Integrated gan power module

Abstract

Integrated power modules in accordance with the present technology can include a printed circuit board featuring a first surface and a second surface. The integrated power modules can include one or more surface mount components coupled with the first surface of the printed circuit board. The integrated power modules can include a thermal transfer substrate. The integrated power modules can include one or more gallium nitride transistors coupled between and soldered to each of the second surface of the printed circuit board and the thermal transfer substrate. The integrated power modules can include one or more spacers coupled between and soldered to each of the printed circuit board and the thermal transfer substrate.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Non-Provisional Application No. 17 / 387,093, filed July 28, 2021, entitled “INTEGRATED GAN POWER MODULE.” The contents of this application are incorporated herein by reference. TECHNICAL FIELD

[0003] The present technology relates to power modules. More specifically, the present technology relates to power modules incorporating gallium nitride components. BACKGROUND

[0004] Power modules are useful for improving efficiency and power density while reducing cost. As more devices with increasing power demands are developed, improved power modules are needed. SUMMARY

[0005] An integrated power module according to some embodiments of the present technology can include a printed circuit board characterized by a first surface and a second surface. The integrated power modules can include one or more surface mount components coupled with the first surface of the printed circuit board. The integrated power modules can include a thermal transfer substrate. The integrated power modules can include one or more gallium nitride transistors coupled between and soldered to each of the second surface of the printed circuit board and the thermal transfer substrate. The integrated power modules can include one or more spacers coupled between and soldered to each of the printed circuit board and the thermal transfer substrate.

[0006] In some embodiments, the heat transfer substrate can be an insulated metal substrate. The insulated metal substrate can include a copper base and one or more insulating layers. The one or more surface mount components can include at least one of a gate driver, a capacitor, a diode, a switch, or a thermistor. The one or more standoffs can include solder plated copper standoffs. At least one standoff can be coupled with a via formed through the printed circuit board and configured to transfer heat from the one or more surface mount components to the heat transfer substrate. The module can include a mold extending between the printed circuit board and the heat transfer substrate and further extending around the one or more gallium nitride transistors and the one or more standoffs. The module can include a potting extending across the first surface of the printed circuit board and extending around the one or more surface mount components. The heat transfer substrate can be a direct bonded copper plate. The direct bonded copper plate can include a first copper layer coupled with the one or more gallium nitride transistors, a second copper layer, and a ceramic layer. The first copper layer can be characterized by an arcuate profile along the integrated power module. At least a portion of the second copper layer can be removed, thereby exposing the ceramic layer.

[0007] Some embodiments of the present technology can include integrated power modules. These modules can include a printed circuit board characterized by a first surface and a second surface. These modules can include one or more surface mount components coupled with the first surface of the printed circuit board. These modules can include a first heat transfer substrate. These modules can include a second heat transfer substrate. These modules can include a first gallium nitride transistor coupled between and soldered to each of the second surface of the printed circuit board and the first heat transfer substrate. These modules can include a second gallium nitride transistor coupled between and soldered to each of the second surface of the printed circuit board and the second heat transfer substrate.

[0008] In some embodiments, the modules can include at least four heat transfer substrates including the first heat transfer substrate and the second heat transfer substrate. The modules can include at least four gallium nitride transistors including the first gallium nitride transistor and the second gallium nitride transistor. The first heat transfer substrate and the second heat transfer substrate can each be an insulated metal substrate including a copper base and one or more insulating layers. The modules can include a molding that extends along the second surface of the printed circuit board and between the first heat transfer substrate and the second heat transfer substrate. The first heat transfer substrate and the second heat transfer substrate can each be direct bonded copper including a ceramic layer between copper layers. The modules can include a transformer core coupled with the first surface of the printed circuit board. The transformer core can divide the surface mount components into a first subset of surface mount components and a second subset of surface mount components. The first heat transfer substrate can be coupled with the printed circuit board in association with the first subset of surface mount components. The second heat transfer substrate can be coupled with the printed circuit board in association with the second subset of surface mount components. The modules can include one or more first spacers coupled between and soldered to each of the printed circuit board and the first heat transfer substrate. The modules can include one or more second spacers coupled between and soldered to each of the printed circuit board and the second heat transfer substrate.

[0009] Some embodiments of the present technology can include integrated power modules. The modules can include a printed circuit board featuring a first surface and a second surface. The modules can include one or more surface mount components coupled with the first surface of the printed circuit board. The modules can include a heat transfer substrate including an insulated metal substrate having a copper base and one or more insulating layers. The modules can include one or more gallium nitride transistors coupled between and soldered to each of the second surface of the printed circuit board and the heat transfer substrate. The modules can include one or more spacers coupled between and soldered to each of the printed circuit board and the heat transfer substrate. The one or more spacers can include solder plated copper spacers.

[0010] Such technology can provide significant benefits over conventional technology. For example, power modules according to some embodiments of the technology can feature increased power density due to improved material configurations. Additionally, power modules according to some embodiments of the technology can improve heat transfer from auxiliary circuits, which can improve performance over conventional technology. These and other embodiments, along with many of their advantages, are described in more detail in conjunction with the following description and drawings. BRIEF DESCRIPTION OF DRAWINGS

[0011] A further understanding of the nature and advantages of the disclosed embodiments can be realized by reference to the remaining portions of the specification and the drawings.

[0012] Figure 1 A schematic cross-sectional view of a power module according to some embodiments of the technology is shown.

[0013] Figure 2 A schematic cross-sectional view of a power module according to some embodiments of the technology is shown.

[0014] Figure 3 A schematic cross-sectional view of a power module according to some embodiments of the technology is shown.

[0015] Figure 4 A schematic cross-sectional view of a power module according to some embodiments of the technology is shown.

[0016] Figure 5 A schematic cross-sectional view of a power module according to some embodiments of the technology is shown.

[0017] Several of the figures in the drawings are included as schematic representations of embodiments of the technology. It should be understood that the figures are merely meant to be illustrative and are not to be taken in a literal sense. Unless specifically indicated, the drawings are not to scale and are not intended to be of any particular proportion. Further, as schematic representations, the drawings are provided to aid in understanding and can not include all aspects or information as compared to actual representations, and can include exaggerated materials for illustrative purposes.

[0018] In the drawings, like reference numerals can be used to denote similar components and / or features throughout the several views. Further, various components of the same type can be distinguished from one another by a letter suffix, e.g., 103a, 103b, etc. Where the context permits, reference can be made to a group of similar components collectively or individually by reference to one of the group using an unsuffixed reference numeral, e.g., 103, and an appropriate adjective. DETAILED DESCRIPTION

[0019] Integrated power modules provide packaged semiconductor devices with higher power density than many standalone configurations deliver. As the power demands of large numbers of devices and machines increase, improved power modules are being developed. For systems requiring increased power levels, the integration of semiconductor devices can determine the overall power density of the power module. As increased demands and faster switching speeds are pursued, materials featuring wider bandgaps are being used. For example, power modules are attempting to incorporate switches or diodes including silicon carbide or gallium nitride. However, these faster switching materials can generate increased heat that, if not properly dissipated from the system, can inhibit performance.

[0020] Many conventional power modules attempting to incorporate silicon carbide or gallium nitride are limited in operational capability due to lower heat dissipation, which is often a result of the module configuration. A potential solution can be to improve the conduction path from the semiconductor devices to an associated heat sink, such as a cold plate, which can be performed by reducing the component spacing and layer spacing. However, these reductions can be impeded or prevented due to component mismatches. For example, producing a flat power module including a flat heat extraction surface can improve conduction contact with a cold plate or other heat sink. Similarly, increasing the coupling between the circuitry, semiconductor switches, and a backplane, which can then be coupled with a heat sink, can improve heat dissipation during operation.

[0021] In conventional designs, producing these closer couplings can be impeded due to mismatches between components. For example, a circuit board on which circuitry is disposed can feature a different coefficient of thermal expansion compared to a backplane. If the semiconductor switches are directly coupled with each of the circuit board and the backplane, at least one of these components can warp during a soldering operation. For example, the backplane can warp during a soldering operation, which can cause a number of problems. The circuit board can be fiberglass and copper, while the backplane, such as a direct bonded copper, can include a ceramic featuring different thermal properties that will cause the backplane to warp. During cooling after soldering, the connections can break, which can limit performance, if not cause yield loss. Additionally, a warped or non-flat backplane can impede coupling with a heat sink, requiring increased coupling material, such as thermal paste, which can increase thermal resistance between components and limit performance due to lower heat dissipation. Thus, many conventional designs are limited to separating the circuit board from the switches and including additional gate drive boards and board-to-board connectors, or producing structures that will necessarily include a warped backplane when the switches are soldered to each of the circuit board and the backplane. Alternatively, some conventional techniques can include a gap pad between the semiconductor devices and the backplane, which can greatly reduce heat dissipation to a heat sink, limiting the operational capability of the module.

[0022] The present technology overcomes these problems by utilizing additional baseplate materials or designs that can accommodate for differences in thermal expansion between materials and can allow for closer coupling. By providing a direct coupling solution with the semiconductor devices, gate drivers and other components can be positioned closer to the switches, which can be or include gallium nitride. With this closer connection, the decoupling loop and gate drive loop for capacitors can be greatly reduced, improving switch speed. As a result, dv / dt and di / dt related losses can be minimized in the present technology, which can allow devices according to some embodiments of the present technology to operate over a wider current and voltage range. Improved heat sinking can also be provided, which can allow gallium nitride switches to operate faster and more efficiently, further improving device performance.

[0023] While the remainder of the specification will refer to power modules including gallium nitride switches, those skilled in the art will readily understand that the present technology is not so limited. The materials and technology can be used with any power module topology and components, including other semiconductor materials such as silicon carbide or other materials. Further, the present technology can be applicable to power modules used in any technology, which can include but are not limited to power conversion equipment including motor drives, power supplies, AC-DC power converters, high voltage to low voltage converters, or uninterruptible power supplies. These devices can be capable of implementation in grid applications, green technologies such as including solar panels, home appliances, or any other system or device that can benefit from aspects of the present technology.

[0024] Figure 1 A schematic cross-sectional view of a power module 100 is shown according to some embodiments of the present technology. This figure can illustrate components and configurations that can be incorporated in any power module according to some embodiments of the present technology. This figure shows a top side cooling device in a configuration that can maintain a substantially uniform gap between the circuit board and the baseplate. While some embodiments of the present technology can utilize direct bonded copper as a baseplate or heat transfer substrate, as will be further described below, in some embodiments as shown, the baseplate or heat transfer substrate can be or include an insulated metal substrate as a heat transfer substrate 105. Figure 1 A power module is shown that has been coupled with a cooling plate 103 or heat sink, which can be a gas or liquid flow heat sink. It should be understood that the heat sink is shown for understanding of the coupling according to some embodiments of the present technology and can not be included in a power module including the power module 100 according to some embodiments of the present technology, such as where the heat sink can be incorporated with a system or device in which the power module is installed.

[0025] An insulated metal substrate or IMS board can include a metal substrate 106 and one or more layers shown as layers 108. Layers 108 can represent one or more layers of insulating material and / or copper foil as will be understood to be included in an IMS board. In some embodiments, a single insulating layer and a single copper foil layer can be included, but in other embodiments additional layers can be included. For example, by including multiple layers, one or more of the layers can serve as a ground layer or electromagnetic compatibility shield, as well as a current and / or heat distribution layer. Thus, it will be understood that in embodiments of the technology, layers 108 can include one or more layers of each of insulating and / or foil. Additionally, metal substrate 106 can be or include any kind of metal, such as aluminum, copper, or other metals, but in some embodiments the metal can be copper. While aluminum is used in some IMS boards, aluminum can be characterized by a coefficient of thermal expansion that can limit or otherwise affect coupling between layers in a configuration as shown. In some embodiments, by utilizing copper as metal substrate 106, a flat substrate and more complete coupling can be maintained during a soldering process. Thus, while an integrated metal substrate can increase local thermal resistance at one or more insulating layers, such as compared to a directly bonded copper substrate, the substrate can provide a substantially flat profile at a base surface to couple with a cold plate or other device.

[0026] An integrated metal substrate can maintain an overall increased heat dissipation potential as compared to a directly bonded carbon, which can be warped in the case of including soldering as described above and can be characterized by a greater overall barrier between a power module and a cold plate. Substantially flat means to include machine tolerances that can prevent a perfect flatness as well as natural surface roughness, but substantially flat can maintain a surface profile that can maintain a consistent surface that can provide contact with a cold plate or other component at greater than or about 90% of a base of the integrated metal substrate, and can maintain contact at greater than or about 95%, greater than or about 97%, greater than or about 99% or more. Similarly, in the case that a thermally conductive grease or paste can be disposed between an integrated metal substrate and a cold plate, a thickness of the thermally conductive paste can be consistent in thickness to + / - 1%, + / - 0.5%, + / - 0.1% or less over greater than or about 90% of a contact area, and can be maintained over greater than or about 95% of a contact area, greater than or about 97% of a contact area, greater than or about 99% of a contact area or more of a contact area.

[0027] The integrated power module 100 can include a circuit board 110, which can be any type of printed circuit board, such as an FR4 board in non-limiting embodiments of the present technology. It should be appreciated that the circuit board 110 can be any board that can be or include one or more fiberglass layers and / or copper layers, as well as any other circuit board material. Any substrate that is operable to hold auxiliary circuitry or components can be included in embodiments of the present technology, and can be used as the circuit board 110. The circuit board 110 can be characterized by a first surface 112 and a second surface 114, which can be opposite the first surface 112 as shown. Along the first surface 112 can be mounted or coupled with the first surface one or more components of a power module, such as surface mount components. The components 115 and 117 shown can be or include any kind of component in any configuration.

[0028] It should be appreciated that the present technology can be used in power modules characterized by any kind of topology, and can include any kind of component. For example, the components can be or include capacitors, gate drivers, diodes, switches, thermistors, connectors such as including for transformers, or sensors, which can be included to produce any topology, such as topologies that can include switches, bridge rectifiers, power converters, neutral point clamped configurations, inverters, or other topologies that can include any kind of component to produce circuitry of various configurations. Accordingly, the figures and subsequent figures are not intended to limit any aspect of the present technology. As shown, the components 115 and 117 can be soldered to the circuit board 110, but the present technology can include any other coupling.

[0029] In some embodiments, the integrated power module 100 optionally can include a dam 120 or other structure that can be coupled with the circuit board 110 around a perimeter of an active area of the first surface 112 of the circuit board 110. The dam can be a plastic, rubber, or some polymeric material that can be glued or otherwise adhered to the first surface 112 of the circuit board 110 as shown. Optionally included within the dam 120 can be a potting 122 that extends across the first surface 112 of the circuit board 110, and which can further extend around one or more surface mount components as shown. The potting 122 can be any kind of material, such as any rubber material, epoxy, silicone, or any other encapsulation material that can be used in semiconductor or electronics technology. Additionally, the potting 122 can be characterized by an increased thermal conductivity, which can provide improved heat dissipation from components such as capacitors.

[0030] Coupled with the second surface 114 of the circuit board 110 can be one or more components that can also be coupled with the insulated metal substrate. As shown, in some embodiments, the circuit board 110 can be separated from the heat transfer substrate by one or more components, but in some embodiments, the circuit board can include certain components embedded and can extend to contact the heat transfer substrate. The components disposed between the circuit board 110 and the heat transfer substrate 105 can include one or more gallium nitride components 125 used in the power module, such as switches or transistors. Although the remaining description identifies the components as including gallium nitride, it should be understood that in some embodiments, additional semiconductor materials can be used, such as silicon-containing materials including silicon or silicon carbide. Additionally, although two gallium nitride components 125 are shown, it should be understood that a power module according to some embodiments of the present technology can include any number of gallium nitride components 125, including greater than or about 2, greater than or about 4, greater than or about 6, greater than or about 8, greater than or about 10, or more, depending on, for example, the topology, device size, and component configuration.

[0031] The gallium nitride components 125 can be coupled between the circuit board 110 and the heat transfer substrate 105 as previously noted, and can be in contact with each component, such as directly soldered to each of the second surface 114 of the circuit board 110 and the heat transfer substrate 105, as shown. Additionally, to improve coupling and retention during the soldering process, in some embodiments, an underfill 126 can be included along any surface of the gallium nitride components 125, such as between the solder contacts along the second surface 114 of the circuit board 110, as shown. The underfill 126 can be any number of materials used for solder underfill, and can include an epoxy or other polymeric material as well as any number of fillers, flow agents, or other materials.

[0032] In some embodiments, a power module according to the present technology can include one or more spacers 130 that can be positioned at one or more locations between the circuit board 110 and the heat transfer substrate 105. Similar to the gallium nitride components 125, the spacers 130 can be coupled between the circuit board 110 and the heat transfer substrate 105, and can be soldered to each of the circuit board 110 and the heat transfer substrate 105. The spacers 130 can include a metallic material, such as copper or some other material, that can provide one or more effective effects to the power module, and the metallic material can be plated with solder or other conductive coupling material. For example, the spacers 130 can be incorporated to maintain a particular gap distance between the circuit board 110 and the heat transfer substrate 105 during a reflow operation in which the solder on each side of the gallium nitride components 125 and / or the spacers 130 can be melted to engage with the corresponding surfaces of the circuit board and the heat transfer substrate.

[0033] The spacers 130 can be positioned around the periphery of the board, as well as within the interior region, and in some embodiments can be used to facilitate heat transfer from the circuit board. For example, in some embodiments one or more vias 132 can be formed proximate the location of one or more spacers, which can more easily draw heat from the surface mount components to the spacers and underlying heat transfer substrate. The vias 132 can extend at least partially through the circuit board 110, and in some embodiments can extend completely through the circuit board 110. In embodiments of the technology, the vias can be coupled with traces or other heat spreaders within the circuit board, as well as proximate or coupled with one or more surface mount components. The spacers 130 can similarly provide current sharing between the circuit board and heat transfer substrate based on the coupling with the component layer. Additionally, the spacers can be incorporated to provide electromagnetic compatibility shielding connection locations around the power module. In some embodiments, the spacers can be coupled with the foil layer of the heat transfer substrate, as well as with the base metal layer. Regardless, the spacers can provide access to the heat transfer substrate, which can in turn provide lateral and vertical distribution and dissipation of heat.

[0034] In some embodiments, a molding 140 can be incorporated between and extend along and / or contact each of the circuit board 110 and the heat transfer substrate 105. The molding 140 can be any kind of encapsulation material used, for example, in semiconductor packaging, and can include any of the previously noted materials for potting, as well as other epoxies, hardeners, fillers, catalysts, or other agents that can be incorporated in a molding or overmolding. In some embodiments, the molding 140 can extend around the gallium nitride components 125, as well as the spacers 130, and can provide additional rigidity to the power module and components.

[0035] Additionally, the molding 140 can provide environmental protection, which can facilitate lower leakage and clearance requirements, and which can allow for closer coupling of components, for example. This can increase module density, while providing a stable package that can further distribute heat for improved heat transfer. Although shown with similar lateral dimensions as each of the circuit board 110 and the heat transfer substrate 105, in some embodiments the components can not be similarly sized. For example, in some embodiments the circuit board 110 can be characterized by a longer lateral dimension than the heat transfer substrate. In some embodiments, the molding can then extend around the heat transfer substrate and increase the lateral dimension in order to provide dimensional consistency around the power module. For example, during dicing, the molding and / or the circuit board can be trimmed to provide vertical sidewalls for each material.

[0036] A power module incorporating embodiments of the technology can also include a heat transfer substrate 105 that is coupled with the circuit board 110 and that is configured to provide heat transfer from the circuit board to the heat transfer substrate. In some embodiments, the heat transfer substrate can be coupled with the circuit board via a base metal layer 120, which can be coupled with the circuit board 110 and the heat transfer substrate 105. In some embodiments, the base metal layer can be coupled with the circuit board via a solder layer 115, which can be coupled with the circuit board 110 and the base metal layer 120. In some embodiments, the base metal layer can be coupled with the heat transfer substrate via a solder layer 115, which can be coupled with the heat transfer substrate 105 and the base metal layer 120. In some embodiments, the base metal layer can be coupled with the circuit board and the heat transfer substrate via a solder layer 115, which can be coupled with each of the circuit board 110, the base metal layer 120, and the heat transfer substrate 105. Figure 1One or more modifications of the illustrated structure, and the one or more modifications can provide additional flexibility to the module for a variety of environmental and configuration capabilities. It should be appreciated that any of the designs illustrated can show additional features of the power module 100, or can include any of the features or aspects of the power module 100 described above.

[0037] Turning to Figure 2 , a schematic cross-sectional view of a combined power module 200 is shown, and the combined power module can include more than one heat transfer substrate. The combined power module 200 can include any of the features, aspects, components, or materials from the combined power module 100, and in some embodiments can show additional features of the combined power module 100. For example, the combined power module 200 can include any of the components as previously described, and these components can be included in the power module 200. The combined power module 200 can include a plurality of heat transfer substrates, such as a first heat transfer substrate 205a and a second heat transfer substrate 205b, which can include any of the aspects of the heat transfer substrate previously discussed, and which can be insulated metal substrates as previously described. The module can include a circuit board 210, which can include one or more surface mount components 215 on a first surface of the circuit board, and which can be any of the materials and components previously described.

[0038] The power module can include one or more gallium nitride components as previously described, and can include a number of heat transfer substrates that is less than or equal to the number of gallium nitride components. For example, each gallium nitride component can include a corresponding heat transfer substrate, or a plurality of gallium nitride components can share a heat transfer substrate. Although any variety of transistors or switches can be included in embodiments according to the present technology, in some embodiments the power module can include at least a first gallium nitride component 225a and a second gallium nitride component 225b. Each of the components can be coupled between and soldered to a second surface of the circuit board 210. Additionally, the components can be soldered to corresponding heat transfer substrates. For example, as shown, the first gallium nitride component 225a can be coupled with the first heat transfer substrate 205a, and the second gallium nitride component 225b can be coupled with the second heat transfer substrate 205b. As shown, the power module can also include a third heat transfer substrate coupled with a third gallium nitride component and a fourth heat transfer substrate coupled with a fourth gallium nitride component. Thus, any variety of transistors and heat transfer substrates can be incorporated in power modules according to embodiments of the present technology.

[0039] In some embodiments, as previously discussed, a potting can optionally be included, and a mold 240 can be included to support the power module and provide rigidity to the individual heat transfer substrates and transistors. The mold 240 can extend along the second surface of the circuit board 210, and can extend around and between the heat transfer substrates and gallium nitride components. As previously explained, bonding the gallium nitride components to the circuit board and heat transfer substrates can cause a certain amount of distortion in one of the substrates. By limiting the size of the substrate to be similar to the size of the components, the stress that results from the mismatch can be accommodated. Additionally, after the reflow operation and / or mold formation, a planarization operation can be performed along the base of the power module to ensure a substantially planar surface across and along each of the heat transfer substrates for coupling with, for example, a cold plate. Although heat transfer can be reduced relative to larger heat transfer substrates as shown elsewhere in this disclosure, in some embodiments, the individual heat transfer substrates or planarization operation can allow the heat transfer substrates to have greater flexibility, which can provide for reduced package size, as will be further described below.

[0040] Figure 3 A schematic cross-sectional view of a power module 300 is shown, in accordance with some embodiments of the present technology, and the power module can include a directly bonded copper substrate as a heat transfer substrate. The power module 300 can include any features, aspects, components, or materials from the power module 100, and in some embodiments can exhibit additional features of the power module 100. For example, the power module 300 can include a heat transfer substrate 305 featuring a reduced thickness, such as, for example, a directly bonded copper substrate. The power module can include any other components as previously discussed for any other power module. For example, the module can include a circuit board 310, which can include one or more surface mount components 315 on a first surface of the circuit board, and which can be any of the materials and components previously described. The power module 300 can include any number of gallium nitride components 325 and spacers 330, which can be or include any of the components or configurations as discussed above. The module can also optionally include a potting and / or a mold as discussed above.

[0041] As previously discussed, the soldering process for coupling gallium nitride components to circuit boards and heat transfer substrates can cause warping of the directly bonded copper substrate due to the difference in thermal expansion coefficients between the substrate and the circuit board. Solder plated on each of the components can be used to accommodate the buckling that will occur, thus protecting the coupling from breakage during cooling. For example, the thickness of the solder or the size of the solder bumps can be adjusted across the substrate, with increased amounts of solder utilized near edge regions or other locations where more deflection may occur. When using a directly bonded copper substrate, the substrate may comprise a first copper layer and a second copper layer on opposite surfaces of a ceramic substrate, wherein the first copper layer can be coupled to the component.

[0042] The cooling process after soldering can cause the heat transfer substrate to warp in any way, resulting in an arcuate profile. As previously explained, conventional techniques are limited to adding a thermal coupling layer, such as thermal paste, which can, for example, reduce heat transfer between the heat transfer substrate and the cold plate. This technique can include modifications to the substrate and the soldering process. For example, pressure can be applied across the power module during the reflow process in which the solder can be heated, and during the subsequent cooling period, upwards onto the heat transfer substrate and / or downwards onto the circuit board, which can reduce the amount of warping during cooling. Similarly, the amount of solder can be adjusted to accommodate the stresses induced by the process. Thus, the amount of warping can be reduced or minimized.

[0043] Additionally, in some embodiments, the subsequent planarization operation can be performed along the back side of the heat transfer substrate. For example, as... Figure 3 As shown, a portion of the second copper layer, and a portion of the ceramic layer that may be exposed during removal, can be removed, depending on the degree of deflection, such as by grinding or other removal operations. This removal can produce a substantially flat profile across the back side of the heat transfer substrate. Therefore, during subsequent coupling with the cold plate, a similar contact or thermal paste thickness as described above can be provided, for example. Although there is potential copper loss in the edge regions as shown, the improved thermal conductivity of the directly bonded substrate improves overall performance. Additionally, subsequent operations can be performed to ensure copper plating along the surface of the substrate. For example, copper foil can be applied across the back side of the heat transfer substrate after the removal operation, or copper can be applied or sputtered across the back side to improve the heat transfer profile. Therefore, in some embodiments of this technology, a directly bonded copper substrate can be used as a heat transfer substrate by accommodating deformation that may occur during bonding.

[0044] Additionally, directly bonded copper substrates can be used as previously discussed... Figure 2 In similar configurations discussed, a separate heat transfer substrate is coupled to each of the gallium nitride switches. Figure 4A schematic cross-sectional view of an integrated power module 400 is shown in accordance with some embodiments of the present technology, and the integrated power module can show a direct bonded copper substrate incorporated as a separate heat transfer substrate. The integrated power module 400 can include any features, aspects, components, or materials from the integrated power module 100, and in some embodiments can show additional features of the integrated power module 100. Additionally, the integrated power module 400 can include any features or aspects of the integrated power module 200 discussed above, and the integrated power module 400 can include similar designs.

[0045] For example, the integrated power module 400 can include any of the components as previously described, and these components can be included in the power module 400. The integrated power module 400 can include a plurality of heat transfer substrates, such as a first heat transfer substrate 405a and a second heat transfer substrate 405b, which can include any aspects of the heat transfer substrates previously discussed, and which can be direct bonded copper substrates as previously described. The module can include a circuit board 410, which can include one or more surface mount components 415 on a first surface of the circuit board, and which can be any of the materials and components previously described.

[0046] The power module can include one or more gallium nitride components as previously described, and can include a number of heat transfer substrates less than or equal to the number of gallium nitride components. For example, each gallium nitride component can include a corresponding heat transfer substrate. Although any variety of transistors or switches can be included in embodiments in accordance with the present technology, in some embodiments the power module can include at least a first gallium nitride component 425a and a second gallium nitride component 425b. Each of the components can be coupled between and soldered to a second surface of the circuit board 410. Additionally, the components can be soldered to corresponding heat transfer substrates. For example, as shown, the first gallium nitride component 425a can be coupled with the first heat transfer substrate 405a, and the second gallium nitride component 425b can be coupled with the second heat transfer substrate 405b. Again, it should be understood that any variety of transistors and heat transfer substrates can be incorporated in power modules in accordance with embodiments of the present technology. In some embodiments, as previously discussed, a potting can be optionally included, and a molding 440 can be included to support the power module and provide rigidity to the separate heat transfer substrates and transistors. The molding 240 can extend along the second surface of the circuit board 210, and can extend around and between the heat transfer substrates and the gallium nitride components.

[0047] As explained above, directly bonded copper substrates are more likely to warp during cooling after a soldering process. By utilizing a heat transfer substrate that is similar in size or slightly larger than the switch, deformation during cooling can be limited or prevented. Additionally, as previously discussed, subsequent planarization can be performed along the backside of the power module. However, with a reduced size of the heat transfer substrate, planarization can be limited and can substantially maintain the copper on the backside of the directly bonded copper substrate, which can improve heat transfer from the device.

[0048] Figure 5 A schematic cross-sectional view of a combined power module 500 is shown in accordance with some embodiments of the present technology, and the combined power module can show a power converter with integrated transformer coils. The combined power module 500 can include any features, aspects, components, or materials from any of the combined power modules as discussed above, and in some embodiments can show additional features of any of the previously described combined power modules. For example, the combined power module 500 can be a power converter that includes multiple power modules on a single circuit board. For example, the power converter can include an AC to DC converter with each module and associated transformer, a high voltage to low voltage converter with each module and associated transformer, or any other configuration.

[0049] As shown, the configuration can include any of the components as previously described, and these components can be included in the power module 500. The combined power module 500 can include multiple heat transfer substrates, such as a first heat transfer substrate 505a and a second heat transfer substrate 505b, which can include any of the aspects of the heat transfer substrates previously discussed, and which can be any of the substrates as previously described. The module can include a circuit board 510, which can include one or more surface mount components 515 on a first surface of the circuit board, and which can be any of the materials and components previously described. Additionally, the components mounted across the circuit board can be divided into a first subset of components and a second subset of components, which can be located on either side of a transformer coil 520, which can separate two modules of the converter. It should be understood that the transformer is shown schematically to facilitate understanding of the device, and can be much larger than shown relative to other components of the converter or module.

[0050] The transformer coil 520 can be coupled with the first surface of the circuit board between the two modules formed, and a second transformer coil can be coupled with a second surface of the circuit board. This design can eliminate the need for transformer connectors, where the transformer can be characterized by an embedded coil in the circuit board. The configuration can also provide a lower profile converter. Additionally, when used, the potting included on the top side can also be included around the transformer coil, which can support and protect the components of the entire module.

[0051] The heat transfer substrates can be separated to support the bonded modules, where heat transfer substrate 505a can support a first module of the converter, and heat transfer substrate 505b can support a second module of the converter. For example, heat transfer substrate 505a can be coupled with first subset of gallium nitride components 525a and optional spacers 530a, and the heat transfer substrate can be coupled with a first region of circuit board 510 and associated with components on the circuit board for the first module. Similarly, heat transfer substrate 505b can be coupled with second subset of gallium nitride components 525b and optional spacers 530b, and the heat transfer substrate can be coupled with a second region of circuit board 510 and associated with components on the circuit board for the second module. The components and couplings can include any aspects of similarly named components as previously described. By utilizing components and configurations in accordance with embodiments of the present technology, improved power modules can be created that can overcome limitations in conventional configurations and improve efficiency and heat transfer within the device.

[0052] In the preceding description, for purposes of explanation, numerous specific details are set forth in order to provide an understanding of embodiments of the present technology. It will be apparent, however, to one skilled in the art that embodiments can be practiced without some of these specific details, or with additional details, apart from those not relevant to the disclosure.

[0053] Several embodiments are disclosed, and one skilled in the art will readily recognize that the disclosure is applicable to a wide variety of modifications and equivalent structures, and equivalent material substitutions, and changes in the specific details, configurations, and arrangements of the components and configurations as described and illustrated. Accordingly, there are many alternatives to the embodiments described and illustrated, and many implementations of the technology will now be or become apparent to those skilled in the art.

[0054] If a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range, is encompassed. Any narrower range or any other specified range is also encompassed. The upper and lower limits of these smaller ranges can independently be included or excluded in the smaller ranges, and the endpoints are included in the smaller ranges but not in the range subject to any exclusions. Unless the context clearly indicates otherwise, within the scope of the disclosure, the use of a sequential list, e.g., a list including a first item and a second item, implies that the first item precedes the second item and can be followed by a third item. Lists that are described as sequential include each recited member. When each member is preceded

[0055] As used herein and in the appended claims, the singular forms "a," "an," and "the" include plural reference unless the context clearly dictates otherwise. Thus, for example, a reference to "a material" includes a plurality of such materials, and a reference to "a spacer" includes reference to one or more spacers and equivalents thereof known to those skilled in the art, and so forth.

[0056] In addition, the words "comprise," "comprising," "include," "including," and "contains," when used in this specification and in the following claims, are intended to specify the presence of stated features, integers, components, or operations, but they do not preclude the presence or addition of one or more other features, integers, components, operations, acts, or groups.

Claims

1. An integrated power module, comprising: A printed circuit board, characterized in that it includes a first surface and a second surface, and includes a thermal via extending from the second surface to the first surface; One or more surface mount components, said one or more surface mount components being coupled to the first surface of the printed circuit board; Heat transfer substrate; One or more gallium nitride transistors, the one or more gallium nitride transistors being coupled between the second surface of the printed circuit board and the heat transfer substrate and soldered to each of the second surface of the printed circuit board and the heat transfer substrate; and A spacer is coupled between the printed circuit board and the heat transfer substrate and soldered to each of the printed circuit board and the heat transfer substrate, wherein the spacer is directly coupled to the thermal via.

2. The integrated power module according to claim 1, wherein the heat transfer substrate is an insulating metal substrate.

3. The integrated power module according to claim 2, wherein the insulating metal substrate comprises a copper substrate and one or more insulating layers.

4. The integrated power module of claim 1, wherein the one or more surface mount components include at least one of a gate driver, a capacitor, a diode, a switch, or a thermistor.

5. The integrated power module of claim 1, wherein the one or more spacers comprise solder-plated copper spacers.

6. The integrated power module of claim 5, wherein at least one spacer is coupled to a via formed through the printed circuit board and is configured to transfer heat from the one or more surface mount components to the heat transfer substrate.

7. The integrated power module according to claim 1, further comprising: A molded component that extends between the printed circuit board and the heat transfer substrate, and further extends around the one or more gallium nitride transistors and the one or more spacers.

8. The integrated power module according to claim 1, further comprising: A potting compound that extends across the first surface of the printed circuit board and around the one or more surface mount components.

9. An integrated power module, comprising: A printed circuit board, characterized in that it includes a first surface and a second surface, and includes a thermal via extending from the second surface to the first surface; One or more surface mount components, said one or more surface mount components being coupled to the first surface of the printed circuit board; First heat transfer substrate; Second heat transfer substrate; A first gallium nitride transistor is coupled between the second surface of the printed circuit board and the first heat transfer substrate and is soldered to each of the second surface of the printed circuit board and the first heat transfer substrate. A second gallium nitride transistor is coupled between the second surface of the printed circuit board and the second heat transfer substrate and is soldered to each of the second surface of the printed circuit board and the second heat transfer substrate. and A first spacer is coupled between the printed circuit board and the first heat transfer substrate and soldered to each of the printed circuit board and the first heat transfer substrate, wherein the spacer is directly coupled to the thermal via.

10. The integrated power module of claim 9, wherein at least one of the first heat transfer substrate and the second heat transfer substrate comprises a directly bonded copper plate.

11. The integrated power module of claim 10, wherein the directly bonded copper plate comprises a first copper layer, a second copper layer, and a ceramic layer coupled to the one or more gallium nitride transistors, and wherein the first copper layer is characterized by an arcuate profile along the integrated power module.

12. The integrated power module of claim 11, wherein at least a portion of the second copper layer is removed to expose the ceramic layer.

13. The integrated power module according to claim 9, further comprising: At least four heat transfer substrates, the at least four heat transfer substrates including the first heat transfer substrate and the second heat transfer substrate; and At least four gallium nitride transistors, the at least four gallium nitride transistors including the first gallium nitride transistor and the second gallium nitride transistor.

14. The integrated power module according to claim 9, wherein the first heat transfer substrate and the second heat transfer substrate are each an insulating metal substrate comprising a copper substrate and one or more insulating layers.

15. The integrated power module according to claim 9, further comprising: A molded component that extends along the second surface of the printed circuit board and extends between the first heat transfer substrate and the second heat transfer substrate.

16. The integrated power module of claim 9, wherein the first heat transfer substrate and the second heat transfer substrate are each copper comprising a directly bonded ceramic layer between copper layers.

17. The integrated power module according to claim 9, further comprising: A transformer core coupled to the first surface of the printed circuit board, wherein the transformer core divides the surface mount component into a first subgroup of surface mount components and a second subgroup of surface mount components.

18. The integrated power module of claim 17, wherein the first heat transfer substrate is coupled to the printed circuit board in association with the first subgroup of the surface mount components, and wherein the second heat transfer substrate is coupled to the printed circuit board in association with the second subgroup of the surface mount components.

19. The integrated power module according to claim 17, further comprising: One or more second spacers are coupled between the printed circuit board and the second heat transfer substrate and soldered to each of the printed circuit board and the second heat transfer substrate.

20. An integrated power module, comprising: A printed circuit board, characterized in that it includes a first surface and a second surface, and includes a via extending from the second surface to the first surface; One or more surface mount components, said one or more surface mount components being coupled to the first surface of the printed circuit board; A heat transfer substrate, the heat transfer substrate comprising an insulating metal substrate having a copper substrate and one or more insulating layers; One or more gallium nitride transistors, the one or more gallium nitride transistors being coupled between the second surface of the printed circuit board and the heat transfer substrate and soldered to each of the second surface of the printed circuit board and the heat transfer substrate; and A spacer, the spacer being coupled between the printed circuit board and the heat transfer substrate and soldered to each of the printed circuit board and the heat transfer substrate, wherein: The spacer is directly coupled to the via; and The one or more spacers mentioned above include solder-plated copper spacers.

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