Power electronics assembly with embedded power electronics

Abstract

A power electronic assembly with embedded power electronic devices is disclosed. In one embodiment, the power electronic assembly includes a circuit board assembly and a power electronic device assembly embedded in a substrate, the circuit board assembly including an electrically insulating substrate. The power electronic device assembly includes an S-cell, the S-cell including an inner graphite layer, a metal layer encapsulating the inner graphite layer, and a first surface of the metal layer, the first surface including a recess disposed within the first surface. The power electronic device assembly further includes a power electronic device disposed within the recess of the first surface.

Description

Technical Field

[0001] This specification relates in general to power electronic components, and more particularly to apparatus and methods for power electronic components that achieve a compact package size while having low total thermal resistance. Background Technology

[0002] With the increasing use of electronic devices in vehicles, there is a need to make electronic systems more compact. One component of these electronic systems is the power electronic device used as a switch in the inverter circuit. Power electronic devices generate a lot of heat and therefore have significant cooling requirements.

[0003] Furthermore, power electronic devices, traditionally made of silicon, are now trending towards being made of silicon carbide. The use of silicon carbide results in greater heat flux because it limits the device footprint. For these and many other reasons, there is a need to improve the cooling of power electronic devices while maintaining a compact package size. Summary of the Invention

[0004] In one embodiment, a power electronic assembly includes a circuit board assembly and a power electronic device assembly. The circuit board assembly includes an electrically insulating substrate, and the power electronic device assembly is embedded in the substrate. The power electronic device assembly includes an S-unit, which includes an inner graphite layer, a metal layer encapsulating the inner graphite layer, and a first surface of the metal layer. The first surface includes a recess disposed within the first surface. The power electronic device assembly also includes a power electronic device disposed within the recess of the first surface.

[0005] In another embodiment, a power electronic assembly includes a circuit board assembly and a cold plate. The circuit board assembly includes an electrically insulating substrate and a plurality of power electronic device assemblies embedded in the substrate. Each power electronic device assembly includes an S-unit, the S-unit further including an inner graphite layer, a metal layer encapsulating the inner graphite layer, an insulating layer bonded to a second surface of the metal layer, and a first surface of the metal layer, the first surface including a recess disposed within the first surface. The power electronic device assembly also includes a power electronic device disposed within the recess of the first surface. The circuit board assembly also includes a surface metal layer on the surface of the substrate and a plurality of thermal vias thermally coupling the S-units to the surface metal layer. The surface metal layer of the circuit board assembly is bonded to the first surface of the cold plate.

[0006] These features and additional features provided by the embodiments described herein will be more fully understood in conjunction with the accompanying drawings and in view of the following detailed description. Attached Figure Description

[0007] The embodiments illustrated in the accompanying drawings are illustrative and exemplary in nature and are not intended to limit the subject matter defined by the claims. The following detailed description of the illustrative embodiments will be understood when read in conjunction with the following drawings, wherein similar structures are indicated by similar reference numerals, and wherein:

[0008] Figure 1 A perspective view of a power electronic assembly according to one or more embodiments described and illustrated herein is schematically depicted;

[0009] Figure 2 One or more embodiments described and illustrated herein are illustrated schematically. Figure 1 An exploded perspective view of an exemplary power electronic component shown;

[0010] Figure 3 Cross-sectional views of exemplary power electronic components according to one or more embodiments described and illustrated herein are schematically depicted;

[0011] Figure 4 A top perspective view of an exemplary S-unit according to one or more embodiments described and illustrated herein is schematically depicted;

[0012] Figure 5 A cross-sectional view of an exemplary S-cell according to one or more embodiments described and illustrated herein is schematically depicted;

[0013] Figure 6 A cross-sectional view of another exemplary power electronic component according to one or more embodiments described and illustrated herein is schematically depicted;

[0014] Figure 7 One or more embodiments described and illustrated herein are illustrated schematically. Figure 6 A partial exploded view of an exemplary power electronic device assembly of the power electronic components shown.

[0015] Figure 8 One or more embodiments described and illustrated herein are illustrated schematically. Figure 7 Another partial exploded view of the exemplary power electronic device shown;

[0016] Figure 9 One or more embodiments described and illustrated herein are illustrated schematically. Figure 7 A perspective assembly diagram of an exemplary power electronic device is shown.

[0017] Figure 10 One or more embodiments described and illustrated herein are illustrated schematically. Figure 7 A cross-sectional view of an exemplary power electronic device is shown;

[0018] Figure 11 A cross-sectional view of another exemplary power electronic component according to one or more embodiments described and illustrated herein is schematically depicted;

[0019] Figure 12 A cross-sectional view of another exemplary power electronic component according to one or more embodiments described and illustrated herein is schematically depicted;

[0020] Figure 13 One or more embodiments described and illustrated herein are illustrated schematically. Figure 12 A partial exploded view of an exemplary power electronic device assembly of the power electronic components shown.

[0021] Figure 14 One or more embodiments described and illustrated herein are illustrated schematically. Figure 13 A perspective assembly diagram of an exemplary power electronic device is shown; and

[0022] Figure 15 One or more embodiments described and illustrated herein are illustrated schematically. Figure 13 A cross-sectional perspective view of an exemplary power electronic device. Detailed Implementation

[0023] The embodiments described herein generally relate to power electronic assemblies having one or more power electronic device assemblies directly embedded in a circuit board (e.g., a printed circuit board). By fully embedding one or more power electronic device assemblies into the circuit board, a layer of hot grease between the circuit board and the cold plate of the power electronic device can be removed. Removing the hot grease layer reduces the thermal resistance between the power electronic device and the cold plate, thereby improving thermal performance.

[0024] The power electronic device assembly disclosed herein includes power electronic devices fixed to a mounting substrate, referred to herein as an S-cell. As described in more detail below, the S-cell includes a graphite layer providing enhanced thermal diffusion capabilities. Furthermore, embodiments of this disclosure include one or more electrically insulating layers that electrically isolate the power electronic devices (multiple power electronic devices) from a cold plate. For example, the electrically insulating layer of the S-cell makes it possible to remove the electrically insulating layer between the printed circuit board and the cold plate, since the electrical isolation is provided by the S-cell itself.

[0025] As described in more detail below, the S-cell of this disclosure provides enhanced thermal performance because the graphite layer promotes heat flux flow to the cold plate.

[0026] The power electronic device assemblies, circuit board assemblies, and power electronic components described herein can be used in electrified vehicles (e.g., but not limited to electric vehicles, hybrid electric vehicles), any electric motor, generator, industrial tool, household appliance, etc. The power electronic components described herein can be electrically connected to an electric motor and / or battery and configured as an inverter circuit that operates to convert direct current (DC) power into alternating current (AC) power.

[0027] As used herein, "power electronic device" refers to any electrical component used to convert direct current (DC) power to alternating current (AC) power or vice versa. Examples can also be used in AC-AC converter and DC-DC converter applications. Non-limiting examples of power electronic devices include power metal-oxide-semiconductor field-effect transistors (MOSFETs), insulated-gate bipolar transistors (IGBTs), thyristors, and power transistors.

[0028] As used in this article, "fully embedded" means that every surface of a component is surrounded by a substrate. For example, when a power electronic device assembly is fully embedded in a circuit board substrate, it means that the material of the circuit board substrate covers every surface of the circuit board substrate. When a component has one or more surfaces exposed, the component is "partially embedded."

[0029] As used herein, “S-cell” is an operable mounting substrate for attaching to a power electronic device, and the mounting substrate includes at least a metal layer (e.g., copper) surrounding a graphite layer.

[0030] The following describes in detail various embodiments of power electronic device assemblies, circuit board assemblies, and power electronic components. Wherever possible, the same reference numerals will be used throughout the drawings to refer to the same or similar parts.

[0031] Now for reference Figure 1 and Figure 2 An exemplary power electronic component 100 is shown in both an assembly diagram and an exploded view. Figure 1 and Figure 2 The power electronic assembly 100 shown includes a cold plate 102, a bonding layer 104, and a circuit board assembly 106. The cold plate 102 may be a power electronic device 140 (see example) that is embedded in the substrate material of the circuit board assembly 106. Figure 3 Any device that removes heat flux. Non-limiting examples of cold plates include heat sinks, single-phase liquid cooling, two-phase liquid cooling, and steam chambers. Figure 1 and Figure 2 The cold plate 102 is shown configured as a single-phase liquid cooling device. The cold plate 102 includes a fluid inlet 132 and a fluid outlet 134, which are fluidly connected to a fluid chamber 115 within the cold plate 102. Brief Reference Figure 3Cooling fluid 135 from a reservoir (not shown) flows into fluid chamber 115 through fluid inlet 132 and exits fluid chamber 115 through fluid outlet 134. At the fluid outlet, the cooling fluid returns to the reservoir, for example, after flowing through a heat exchanger (not shown) to remove heat from the cooling fluid. Although not shown, a fin array can be provided in fluid chamber 115 to provide additional surface area for transferring heat to cooling fluid 135. Figure 3 As shown, cold cooling fluid 135 enters the cold plate 102 through fluid inlet 132, flows through fluid chamber 115, and exits the fluid outlet 134 as warm cooling fluid.

[0032] The circuit board assembly 106 is fixed to the first surface 103 of the cold plate 102. Figure 1 and Figure 2 The diagram illustrates securing a circuit board assembly 106 to a first surface 103 of a cold plate 102 using fasteners 101 (e.g., bolts and nuts). These fasteners are configured to pass through through-holes 105 in the cold plate 102, through-holes 107 in the bonding layer 104, and through-holes in the circuit board assembly 106. When using fasteners 101, the bonding layer 104 may be a layer of thermal grease to reduce thermal resistance between the circuit board assembly 106 and the cold plate 102.

[0033] In other embodiments, the circuit board assembly 106 is secured to the first surface 103 of the cold plate 102 via a bonding layer 104 configured as a solder layer. For example, the bottom surface of the circuit board assembly 106 may include a metal layer that enables the circuit board assembly 106 to be secured to the first surface 103 of the cold plate 102 via the solder layer. It should be understood that other bonding methods may also be used.

[0034] Now for reference Figure 3 A cross-sectional view of an exemplary power electronic assembly 100A is shown. In the illustrated embodiment, an additional electrical component 130 is attached to the second surface of the cold plate 102. As a non-limiting example, the additional electrical component 130 may be, for example, a capacitor in an inverter circuit. It should be understood that in other embodiments, the additional electrical component 130 may not be attached to the cold plate 102.

[0035] The circuit board assembly 106 includes a substrate 111 made of an electrically insulating material. The electrically insulating material may be a material used in the manufacture of a printed circuit board, such as, but not limited to, FR-4. The circuit board assembly 106 also includes an embedded metal layer 110 (or other conductive layer), a plurality of vias 112 (e.g., both conductive and thermal vias), and a plurality of power electronic device assemblies 120.

[0036] As a non-limiting example, circuit board assembly 106 may include six power electronic device assemblies 120 for inverter circuitry in an electric vehicle. However, it should be understood that any number of power electronic device assemblies may be used depending on the application.

[0037] Each power electronic device assembly 120 includes an S-unit 121 and a power electronic device 140 attached to the S-unit 121. As described above, the S-unit 121 is a substrate to which the power electronic device 140 is attached. It provides a conductive surface to establish connections with electrodes on the bottom surface of the power electronic device 140. The S-unit 121 further provides heat dissipation functionality.

[0038] Figure 4 and Figure 5 Exemplary S-unit 121 is shown in both top perspective view and cross-sectional view. Figure 4 and Figure 5 The illustrated S-cell 121 includes an internal graphite layer 125 encapsulated by a metal layer 122. The metal layer 122 includes a surface 128 having a recess 127 sized to receive a power electronic device 140. As described in more detail below, the metal layer 122 provides a conductive surface 128 to which conductive vias can contact to establish an electrical connection with electrodes on the bottom surface of the power electronic device 140. The recess 127 can be formed, for example, by chemical etching.

[0039] The metal layer 122 can be made of any suitable metal or alloy. As a non-limiting example, copper and aluminum can be used as metal layer 122.

[0040] A graphite layer 125 is provided to facilitate heat diffusion on the S-unit 121 and toward the cold plate 102. The crystalline structure of graphite provides it with high thermal conductivity, making it advantageous for conducting heat flux to the cold plate 102. However, graphite does not have an isothermal distribution. Instead, graphite has a non-isothermal distribution with high thermal conductivity along two axes and low thermal conductivity along a third axis. Considering the non-isothermal distribution of graphite, the S-unit 121 is designed in a rectangular shape, such that its length dimension is greater than its width dimension. (Reference) Figure 4 The graphite layer 125 has high thermal conductivity along both the x-axis and z-axis. Therefore, the S-cell 121 is designed such that its length along the x-axis is greater than its width along the y-axis. Heat flux will preferentially travel along the x-axis and z-axis. As described in more detail below, thermal vias 112 can be positioned along the x-axis at the edge of the S-cell to receive heat flux and move it toward the cold plate 102. Heat flux will also travel along the z-axis toward the cold plate 102.

[0041] Refer again Figure 3Electrical connections to the multiple electrodes 141, 142 and the metal layer 122 can be established via multiple vias 112. These vias can provide drive signals to the power electronic device 140, as well as current paths for switching current. Note that in some embodiments, some of the vias 112 can be configured as thermal vias that do not conduct drive signals or switching current.

[0042] The circuit board assembly 106 is bonded to the cold plate 102 via a bonding layer 104. Figure 3 In the illustrated embodiment, the bonding layer 104 provides both mechanical bonding between the circuit board assembly 106 and the cold plate 102 and electrical insulation between the circuit board assembly 106 and the cold plate 102. Figure 3 The bonding layer 104 is a reactive multilayer system (RMS) bonding layer with electrical insulating properties. During RMS bonding, stacked layers of foil, such as metal foil and electrically insulating foil, enter a reactive state via an ignition spark, resulting in a reaction that leads to intermetallic bonding. The reactive RMS bonding layer bonds a circuit board assembly 106 having a metallic bottom surface (e.g., in the form of an exposed metal layer 110) to a cold plate 102 that is also metallic (e.g., aluminum or copper). In some embodiments, a first metal layer 117A is disposed on the circuit board assembly 106, and a second metal layer 117B is disposed on the cold plate 102 to enhance bonding. For example, both the first metal layer 117A and the second metal layer 117B can be solder layers or brazing layers.

[0043] RMS bonding layer 104 provides excellent thermal performance, allowing heat flux from power electronics 140 to cold plate 102, and also provides electrical isolation. By providing bonding layer 104 that not only bonds circuit board assembly 106 to cold plate 102 but also provides electrical insulation, a separate dedicated electrical insulation layer is no longer required. This reduces the overall size of the power electronics assembly 100A package. The overall size of the power electronics assembly 100A package is further reduced by embedding power electronics assembly 120 within circuit board assembly 106.

[0044] Now for reference Figure 6 Another power electronic device assembly 100B is shown. The electrical isolation between the circuit board assembly 106' and the cold plate 102 is not achieved through... Figure 1-3 Instead of providing electrical isolation through the bonding layer shown, it is provided by the metallized insulating layer 124 of the S-unit 121' of one or more power electronic device components 120'.

[0045] Figure 6The bonding layer 104' of the illustrated embodiment can be configured as any bonding layer, such as, but not limited to, a solder layer, a brazing layer, or an RMS bonding layer. One or more exposed metal layers 110 (e.g., copper layers) provide a metal surface for the circuit board assembly 106', to which the bonding layer 104' is bonded. In some embodiments, the bonding layer 104' can be a thermal grease layer when the power electronic device assembly 100B is held together by fasteners 101. Thermal vias 112 extend from the bottom of the power electronic device assembly 120' toward the bottom of the circuit board assembly 106' to provide a thermal path for the heat flux generated by the power electronic device 140.

[0046] Figure 7 and Figure 8 It shows Figure 6 A partial exploded view of an exemplary power electronic device assembly 120'. Figure 9 It is a top-down perspective view. Figure 10 This is a cross-sectional view of an exemplary power electronic device assembly 120'. The power electronic device assembly 120' includes a power electronic device 140 fixed to the S-unit 121'. Generally, refer to... Figure 7-10 S-cell 121' includes an internal graphite layer 125, which is encapsulated by a metal layer 122, such as a copper layer. The metal layer 122 includes a surface 128 with a recess 127 having dimensions for receiving power electronic devices 140. As described above, the graphite layer 125 provides enhanced thermal performance.

[0047] Figure 7 A power electronic device 140 and a bonding layer 143 relative to the recess 127 are depicted. The bonding layer 143, which secures the power electronic device 140 to the metal layer 122, can be, for example, a solder layer. As another example, the bonding layer 143 can be a transient liquid bonding layer 143. The power electronic device 140 includes a plurality of electrodes 141, 142 on its top surface. The large electrode 141 can be a power electrode, while the small electrode 142 can be a signal electrode. It should be noted that although in Figure 7-10 Although not visible in the center, the power electronic device 140 also includes one or more electrodes on its bottom surface. By placing the power electronic device 140 into the recess 127, these one or more electrodes on the bottom surface of the power electronic device are electrically connected to the second metal layer 126. Therefore, an electrical connection can be established with the bottom electrodes of the power electronic device 140 through the second metal layer 126.

[0048] Unit S 121' also includes a metallized insulating layer 124 that provides electrical isolation between the metal layer 122 and the cold plate 102. The metallized insulating layer 124 is metallized so that it can be bonded to the metal layer 122. The metallized insulating layer 124 can be made of any electrically insulating material, such as, but not limited to, ceramic materials. As a non-limiting example, the metallized insulating layer 124 can be metallized alumina. The metallization of the insulating material of the metallized insulating layer 124 enables it to be bonded. It should be noted that the main surface of the metallized insulating layer 124 should be metallized, but the side edges should not be metallized to prevent electrical short circuits.

[0049] The exemplary S-unit 121' also includes a second metal layer 126 bonded to the metallized insulating layer 124. The metallized insulating layer 124 can be bonded to the metal layer 122 and the second metal layer 126 using any bonding technique. The second metal layer 126 provides additional heat diffusion and provides thermal connection points for the thermal via 112 to allow heat flux to move toward the bottom metal layer 110 and ultimately toward the cold plate 102, as... Figure 6 As shown. For example, the via 112 shown contacting the second metal layer 126 of S unit 121' can be a thermally conductive via, configured to conduct heat flux toward the bottom layer near the cold plate 102. Furthermore, the thermal via 112 can be electrically coupled to an end of the top surface of the metal layer 122 to move heat flux downwards from the metal layer 122 toward the cold plate 102. In this way, heat flux is optimally directed away from the power electronics 140 and toward the cold plate 102.

[0050] Figure 11 A power electronic device assembly 110C is shown, which is similar to Figure 6 The power electronic device assembly 106″ differs in that the S-cells 121″ of the power electronic device assembly 120″ do not include a second metal layer. Instead, the substrate 111 material of the circuit board assembly 106″ exposes the metallized insulating layer 124 of each S-cell 121″. This exposure of the metallized insulating layer 124 provides the circuit board assembly 106″ with the ability to bond directly to the surface of the cold plate 102 at the metallized insulating layer 124, rather than through an intermediate layer. For example, the circuit board assembly 106″ can be bonded via a bonding layer 104″ (e.g., a solder layer) that bonds one or more metal layers 110 and the metallized insulating layer 124 to the surface of the cold plate 102. This can be advantageous because it can reduce the size of the power electronic device assembly 110C.

[0051] Figure 12 A power electronic device assembly 100D is shown, which is similar to Figure 6The power electronic assembly 100B is shown. The electrical isolation of the power electronic assembly 100D is not provided by the metallized insulating layer 124, but by the metal substrate 150 layer directly bonded to the S unit 121″′ of the power electronic device assembly 120″′.

[0052] Figure 13 A partial exploded view of an exemplary power electronic device assembly 120″′ is shown, which includes a power electronic device 140 fixed to a recess 127 of an S unit 121″′ by a bonding layer 143. Figure 14 An assembled perspective view of the power electronic device assembly 120″′ is shown. Figure 15 This is a cross-sectional perspective view of the power electronic device assembly 120″′. (Reference) Figure 13-15 The exemplary S-cell 121″′ includes a graphite layer 125 encapsulated by a metal layer 122. The S-cell 121″′ also includes a directly bonded metal (DBM) substrate 150 bonded to the bottom surface of the metal layer 122. The DBM substrate 150 may be, for example, a directly bonded copper (DBC) substrate. The DBM substrate 150 has an insulating layer 152, which may be a ceramic material, such as alumina. The DBM substrate 150 also has a first DBM metal layer 151 directly bonded to a first surface of the insulating layer 152 (e.g., the ceramic layer) and a second DBM metal layer 153 directly bonded to a second surface of the insulating layer 152.

[0053] A second DBM metal layer 153, which may be copper, is bonded to the bottom surface of metal layer 122. Insulating layer 152 provides electrical insulation for power electronic devices.

[0054] Refer again Figure 12 Multiple thermal vias 112 contact the first DBM layer 151 and extend toward the bottom metal layer 110 to carry heat flux from the S-cell 121″′ to the bottom of the circuit board assembly 106″′. The circuit board assembly 106″′ can then be bonded to the surface of the cold plate 102 at the exposed metal layer 110 via a bonding layer 104, which may be, for example, a solder layer.

[0055] Similar to Figure 11 In some embodiments of the power electronic components, the substrate 111 material of the circuit board assembly 106″′ may expose the first DBM layer 151. In such embodiments, the circuit board assembly 106″′ may be bonded to the surface of the cold plate 102 at the first DBM layer 151, rather than at the intermediate metal layer.

[0056] It should now be understood that embodiments of this disclosure relate to circuit board assemblies, power electronic device assemblies, and power electronic components that include S-cells fully embedded within a circuit board substrate. The S-cells of the embodiments described herein include an encapsulated graphite layer to improve thermal performance. Electrical isolation can be provided through electrically insulating components of the S-cell. Directly embedding the power electronic device assembly into the circuit board and eliminating the separate electrical isolation layer between the circuit board and the cold plate significantly reduces the overall size of the power electronic device while also providing enhanced thermal performance.

[0057] It is worth noting that the terms “approximately” and “about” are used herein to indicate the degree of inherent uncertainty attributable to any quantitative comparison, value, measurement, or other representation. These terms are also used herein to indicate the extent to which a quantitative representation may differ from the stated reference without altering the fundamental function of the subject matter.

[0058] Although specific embodiments have been described and illustrated herein, it should be understood that various other changes and modifications may be made without departing from the scope of the claimed subject matter. Furthermore, while various aspects of the claimed subject matter have been described herein, these aspects need not necessarily be used in combination. Therefore, the appended claims are intended to cover all such changes and modifications falling within the scope of the claimed subject matter.

[0059] It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments described herein without departing from the scope of the claimed subject matter. Therefore, this specification is intended to cover modifications and variations of the various embodiments described herein, provided that such modifications and variations fall within the scope of the appended claims and their equivalents.

Claims

1. A power electronic component, comprising: Circuit board assembly, the circuit board assembly comprising: The substrate is electrically insulating; A power electronic device assembly embedded in the substrate, the power electronic device assembly comprising: S-unit, the S-unit comprising: An inner graphite layer, the inner graphite layer comprising high thermal conductivity along a cross-sectional direction and an in-plane first direction and low thermal conductivity along an in-plane second direction perpendicular to the in-plane first direction, wherein the high thermal conductivity is greater than the low thermal conductivity. A metal layer encapsulating the inner graphite layer; and The first surface of the metal layer includes a recess disposed within the first surface; and A power electronic device, wherein the power electronic device is disposed within the recess on the first surface. Wherein, the length of the S-unit along the first direction in the plane is greater than the width of the S-unit along the second direction in the plane.

2. The power electronic component according to claim 1, wherein, The circuit board assembly also includes a plurality of thermal vias embedded in the substrate and thermally coupled to the power electronic device.

3. The power electronic assembly of claim 1 further includes a cold plate, wherein the circuit board assembly is bonded to the surface of the cold plate via a bonding layer.

4. The power electronic component according to claim 3, wherein, The bonding layer is electrically insulating.

5. The power electronic component according to claim 3, wherein, The bonding layer is a reactive multilayer system bonding layer.

6. The power electronic component according to claim 1, wherein, The S-unit also includes a metallized insulating layer bonded to a second surface of the metal layer.

7. The power electronic component according to claim 6 further includes a cold plate, wherein: The metallized insulating layer of the S unit is exposed at the surface of the circuit board assembly; The circuit board assembly is bonded to the surface of the cold plate at the metallized insulating layer of the S unit.

8. The power electronic component according to claim 7, wherein, The circuit board assembly is bonded to the surface of the cold plate at the metallized insulating layer of the S unit via a reactive multilayer system.

9. The power electronic component according to claim 6, wherein, The S-unit further includes a second metal layer bonded to the metallized insulating layer.

10. The power electronic component according to claim 9, wherein, The circuit board assembly also includes a plurality of thermal vias thermally coupled to the second metal layer.

11. The power electronic component according to claim 1, wherein: The S-unit further includes a directly bonded metal substrate, the directly bonded metal substrate comprising: The first directly bonded metal layer; A ceramic layer, said ceramic layer being bonded to the first directly bonded metal layer; and A second directly bonded metal layer is attached to the ceramic layer.

12. The power electronic assembly according to claim 11, further comprising a cold plate, wherein: The second directly bonded metal layer is exposed at the surface of the circuit board assembly; and The circuit board assembly is bonded to the first surface of the cold plate at the second directly bonded metal layer of the S unit.

13. A power electronic component, comprising: Circuit board assembly, the circuit board assembly comprising: The substrate is electrically insulating; Multiple power electronic device components embedded in the substrate, each power electronic device component comprising: S-unit, the S-unit comprising: An inner graphite layer, the inner graphite layer comprising high thermal conductivity along a cross-sectional direction and an in-plane first direction and low thermal conductivity along an in-plane second direction perpendicular to the in-plane first direction, wherein the high thermal conductivity is greater than the low thermal conductivity. A metal layer encapsulating the inner graphite layer; An insulating layer, said insulating layer being bonded to a second surface of said metal layer; and The first surface of the metal layer includes a recess disposed within the first surface; and A power electronic device, wherein the power electronic device is disposed within the recess on the first surface; A surface metal layer on the surface of the substrate; and Multiple thermal vias thermally couple the S-unit to the surface metal layer; and A cold plate, wherein the surface metal layer of the circuit board assembly is bonded to a first surface of the cold plate. Wherein, the length of the S-unit along the first direction in the plane is greater than the width of the S-unit along the second direction in the plane.

14. The power electronic component according to claim 13, wherein, The insulating layer includes a metallized insulating layer.

15. The power electronic component according to claim 13, wherein, The insulating layer includes a directly bonded metal substrate, the directly bonded metal substrate comprising: The first directly bonded metal layer; A ceramic layer, said ceramic layer being bonded to the first directly bonded metal layer; and A second directly bonded metal layer is attached to the ceramic layer.

16. The power electronic assembly of claim 13, further comprising a capacitor fixed to a second surface of the cold plate opposite to the first surface.

17. The power electronic component according to claim 13, wherein: The cold plate includes a fluid chamber, a fluid inlet, and a fluid outlet; and The fluid inlet and the fluid outlet are thermally coupled to the fluid chamber.

18. The power electronic component according to claim 13, wherein, The circuit board assembly is secured to the first surface of the cold plate by fasteners and a layer of hot grease.

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