Pcb embedded power module

Abstract

The utility model relates to a kind of PCB embedded power module.The PCB embedded power module includes multilayer circuit board (1) and radiator (2).Multilayer circuit board includes base layer (11) insulating layer (14) and copper foil layer (15).Base layer is provided with embedded hole (111), and the metal base block (12) of bearing chip (13) is set in the embedded hole.Base layer, insulating layer and copper foil layer are sequentially superposed and form multilayer circuit board in the way of pressing together.Multilayer circuit board and radiator are pressed together by the heat-conducting insulating accumulation film (3) between copper foil layer and radiator.The PCB embedded power module of the utility model is directly pressed together by the high-thermal-conductivity insulating accumulation film of external high-thermal-conductivity insulating accumulation film copper foil layer of multilayer circuit board and radiator, does not need to press together medium layer formed by high-thermal-conductivity insulating material in multilayer circuit board, also does not need large-area welding or sintering, reduce cost and reduce thermal resistance.

Description

Technical Field

[0001] This utility model relates to the field of power module technology, and in particular to a PCB embedded power module. Background Technology

[0002] Applications involving high voltage, high current, and high power, such as electric vehicles and industrial equipment, place high demands on the heat dissipation performance of PCB-embedded power modules. To quickly conduct heat from the heat source (e.g., the chip) to the heat sink outside the PCB, several methods have been developed based on the stacked structure of the PCB itself. These methods include embedding a large copper block in the PCB or using a dielectric layer formed of a highly thermally conductive insulating material, and then bonding this dielectric layer to the water-cooled heat sink by welding or sintering.

[0003] However, using copper blocks or high thermal conductivity insulating materials as dielectric layers within PCB boards increases the risk of cracking and delamination. Furthermore, because the areas where PCBs are soldered or sintered are relatively large, a certain thickness of the bonding layer material is required to ensure reliability, resulting in higher thermal resistance and higher costs. Utility Model Content

[0004] The purpose of this utility model is to solve at least one of the above-mentioned problems and / or other problems existing in the prior art.

[0005] To achieve the above objectives, according to one aspect of this utility model, a PCB embedded power module is provided, comprising a multilayer circuit board and a heat sink. The multilayer circuit board includes a substrate layer, an insulating layer, and a copper foil layer. The substrate layer has embedding holes, and a metal substrate carrying a chip is disposed within the embedding holes. The substrate layer, the insulating layer, and the copper foil layer are sequentially stacked and laminated to form the multilayer circuit board. The multilayer circuit board and the heat sink are laminated together by a thermally conductive and insulating deposited film disposed between the copper foil layer and the heat sink.

[0006] According to one embodiment of the present invention, the surface of the heat sink that is bonded to the copper foil layer is locally treated to obtain a roughness suitable for bonding with the deposited film in the bonding area.

[0007] According to one embodiment of the present invention, the thickness of the deposited film is 0.1 to 0.2 mm.

[0008] According to one embodiment of the present invention, the insulating layer has a plurality of through holes arranged in an array in the region corresponding to the metal substrate, each through hole having a heat-conducting pillar disposed therein, and the two ends of each heat-conducting pillar being connected to the metal substrate and the copper foil layer, respectively.

[0009] According to one embodiment of the present invention, the insulating layer includes a central region corresponding to the chip and a peripheral region disposed outside the central region, and the plurality of through holes are arranged in different ways in the central region and the peripheral region.

[0010] According to one embodiment of the present invention, a plurality of through holes in the central region are arranged in an array on a plurality of concentric nested circles, and a plurality of through holes in the peripheral region are arranged in an array on a plurality of concentric nested rectangles. No through holes are provided in the regions corresponding to the corners of the chip.

[0011] According to one embodiment of the present invention, the heat-conducting column and the metal base block are integrally formed into a whole.

[0012] According to one embodiment of the present invention, the heat-conducting pillar is formed in the through hole of the insulating layer by means of copper plating.

[0013] According to one embodiment of the present invention, on the copper foil layer, the peripheral blank area and / or the slot area of ​​the circuit pattern are filled by resin pressing to form an outer peripheral filling part and / or a slot filling part.

[0014] According to one embodiment of the present invention, the heat sink is configured as a copper-based heat sink or an aluminum-based heat sink with copper plated on the surface bonded to the copper foil layer.

[0015] The PCB embedded power module of this invention directly presses the copper foil layer of the multilayer circuit board and the heat sink together by means of an external high thermal conductivity insulating film. It does not require pressing a dielectric layer formed by high thermal conductivity insulating material inside the multilayer circuit board, nor does it require large-area welding or sintering, thereby reducing costs and thermal resistance. Attached Figure Description

[0016] The features and advantages of this utility model will become clear from the following detailed description provided with reference to the accompanying drawings. It should be understood that the following drawings are merely schematic and not necessarily drawn to scale, and therefore should not be considered as limitations on this utility model, wherein:

[0017] Figure 1 A perspective view of a PCB embedded power module according to an embodiment of the present invention is shown.

[0018] Figure 2 An exploded view of the PCB embedded power module is shown.

[0019] Figure 3 Show Figure 2 A magnified view of point A in the image.

[0020] Figure 4A schematic diagram of the bottom side of the metal substrate in the PCB embedded power module is shown.

[0021] Figure 5 This is a top view of the PCB-embedded power module.

[0022] Figure 6 Show along Figure 5 A cross-sectional view of the BB line.

[0023] Figure 7 Show Figure 6 A magnified view of point C in the image.

[0024] Explanation of reference numerals in the attached figures:

[0025] 1. Multilayer circuit board; 11. Substrate layer; 111. Embedded hole; 12. Metal substrate; 121. Central area; 122. Peripheral area; 13. Chip; 14. Insulating layer; 141. Through hole; 142. Heat-conducting pillar; 143. Central area; 144. Peripheral area; 15. Copper foil layer; 151. Outer perimeter filling; 152. Inter-slot filling; 2. Heat sink; 21. Bonding area; 22. Heat sink substrate; 23. Fin; 3. Deposited film. Detailed Implementation

[0026] Embodiments of the present invention are described below with reference to the accompanying drawings. In the following description, numerous specific details are set forth to enable those skilled in the art to more fully understand and implement the present invention. However, it will be apparent to those skilled in the art that implementations of the present invention may not include some of these specific details. Furthermore, it should be understood that the present invention is not limited to the specific embodiments described. Rather, the present invention can be conceived to be implemented with any combination of the features and elements described below, regardless of whether they relate to different embodiments. Therefore, the following aspects, features, embodiments, and advantages are for illustrative purposes only and should not be construed as elements or limitations of the claims unless expressly set forth in the claims.

[0027] The terms “include” and “have” in the following text are used to indicate an open-ended inclusion, meaning that there may be other elements / components besides those listed.

[0028] Figures 1 to 7 A PCB embedded power module according to an embodiment of the present invention is shown. Figure 1 and Figure 2 As shown, the PCB embedded power module according to this embodiment may include a multilayer circuit board 1, a heat sink 2, and a stacked film 3.

[0029] refer to Figure 2 , Figures 5 to 7As shown, the multilayer circuit board 1 includes at least a substrate layer 11, an insulating layer 14, and a copper foil layer 15, which are stacked in sequence and bonded together by pressing. Figure 2 The diagram also shows that the multilayer circuit board 1 has other layer structures on the side of the substrate layer 11 away from the insulating layer 14 and the copper foil layer 15. These layer structures can be configured as signal layers, mechanical layers or solder mask layers, etc. They are not related to the technical solutions of this disclosure, and their detailed descriptions are omitted here.

[0030] The substrate layer 11 is typically made of a resin-based composite material (e.g., epoxy resin + glass fiber composite material, represented by FR-4). The substrate layer 11 has a plurality of embedding holes 111, each embedding hole 111 extending through the entire thickness of the substrate layer 11. A metal substrate 12 may be disposed within each embedding hole 111, the metal substrate 12 supporting the chip 13.

[0031] The number of embedded holes 111 is related to the number of chips 13 that need to be configured. For example, as Figure 1 , Figure 2 and Figure 5 As shown, the power module of this embodiment has three multilayer circuit boards 1 arranged side by side, all of which are connected to a heat sink 2 forming a single unit. In another embodiment, the three multilayer circuit boards 1 shown in the figure can also be constructed as a single unit. Figure 2 As shown, each multilayer circuit board 1 has four metal substrates 12, each of which carries four chips 13. Correspondingly, each multilayer circuit board 1 has four embedding holes 111 on its substrate layer 11. Of course, the number of metal substrates 12, chips 13, and embedding holes 111 included in each multilayer circuit board 1 can also be other.

[0032] The metal substrate 12 is generally rectangular or has other shapes that fit the shape of the chip 13. The metal substrate 12 is preferably made of copper. The chip 13 supported by the metal substrate 12 can be a MOSFET chip or an IGBT chip, and typically includes components such as power transistors and power diodes.

[0033] The insulating layer 14 is, for example, a prepreg (PP layer) primarily formed of resin (e.g., epoxy resin) and reinforcing material (e.g., fiberglass cloth). The insulating layer 14 may have multiple dominant thermal regions, each corresponding to a metal substrate 12. The insulating layer 14 may have multiple through-holes 141 arranged in an array within each dominant thermal region, such as... Figure 3 As shown. Each through hole 141 is provided with a heat-conducting pillar 142.

[0034] In this embodiment, as Figure 4As shown, the heat-conducting pillar 143 can be integrally formed with the metal substrate 12 and inserted into the corresponding through-hole 141 when the insulating layer 14 and the substrate layer 11 are pressed together. In other embodiments, the heat-conducting pillar 143 can be formed in the various through-holes 141 on the insulating layer 14 by a copper plating process or other processes.

[0035] The copper foil layer 15 assists in heat dissipation for high-power components (such as chip 13). The copper foil layer 15 can also be patterned with circuitry through etching or photolithography. When the multilayer structure of the multilayer circuit board 1 is laminated into a single unit, one end of each heat-conducting pillar 142 is electrically and thermally connected to the corresponding metal substrate 12, and the other end of each heat-conducting pillar 142, facing away from the metal substrate 12, is electrically and thermally connected to the copper foil layer 15. Thus, the heat generated by the chip 13 can be conducted to the copper foil layer 15 via the array of heat-conducting pillars 142.

[0036] Figure 3 and Figure 4 The central portion of the image shows the approximate projection positions of chip 13 on the dominant heat-generating region of insulating layer 14 and the bottom surface of metal substrate 12, respectively, within a square frame. The circumcircle of this square frame (i.e., chip 13) is also shown. Figure 3 As shown, the dominant thermal region on the insulating layer 14 corresponding to a metal substrate 12 can be roughly divided by the outer circle of the chip 13 into a central region 143 corresponding to the chip 13 and a peripheral region 144 disposed radially outside the central region 143. Similarly, as Figure 4 As shown, the bottom surface of the metal substrate 12 can be roughly divided into a central region 121 corresponding to the chip 13 and a peripheral region 122 located radially outside the central region 121, with the outer circle of the chip 13 as the boundary.

[0037] In the dominant thermal region corresponding to each metal substrate 12 on the insulating layer 14, a plurality of through holes 141 are arranged in different ways in the central region 143 and the peripheral region 144. For example, as Figure 3 As shown, multiple through holes 141 in the central region 143 are arranged in an array on multiple concentric nested circles, and multiple through holes 141 in the outer region 144 are arranged in an array on multiple concentric nested rectangles. Correspondingly, on the bottom surface of the metal substrate 12, multiple heat-conducting pillars 142 in the central region 121 are arranged in an array on multiple concentric nested circles, and multiple heat-conducting pillars 142 in the outer region 122 are arranged in an array on multiple concentric nested rectangles, as shown. Figure 4 As shown. Of course, in some other embodiments, the through holes 141 or the heat-conducting pillars 142 can also be arranged in an array in any other suitable form.

[0038] Preferably, in the dominant thermal regions corresponding to each metal substrate 12 on the insulating layer 14, a plurality of through-holes 141 are arranged more densely in the central region 143 than in the peripheral region 144, and / or the diameter of the through-holes 141 in the central region 143 is larger than the diameter of the through-holes 141 in the peripheral region 144. Correspondingly, on the bottom surface of the metal substrate 12, a plurality of heat-conducting pillars 142 are arranged more densely in the central region 121 than in the peripheral region 122, and / or the diameter of the heat-conducting pillars 142 in the central region 121 is larger than the diameter of the heat-conducting pillars 142 in the peripheral region 122. Thus, the region corresponding to the chip 13 has a larger and more concentrated heat conduction channel, thereby reducing thermal resistance.

[0039] In addition, such as Figure 3 and Figure 4 As shown, no through-holes 141 or heat-conducting pillars 142 are provided in the areas roughly corresponding to the four corners of chip 13. Because the temperature in these areas is lower, the strain energy density is reduced, and fatigue resistance is improved. Therefore, the problem of cracking / delamination that easily occurs in these areas when through-holes or heat-conducting pillars are uniformly distributed is suppressed, improving reliability.

[0040] Typically, the coverage area of ​​the copper foil layer 15 is slightly smaller than that of the insulating layer 14, so that a void area corresponding to the periphery of the insulating layer 14 is formed at the periphery of the copper foil layer 15 according to the voltage level and pollution level. This void area can be filled with resin lamination to form a shape such as... Figure 2 The outer peripheral filling portion 151 is shown. Further, the circuit pattern formed on the copper foil layer 15 has hollowed-out grooves, which can also be filled with resin to form a shape such as... Figure 2 The slot filling portion 152 shown is an outer peripheral filling portion 151. The slot filling portion 152 ensures the structural integrity and electrical reliability of the entire power module.

[0041] like Figure 2 , Figure 6 and Figure 7 As shown, the radiator 2 may include a radiator base plate 22 having a bonding region 21 and a plurality of fins 23 extending from the radiator base plate 22 toward a side opposite to the bonding region 21. The radiator 2 may be a water-cooled radiator, wherein cooling water can circulate in a flow path inside the radiator 2. Compared to air-cooled radiators, water-cooled radiators have higher cooling efficiency and lower noise.

[0042] In this embodiment, the heat sink 2 can be a copper-based heat sink or an aluminum-based heat sink. Compared to aluminum-based heat sinks, copper-based heat sinks have excellent thermal conductivity, but are more expensive. Aluminum-based heat sinks have slightly lower thermal conductivity, but are less expensive. Copper can be plated on the surface of aluminum-based heat sinks to improve heat transfer efficiency, reduce interfacial contact thermal resistance, and prevent electrochemical corrosion.

[0043] In this embodiment, the bonding area 21 of the heat sink 2 is directly pressed together with the copper foil layer 15 of the multilayer circuit board 1 using a deposited film 3. For this purpose, the surfaces where the heat sink 2 and the copper foil layer 15 are bonded can be locally treated to obtain a roughness suitable for bonding with the deposited film 3 in the bonding area 21. Preferably, the thickness of the deposited film 3 is in the range of 0.1 to 0.2 mm.

[0044] The deposited film 3 used in this embodiment simultaneously satisfies both high thermal conductivity (efficient heat transfer) and high insulation resistance (avoiding leakage or charge interference). It is typically formed by stacking layers of highly thermally conductive and insulating nanounits (such as ceramic nanosheets or inorganic nanoparticles) with an insulating substrate material. The orderly arrangement of the thermally conductive units constructs the heat transfer path, while the insulating substrate or interface design blocks electron conduction. Such deposited films are readily available on the market.

[0045] In existing PCB-embedded power modules, the multilayer circuit board 1 typically has a dielectric layer formed of a high thermal conductivity insulating material laminated outside the copper foil layer 15. This dielectric layer is bonded to the heat sink by soldering or sintering. For this high thermal conductivity insulating material laminated within the PCB, it needs to meet requirements such as a thermal conductivity of not less than 10 W / (mK), good flowability / filling properties, high peel strength, and moderate lamination pressure. Materials on the market that simultaneously meet these requirements are very rare, because high thermal conductivity requires more thermally conductive filler, which reduces the material's flowability and adhesion strength, and requires greater processing pressure, thus contradicting the requirements for process and mechanical properties. If such a material is placed within the PCB stack, the inconsistency between its thermal conductivity and mechanical and dielectric properties (i.e., compatibility issues) can easily be amplified during later reliability testing of the PCB, leading to failures.

[0046] Furthermore, if soldering (such as brazing) is used to connect the large heat dissipation surface on the bottom of the PCB to the water-cooled radiator, the commonly used lead-free solders such as SAC305, SnSb5, or SnSb10 have low melting points (between 217 and 250°C), meaning their homogenization temperature (K-scale) is very high (for example, for SAC305, its homogenization temperature at room temperature of 23°C is 0.6 times its melting point). For high-power devices, the operating temperature or high-temperature range of the solder joint is usually 125 to 150°C or higher. Therefore, the strain energy density caused by a large amount of creep strain will be very high, leading to rapid failure of a large area of ​​the solder joint. It is difficult to pass 1000 reliability cycle tests with a high yield and adapt to high-temperature operation. If sintering (such as silver / copper sintering, transient liquid phase soldering) is used to connect the PCB heat dissipation surface to the heat sink, although the reliability and yield are better than soldering, the large-area sintering requires a certain bonding layer thickness (usually greater than 300 micrometers or more) to ensure reliability, resulting in no advantage in thermal resistance. Moreover, precious metal sintering is expensive and has a low cost-performance ratio.

[0047] Compared to existing technologies, the PCB-embedded power module in this embodiment directly laminates the copper foil layers of the multilayer circuit board to the heat sink using an external high thermal conductivity insulating film. This eliminates the need for an internal dielectric layer formed of high thermal conductivity insulating material, as well as large-area soldering or sintering. This not only reduces the overall thickness of the power module and lowers costs, but also correspondingly reduces thermal resistance.

[0048] Furthermore, as described above, the PCB embedded power module according to this utility model also optimizes the arrangement of the through-hole 141 for conducting heat from the chip 13 to the copper foil layer 15 for heat dissipation and the heat-conducting pillar 142 disposed therein, which not only reduces thermal resistance, but also reduces the strain energy density in the corner region of the chip 13, thereby improving its fatigue resistance and reliability.

[0049] Various modifications and variations can be made to the embodiments disclosed above without departing from the scope or spirit of this invention. Other embodiments of this invention will be apparent to those skilled in the art based on the practice of this invention disclosed in this specification. This specification and the examples disclosed herein should be considered illustrative only, and the true scope of this invention is defined by the appended claims and their equivalents.

Claims

1. A PCB embedded power module, comprising a multilayer circuit board (1) and a heat sink (2), characterized in that, The multilayer circuit board (1) includes: A substrate layer (11) is provided with an embedding hole (111), and a metal substrate (12) carrying a chip (13) is disposed in the embedding hole; Insulating layer (14); and Copper foil layer (15); The substrate layer (11), the insulating layer (14) and the copper foil layer (15) are stacked in sequence and pressed together to form the multilayer circuit board (1). The multilayer circuit board (1) and the heat sink (2) are pressed together by a thermally conductive and insulating stacked film (3) disposed between the copper foil layer (15) and the heat sink (2).

2. The PCB embedded power module according to claim 1, characterized in that, The surface of the heat sink (2) that is bonded to the copper foil layer (15) is locally treated to obtain a roughness suitable for bonding with the deposited film (3) in the bonding area (21).

3. The PCB embedded power module according to claim 1, characterized in that, The thickness of the deposited film (3) is 0.1 to 0.2 mm.

4. The PCB embedded power module according to any one of claims 1 to 3, characterized in that, The insulating layer (14) has a plurality of through holes (141) arranged in an array in the region corresponding to the metal substrate (12), and each through hole is provided with a heat-conducting pillar (142), and the two ends of each heat-conducting pillar (142) are respectively connected to the metal substrate (12) and the copper foil layer (15).

5. The PCB embedded power module according to claim 4, characterized in that, The insulating layer (14) includes a central region (143) corresponding to the chip (13) and a peripheral region (144) disposed outside the central region, and the plurality of through holes (141) are arranged in different ways in the central region (143) and the peripheral region (144).

6. The PCB embedded power module according to claim 5, characterized in that, The central region (143) has a plurality of through holes (141) arranged in an array on a plurality of concentric nested circles, and the peripheral region (144) has a plurality of through holes (141) arranged in an array on a plurality of concentric nested rectangles. No through holes are provided in the region corresponding to the corner of the chip (13).

7. The PCB embedded power module according to claim 4, characterized in that, The heat-conducting pillar (142) and the metal base block (12) are integrally formed into a whole.

8. The PCB embedded power module according to claim 4, characterized in that, The heat-conducting pillar (142) is formed in the through hole (141) of the insulating layer (14) by means of copper plating.

9. The PCB embedded power module according to any one of claims 1 to 3, characterized in that, On the copper foil layer (15), the peripheral blank area and / or the slot area of ​​the circuit pattern are filled with resin to form an outer peripheral filling part (151) and / or a slot filling part (152).

10. The PCB embedded power module according to any one of claims 1 to 3, characterized in that, The radiator (2) is configured as a copper-based radiator or an aluminum-based radiator with copper plated on the surface bonded to the copper foil layer (15).

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