Cold plate comprising s-units

Abstract

The present disclosure relates to cold plates including S-units. Power electronic systems including power electronic device assemblies with cold plates are described. A cold plate includes an S-unit having a body including graphite or a graphite composite. The body defines a power device recess. The S-unit is disposed within a cavity of the cold plate. The cold plate further includes a bonding material that bonds the S-unit to a base wall of the cavity.

Description

Technical Field

[0001] This specification generally relates to power electronic assemblies, and more specifically, to cooling devices for power electronic assemblies. 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 equipment used as a switch in the inverter. Due to the heat generated, power electronic equipment has significant cooling requirements.

[0003] Furthermore, power electronic devices, traditionally made of silicon, are now trending towards using silicon carbide. The use of silicon carbide results in greater heat flux because it allows for a smaller 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 aspect, a cold plate includes an S-cell having a body comprising graphite or a graphite composite material. The body defines a recess for electrical equipment. The S-cell is disposed within a cavity of the cold plate. The cold plate further includes a bonding material for bonding the S-cell to a base wall of the cavity.

[0005] In another aspect, a power electronic device assembly includes a cold plate defining a cavity and a power electronic device. The cold plate includes an S-unit disposed within the cavity of the cold plate. The S-unit has a body comprising graphite or a graphite composite material. The body defines a recess for the power electronic device. The cold plate also includes a bonding material for bonding the S-unit to a base wall of the cavity. The power electronic device is embedded within the recess of the S-unit.

[0006] In another aspect, a power electronic system includes a circuit board assembly and a power electronic device assembly coupled to the circuit board assembly. The power electronic device assembly includes a cold plate defining a cavity and power electronic devices. The cold plate includes an S-unit disposed within the cavity of the cold plate. The S-unit has a body comprising graphite or a graphite composite material. The body defines a power device recess. The cold plate also includes a bonding material for bonding the S-unit to a base wall of the cavity. The power electronic device is embedded within the power device recess of the S-unit.

[0007] These features and additional features provided by the various aspects and embodiments described herein will be more fully understood in light of the following detailed description, taken in conjunction with the accompanying drawings. Attached Figure Description

[0008] The various aspects and embodiments set forth 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, in which the same structures are indicated by the same reference numerals, and in the drawings:

[0009] Figure 1 A perspective view schematically depicting an illustrative power electronic system according to one or more embodiments described and illustrated herein;

[0010] Figure 2 Schematic depiction of one or more embodiments according to the description and illustration herein Figure 1 An exploded perspective view of a power electronic system shown in the diagram.

[0011] Figure 3 A cross-sectional view schematically depicting an illustrative power electronic system according to one or more embodiments described and illustrated herein;

[0012] Figure 4 The schematic diagram illustrates a cross-sectional view of an illustrative S-unit according to one or more embodiments described and illustrated herein;

[0013] Figure 5 Schematic diagram illustrating one or more embodiments described and illustrated herein. Figure 4 A perspective view of the S-cell; and

[0014] Figure 6 The schematic diagram illustrates a top exploded perspective view of an exemplary cold plate according to one or more embodiments described and illustrated herein, the cold plate having a plurality of S-units embedded therein. Detailed Implementation

[0015] The embodiments described herein generally relate to power electronic systems having a circuit board assembly coupled to a power electronic device assembly, the power electronic device assembly including a cold plate containing an S-cell. The power electronic device may be embedded within the S-cell and / or the circuit board assembly. The S-cell has specific dimensions and shapes to ensure specific thermal conductivity for dissipating heat generated by the power electronic device.

[0016] The power electronic device assembly disclosed herein includes a power electronic device fixed to a mounting substrate, referred to herein as an S-cell. As described in more detail below, the S-cell includes an electrically insulating layer that electrically insulates the bottom electrode of the power electronic device from other components of the power electronic device assembly. For example, the integrated 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 electrical isolation is provided by the S-cell itself.

[0017] As described in more detail below, the S-cell of this disclosure provides enhanced thermal performance due to the graphite layer that promotes heat flux flow to the cold plate. The S-cell described herein comprises stacked metal, graphite, and one or more electrically insulating layers in a compact package. Because the graphite in the S-cell described herein does not have an isothermal profile, the S-cell described herein has a specific shape and size to ensure adequate thermal diffusion. More specifically, portions of the S-cell extending along two axes can define regions of high thermal conductivity relative to portions of the S-cell extending along a third axis that have relatively low thermal conductivity. The final shape of the S-cell (e.g., rectangular) can allow heat to diffuse along the high thermal conductivity axis rather than the low thermal conductivity axis, thereby improving overall thermal diffusion within the S-cell and / or reducing thermal diffusion to adjacent S-cells, thus avoiding the problem of concentrated S-cell overheating in power electronic systems.

[0018] The cold plates, power electronics assemblies, circuit board assemblies, power electronic systems, etc., described herein can be used in electric vehicles, such as, but not limited to, pure electric vehicles, hybrid electric vehicles, any electric motor, generator, industrial tool, household appliance, etc. The various assemblies described herein can be electrically coupled to an electric motor and / or battery and can be configured as inverter circuits operable to convert direct current (DC) power to alternating current (AC) power.

[0019] As used herein, "power electronic device" means any electrical component used to convert direct current (DC) power to alternating current (AC) power and 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.

[0020] The phrase “fully embedded” as used in this article means that every surface of a component is surrounded by a substrate. For example, when a power electronics 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 one or more surfaces of a component are exposed, the component is “partially embedded.”

[0021] As used herein, “S-cell” is a mounting substrate operable to be fixed to a power electronic device, inserted into a cavity of a cold plate, and comprising one or more of a metal layer, a graphite layer, and an electrical insulating layer.

[0022] Various embodiments of power electronic device assemblies, power electronic systems, and cold plates are described in detail below. Wherever possible, the same reference numerals will be used throughout the drawings to refer to the same or similar parts.

[0023] See now Figure 1 and Figure 2 The figure illustrates the example power electronic system 100 using both assembly and exploded views. Figure 1 and Figure 2 The power electronic system 100 shown in the diagram includes a cold plate 102 and a circuit board assembly 106. Although not shown in Figure 1 and Figure 2 As shown, however, in some embodiments, a bonding layer or thermal grease layer may be disposed between the cold plate 102 and the circuit board assembly 106. The cold plate 102 may be capable of being disposed between the power electronic device 140 (see Figure 140). Figure 3 Any device for removing heat flux, power electronic device coupled to or embedded in the cavity 103 of the cold plate 102 and / or coupled to or embedded in the substrate material of the circuit board assembly 106. Non-limiting examples of the cold plate 102 include radiators, single-phase liquid cooling, two-phase liquid cooling, and vapor chambers. Figure 1 and Figure 2 The diagram illustrates that the cold plate 102 is constructed as a single-phase liquid cooling device. The cold plate 102 includes a fluid inlet 132 and a fluid outlet 134, which are fluidly coupled to a fluid chamber 115 within the cold plate 102. Although Figure 1 and Figure 2 Fluid inlet 132 and fluid outlet 134 are depicted as being on the same side of cold plate 102, but this disclosure is not limited to such an embodiment. That is, in other embodiments, fluid inlet 132 and fluid outlet 134 may be located on other surfaces. For example, Figure 6 A fluid inlet 132 on a first surface and a fluid outlet 134 on a second surface opposite to the first surface are depicted. (Brief Reference) Figure 3 Cooling fluid (depicted as moving arrow 135) from a storage tank (not shown) flows into the fluid chamber 115 through the fluid inlet 132 and exits the fluid chamber 115 through the fluid outlet 134. At the fluid outlet 134, the cooling fluid returns to the storage tank, for example, after flowing through a heat exchanger (not shown) to remove heat from the cooling fluid. Although not shown, a fin array may be provided in the fluid chamber 115 to provide additional surface area for heat transfer to the cooling fluid 135.

[0024] See you again Figure 1 and Figure 2 The circuit board assembly 106 is coupled (e.g., fixed) to the first surface 107 of the cold plate 102. Figure 1 and Figure 2The diagram illustrates that circuit board assembly 106 is secured to the first surface 107 of cold plate 102 by fasteners 101 (e.g., bolts and nuts) arranged through through holes 105 and 109 of cold plate 102 and cold plate assembly 106. When using fasteners 101, the bonding layer disposed between cold plate 102 and circuit board assembly 106 can be a thermal grease layer to reduce the thermal resistance between circuit board assembly 106 and cold plate 102. It should be noted that such a bonding layer constituting a thermal grease layer will not have dedicated through holes. It should be appreciated that, especially when additional electrical components 130 (see...) are added... Figure 3 When coupled to the cold plate 102, it can be used as follows: Figure 1 and Figure 2 Such embodiments are shown. If such components are not included, through holes 105, 109 and fastener 101 can be omitted, as described below.

[0025] In other embodiments, the circuit board assembly 106 is coupled (e.g., fixed) to a first surface 107 of the cold plate 102 via a bonding layer disposed between the circuit board assembly 106 and the first surface 107 of the cold plate 102, and is constituted 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 coupled (e.g., fixed) to the first surface 107 of the cold plate 102 via a solder layer. Other bonding methods may also be used without departing from the scope of this disclosure.

[0026] In other embodiments, the circuit board assembly 106 may be a 3D-printed layer directly 3D-printed onto the cold plate 102 (e.g., 3D-printed onto the first surface 107 of the cold plate 102). It should be appreciated that, in such embodiments, the 3D-printed layer of the circuit board assembly 106 reduces the overall thermal resistance. Other additive manufacturing processes for attaching the circuit board assembly 106 to the cold plate 102 may also be considered and included within the scope of this disclosure.

[0027] In other embodiments, the circuit board assembly 106 may be laminated to the first surface 107 of the cold plate 102. Additionally, laser drilling can be used to drill holes in the various components of the circuit board assembly 106 and the power electronics assembly 120. Figure 3 Via connections are made between the components. That is, vias are drilled through the laminated circuit board assembly 106 to the top surface of each conductive layer and the power electronics assembly 120. The vias are then filled with copper by electroplating to establish electrical connections between the components.

[0028] Now for reference Figure 3The figure illustrates a cross-sectional view of an example power electronic system 100. In the illustrated embodiment, an additional electrical component 130 is coupled (e.g., fixed) to a second surface of the cold plate 102. As a non-limiting example, the additional electrical component 130 may, for example, be a capacitor of an inverter circuit. It should be understood that in other embodiments, the additional electrical component 130 may not be fixed to the cold plate 102.

[0029] The circuit board assembly 106 includes a substrate 111 made of an electrically insulating material. The electrically insulating material can be a material used to fabricate printed circuit boards, such as, but not limited to, FR-4. The circuit board assembly 106 also includes an embedded conductive layer 110 and a plurality of vias 112 (both conductive and thermal vias). In some embodiments, the circuit board assembly 106 may also include a plurality of power electronic device assemblies 120 wholly or partially embedded therein. However, Figure 3 The embodiment shown illustrates a power electronics assembly 120 embedded within an S-unit 121, which is arranged within a cavity 103 of a cold plate 102, as described in more detail herein.

[0030] As a non-limiting example, the cold plate 102 may include six cavities 103 for receiving six S-cells 121 and six power electronics assemblies 120 for inverter circuitry in electric vehicles. However, it should be understood that, depending on the application, any number of S-cells and power electronics assemblies may be used.

[0031] Each power electronic device assembly 120 includes an S-unit 121 received within a cavity 103 of a cold plate 102 and a power electronic device 140 coupled (e.g., fixed) to the S-unit 121. As described above, the S-unit 121 is a substrate to which the power electronic device 140 is bonded. The S-unit 121 provides a conductive surface area for connection to electrodes on the bottom surface of the power electronic device 140. The S-unit 121 also provides thermal diffusion functionality and electrical isolation. However, in some embodiments, an additional electrical insulating layer 180 may be inserted between the S-unit 121 and the base wall 104 of the cavity 103 of the cold plate 102 to provide additional electrical isolation, as described in further detail herein.

[0032] As a non-limiting example, for a total of six S-units 121, the S-units 121 can be arranged in each of the six cavities 103 of the cold plate. Furthermore, for a total of six power electronic device assemblies 120, a power electronic device assembly 120 can be embedded in each of the six S-units 121. In conventional arrangements, the shape and size of conventional S-units result in uniform heat diffusion from each S-unit, leading to heat diffusion between S-units, particularly in the centrally located S-unit, thereby reducing the overall cooling performance of the cold plate. Therefore, the S-units 121 of this disclosure have special shapes and sizes to ensure that heat flux is guided in a manner that avoids heat diffusion to adjacent S-units, as described below.

[0033] Figure 4 and Figure 5 Example S-cell 121 is illustrated in cross-sectional and top perspective views. S-cell 121 includes a body 131 formed by multiple stacked layers. Specifically, Figure 4 and Figure 5 The S-unit 121 shown in the diagram includes a body 131, which includes a first metal layer 122, a graphite layer 124, and a second metal layer 126. The second metal layer 126 includes a first surface 125 facing the graphite layer and a second surface 128 opposite to the first surface 125. The second surface has a groove 127, the dimensions of which are determined to receive a power electronic device 140 therein. Figure 4 and Figure 5 As shown, the first metal layer 122 and the second metal layer 126 at least partially surround the graphite layer 124. The term "graphite composite material" as used herein means a structure in which graphite is at least partially surrounded by metal, such as... Figure 4 and Figure 5 As shown in the diagram and described in further detail below, the second metal layer 126 provides a conductive surface to which conductive vias can contact to form an electrical connection with electrodes on the bottom surface of the power electronic device 140. It should be appreciated that... Figure 4 and Figure 5 The layers of S-unit 121 shown are merely illustrative. That is, for example, S-unit 121 may have one or more graphite layers that are at least partially surrounded by a metal portion (e.g., one or more metal layers, a metal shell, a metal enclosure, etc.). In other examples, S-unit 121 may include one or more graphite layers that are completely surrounded by a metal portion such that the metal portion encapsulates the one or more graphite layers therein. Any of these examples are covered by the term "graphite composite material" as used herein.

[0034] As a non-limiting example, the layers of the S-unit can be joined together by a high-temperature active metal brazing method to form the bonding layer 129 (i.e., the active metal brazing layer). However, it should be understood that other known and undeveloped techniques can be used to join the layers.

[0035] Notice, Figure 4 and Figure 5 In the embodiment illustrated, the S-unit 121 includes a graphite layer 124 and a pair of metal layers (i.e., a first metal layer 122 and a second metal layer 126) to provide along... Figure 5 The S-cells are symmetrical along the z-axis in the coordinate system shown. The symmetry of the S-cells 121 balances the forces on the S-cells during the high-temperature bonding process. Since the first metal layer 122, the second metal layer 126, and the graphite layer 124 have different coefficients of thermal expansion, it may be desirable to have a symmetrical substrate stack to balance thermally induced stresses during the bonding process.

[0036] The first metal layer 122 and the second metal layer 126 can be made of any suitable metal or alloy. As a non-limiting example, copper and aluminum can be used as the first metal layer 122 and the second metal layer 126. It should be further understood that the metal portions used to at least partially or completely surround the graphite layers as discussed herein can also be any suitable metal or alloy, such as (but not limited to) copper and / or aluminum.

[0037] Provided in Figure 5 The graphite layer 124 shown in the embodiment facilitates crossing the S-unit 121 and towards the cold plate 102 ( Figure 3 Thermal diffusion. The crystalline structure of graphite provides it with high thermal conductivity, which facilitates the conduction of heat flux to the cold plate 102. However, graphite does not have an isothermal profile. Instead, graphite has a non-isothermal profile with high thermal conductivity along two axes and low thermal conductivity along a third axis. Considering the non-isothermal profile of graphite, the S-unit 121 is designed in a rectangular shape, with its length dimension greater than its width dimension. See also Figure 5 Graphite layer 124 along Figure 5 The x-axis and z-axis in the coordinate system shown have high thermal conductivity. Therefore, the S-cell 121 is designed such that its dimension along the x-axis is larger than its dimension along the y-axis. That is, the width w of the S-cell 121 generally corresponds to the y-axis in the coordinate system, the length l of the S-cell 121 generally corresponds to the x-axis in the coordinate system, and the depth d of the S-cell 121 generally corresponds to the z-axis of the S-cell 121. The length l and width w generally define a plane that gives the S-cell 121 a rectangular shape as described herein, and generally further define a transverse plane in which the recess 127 is oriented. The depth d generally defines the thickness of the S-cell 121, and generally further defines a vertical plane in which the recess 127 is oriented.

[0038] Due to the rectangular shape of the S-cell and the properties of graphite, the length l and depth d of the S-cell 121 define directions of relatively high thermal conductivity, while the width w of the S-cell 121 defines directions of relatively low thermal conductivity. In a non-limiting example, the thermal conductivity of the S-cell 121 along the x-axis and z-axis is approximately 1500 W / (mK), while the thermal conductivity of the S-cell 121 along the y-axis is approximately 10 W / (mK). In another non-limiting example, the ratio of the thermal conductivity of the S-cell 121 along the x-axis and z-axis to that along the y-axis is approximately 100:1, approximately 150:1, or greater than approximately 150:1. As a result, heat flux propagates more readily along the x-axis and z-axis relative to the y-axis, and is therefore more likely to propagate along the length l and depth d of the S-cell 121 along the x-axis and z-axis. This movement of heat flux ensures that it is unlikely to propagate along the y-axis to adjacent S-cells 121, thus avoiding the problem of adjacent S-cells 121 overheating each other. As described in more detail herein, thermal vias can be provided along the x-axis at the edges of the S-cells to receive the heat flux and move it toward the cold plate 102. The heat flux will also propagate along the z-axis toward the cold plate 102.

[0039] The second metal layer 126 of the S-unit 121 has a groove 127 formed in its second surface 128. The groove 127 can be formed, for example, by chemical etching. The groove 127 has a receiving power electronic device 140 (see, for example, [link to relevant documentation]). Figure 3 and Figure 6 The size and shape of the second surface 128. The second surface 128 can typically be the second main surface or surface of the second metal layer 126 opposite to the first surface 125 (which is configured as the first main surface or surface of the second metal layer 126). That is, the second metal layer 126 can be a planar layer, whereby the first surface 125 faces the graphite layer 124, while the opposing second surface 128 faces the power electronic device 140 and the circuit board assembly 106. Figure 3 ).

[0040] Figure 6 The illustration shows a partial exploded view of a power electronics assembly 146 including a power electronics device 140 and a cold plate 102 including an S-unit 121. Figure 6 A power electronic device 140 and a bonding layer 143 relative to the recess 127 of the S-cell 121 are depicted. The bonding layer 143 may be, for example, a solder layer. As another example, the bonding layer 143 may 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 may be a power electrode, while the small electrode 142 may be a signal electrode. Note that although in Figure 6While not visible, 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, one or more electrodes on the bottom surface of the power electronic device are electrically connected to the second metal layer 126. Thus, electrical connection to the bottom electrodes of the power electronic device 140 can be achieved through the second metal layer 126.

[0041] See also Figure 3 Electrical connections to multiple electrodes 141, 142 and a second metal layer 126 can be achieved through multiple vias 112. These vias 112 can provide drive signals to the power electronic device 140 and provide current paths for switching current. Note that in some embodiments, some vias 112 can be configured as thermal vias that do not conduct drive signals or switching current. Additionally, the S-cell arrangement within the cavity 103 of the cold plate 102 allows flux movement from the power electronic device 140 to the cold plate via the S-cells, as described herein. In this way, heat flux is optimally guided away from the power electronic device 140 and to the cold plate 102 via the S-cells 121. 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 heated cooling fluid.

[0042] See still Figure 3 and Figure 6 The shape and / or dimensions of the cavity 103 of the cold plate 102 may be configured to receive an S-unit 121 embedded therein or coupled thereto by a power electronic device 140, as described herein. A bonding material 180 may be disposed between the S-unit 121 and one or more walls of the cavity 103 of the cold plate 102. For example, the S-unit 121 may be bonded within the cavity 103 by applying the bonding material 180 to the base wall 104 and / or one or more sidewalls of the cavity 103 to secure the S-unit within the cavity 121. The bonding material 180 is generally not limited to this disclosure and may generally be any material that provides bonding properties. In some embodiments, the bonding material 180 may be a material that acts as an electrical insulator, such as a dielectric. In another example, the bonding material 180 may be an IMS dielectric material. However, other materials with electrical insulating properties may also be considered and included within the scope of this disclosure.

[0043] It should now be understood that embodiments of this disclosure relate to power electronic systems having circuit board assemblies coupled to power electronic device assemblies, the power electronic devices including a cold plate containing S-cells. The power electronic devices may be embedded within the S-cells and / or within the circuit board assembly. The S-cells are formed of graphite or graphite composite materials and have specific dimensions such that the thermal conductivity of the S-cells causes heat flux to move in some directions toward the cold plate and away from adjacent S-cells. Such power electronic systems are compact, providing increased thermal conductivity while maintaining the ability to electrically insulate the S-cells, thereby improving the heat flux from the S-cells to the cold plate and thus improving the thermal diffusion and cooling performance of the PCB compared to conventional packaging.

[0044] Note that the terms “substantially” and “approximately” are used herein to indicate the degree of uncertainty attributable to any quantitative comparison, value, measurement, or other representation. These terms are also used herein to indicate the extent to which quantitative representations may differ from those in the cited references without altering the fundamental function of the subject matter under discussion.

[0045] While specific embodiments have been illustrated and described herein, it should be understood that various other changes and modifications can be made without departing from the scope of the claimed subject matter. Furthermore, although various aspects of the claimed subject matter have been described herein, these aspects need not be used in combination. Therefore, the appended claims are intended to cover all such changes and modifications within the scope of the claimed subject matter.

[0046] 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 to the various embodiments described herein, provided that such modifications and variations are within the scope of the appended claims and their equivalents.

Claims

1. A cold-rolled steel plate, comprising: S-unit, the S-unit having a body comprising graphite or graphite composite material defining an electrical equipment recess, wherein the S-unit is disposed within a cavity of the cold plate; and A bonding material is used to bond the S-unit to the base wall of the cavity.

2. The cold plate according to claim 1, wherein the body of the S-unit includes a length, a width, and a depth, wherein the length and depth of the S-unit have high thermal conductivity relative to the width of the S-unit.

3. The cold plate according to claim 1, wherein the body of the S-unit includes a length and a width, wherein the length is greater than the width.

4. The cold plate according to claim 1, wherein the graphite composite material of the body of the S-unit comprises graphite and at least a metal portion surrounding the graphite.

5. The cold plate according to claim 4, wherein the metal portion completely surrounds the graphite.

6. The cold plate according to claim 4, wherein the metal portion is formed of copper or a copper-containing material.

7. The cold plate according to claim 1, wherein the bonding material comprises an electrically insulating material.

8. The cold plate according to claim 7, wherein the electrical insulating material is a dielectric material.

9. The cold plate according to claim 8, wherein the dielectric material is an insulating metal substrate material.

10. The cold plate according to claim 1 further includes a fluid chamber, a fluid inlet, and a fluid outlet, wherein the fluid inlet and the fluid outlet are thermally coupled to the fluid chamber.

11. A power electronic device assembly, comprising: A cold plate defining a cavity, the cold plate comprising: An S-unit is disposed within the cavity of the cold plate, the S-unit having a body comprising graphite or a graphite composite material, the body defining a groove for electrical equipment, and A bonding material is used to bond the S-unit to the base wall of the cavity; and A power electronic device, which is embedded in the power device recess of the S-unit.

12. The power electronic device assembly according to claim 11, wherein the power electronic device is sintered to one or more surfaces of the power device recess.

13. The power electronic device assembly according to claim 11, wherein the body of the S-unit includes a length, a width, and a depth, wherein the length and depth of the S-unit have high thermal conductivity relative to the width of the S-unit.

14. The power electronic device assembly according to claim 11, wherein the body of the S-unit includes a length and a width, wherein the length is greater than the width.

15. The power electronic device assembly of claim 11, wherein the body of the S-unit further comprises a metal portion that at least partially surrounds the graphite or graphite composite material.

16. The power electronic device assembly according to claim 11, wherein the bonding material comprises an insulating metal substrate material.

17. A power electronic system, comprising: Circuit board assembly; and A power electronic device assembly coupled to the circuit board assembly, the power electronic device assembly comprising: A cold plate defining a cavity, the cold plate comprising: An S-unit is disposed within the cavity of the cold plate, the S-unit having a body comprising graphite or a graphite composite material, the body defining a groove for electrical equipment, and A bonding material is used to bond the S-unit to the base wall of the cavity; and A power electronic device, which is embedded in the power device recess of the S-unit.

18. The power electronic system according to claim 17, wherein: The cold plate is coupled to the circuit board assembly on its first surface; and The capacitor is coupled to a second surface of the cold plate opposite to the first surface.

19. The power electronic system according to claim 17, wherein the body of the S-cell includes a length, a width, and a depth, wherein the length and depth of the S-cell have high thermal conductivity relative to the width of the S-cell.

20. The power electronic system according to claim 17, wherein the body of the S-unit includes a length and a width, wherein the length is greater than the width.

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