Power modules, power units and power conversion equipment

Abstract

This application provides a power module, a power conversion unit, and a power conversion device, belonging to the field of power conversion technology. The power module includes a substrate, at least one power chip, and a molding compound; the at least one power chip is located on the surface of the substrate, and a metal layer is disposed on the surface of the substrate opposite to the power chip; both the at least one power chip and the substrate are located within the molding compound, and a portion of the surface of the metal layer opposite to the power chip is located within the molding compound, while another portion of the metal layer opposite to the power chip is located outside the molding compound. By adopting this application, the risk of insulation failure of the ceramic layer of the substrate can be reduced, and the service life of the ceramic layer can be extended.

Description

Technical Field

[0001] This application relates to the field of power conversion technology, and in particular to a power module, power assembly, and power conversion device. Background Technology

[0002] A power module is a semiconductor device that converts at least one of the voltage, current, and frequency of a power source, and is the core device for power conversion.

[0003] The power chip in a power module generates heat during operation, so power modules are usually used in conjunction with a heat sink. For example, after the power module is packaged, the substrate containing the power chip is soldered to the heat sink base plate. The heat generated by the power chip is transferred to the heat sink and then dissipated outwards.

[0004] After the power module and heat sink are soldered together, a temperature cycling test (TC) is required to assess the reliability of the power module. In the reliability test, the reliability of the power module under temperature changes is evaluated by alternating extreme high and low temperatures.

[0005] Because the coefficients of thermal expansion (CTE) of the power module and the solder layer are different, cracks may occur between them during reliability testing due to the different deformations. For example... Figure 1 As shown, location A is a position prone to cracking. Cracks easily propagate along the boundary between the power module's molding compound and the lower copper layer of the substrate, gradually extending to the ceramic layer of the substrate, causing the ceramic layer to crack. Once the ceramic layer cracks, its insulation performance will decrease, and in severe cases, the upper copper layer on the upper surface and the lower copper layer on the lower surface of the ceramic layer will become conductive, resulting in leakage current. Utility Model Content

[0006] This application provides a power module, a power unit, and a power conversion device that can reduce the risk of insulation failure in the ceramic layer of a substrate.

[0007] In a first aspect, this application provides a power module, the power module comprising a substrate, at least one power chip, and a molding compound;

[0008] The at least one power chip is located on the surface of the substrate, and a metal layer is disposed on the surface of the substrate opposite to the power chip.

[0009] The substrate and the at least one power chip are both located within the molding compound, and a portion of the metal layer facing away from the power chip is located within the molding compound, while another portion of the metal layer facing away from the power chip is located outside the molding compound.

[0010] In the scheme shown in this application, the metal layer at the bottom of the power module, which is used to weld to the heat sink base plate, is away from the surface of the power chip. Part of it is encapsulated in the molded body, and the other part is exposed outside the molded body. Therefore, after the power module and the heat sink base plate are welded, even if cracks are generated between the power module and the welding layer due to inconsistent deformation during reliability testing, the cracks will propagate along the horizontal interface between the surface of the metal layer and the welding layer. The cracks are not likely to propagate to the vertical interface between the side of the metal layer and the molded body. Since the cracks are not likely to propagate along the vertical interface between the side of the metal layer and the molded body, the cracks are not likely to propagate along the vertical interface to the ceramic layer of the substrate. This reduces the risk of insulation failure of the ceramic layer of the substrate and helps to extend the service life of the substrate.

[0011] In one implementation, the substrate is a copper-clad ceramic substrate, including a ceramic layer and a first copper layer located on the surface of the ceramic layer, wherein at least one power chip is located on the surface of the first copper layer, and both the ceramic layer and the first copper layer are located within the molding compound.

[0012] In the scheme shown in this application, the copper-clad ceramic substrate, also known as a copper-clad ceramic plate or a ceramic-based copper-clad plate, is a substrate in which copper foil is sintered onto the ceramic surface using direct copper bonding (DBC) or active metal brazing (AMB) techniques. Substrates processed using DBC technology are called DBC substrates, and substrates processed using AMB technology are called AMB substrates. Copper-clad ceramic substrates possess excellent thermal cycling performance, shape stability, high rigidity, and high thermal conductivity, and various patterns can be etched onto the first copper layer.

[0013] In one implementation, the substrate is a single-sided copper-clad ceramic substrate, and the power module further includes a heat dissipation metal layer located on the surface of the ceramic layer opposite to the first copper layer.

[0014] In the solution shown in this application, the substrate includes a ceramic layer, a first copper layer on the upper surface of the ceramic layer, and no copper layer on the lower surface of the ceramic layer. In this case, the metal layer disposed on the surface of the substrate away from the power chip can be a heat dissipation metal layer.

[0015] In one implementation, the substrate is a single-sided copper-clad ceramic substrate, the heat dissipation metal layer is disposed on the surface of the ceramic layer opposite to the first copper layer, and the orthographic projection of the heat dissipation metal layer on the surface of the first copper layer covers the first copper layer.

[0016] In the solution shown in this application, the heat dissipation metal layer has a large area, which is beneficial to improving the heat transfer effect between the power module and the heat sink.

[0017] In one implementation, the substrate is a double-sided copper-clad ceramic substrate, and the substrate further includes a second copper layer located on the surface of the ceramic layer opposite to the first copper layer, and the metal layer is the second copper layer.

[0018] In the solution shown in this application, the substrate includes a ceramic layer, a first copper layer on the upper surface of the ceramic layer, and a second copper layer on the lower surface of the ceramic layer. In this case, the metal layer disposed on the surface of the substrate away from the power chip can be the second copper layer.

[0019] In one implementation, the substrate is a double-sided copper-clad ceramic substrate, and the substrate further includes a second copper layer located on the surface of the ceramic layer opposite to the first copper layer.

[0020] The power module further includes a heat dissipation metal layer located on the surface of the second copper layer away from the ceramic layer. The first copper layer, the ceramic layer, and the second copper layer are all located within the molding compound, and the metal layer is the heat dissipation metal layer.

[0021] In the solution shown in this application, the substrate includes a ceramic layer, a first copper layer on the upper surface of the ceramic layer, and a second copper layer on the lower surface of the ceramic layer. In this case, the metal layer disposed on the surface of the substrate away from the power chip can be a heat dissipation metal layer.

[0022] In one implementation, the substrate is a double-sided copper-clad ceramic substrate, wherein the area of ​​the second copper layer is greater than or equal to the area of ​​the first copper layer.

[0023] In the solution shown in this application, the orthographic projection of the second copper layer onto the plane where the first copper layer is located covers the first copper layer. The larger the area of ​​the second copper layer, the easier it is to transfer the heat from the first copper layer to the heat dissipation base plate.

[0024] In one implementation, the substrate is a double-sided copper-clad ceramic substrate, and a metal layer is disposed on the surface of the second copper layer away from the ceramic layer, wherein the area of ​​the metal layer is greater than or equal to the area of ​​the second copper layer.

[0025] In the solution shown in this application, the orthographic projection of the metal layer on the plane where the second copper layer is located covers the second copper layer. The larger the area of ​​the metal layer, the easier it is to transfer the heat on the second copper layer to the heat dissipation base plate.

[0026] In one implementation, the substrate is a double-sided copper-clad ceramic substrate, and a metal layer is disposed on the surface of the second copper layer away from the ceramic layer. The area of ​​the metal layer is larger than the area of ​​the second copper layer. The metal layer is disposed on both the surface of the second copper layer away from the ceramic layer and the side surface of the second copper layer.

[0027] In the solution shown in this application, the area of ​​the metal layer is larger than the area of ​​the second copper layer and smaller than or equal to the area of ​​the ceramic layer. The larger area of ​​the metal layer is beneficial to improving the heat transfer effect between the power module and the heat sink.

[0028] In one implementation, the edges of the metal layer that are away from the surface of the power chip are all located within the molding compound.

[0029] In the solution shown in this application, the molding compound completely covers the edges of the metal layer on the surface away from the power chip. This causes the molding compound and the solder layer, at locations prone to cracking, to be recessed towards the center and away from the sides of the metal layer. This ensures that the vertical contact interface between the sides of the metal layer and the molding compound is not on the crack propagation path. Therefore, even if cracks occur at locations prone to cracking, the cracks are less likely to propagate along the aforementioned vertical contact interface to the ceramic layer, greatly reducing the risk of insulation failure of the ceramic layer and extending its service life.

[0030] In one implementation, the shape of the metal layer facing away from the surface of the power chip is polygonal, and the apex corners of the metal layer facing away from the surface of the power chip are all located within the molding compound.

[0031] In the solution shown in this application, the locations where cracks are prone to occur between the power module and the solder layer are mainly concentrated at the top corner of the power module. Therefore, the metal layer encapsulated by the molding compound can be positioned away from the top corner of the power chip surface.

[0032] In one implementation, the midpoint of each edge of the metal layer away from the surface of the power chip is located within the molding compound.

[0033] In the solution shown in this application, the molding compound covers the top corners of the metal layer away from the power chip surface and the midpoints of each edge, which can further reduce the risk of insulation failure of the ceramic layer of the substrate and extend the service life of the ceramic layer.

[0034] In one implementation, the area of ​​the metal layer opposite to the power chip surface covered by the molding compound is polygonal or fan-shaped.

[0035] In one implementation, an exposed portion of the metal layer, facing away from the surface of the power chip and located outside the molding compound, is fixedly connected to a boss on a heat sink base plate via a solder layer, and the orthographic projection of the exposed portion on the heat sink base plate covers the boss.

[0036] In the solution shown in this application, the exposed portion of the metal layer that is away from the surface of the power chip and located outside the plastic package is welded to the heat sink base plate. The bosses on the heat sink base plate can be welded to the portion of the metal layer that is away from the surface of the power chip and located outside the plastic package, thereby increasing the contact area between the metal layer and the bosses and ensuring the heat transfer between the metal layer and the heat sink base plate.

[0037] In one implementation, the area of ​​the portion of the metal layer that is away from the surface of the power chip and located within the molding compound is smaller than the area of ​​the portion of the metal layer that is away from the surface of the power chip and located outside the molding compound.

[0038] In the scheme shown in this application, the sum of the areas of the encapsulated portions of the metal layer that are away from the surface of the power chip and located within the molding compound is smaller than the area of ​​the exposed portions of the metal layer that are away from the surface of the power chip and located outside the molding compound. This is because the main function of the metal layer away from the surface of the power chip is to be soldered to the heat sink to transfer the heat generated by the power chip to the heat sink. Therefore, the area of ​​the portion of the metal layer away from the power chip and located outside the molding compound needs to be larger. The larger this area, the larger the contact area between the surface of the metal layer away from the power chip and the heat sink, and the better the heat transfer effect.

[0039] In one implementation, the portion of the metal layer that is opposite to the surface of the power chip and located outside the molding compound, when projected onto the surface of the substrate, covers all the power chips on the surface of the substrate.

[0040] In the solution shown in this application, the area of ​​the metal layer that is away from the surface of the power chip and located outside the plastic package is large enough to cover all the power chips. Therefore, the heat generated by any power chip can be transferred to the heat sink along a vertical path, shortening the heat transfer path and improving the heat dissipation effect.

[0041] In one implementation, the bottom surface of the molding compound has multiple support structures for abutting against a heat sink base plate to control the thickness of the solder layer between the portion of the metal layer facing away from the surface of the power chip and located outside the molding compound and the heat sink base plate.

[0042] In the solution shown in this application, when the plastic package covering the metal layer away from the surface of the power chip is relatively thin, multiple support structures can be set on the bottom surface of the plastic package to control the thickness of the solder layer.

[0043] In one implementation, the orthogonal projections of the plurality of support structures onto the plane containing the metal layer all fall outside the metal layer.

[0044] In the scheme shown in this application, the support structure is set on the molding compound and is made of the same material as the molding compound. Its heat transfer is poor. In order not to block the heat transfer between the metal layer and the heat dissipation base plate, the orthographic projection of the support structure on the plane where the metal layer is located can be located outside the metal layer.

[0045] In one implementation, the supporting structure is spherical, hemispherical, or columnar in shape.

[0046] In one implementation, the bottom surface of the molding compound is used to abut against a heat sink base plate to control the thickness of the solder layer between the portion of the metal layer facing away from the surface of the power chip and located outside the molding compound and the heat sink base plate.

[0047] In the solution shown in this application, when the encapsulation covering the metal layer is relatively thick, the entire bottom surface of the encapsulation can abut against the heat dissipation base plate to control the thickness of the solder layer.

[0048] In a second aspect, a power module is provided, the power module including a heat sink, a solder layer and any of the power modules described in the first aspect;

[0049] The radiator includes a heat dissipation base plate and heat dissipation fins located on the surface of the heat dissipation base plate;

[0050] The portion of the metal layer that is away from the surface of the power chip and located outside the plastic package is fixedly connected to the surface of the heat sink base plate that is away from the heat sink fins through the welding layer.

[0051] In the solution shown in this application, the heat generated by the power chip can be transferred to the heat sink through the metal layer and the solder layer, and then dissipated outward through the heat sink.

[0052] In one implementation, the heat sink base plate has a boss on the surface opposite to the heat sink fins, and the portion of the metal layer opposite to the surface of the power chip and located outside the molding compound is fixedly connected to the platform of the boss through the solder layer.

[0053] In the solution shown in this application, the boss serves as a pad for the heat dissipation base plate and is fixedly connected to the portion of the metal layer that is away from the surface of the power chip and exposed in the molding compound through a solder layer.

[0054] In one implementation, the portion of the metal layer that is away from the surface of the power chip and located outside the molding compound, on the heat sink base, covers the protrusion on the heat sink base.

[0055] In the solution shown in this application, all the protrusions of the heat sink base plate are exposed outside the power chip and located outside the plastic package, and are fixed by a solder layer, which helps to increase the solder interface and improve the heat transfer between the heat sink base plate and the metal layer.

[0056] In one implementation, the heat sink base plate has a plurality of support pillars on the surface opposite to the heat sink fins. The plurality of support pillars are used to abut against the portion of the metal layer opposite to the power chip and located outside the molding compound to control the thickness of the solder layer between the metal layer and the heat sink base plate.

[0057] In the solutions shown in this application, where the heat sink base has a boss, multiple support pillars can be disposed on the platform of the boss. In solutions where the bottom of the power module does not abut against the heat sink base—for example, where the power module's molding compound does not abut against the heat sink base and the bottom surface of the molding compound has no support structure—the heat sink base can have support pillars. These support pillars abut against the portion of the metal layer facing away from the power chip and located outside the molding compound. The support pillars are used to control the thickness of the solder layer between the portion of the metal layer outside the molding compound and the heat sink base. For example, this ensures that the thickness of the portion of the metal layer outside the molding compound and the heat sink base is substantially equal at all locations, avoiding holes and collapses.

[0058] In one implementation, the power module further includes a heat sink, with the side of the heat sink base plate facing away from the power module facing the heat sink, and the heat sink base plate in contact with the heat dissipation medium inside the heat sink.

[0059] In the solution shown in this application, the side of the heat sink facing away from the power chip is immersed in a heat sink and comes into contact with the heat dissipation medium in the heat sink. The heat dissipation medium in the heat sink carries away the heat from the heat sink as it flows, thereby achieving the purpose of heat dissipation for the power chip.

[0060] Thirdly, a power conversion device is provided, the power conversion device including a housing, a circuit board, and a power module as described in any of the second aspects;

[0061] Both the circuit board and the power module are located in the housing, and the power chip of the power module is electrically connected to the circuit board. Attached Figure Description

[0062] Figure 1 This is a schematic diagram of a power module and heat sink after welding, provided by existing technology;

[0063] Figure 2 This is a schematic diagram of the structure of a power module including a single-sided copper-clad ceramic substrate provided in an exemplary embodiment of this application;

[0064] Figure 3 This is a schematic diagram of the structure of a power module including a double-sided copper-clad ceramic substrate, wherein the second copper layer of the double-sided copper-clad ceramic substrate serves as a metal layer, provided by an exemplary embodiment of this application.

[0065] Figure 4 This is a schematic diagram of a power module structure provided by an exemplary embodiment of this application, including a double-sided copper-clad ceramic substrate, wherein a heat dissipation metal layer is disposed on the surface of the second copper layer of the double-sided copper-clad ceramic substrate;

[0066] Figure 5 This is a schematic diagram of the power module and the heat sink base plate of the heat sink provided in an exemplary embodiment of this application after welding;

[0067] Figure 6 This is a schematic diagram of the bottom surface of a power module provided in an exemplary embodiment of this application;

[0068] Figure 7 This is a schematic diagram of the bottom surface of a power module provided in an exemplary embodiment of this application;

[0069] Figure 8 This is a schematic diagram of the bottom surface of a power module provided in an exemplary embodiment of this application;

[0070] Figure 9 This is a schematic diagram of the bottom surface of a power module provided in an exemplary embodiment of this application;

[0071] Figure 10 This is a schematic diagram of the bottom surface of a power module provided in an exemplary embodiment of this application;

[0072] Figure 11 This is a schematic diagram of the power module and heat sink after welding, provided in an exemplary embodiment of this application;

[0073] Figure 12 This is a schematic diagram of the power module and heat sink after welding, provided in an exemplary embodiment of this application;

[0074] Figure 13This is a schematic diagram of the power module and heat sink after welding, provided in an exemplary embodiment of this application;

[0075] Figure 14 This is a schematic diagram of the power module and heat sink after welding, provided in an exemplary embodiment of this application;

[0076] Figure 15 This is a schematic diagram of the bottom surface of a power module provided in an exemplary embodiment of this application.

[0077] Explanation of reference numerals in the attached figures

[0078] 1. Power module; 11. Substrate; 12. Power chip; 13. Molded package; 110. Ceramic layer; 111. First copper layer; 112. Second copper layer; 112A. Encapsulation portion; 112B. Exposed portion; 14. Heat dissipation metal layer.

[0079] 2. Radiator; 21. Heat sink base plate; 22. Heat sink fins; 211. Boss; 212. Support column.

[0080] 3. Welding layer; 131. Supporting structure. Detailed Implementation

[0081] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0082] This embodiment relates to a power conversion device, which can be a device used in electric vehicles (such as a motor controller) or a device used in energy storage systems (such as an uninterruptible power supply or a transformer). This embodiment does not limit the specific application scenario of the power conversion device.

[0083] The power conversion equipment includes a power module, which is a semiconductor device that converts at least one of the voltage, current, and frequency of a power supply. Structurally, it mainly consists of a substrate and a power chip located on the substrate. Specifically, the power module can be an insulated-gate bipolar transistor (IGBT) power module or a silicon carbide (SiC) power module.

[0084] The power chip inside the power module generates heat during operation, so a heat sink is needed to dissipate heat from the power chip. For example, the heat sink is interconnected with the power module, and the power module transfers the heat generated by the internal power chip to the heat sink, which then dissipates the heat to the outside.

[0085] Currently, one common interconnection method between power modules and heat sinks is through thermal interface material (TIM). For example, both the power module and the heat sink are mounted on the motherboard, with the heat sink pressing against the power module. The heat sink's base plate and the power module's substrate face each other, and a TIM pad is placed between the base plate and the substrate. TIM is a thermally conductive silicone grease with some elasticity, capable of absorbing the gap between the base plate and the substrate, reducing the contact thermal resistance between them.

[0086] Among these, welding and sintering interconnects, compared to TIM interconnects, offer superior heat transfer and stability, making them a hot research topic in the industry. Although sintering provides higher heat transfer and stability than welding, the material costs used in sintering remain high. Welding interconnects, on the other hand, offer the advantage of lower costs. Therefore, in the field of power module and heat sink interconnects, welding interconnects are a key area of ​​research and mass production development in the industry.

[0087] The soldering interconnection between power modules and heat sinks includes pre-soldering and post-soldering. Pre-soldering involves soldering the substrate to the heat sink before encapsulation. For example, after the power chip is fixed to the surface of the substrate, the surface of the substrate facing away from the power chip is soldered to the heat sink. Finally, encapsulation is performed, and the encapsulated plastic package covers the solder layer, making the power module and heat sink less prone to cracking at the solder layer, resulting in higher reliability. However, in this pre-soldering process, one power module corresponds to one heat sink, and since the size of the power module is generally small, the size of the heat sink is also relatively small, resulting in a lower heat dissipation effect compared to post-soldering.

[0088] Post-soldering refers to the soldering of the substrate to the heat sink after the power module has been packaged. For example, after the power module is packaged, the surface of the substrate facing away from the power chip has an exposed metal layer, which serves as the substrate's solder pads and is then soldered to the heat sink. In this post-soldering process, multiple power modules can be connected to a single heat sink. The heat sink is larger in size, has a larger heat dissipation area, and its heat dissipation effect is significantly better than that of pre-soldering. Therefore, post-soldering is the most common method for interconnecting power modules and heat sinks.

[0089] While post-soldering can give the heat sink better heat dissipation performance, it can easily cause cracks in the ceramic layer of the substrate, which will lead to a decrease in the insulation performance of the substrate. In severe cases, it can cause the power module to leak current to the outside. The reasons are as follows.

[0090] like Figure 1 The diagram shown is a schematic of the power module 1 and the heat sink base plate 21 after welding in the prior art. (Refer to...) Figure 1As shown, the substrate 11 of the power module 1 is a double-sided copper-clad ceramic substrate, including a ceramic layer 110, a first copper layer 111 located on the upper surface of the ceramic layer 110, and a second copper layer 112 located on the lower surface of the ceramic layer 110. The power chip 12 is disposed on the first copper layer 111. The first copper layer 111 is used to realize the electrical interconnection between different power chips and the electrical interconnection between the power chip 12 and other components. The second copper layer 112 is used for soldering to the heat sink base plate 21. The ceramic layer 110, the first copper layer 111, and all components located on the first copper layer 111 of the power module 1 are all encapsulated in a molding compound 13, while the second copper layer 112 is exposed for soldering to the heat sink base plate 21.

[0091] After the power module and heat sink are soldered, a temperature cycling test (TC) is required to assess their reliability. For example, the power module with the heat sink is placed in a constant temperature chamber and cycled between extreme temperatures, such as -40 degrees to +125 degrees and +125 degrees to -40 degrees, for 500 to 2000 cycles to test the reliability of the power module.

[0092] refer to Figure 1 As shown, in the packaged power module, the molding compound 13 occupies a large proportion, and the power module as a whole exhibits the properties of the molding compound 13. Therefore, the coefficient of thermal expansion (CTE) of the power module and the solder layer are different. In reliability testing, the different deformations of the power module and the solder layer will cause cracks to appear at their interface. For example, in… Figure 1 A crack occurs at the junction of the middle solder layer 3, the molding compound 13, and the second copper layer 112. Figure 1 At position A, the crack that originates at position A is likely to extend upwards along the vertical interface between the second copper layer 113 and the molding compound 13, reaching the ceramic layer 110 and further causing cracking of the ceramic layer 110. Once there are cracks or fissures in the ceramic layer 110, the insulation performance of the ceramic layer 110 will be reduced, and the electrical isolation between the first copper layer 111 and the second copper layer 112 will deteriorate. When there is a large voltage or current on the first copper layer 111, the ceramic layer 110 is easily broken down, causing the power module to leak current.

[0093] Therefore, this embodiment provides a power module, such as... Figures 2 to 4 The diagram shown is a structural schematic of power module 1.

[0094] refer to Figure 2As shown, the power module 1 includes a substrate 11, at least one power chip 12, and a molding compound 13. The at least one power chip 12 is located on the surface of the substrate 11. A metal layer is disposed on the surface of the substrate 11 facing away from the molding compound 13. The substrate 11 and all the power chips 12 are located within the molding compound 13. A portion of the metal layer on the surface of the substrate 11 facing away from the power chip 12 is located within the molding compound 13, and another portion is located outside the molding compound 13. Specifically, a portion of the metal layer facing away from the power chip 12 is located within the molding compound 13, and another portion is located outside the molding compound 13. The portion of the metal layer facing away from the power chip 12 and located outside the molding compound 13 serves as a solder pad for soldering to a heat sink 21. The portion of the molding compound 13 encapsulating the metal layer facing away from the power chip serves as a solder resist to prevent soldering to the heat sink 21.

[0095] Among them, the substrate 11 can be a copper-clad ceramic substrate, also known as a copper-clad ceramic plate or a ceramic-based copper-clad plate, which is a substrate in which copper foil is sintered onto the ceramic surface through direct bond copper (DBC) or active metal brazing (AMB) technology.

[0096] As an example, see reference Figure 2 As shown, substrate 11 is a single-sided copper-clad ceramic substrate, including a ceramic layer 110 and a first copper layer 111 located on the surface of the ceramic layer 110. All power chips 12 are located on the surface of the first copper layer 111, and the ceramic layer 110, the first copper layer 111, and all power chips 12 are located within the molding compound 13. (Continue to refer to...) Figure 2 As shown, the power module also includes a heat dissipation metal layer 14, which is disposed on the surface of the ceramic layer 110 facing away from the power chip 12. A portion of the surface of the heat dissipation metal layer 14 facing away from the ceramic layer 110 is located within the molding compound 13, and another portion is located outside the molding compound 13. The heat dissipation metal layer 14 can also be made of copper.

[0097] As another example, see Figure 3 As shown, substrate 11 is a double-sided copper-clad ceramic substrate, comprising not only a ceramic layer 110 and a first copper layer 111 on the upper surface of the ceramic layer 110, but also a second copper layer 112 on the lower surface of the ceramic layer 110. The first copper layer 111 and the second copper layer 112 are located on two opposite surfaces of the ceramic layer 110. All power chips 12 are located on the first copper layer 111. The ceramic layer 110 and all power chips 12 are located within the molding compound 13. The second copper layer 112 can serve as the aforementioned metal layer, meaning that part of the surface of the second copper layer 112 facing away from the ceramic layer 110 is located within the molding compound 13, and the other part is located outside the molding compound 13.

[0098] As another example, see Figure 4 As shown, substrate 11 is also a double-sided copper-clad ceramic substrate, including a ceramic layer 110, a first copper layer 111, and a second copper layer 112. All power chips 12 are located on the surface of the first copper layer 111, and all power chips 12, the first copper layer 111, the ceramic layer 110, and the second copper layer 112 are located within the molding compound 13. (Continue to refer to...) Figure 4 As shown, the power module 1 also includes a heat dissipation metal layer 14, which is disposed on the surface of the second copper layer 112 facing away from the ceramic layer 110. A portion of the surface of the heat dissipation metal layer 14 facing away from the second copper layer 112 is located within the molding compound 13, and another portion is located outside the molding compound 13. The heat dissipation metal layer 14 can also be made of copper.

[0099] refer to Figure 4 As shown, the area of ​​the heat dissipation metal layer 14 can be slightly equal to the area of ​​the second copper layer 112. That is, the orthogonal projection of the heat dissipation metal layer 14 onto the plane where the second copper layer 112 is located exactly covers the second copper layer 112.

[0100] The area of ​​the heat dissipation metal layer 14 is larger than the area of ​​the second copper layer 112. That is, the orthogonal projection of the heat dissipation metal layer 14 onto the plane of the second copper layer 112 covers the second copper layer 112. Since the heat dissipation metal layer 14 is deposited on the surface of the second copper layer 112, it will also be deposited on the uncoated area of ​​the lower surface of the ceramic layer 110 during the deposition process. Therefore, in the scheme where the area of ​​the heat dissipation metal layer 14 is larger than that of the second copper layer 112, the heat dissipation metal layer 14 will generally cover the side of the second copper layer 112.

[0101] In one example, the area of ​​the heat dissipation metal layer 14 can be slightly smaller than the area of ​​the second copper layer 112, but the larger the area of ​​the heat dissipation metal layer 14, the easier it is to transfer heat from the power module to the heat dissipation base plate 21.

[0102] Based on the above, the metal layer disposed on the surface of the substrate away from the power chip can be the second copper layer of the double-sided copper-clad ceramic substrate, or it can be a heat dissipation metal layer additionally disposed on the surface of the substrate away from the power chip. For the latter, the substrate can be a single-sided copper-clad ceramic substrate or a double-sided copper-clad ceramic substrate.

[0103] In this embodiment, it is not limited whether the substrate 11 is a single-sided copper-clad ceramic substrate or a double-sided copper-clad ceramic substrate. In the case of a double-sided copper-clad ceramic substrate, it is not limited whether the metal layer is the second copper layer of the double-sided copper-clad ceramic substrate or an additional heat-dissipating metal layer. For ease of explanation, it can be referred to as follows: Figure 3The second copper layer 112 shown is a schematic diagram of a metal layer. For ease of explanation, the portion of the second copper layer 112 that is away from the surface of the ceramic layer 110 and located in the encapsulation 13 can be referred to as the encapsulated portion 112A, and the portion of the second copper layer 112 that is away from the surface of the ceramic layer 110 and located outside the encapsulation 13 can be referred to as the exposed portion 112B.

[0104] like Figure 5 As shown, Figure 3 The diagram shown is a schematic of the power module 1 and the heat sink base plate 21 after welding. (Refer to...) Figure 5 As shown, the exposed portion 112B of the second copper layer 112, which is away from the surface of the ceramic layer 110 and located outside the encapsulation 13, is fixedly connected to the heat dissipation base plate 21 by a welding layer 3.

[0105] In this embodiment, the welding layer 3 is a structural layer formed by filling the space between the second copper layer 112 and the heat sink base plate 21 with molten solder after the power module and heat sink are fixed by tools and cooled and solidified. The exposed portion 112B of the second copper layer 112 serves as the pad for the power module 1, and the boss 211 on the surface of the heat sink base plate 21 serves as the pad for the heat sink base plate 21. The upper surface of the welding layer 3 is fixedly connected to the second copper layer 112, and the lower surface of the welding layer 3 is fixedly connected to the platform of the boss 211. The surface of the heat sink base plate 21 may not have the boss 211. This embodiment does not specifically limit whether the heat sink base plate 21 has the boss 211; the description uses a heat sink base plate 21 with the boss 211 as an example.

[0106] like Figure 5 During reliability testing of the power module shown, even though cracks appeared between the power module 1 and the solder layer 3 due to different deformations, the cracks occurred at the contact interface between the molding compound 13 and the solder layer 3. (Refer to...) Figure 5 At position B, after a crack forms, it propagates inward along the horizontal contact interface between the lower surface of the second copper layer 112 and the upper surface of the solder layer 3, as indicated by the arrow. The vertical direct contact interface between the molding compound 13 and the side of the second copper layer 112 is not on the threaded propagation path. Therefore, the crack at position B is unlikely to propagate to the vertical direct contact interface between the molding compound 13 and the side of the second copper layer 112. Consequently, the crack at position B is unlikely to propagate along the vertical direct contact interface between the molding compound 13 and the side of the second copper layer 112 to the ceramic layer 110. This prevents the ceramic layer 110 from cracking, ensuring its insulation performance, reducing the risk of cracking, and extending its service life.

[0107] In this embodiment, the plane where the ceramic layer 110 is located is taken as the horizontal plane, and the plane perpendicular to the ceramic layer 110 is taken as the vertical plane.

[0108] In one example, a raised structure, such as multiple protruding pillars or bosses, can be provided on the exposed portion 112B of the second copper layer 112. The raised structure can block the crack generated at position B from continuing to expand inward, thereby ensuring a good connection between the exposed portion of the second copper layer 112 and the heat dissipation base plate 21 and ensuring good heat transfer performance.

[0109] In one example, the molding compound 13 can completely cover the edge of the second copper layer 112 that faces away from the surface of the ceramic layer 110, such that... Figure 6 As shown, Figure 3 The diagram shown is a structural schematic of the bottom of the power module. (Refer to...) Figure 6 As shown, the entire edge of the second copper layer 112 away from the surface of the ceramic layer 110 is located in the encapsulation 13. Therefore, the encapsulation portion 112A of the second copper layer 112 includes the edge of the second copper layer 112 away from the surface of the ceramic layer 110 and the surface portion of the adjacent edge.

[0110] In another example, the molding compound 13 can cover some key locations of the second copper layer 112, such as... Figures 7 to 9 As shown, Figure 3 The diagram shown is a structural schematic of the bottom of the power module. (Refer to...) Figure 7 and Figure 8 As shown, the surface of the second copper layer 112 facing away from the ceramic layer 110 is polygonal, and the apex corner of the surface of the second copper layer 112 facing away from the ceramic layer 110 is located within the molding compound 13. (Reference) Figure 9 As shown, the surface of the second copper layer 112 facing away from the ceramic layer 110 is not only located in the apex region of the encapsulation 13, but also in the region where the midpoint of each edge of the surface is located. That is, the encapsulation portion 112A of the second copper layer 112 includes the portion of the second copper layer 112 near the apex, or the encapsulation portion 112A includes the portion of the second copper layer 112 near the apex and the portion near the midpoint.

[0111] In one example, the region where the apex of the surface of the second copper layer 112 facing away from the ceramic layer 110 is located within the molding compound 13, and the shape of the region of the second copper layer 112 facing away from the ceramic layer 110 covered by the molding compound 13 is polygonal or sector-shaped. For example, the shape of the region of the second copper layer 112 facing away from the ceramic layer 110 covered by the molding compound 13 is polygonal, such as a triangle, quadrilateral, or pentagon, etc. These polygons can be regular or irregular. (See reference) Figure 7 As shown, the area of ​​the second copper layer 112 facing away from the ceramic layer 110 and covered with the molding compound 13 is pentagonal in shape, as shown in the reference diagram. Figure 8As shown, the area of ​​the second copper layer 112 that is covered with the encapsulant 13 on the surface opposite to the ceramic layer 110 is fan-shaped.

[0112] Similarly, the region where the midpoint of each edge on the surface of the second copper layer 112 facing away from the ceramic layer 110 is located within the molding compound 13, and the region on the surface of the second copper layer 112 facing away from the ceramic layer 110 covered by the molding compound 13 is polygonal or fan-shaped, as shown in the reference. Figure 9 As shown, the area of ​​the second copper layer 112 facing away from the ceramic layer 110 and covered with the encapsulant 13 is fan-shaped. Specifically, the fan shape can be a right-angled fan shape or a semi-circular fan shape, etc.

[0113] In another example, the molding compound 13 not only completely covers the edge of the second copper layer 112, but also extends further inward at key locations of the second copper layer 112, for example... Figure 10 As shown, Figure 3 The diagram shown is a structural schematic of the bottom of the power module. (Refer to...) Figure 10 As shown, the molding compound 13 not only covers the edge area of ​​the second copper layer 112, but also extends inward at the top corner, covering a larger area at the top corner of the second copper layer 112. Figure 10 The shape of the area on the second copper layer 112 covered by the encapsulant 13 is shown in a fan shape.

[0114] In one example, since the primary function of the surface of the second copper layer 112 facing away from the ceramic layer 110 is to be soldered to the heat sink 21 to transfer the heat generated by the power chip 12 to the heat sink 21, therefore, referring to... Figures 6 to 10 As shown, the area of ​​the surface of the second copper layer 112 facing away from the ceramic layer 110 within the encapsulation 13 is smaller than the area outside the encapsulation 13. That is, the sum of the areas of all encapsulated portions 112A is less than the sum of the areas of the exposed portions 112B, so that most of the surface of the second copper layer 112 facing away from the ceramic layer 110 is exposed outside the encapsulation 13.

[0115] In one example, since the function of the second copper layer 112 away from the surface of the ceramic layer 110 is to transfer the heat generated by the power chip to the heat sink 21, the area of ​​the second copper layer 112 away from the surface of the ceramic layer 110 and located outside the molding compound 13 is larger than the area occupied by all the power chips. That is, the area of ​​the exposed portion 112B of the second copper layer 112 is larger than the area occupied by all the power chips.

[0116] For example, the portion of the second copper layer 112 that faces away from the surface of the ceramic layer 110 and is located outside the molding compound 13, when projected onto the surface of the ceramic layer 110, covers all the power chips 12 on the surface of the ceramic layer 110. Alternatively, it can be understood that the projected images of all the power chips 12 onto the surface of the second copper layer 112 facing away from the ceramic layer 110 all fall on the exposed portion 112B of the second copper layer 112. In this way, the heat generated by any one power chip can be transferred vertically to the heat sink 21 via the second copper layer 112, shortening the heat transfer path.

[0117] In one example, refer to Figure 5 As shown, the orthographic projection of the encapsulated portion 112A of the second copper layer 112, which is away from the surface of the ceramic layer 110 and located in the encapsulation 13, onto the surface of the heat sink base plate 21 falls outside the boss 211 on the surface of the heat sink base plate 21. This can also be understood as the orthographic projection of the exposed portion 112B of the second copper layer 112, which is away from the surface of the ceramic layer 110 and located outside the encapsulation 13, onto the heat sink base plate 21, covering the boss 211, so that the boss 211 and the exposed portion 112B are fixedly connected by the solder layer 3.

[0118] In one example, the thickness of the solder layer 3 between the second copper layer 112 and the heat sink base plate 21 needs to meet certain requirements. For example, the actual thickness of the solder layer 3 is equal to the target thickness within the tolerance range. Or, the solder layer 3 is arranged with equal thickness between the second copper layer 112 and the heat sink base plate 21. If it is not uniform, it will cause the power module to warp.

[0119] In the scheme where the heat dissipation base plate 21 has a boss 211, the thickness of the welding layer 3 mainly refers to the thickness of the welding layer 3 between the exposed portion 112B of the second copper layer 112 and the platform of the boss 211. In the scheme where the heat dissipation base plate 21 does not have a boss 211, the thickness of the welding layer 3 mainly refers to the thickness of the welding layer 3 between the exposed portion 112B of the second copper layer 112 and the heat dissipation base plate 21.

[0120] One method for controlling the thickness of weld layer 3 is as follows, referring to... Figure 5 As shown, the surface of the heat dissipation base plate 21 has a plurality of support pillars 212. Each of the plurality of support pillars 212 is used to abut against the exposed portion 112B of the second copper layer 112 during the welding of the exposed portion 112B of the second copper layer 112 and the heat dissipation base plate 21, in order to control the thickness of the weld layer 3 formed after the molten solder solidifies.

[0121] In the design where the heat dissipation base plate 21 has a boss 211 on its surface, refer to Figure 5 As shown, the support column 212 is mounted on the platform of the boss 211. (Reference) Figure 11As shown, in the scheme where there are no protrusions 211 on the surface of the heat dissipation base plate 21, multiple support columns 212 are set on the surface of the heat dissipation base plate 21 facing the power module.

[0122] Another method for controlling the thickness of weld layer 3 could be, for example... Figure 12 As shown, the encapsulant 13 covering the surface of the second copper layer 112 away from the ceramic layer 110 is relatively thick. During the welding process between the exposed portion 112B of the second copper layer 112 and the heat sink base plate 21, the bottom surface of the encapsulant 13 abuts against the heat sink base plate 21 to control the thickness of the welding layer 3.

[0123] Another method for controlling the thickness of weld layer 3 could be, such as... Figure 13 and Figure 14 As shown, the thickness of the encapsulant 13 covering the surface of the second copper layer 112 away from the ceramic layer 110 is relatively thin, but the bottom surface of the encapsulant 13 has multiple support structures 131. Each support structure 131 is used to abut against the heat dissipation base plate 21 during the welding of the exposed part 112B of the second copper layer 112 and the heat dissipation base plate 21, and is used to control the thickness of the welding layer 3.

[0124] Among them, the support structure 131 on the bottom surface of the molding compound 13 is referenced. Figure 13 As shown, it can be columnar. In another example, refer to... Figure 14 As shown, the support structure 131 can also be hemispherical or spherical. However, in this embodiment, the specific shape of the support structure 131 on the bottom surface of the encapsulated body 13 is not limited.

[0125] In one example, such as Figure 13 and Figure 14 and refer to Figure 15 As shown, multiple support structures 131 are located outside the second copper layer 112. That is, the orthogonal projection of multiple support structures 131 on the plane of the surface of the second copper layer 112 away from the ceramic layer 110 falls outside the surface of the second copper layer 112 away from the ceramic layer 110, so as to avoid the thicker support structures 131 from blocking the heat transfer between the exposed part 112B of the second copper layer 112 and the heat dissipation base plate 21.

[0126] In one example, multiple support structures 131 can be evenly distributed along the edge of the molding compound 13 on the bottom surface of the molding compound 13, such as... Figure 15 As shown, Figure 14 The diagram shows the bottom surface of the power module. A support structure 131 is arranged at the top corner of the plastic package 13, and a support structure 131 is arranged at the midpoint of each edge of the plastic package 13.

[0127] In a scheme where the molding compound 13 encapsulates the second copper layer 112 at key locations, such as the apex corner of the surface of the second copper layer 112 facing away from the ceramic layer 110 and the midpoint of each edge, the support structure 131 can be disposed on the bottom surface of the molding compound 13 covering the surface of the second copper layer 112. In this embodiment, the specific location of the support structure 131 on the molding compound 13 is not limited; it only needs to be located on the bottom surface of the molding compound 13 and adjacent to its edge.

[0128] Based on the above, the thickness of the solder layer 3 can be controlled by having multiple support pillars 212 on the surface of the heat dissipation base plate 21 abut against the exposed portion 112B of the second copper layer 112, or by having the bottom surface of the molding compound 13 abut against the heat dissipation base plate 21, or by having multiple support structures 131 on the bottom surface of the molding compound 13 abut against the heat dissipation base plate 21. Of course, a combination of these methods can also be used. For example, the support pillars 212 on the surface of the heat dissipation base plate 21 abut against the exposed portion 112B, and the support structures 131 on the bottom surface of the molding compound 13 abut against the exposed portion 112B, with the support pillars 212 and support structures 131 working together to control the thickness of the solder layer 3. Another example is that the support pillars 212 on the heat dissipation base plate 21 abut against the exposed portion 112B, and the bottom surface of the molding compound 13 abuts against the heat dissipation base plate 21, with the support pillars 212 and the bottom surface of the molding compound 13 working together to control the thickness of the solder layer 3.

[0129] In this embodiment, the metal layer at the bottom of the power module, used for welding to the heat sink base plate, is opposite to the surface of the power chip. Part of it is encapsulated in a plastic package, and the other part is exposed outside the plastic package. Therefore, after the power module and the heat sink base plate are welded, even if cracks are generated between the power module and the welding layer due to inconsistent deformation during reliability testing, the cracks will propagate along the horizontal interface between the metal layer and the welding layer, which is opposite to the surface of the power chip. The cracks are not likely to propagate to the vertical interface between the side of the metal layer and the plastic package. Since the cracks are not likely to propagate along the vertical interface between the side of the metal layer and the plastic package, they are also not likely to propagate along the vertical interface to the ceramic layer of the substrate. This reduces the risk of insulation failure of the ceramic layer and extends the service life of the ceramic layer.

[0130] This embodiment also provides a power module, which includes a heat sink 2, a solder layer 3, and the power module 1 described above. The heat sink 2 includes a heat dissipation base plate 21. As described above, the power module 1 includes a substrate 11, at least one power chip 12, and a molding compound 13. At least one power chip 12 is located on the surface of the substrate 11. A metal layer is disposed on the surface of the substrate 11 opposite to the power chip 12. The substrate 11 and all the power chips 12 are located in the molding compound 13. However, the surface of the metal layer opposite to the power chip 12 is partially located in the molding compound 13 and partially exposed outside the molding compound 13. The portion of the metal layer opposite to the power chip 12 and exposed outside the molding compound 13 is fixedly connected to the heat dissipation base plate 21 through the solder layer 3. Thus, the heat generated by the power chip 12 is transferred to the heat dissipation base plate 21 via the metal layer.

[0131] Using a double-sided copper-clad ceramic substrate as an example, with the metal layer being a second copper layer 112 on the surface of the ceramic layer 110 of the substrate 11, see reference. Figure 5 As shown, the portion of the second copper layer 112 that is away from the power chip 12 and located outside the molding compound 13 is fixedly connected to the heat sink 21 via a solder layer 3. The solder layer 3 is a structural layer formed by the solidification of molten solder filling the space between the heat sink 31 and the second copper layer 112.

[0132] In one example, continue to refer to Figure 5 As shown, the heat sink 2 also includes heat dissipation fins 22, which are located on the surface of the heat sink base plate 21 opposite to the power module 1. The heat sink 2 increases the heat dissipation area and improves the heat dissipation effect by using a large number of heat dissipation fins 22.

[0133] In one example, the surface of the heat sink 21 facing the power module 1 may have a boss 211, which serves as a pad for the heat sink 21 and is fixedly connected to the portion of the second copper layer 112 that is away from the surface of the power chip 12 and exposed in the molding compound 13 via a solder layer 3.

[0134] In one example, since the exposed portion 112B of the second copper layer 112 serves as a solder pad and the enclosed portion 112A of the second copper layer 112 serves as a solder resist area, the platform area of ​​the boss 211, which serves as a solder pad on the heat dissipation base plate 21, can be less than or equal to the area of ​​the exposed portion 112B of the second copper layer 112, in order to save on the material cost of the heat dissipation base plate 21.

[0135] In one example, it is still possible to refer to... Figure 5As shown, the surface of the heat sink 21 facing the power module 1 may have multiple support pillars 212. The multiple support pillars 212 are used to abut against the portion of the second copper layer 112 that is away from the surface of the power chip 12 and located outside the molding compound 13, so as to control the thickness of the solder layer 3 between the exposed portion 112B of the second copper layer 112 and the heat sink 21.

[0136] In the design where the heat dissipation base plate 21 has a boss 211, multiple support columns 212 are set on the platform of the boss 211 to control the thickness of the solder layer 3 between the exposed portion 112B of the second copper layer 112 and the platform of the boss 211.

[0137] In the design with multiple support pillars 212 on the heat sink base 21, the molding compound 13 covering the surface of the second copper layer 112 away from the power chip 12 can be relatively thin to reduce the impact of the molding compound 13 on the heat transfer performance between the second copper layer 112 and the heat sink base 21. Alternatively, in the design with multiple support pillars 212 on the heat sink base 21, the bottom surface of the molding compound 13 does not need to have a support structure 131 to reduce the impact of the support structure 131 on the heat transfer performance between the second copper layer 112 and the heat sink base 21.

[0138] In one example, to accelerate heat dissipation, the power module may also include a cooling tank with an inlet and an outlet. The cooling tank contains a flowing cooling medium (such as water). The side of the heat sink 21 facing away from the power chip 12 faces the cooling tank. The heat sink fins 22 are immersed in the cooling medium in the cooling tank, and the side of the heat sink 21 facing away from the power chip 12 can also be immersed in the cooling tank. Thus, both the heat sink fins 22 and the heat sink 21 are in contact with the cooling medium in the cooling tank. The flowing cooling medium continuously carries away heat from the power module, dissipating heat from the power chip 12 within the power module.

[0139] This embodiment also provides a power conversion device, which includes a housing, a circuit board, and the aforementioned power module. Both the circuit board and the power module are located within the housing, and the power chip of the power module is electrically connected to the circuit board. For example, the circuit board is fixed in the housing, the power module is fixed on the circuit board, and the exposed pins of the power module in the plastic package are fixedly connected to the pads on the circuit board.

[0140] The terminology used in the embodiments section of this application is for explaining the embodiments of this application only and is not intended to limit this application. Unless otherwise defined, the technical or scientific terms used in the embodiments of this application should have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms "first," "second," and similar terms used in this application specification and claims do not indicate any order, quantity, or importance, but are only used to distinguish different components. Similarly, the terms "a" or "one," etc., do not indicate a quantity limitation, but indicate the presence of at least one. The terms "comprising," "including," etc., mean that the elements or objects preceding "comprising" or "including" cover the elements or objects listed after "comprising" or "including" and their equivalents, and do not exclude other elements or objects. "Above," "below," "left," "right," etc., are only used to indicate relative positional relationships, and the relative positional relationship may also change accordingly when the absolute position of the described object changes. "A plurality of" means two or more, unless otherwise expressly defined.

[0141] The above description is merely an optional embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the principles of this application should be included within the protection scope of this application.

Claims

1. A power module, characterized in that, The power module includes a substrate (11), at least one power chip (12), and a plastic package (13); The at least one power chip (12) is located on the surface of the substrate (11), and a metal layer is arranged on the surface of the substrate (11) opposite to the power chip (12); The at least one power chip (12) and the substrate (11) are both located in the encapsulation (13), and a portion of the metal layer facing away from the surface of the power chip (12) is located in the encapsulation (13), while another portion of the metal layer facing away from the surface of the power chip (12) is located outside the encapsulation (13).

2. The power module according to claim 1, characterized in that, The substrate (11) is a copper-clad ceramic substrate, including a ceramic layer (110) and a first copper layer (111) and a second copper layer (112) located on both sides of the ceramic layer (110). The at least one power chip (12) is located on the surface of the first copper layer (111). The ceramic layer (110) and the first copper layer (111) are both located in the molding compound (13). The metal layer is the second copper layer (112).

3. The power module according to claim 1, characterized in that, The substrate (11) is a copper-clad ceramic substrate, including a ceramic layer (110) and a first copper layer (111) and a second copper layer (112) located on both sides of the ceramic layer (110), and the at least one power chip (12) is located on the surface of the first copper layer (111). The power module further includes a heat dissipation metal layer (14), which is located on the surface of the second copper layer (112) away from the first copper layer (111). The ceramic layer (110), the first copper layer (111) and the second copper layer (112) are all located in the encapsulation (13), and the metal layer is the heat dissipation metal layer (14).

4. The power module according to any one of claims 1 to 3, characterized in that, The edges of the metal layer that are away from the surface of the power chip (12) are all located in the encapsulation (13).

5. The power module according to any one of claims 1 to 4, characterized in that, The metal layer is polygonal in shape, and the apex corners of the metal layer that are away from the surface of the power chip (12) are all located in the molding compound (13).

6. The power module according to claim 5, characterized in that, The midpoint of each edge of the metal layer away from the surface of the power chip (12) is located in the encapsulation (13).

7. The power module according to any one of claims 1 to 6, characterized in that, The area of ​​the portion of the metal layer that is away from the surface of the power chip (12) and located within the molding compound (13) is smaller than the area of ​​the portion of the metal layer that is away from the surface of the power chip (12) and located outside the molding compound (13).

8. The power module according to any one of claims 1 to 7, characterized in that, The portion of the metal layer that is away from the surface of the power chip (12) and located outside the encapsulation (13) has an orthographic projection on the surface of the substrate (11) that covers all the power chips (12) on the surface of the substrate (11).

9. The power module according to any one of claims 1 to 8, characterized in that, The bottom surface of the encapsulation (13) has a plurality of support structures (131) for abutting against the heat dissipation base plate (21) to control the thickness of the solder layer (3) between the portion of the metal layer away from the surface of the power chip (12) and located outside the encapsulation (13) and the heat dissipation base plate (21).

10. The power module according to claim 9, characterized in that, The orthographic projections of the plurality of support structures (131) onto the plane of the metal layer all fall outside the metal layer.

11. The power module according to any one of claims 1 to 8, characterized in that, The bottom surface of the encapsulation (13) is used to abut against the heat sink base plate (21) to control the thickness of the solder layer (3) between the portion of the metal layer that is away from the surface of the power chip (12) and located outside the encapsulation (13) and the heat sink base plate (21).

12. A power module, characterized in that, The power module includes a heat sink (2), a solder layer (3), and a power module (1) as described in any one of claims 1 to 11; The radiator includes a heat dissipation base plate (21) and heat dissipation fins (22), and the heat dissipation fins (22) are fixed on the surface of the heat dissipation base plate (21); The portion of the metal layer that is away from the surface of the power chip (12) and located outside the encapsulation (13) is fixedly connected to the surface of the heat sink base plate (21) that is away from the heat sink fins (22) through the welding layer (3).

13. The power module according to claim 12, characterized in that, The heat dissipation base plate (21) has a boss (211) on the surface opposite to the heat dissipation fins (22). The portion of the metal layer opposite to the surface of the power chip (12) and located outside the encapsulation body (13) is fixedly connected to the platform of the boss (211) through the welding layer (3).

14. The power module according to claim 12 or 13, characterized in that, The heat dissipation base plate (21) has a plurality of support pillars (212) on the surface opposite to the heat dissipation fins (22). The plurality of support pillars (212) are used to abut against the portion of the metal layer opposite to the power chip (12) and located outside the encapsulation (13) to control the thickness of the solder layer (3) between the metal layer and the heat dissipation base plate (21).

15. A power conversion device, characterized in that, The power conversion device includes a housing, a circuit board, and a power module as described in any one of claims 12 to 14; Both the circuit board and the power module are located in the housing, and the power chip (12) of the power module is electrically connected to the circuit board.

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