fig. 1). A heat carrier (not shown) may be provided at the side of the frame 904 opposite the transformer 1002.

The primary winding of the transformer 1002 may be located at a layer of a circuit board (not shown), and the secondary winding of the transformer 1002 may be located at the same or opposite layer of the circuit board. For example, one of the primary and secondary windings may be positioned at the top layer 104 (fig. 1) and the other of the primary and secondary windings may be positioned at the bottom layer 112 (fig. 1).

The apparatus 1000 is an example of an apparatus in which an RF structure (e.g., transformer 1002) has a central opening (e.g., central opening 1010), where the apparatus includes a component (e.g., component(s) 1012) on a circuit board that is aligned with the central opening. Apparatus 1000 illustrates that a frame island (e.g., frame island 400) may be coupled to a circuit board, the frame island supporting a component (e.g., component(s) 1012).

Fig. 11A and 11B show an example of an apparatus 1100 with a transmission line 1102. The apparatus 1100 and/or the transmission line 1102 may be used with any of the examples described herein. For example, the RF structure 114 (fig. 1) may form a portion of the transmission line 1102. The transmission line 1102 may be considered a microstrip. The apparatus 1100 includes a frame 1104 defining a cavity 1106. For example, frame 134 (fig. 1) may form a portion of frame 1104. The cavity 1106 may have a similar or identical function as the cavity 130 (fig. 1). The gap 1108 between the outer perimeter of transmission line 1102 and the inner surface of frame 1104 may be selected such that the material (e.g., metal) of frame 1104 does not unduly affect the impedance of transmission line 1102. Here transmission line 1102 meanders through the space provided by cavity 1106. The component 1110 may be positioned on the frame 1104 and thereby cooled by the frame 1104. A heat carrier (not shown) may be provided at the opposite side of the frame 1104 from the transfer line 1102.

Fig. 12 shows another example of the apparatus 100 of fig. 1. The apparatus 100 may be used with any of the examples described herein. Some elements of the device correspond to the elements with the same reference numerals in fig. 1 and are not mentioned below. The RF structures 108 'and 114' may be planar inductive components of the circuit board 102. Here MSCS116 includes stacks 120 and 122, where stack 122 includes portion 128A of layer 128 (e.g., thermal material), metal layer 134 '(e.g., copper), and TIM 124'. The metal layer 134' is not shaped as a frame here, and the stack 120 is not formed in any cavities or recesses here. Conversely, the metal layer 134' may have a polygonal shape (e.g., a pad or other rectangular shape). Stack 120 is formed adjacent to stack 122. Stack 120 includes portion 128A, dielectric layer 126 '(e.g., a ceramic pad), and TIM 124'. That is, portion 128A and/or TIM 124' may be common to both stacks 120 and 122. The dielectric layer 126' may have a polygonal shape (e.g., a pad or other rectangular shape). The metal layer 134 'and the dielectric layer 126' may have the same shape or different shapes from each other. The apparatus 100 may include one or more metal layers 134' (e.g., one or more metal pads). The apparatus 100 may include one or more dielectric layers 126' (e.g., one or more ceramic pads). The laminate 120 is positioned adjacent to the RF structures 108 'and 114' (e.g., on the bottom side) to provide cooling to the circuit board 102 without significantly degrading inductance and/or impedance. The apparatus 100 may also include one or more instances of a frame-based stacking method (e.g., as described with reference to fig. 1). As another example, an apparatus using a frame-based lamination method (e.g., as described with reference to fig. 1) may also include one or more instances corresponding to the examples provided.

The metal layer 134' may have at least one layer 127 covering all or some of its outer surface. Layer 127 may be formed by surface treatment of metal layer 134' to prevent oxidation. In some embodiments, layer 127 may comprise tin. In some embodiments, layer 127 may comprise gold. For example, gold may be applied over the nickel plating of metal layer 134'. The circuit board 102 may be processed by similar or the same substances as in layer 127 applied to the metal layer 134'.

Fig. 13A to 13C show examples of arrangements with circuit boards. In fig. 13A, a circuit board 1300 (e.g., PCB) is shown in top view and has a dielectric layer 1302 (e.g., ceramic material) and a metal layer 1304 (e.g., copper). The circuit board 1300, dielectric layer 1302, and metal layer 1304 may be used with any of the examples described herein. For example, the dielectric layer 1302 may be used to provide cooling for planar inductive components of the circuit board 1300. For example, the metal layer 1304 may be used to provide cooling for non-planar (e.g., soldered) components of the circuit board 1300. Here, the dielectric layer 1302 and the metal layer 1304 are placed side-by-side on the circuit board 1300 (e.g., attached thereto by an adhesive material). The dielectric layer 1302 and the metal layer 1304 form a boundary 1306 between them. The use of the dielectric layer 1302 and the metal layer 1304 may avoid the need to process recesses or cavities in the metal layer (as compared to the layer 134 with the cavity 130 in fig. 1). Thus, the examples provided may represent a less costly and/or simpler way of providing cooling.

One or more components may be positioned in direct contact with the metal layer 1304. In some embodiments, the circuit board 1300 may include at least one concave portion 1308 facing the metal layer 1304. The recesses 1308 may serve a similar or identical purpose as the recesses 204 (fig. 2). For example, the recesses 1308 may accommodate one or more power components 1310 (e.g., transistors) to be mounted on the metal layer 1304. In this example, the recess 1308 and the power component 1310 are shown in dashed lines because they are obscured by the metal plate 1304.

In fig. 13B, the dielectric layer 1302 and the metal layer 1304 are spaced apart compared to the example in fig. 13A. A layer 1312 is disposed between the dielectric layer 1302 and the metal layer 1304. In some embodiments, layer 1312 comprises a material having adhesive properties, including but not limited to a prepreg. For example, during assembly, when the dielectric layer 1302 and the metal layer 1304 are adhered to the circuit board 1300 (e.g., by applying prepreg), adhesive may enter the gap between the dielectric layer 1302 and the metal layer 1304 (e.g., during a pressing operation).

The circuit board 1300 may be provided with one or more dielectric layers 1302. The circuit board 1300 may be provided with one or more metal layers 1304. Each of the dielectric layer 1302 and the metal layer 1304 may have any suitable shape and/or size in view of the circuit board 1300 and its corresponding components. Fig. 13C shows the circuit board 1300 with the dielectric layer 1302 as in the previous example. A smaller metal layer 1304' than the metal layer 1304 (fig. 13A and 13B) is disposed adjacent to the dielectric layer 1302. Another dielectric layer 1302 'is disposed adjacent to the dielectric layer 1302 and the metal layer 1304'. For example, this may correspond to a device having more than two (e.g., more than three) stacks in a multi-layer cooling structure. The configuration of fig. 13C may be used when the planar inductive component of circuit board 1300 is in a larger proportion than the solder component. In some embodiments, the dielectric layers 1302 and 1302' may be a unitary layer.

Further embodiments are summarized in the following examples:

example 1: an apparatus comprising: a circuit board having a Radio Frequency (RF) structure at a first location, the RF structure formed from conductive traces of the circuit board; a heat transfer medium; and a multi-layered cooling structure coupling the circuit board and the heat carrier to each other, the multi-layered cooling structure comprising a first stack adjacent the RF structure at a first location and a second stack at a second location, the first stack comprising an inlay adjacent the heat carrier and a first thermal interface material coupling the inlay and the circuit board to each other, the inlay being more thermally conductive and rigid than the first thermal interface material.

Example 2: the apparatus of example 1, wherein the second laminate is formed from a frame coupled to the circuit board.

Example 3: the apparatus of example 2, further comprising a cavity in the frame, the cavity containing the first laminate.

Example 4: the apparatus of examples 2 or 3, wherein the first thermal interface material compensates for tolerance variations in the frame.

Example 5: the apparatus of any of examples 2-4, wherein the frame comprises at least one of a metal and a circuit board substrate.

Example 6: the apparatus of any of examples 2-5, wherein the first thermal interface material further couples the frame to the circuit board.

Example 7: the apparatus of any of examples 2-6, further comprising a second thermal interface material coupling the frame to the circuit board.

Example 8: the device according to any one of examples 2 to 7, wherein the dimension of the inlay in the direction between the circuit board and the heat carrier is greater than half the dimension of the frame in this direction.

Example 9: the apparatus of any of examples 2-8, further comprising a power component mounted to the frame at the second location, the circuit board including a cavity for receiving the power component.

Example 10: the apparatus of any preceding example, wherein the first thermal interface material comprises at least one of a thermal pad, an adhesive, a bonding film, a matrix fiber aggregate, a solder, and a glue.

Example 11: the apparatus of any preceding example, wherein the RF structure has a central opening, further comprising at least one component on the circuit board aligned with the central opening.

Example 12: the apparatus of example 11, further comprising a frame island coupled to the circuit board, the frame island supporting the component.

Example 13: the apparatus of example 12, wherein the circuit board has a first layer facing the frame island and a second layer opposite the first layer, the at least one component being mounted to the second layer.

Example 14: the apparatus of any preceding example, wherein the RF structure comprises at least one of an inductor, a transformer, and a transmission line.

Example 15: an apparatus as in any preceding example, wherein the circuit board has a first layer facing the multi-layer cooling structure and a second layer opposite the first layer.

Example 16: the apparatus of example 15, wherein the RF structure is located at the first layer.

Example 17: the apparatus of any of the preceding examples, wherein the inlay comprises at least one of a ceramic material and a ferromagnetic ceramic material.

Example 18: an apparatus comprising: a printed circuit board having a Radio Frequency (RF) structure at a first location on a first surface, the printed circuit board having a second surface opposite the first surface, the RF structure being formed from conductive traces of the printed circuit board and including at least one of an inductor, a transformer, and a transmission line; a heat carrier including at least one of a radiator and a water-cooled plate; and a multi-layered cooling structure coupling the printed circuit board and the heat carrier to each other, the multi-layered cooling structure comprising a first stack adjacent the RF structure at a first location and a second stack at a second location, the first stack comprising a ceramic mat coupled to the heat carrier by a thermal paste and a thermal interface material coupling the ceramic mat and the printed circuit board to each other, the thermal interface material comprising at least one of a thermal pad, an adhesive, a bonding film, a matrix-dimensional aggregate, a solder, and an adhesive, the ceramic mat having a higher thermal conductivity and rigidity than the thermal interface material, the second stack comprising a frame coupled to the heat carrier by the thermal paste, the frame comprising at least one of copper and a printed circuit board substrate, the frame coupled to a first surface of the printed circuit board by the adhesive, the frame having a cavity therein for receiving the first stack.

A number of embodiments have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the description.

In addition, the logic flows depicted in the figures do not require the particular order shown, or sequential order, to achieve desirable results. In addition, other steps may be provided, or steps may be eliminated, from the described flows, and other components may be added to, or removed from, the described systems. Accordingly, other implementations are within the scope of the following claims.

While certain features of the described embodiments have been illustrated in the description herein, many modifications, substitutions, changes, and equivalents will now occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the scope of the embodiments. It is to be understood that they have been presented by way of example only, and not limitation, and various changes in form and details may be made. Any portion of the devices and/or methods described herein may be combined in any form, except mutually exclusive combinations. The embodiments described herein may include various combinations and/or subcombinations of the functions, components and/or features of the different embodiments described.