Power module and power conversion device

Abstract

The invention discloses a power module and a power conversion device, the power module comprises a heat conducting bottom plate, a connecting layer, a ceramic substrate and a chip which are sequentially stacked, and a plastic package body wraps the ceramic substrate and the chip. The ceramic substrate comprises an insulating layer and a first metal layer, and the first metal layer is arranged between the insulating layer and the connecting layer. A reinforcing structure is formed on the side, facing the ceramic substrate, of the heat conduction bottom plate. The reinforcing structure is located on the side portion of the connecting layer in the direction perpendicular to the arrangement direction of the heat conduction bottom plate and the connecting layer. The wall face of the reinforcing structure and the face, facing the heat conduction bottom plate, of the first metal layer define a containing space. The accommodating space is filled with the plastic package body. The plastic package body in the accommodating space wraps the surface, facing the heat-conducting bottom plate, of the first metal layer and the joint of the side face of the first metal layer and the insulating layer, and the stress concentration position of the ceramic substrate is transferred to the surface, facing the heat-conducting bottom plate, of the first metal layer from the joint of the side face of the first metal layer and the insulating layer, so that the risk of layering or cracking of the insulating layer is reduced; and the reliability of the power module is improved.

Description

Technical Field

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

[0002] In new energy fields such as photovoltaics and automobiles, power modules are a crucial component of their power electronic systems, widely used in servo motors, inverters, and other parts. A power module is a packaged structure integrating multiple components, including a power chip and a ceramic substrate. Typically, the heat generated by the power chip during operation is dissipated to the outside through the ceramic substrate and thermally conductive base plate (BP). Using a high thermal conductivity ceramic substrate can significantly improve the heat dissipation capacity of the power module. However, high thermal conductivity ceramic materials generally have poor mechanical strength, a high risk of delamination or cracking, and cannot meet the long-term reliability requirements of power modules. Summary of the Invention

[0003] The technical problem to be solved by the embodiments of this application is to provide a power module and power conversion device with high reliability.

[0004] In a first aspect, embodiments of this application provide a power module, which includes a thermally conductive base plate, a ceramic substrate, a chip, a molding compound, and a connecting layer. The thermally conductive base plate, the connecting layer, the ceramic substrate, and the chip are sequentially stacked, and the molding compound encapsulates the ceramic substrate and the chip. The ceramic substrate includes an insulating layer and a first metal layer, with the first metal layer disposed between the insulating layer and the connecting layer. A reinforcing structure is formed on the side of the thermally conductive base plate facing the ceramic substrate. In a direction perpendicular to the stacking direction of the thermally conductive base plate and the connecting layer, the reinforcing structure is located on the side of the connecting layer. The wall of the reinforcing structure and the side of the first metal layer facing the thermally conductive base plate form an accommodating space, and the molding compound fills the accommodating space.

[0005] Power modules packaged using plastic encapsulation exert significant pressure on the sides of the ceramic substrate. The ceramic substrate consists of a ceramic insulating layer and a lower copper layer, and the outer edge of the ceramic insulating layer typically protrudes relative to the outer edge of the lower copper layer. The shape changes drastically at the junction of the lower copper layer and the ceramic insulating layer, which can easily lead to stress concentration. Furthermore, the ceramic insulating layer has poor mechanical strength, making it prone to delamination or cracking, thus failing to meet the long-term reliability requirements of the power module.

[0006] A reinforcing structure is formed on the thermally conductive base plate, located on the side of the base plate facing the ceramic substrate. The reinforcing structure and the first metal layer form an accommodating space, allowing the molding compound to fill between the thermally conductive base plate and the first metal layer. The molding compound provides support to the side of the first metal layer facing the thermally conductive base plate and encapsulates the side of the first metal layer facing the thermally conductive base plate, as well as the connection between the side of the first metal layer and the insulating layer. This transfers stress concentration on the ceramic substrate from the connection between the side of the first metal layer and the insulating layer to the side of the first metal layer facing the thermally conductive base plate, effectively reducing the compression of the molding compound only on the side of the first metal layer and the connection between the insulating layer. This optimizes the stress distribution inside the power module, reduces the risk of insulation layer delamination or cracking, and improves the long-term reliability of the power module. Furthermore, the reinforcing structure is located on the side of the connecting layer, allowing the molding compound filling the space between the thermally conductive base plate and the first metal layer to surround the connecting layer. The molding compound can encapsulate the side of the ceramic substrate and the side facing the thermally conductive base plate as much as possible, further reducing the risk of insulation layer delamination or cracking.

[0007] In one possible implementation, there are multiple reinforcing structures, which surround the connecting layer and are spaced apart.

[0008] In this possible implementation, the reinforcing structural spacing is set around the outer perimeter of the connecting layer, and the molding compound can cover the side of the ceramic substrate and the side facing the heat conduction base plate as much as possible, further reducing the risk of insulation layer delamination or cracking.

[0009] In one possible implementation, the first metal layer has multiple corners, each corner corresponding to a reinforcing structure. One end of the reinforcing structure extends toward one side of the corner, and the other end of the reinforcing structure extends toward the opposite side adjacent to the corner.

[0010] In this possible implementation, the sharp change in shape at the corner of the first metal layer can easily lead to stress concentration, which may cause the insulation layer to crack at the corresponding location. At the corner of the first metal layer, a reinforcing structure extending to the two adjacent sides of the corner is provided, so that the encapsulation filling between the heat-conducting base plate and the first metal layer can extend to the two adjacent sides of the corner, reducing the risk of the insulation layer delaminating or cracking at the corner and improving the reliability of the power module.

[0011] In one possible implementation, the reinforcing structure includes a groove filled with a plastic sealant.

[0012] In this possible implementation, a groove is formed on the heat-conducting base plate. The walls of the groove and the side of the first metal layer facing the heat-conducting base plate together form an accommodating space, resulting in a simple and easy-to-implement structure. Furthermore, the groove design allows the encapsulant filling the space between the heat-conducting base plate and the first metal layer to extend to the outer periphery of the connecting layer, maximizing the contact area between the encapsulant and the side of the first metal layer facing the heat-conducting base plate. This increases the contact area between the encapsulant and the first metal layer, optimizes the internal stress distribution of the power module, reduces the risk of insulation layer delamination or cracking, and improves the reliability of the power module.

[0013] In one possible implementation, along the arrangement direction of the heat-conducting base plate and the ceramic substrate, the orthographic projection of the groove is located away from the edge of the connecting layer and outside the orthographic projection outer edge of the first metal layer.

[0014] In this possible implementation, the side of the groove away from the connecting layer extends beyond the outer edge of the first metal layer, and the edge of the groove away from the connecting layer is offset from the side edge of the first metal layer. The position where the side shape of the ceramic substrate changes abruptly is offset from the position where the molding compound changes abruptly, and the contact area between the molding compound and the first metal layer is increased. This optimizes the stress distribution inside the power module, reduces the risk of insulation layer delamination or cracking, and improves the reliability of the power module.

[0015] In one possible implementation, at least a portion of the orthographic projection of the groove is located within the outer edge of the orthographic projection of the first metal layer along the arrangement direction of the heat-conducting base plate and the ceramic substrate.

[0016] In this possible implementation, the molding compound can fill the space between the thermally conductive base plate and the first metal layer and be located at least partially within the outer edge of the first metal layer, thereby shifting the stress concentration on the ceramic substrate to the side of the first metal layer facing the thermally conductive base plate, reducing the risk of insulation layer delamination or cracking, and improving the reliability of the power module.

[0017] In one possible implementation, the reinforcing structure includes a boss that protrudes towards the first metal layer. The boss is located on the side of the connecting layer, and the side of the boss facing away from the connecting layer, the side of the heat-conducting base plate facing the first metal layer, and the side of the first metal layer facing the heat-conducting base plate form an accommodating space. Along the arrangement direction of the heat-conducting base plate and the ceramic substrate, the orthographic projection of the boss is located within the outer edge of the orthographic projection of the first metal layer.

[0018] In this possible implementation, a portion of the thermally conductive base plate without a boss has a gap with the first metal layer. This creates an accommodating space formed by the side of the boss away from the connecting layer, the side of the thermally conductive base plate facing the first metal layer, and the side of the first metal layer facing the thermally conductive base plate. The molding compound can extend to the side of the first metal layer facing the thermally conductive base plate, shifting the stress concentration on the ceramic substrate to the side of the first metal layer facing the thermally conductive base plate. This reduces the risk of insulation layer delamination or cracking, improving the reliability of the power module. Furthermore, the boss is located on the side of the connecting layer, which can limit the connection layer and effectively reduce the possibility of the connecting layer extending to the side of the first metal layer.

[0019] In one possible implementation, the reinforcing structure includes a boss and a recess, both located on the side of the connecting layer, with the boss positioned between the connecting layer and the recess. Along the alignment direction of the thermally conductive base plate and the ceramic substrate, the orthographic projection of the boss lies within the outer edge of the orthographic projection of the first metal layer. The recess is filled with a molding compound.

[0020] In this possible implementation, the boss and the groove are sequentially arranged on the side of the connecting layer. The side of the boss away from the connecting layer, the side of the first metal layer facing the heat conduction base plate, and the various walls of the groove together form an accommodating space. On the one hand, the boss can limit the connecting layer. On the other hand, the groove further increases the depth of the accommodating space, allowing the molding compound to fill more of the side of the first metal layer facing the heat conduction base plate, enhancing the support for the ceramic substrate, reducing the risk of delamination or cracking of the ceramic substrate, and improving the reliability of the power module.

[0021] In one possible implementation, the side of the boss facing the first metal layer is attached to the first metal layer.

[0022] In the implementation of the reinforced structure including the boss, the boss can support the first metal layer, while effectively reducing the flow of the welding process of the connecting layer to the side of the boss away from the connecting layer, and effectively limiting the connecting layer.

[0023] In one possible implementation, the groove includes a bottom wall, a first side wall, and a second side wall. The first side wall connects to the edge of the bottom wall facing the connecting layer, and the second side wall connects to the edge of the bottom wall away from the connecting layer. The first side wall is inclined towards the second side wall relative to the connection between the first side wall and the bottom wall; and / or, the second side wall is inclined away from the first side wall relative to the connection between the second side wall and the bottom wall.

[0024] In the reinforcement structure including the groove, the first and second sidewalls are located on opposite edges of the bottom wall. The first sidewall is inclined towards the second sidewall relative to its connection with the bottom wall. Even if the encapsulation and the thermally conductive base plate are at risk of delamination or cracking, the delamination or cracking can be concentrated at the connection between the first sidewall and the bottom wall, and is less likely to extend to the connecting layer, thus improving the connection reliability between the thermally conductive base plate and the connecting layer, as well as between the first metal layer and the connecting layer. When the second sidewall is inclined away from the first sidewall relative to its connection with the bottom wall, the edge of the groove away from the connecting layer has a gentler transition, which helps to reduce the stress on the side of the encapsulation away from the connecting layer and reduces the risk of cracking of the encapsulation.

[0025] Secondly, this application provides a power conversion device, which includes a circuit board and a power module as described in the first aspect, the power module being disposed on the circuit board. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application or the background art, the accompanying drawings used in the embodiments of this application or the background art will be described below.

[0027] Figure 1 This is a schematic diagram of the structure of a vehicle provided in one embodiment of this application;

[0028] Figure 2 This is a network diagram of a photovoltaic energy storage system provided in one embodiment of this application;

[0029] Figure 3 This is a schematic diagram of the structure of a power conversion device provided in an embodiment of this application;

[0030] Figure 4 This is a schematic diagram of the structure of a heat-conducting base plate provided in one embodiment of this application;

[0031] Figure 5 A schematic diagram of the structure of a heat-conducting base plate provided in another embodiment of this application;

[0032] Figure 6 This is a schematic diagram of the structure of the heat-conducting base plate and the first metal layer in a power module according to an embodiment of this application;

[0033] Figure 7 This is a schematic diagram of the structure of a power module provided in one embodiment of this application;

[0034] Figure 8 A schematic diagram of a reinforcing structure with different projected shapes in a heat-conducting base plate according to an embodiment of this application;

[0035] Figure 9 A schematic diagram of the structure of a heat-conducting base plate provided in another embodiment of this application;

[0036] Figure 10 This is a schematic diagram of the structure of another heat-conducting base plate provided in another embodiment of this application;

[0037] Figure 11 A schematic diagram of the structure of a heat-conducting base plate with a groove provided in an embodiment of this application;

[0038] Figure 12 A partial structural diagram of a heat-conducting base plate with grooves of different sizes provided in an embodiment of this application;

[0039] Figure 13 A three-dimensional structural schematic diagram of a heat-conducting base plate provided in an embodiment of this application;

[0040] Figure 14 This is a schematic diagram of the structure of a power module provided in another embodiment of this application;

[0041] Figure 15 A schematic diagram of the structure of a power module provided in another embodiment of this application;

[0042] Figure 16 A schematic diagram of the structure of bosses of different shapes on a heat-conducting base plate provided in an embodiment of this application;

[0043] Figure 17 A schematic diagram of a structure with spaced semi-enclosed bosses on a heat-conducting base plate provided in an embodiment of this application;

[0044] Figure 18 This is a partial structural diagram of the groove in a heat-conducting base plate provided in an embodiment of this application;

[0045] Figure 19 This is a schematic diagram of a structure with four corner grooves provided on a heat-conducting base plate according to an embodiment of this application;

[0046] Figure 20 This is a schematic diagram of a structure with an intermittent semi-enclosed groove on a heat-conducting base plate provided in an embodiment of this application.

[0047] Explanation of reference numerals in the attached figures:

[0048] 10-Circuit board, 20-Power module, 21-Chip, 22-Connection terminal, 23-Molded body, 24-Connecting layer, 25-Ceramic substrate, 251-First metal layer, 2511-Corner, 252-Insulating layer, 253-Second metal layer, 26-Heat-conducting base plate, 261-Reinforcing structure, 261a-Accommodation space, 261b-First end, 261c-Second end, 262-Connecting part, 263-Groove, 2631-Bottom wall, 2 632-First sidewall, 2633-Second sidewall, 2634-Notch, 264-Boss, 265-Accommodation space, 27-Cover plate, 100-Power conversion device, 100a-Photovoltaic inverter, 100b-Energy storage converter, 200-Wheel, 300-Engine, 400-Battery module, 500-Photovoltaic module, 600-Box substation, 700-Step-up substation, 800-Power grid, 900-Energy storage system, 1000-Vehicle. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of this application clearer, the application will now be described in further detail with reference to the accompanying drawings.

[0050] Please see Figure 1 , Figure 1 This is a schematic diagram of the structure of a vehicle 1000 provided in an embodiment of this application. The embodiment of this application provides a vehicle 1000, which includes a power conversion device 100, wheels 200, an engine 300, and a battery pack 400. The power conversion device 100 connects the engine 300 and the battery pack 400. The power conversion device 100 can be an inverter or a rectifier. The inverter converts the direct current (DC) power from the battery pack 400 into alternating current (AC) power and supplies power to the engine 300, which drives the wheels 200 to rotate. The rectifier converts the AC power into DC power.

[0051] Among them, vehicle 1000 may include electric vehicles, hybrid vehicles, range-extended electric vehicles, plug-in hybrid electric vehicles, fuel cell vehicles, etc., without specific limitations.

[0052] Specifically, the battery pack 400 is electrically connected to the engine 300 via the power conversion device 100, and the battery pack 400 provides electrical energy to the engine 300. The engine 300 converts the electrical energy into mechanical energy, thereby providing kinetic energy to the vehicle 1000 and driving the wheels 200.

[0053] Please see Figure 2 , Figure 2This is a schematic diagram of a photovoltaic-storage system network provided in one embodiment of this application. The power conversion device 100 can also be used in the photovoltaic-storage system, which includes a photovoltaic inverter 100a, an energy storage converter 100b, a photovoltaic module 500, a prefabricated substation 600, a booster station 700, a power grid 800, and an energy storage system 900. The photovoltaic module 500 converts solar energy into direct current (DC) through the photovoltaic effect. The photovoltaic inverter 100a converts the DC output from the photovoltaic module 500 into alternating current (AC) and further transmits the AC to the prefabricated substation 600. The prefabricated substation 600 converts the low-voltage AC output from the photovoltaic inverter 100a into medium-voltage AC and further transmits the AC to the booster station 700 (power grid 800) or the prefabricated substation 600 corresponding to the energy storage system 900. The energy storage system 900 is used to store the unstable electrical energy from the photovoltaic module 500 and output stable electrical energy to the power grid 800 through the energy storage inverter 100b and the corresponding box-type substation 600. Among them, the photovoltaic inverter 100a and the energy storage inverter 100b are the core equipment for power conversion, and they are collectively referred to as the power conversion device 100.

[0054] Please see Figure 3 , Figure 3 This is a schematic diagram of the structure of a power conversion device 100 provided in an embodiment of this application. The power conversion device 100 includes a circuit board 10 and power modules 20, with the power modules 20 disposed on the circuit board 10. There can be multiple power modules 20, and these multiple power modules 20 are electrically connected to each other.

[0055] The power module 20 includes a chip 21, a connection terminal 22, a molding compound 23, a connection layer 24, a ceramic substrate 25, and a thermally conductive base plate 26. The thermally conductive base plate 26, the connection layer 24, and the ceramic substrate 25 are stacked sequentially, with the thermally conductive base plate 26 connected and fixed to the ceramic substrate 25 via the connection layer 24. The chip 21 and the connection terminal 22 are disposed on the surface of the ceramic substrate 25 facing away from the thermally conductive base plate 26. The molding compound 23 encapsulates the thermally conductive base plate 26, the ceramic substrate 25, the chip 21, the connection layer 24, and the connection terminal 22, wherein the molding compound 23 encapsulates a portion of the connection terminal 22, the connection layer 24, the ceramic substrate 25, and the chip 21.

[0056] Optionally, the power module 20 may also include a cover plate 27, which covers the encapsulated body 23.

[0057] Chip 21 may include active and passive devices. Active devices include one or more of the following: integrated circuit (IC), insulated-gate bipolar transistor (IGBT), metal-oxide-semiconductor field-effect transistor (MOSFET), and diode. Passive devices include one or more of the following: capacitor and resistor. Chips 21 can be connected to each other via control / current conduction lines, which include, but are not limited to, bonding wires (such as aluminum, copper, silver, and their alloy wires) or metal strips / ribbons (such as copper, silver, and aluminum). Chip 21 can dissipate heat to the outside of power module 20 through ceramic substrate 25, connection layer 24, and thermally conductive base plate 26; alternatively, chip 21 can dissipate heat to the outside of power module 20 through ceramic substrate 25, molding compound 23, and thermally conductive base plate 26.

[0058] The connection terminal 22 is used to connect external devices. The connection terminal 22 includes, but is not limited to, pins, current-carrying busbars, or bolt terminals.

[0059] The molding compound 23 can be a molding compound or potting compound. The molding compound 23 fills the side of the thermally conductive base plate 26 facing the ceramic substrate 25, and provides insulating encapsulation for the ceramic substrate 25, the chip 21, and the connection terminal 22. The heat generated by the chip 21 can be conducted to the outside of the power module 20 through the molding compound 23.

[0060] The connecting layer 24 can be used to connect the heat-conducting base plate 26 and the ceramic substrate 25. It can be solder of various compositions, nano silver paste, silver or copper sintered materials, diffusion soldering layers, etc. The connecting layer 24 fixes the ceramic substrate 25 to the heat-conducting base plate 26 by welding.

[0061] The ceramic substrate 25 includes a first metal layer 251, an insulating layer 252, and a second metal layer 253. Along the arrangement direction of the ceramic substrate 25 and the heat-conducting base plate 26, the first metal layer 251 and the second metal layer 253 are respectively disposed on opposite sides of the insulating layer 252, with the first metal layer 251 located on the side of the insulating layer 252 facing the heat-conducting base plate 26. The second metal layer 253 is used to connect one or more chips 21 and connection terminals 22. Both the connection terminals 22 and the chips 21 can be fixed to the second metal layer 253 by solder.

[0062] The ceramic substrate 25 can be a single / double-sided copper-clad ceramic substrate (direct bond copper, DBC or direct copper bonding, DCB), an active metal bonding copper-clad substrate (AMB), an insulated metal substrate (IMS), a substrate, or a printed circuit board 10 (PCB) and other packaging substrates.

[0063] The first metal layer 251 and the second metal layer 253 can be made of copper, aluminum, or other thermally conductive metals. The first metal layer 251 and the second metal layer 253 can be made of the same material or different materials.

[0064] The outer edge of the insulating layer 252 protrudes slightly relative to the outer edges of both the first metal layer 251 and the second metal layer 253. The insulating layer 252 can be made of Al2O3, Si3N4, or AlN, and has good thermal conductivity, which helps to improve the heat dissipation capacity of the power module 20.

[0065] Power modules packaged using plastic encapsulation exert significant pressure on the sides of the ceramic substrate. The ceramic substrate consists of a ceramic insulating layer and a lower copper layer, and the outer edge of the ceramic insulating layer typically protrudes relative to the outer edge of the lower copper layer. The shape changes drastically at the junction of the lower copper layer and the ceramic insulating layer, which can easily lead to stress concentration. Furthermore, the ceramic insulating layer has poor mechanical strength, making it prone to delamination or cracking, thus failing to meet the long-term reliability requirements of the power module.

[0066] In this application, a reinforcing structure 261 is formed on the side of the thermally conductive base plate 26 facing the ceramic substrate 25. In a direction perpendicular to the arrangement direction of the thermally conductive base plate 26 and the connecting layer 24, the reinforcing structure 261 is located on the side of the connecting layer 24. The wall surface of the reinforcing structure 261 and the side of the first metal layer 251 facing the thermally conductive base plate 26 together form an accommodating space 261a. The accommodating space 261a is used to fill the encapsulant 23. Thus, the encapsulant 23 fills the space between the thermally conductive base plate 26 and the first metal layer 251. The encapsulant 23 filled between the thermally conductive base plate 26 and the first metal layer 251 provides support for the side of the first metal layer 251 facing the thermally conductive base plate 26, and the encapsulant 23 encapsulates the thermally conductive base plate 26. The first metal layer 251, facing the heat-conducting base plate 26 and at the connection between the side of the first metal layer 251 and the insulating layer 252, transfers the stress concentration point of the ceramic substrate 25 from the connection between the side of the first metal layer 251 and the insulating layer 252 to the side of the first metal layer 251 facing the heat-conducting base plate 26. This effectively reduces the situation where the molding compound 23 only squeezes the connection between the side of the first metal layer 251 and the insulating layer 252, optimizes the internal stress distribution of the power module 20, reduces the risk of delamination or cracking of the insulating layer 252, and helps to improve the long-term reliability of the power module 20.

[0067] In addition, the reinforcing structure 261 is located on the side of the connecting layer 24, so that the encapsulant 23, which is filled between the heat-conducting base plate 26 and the first metal layer 251, is disposed around the connecting layer 24. The encapsulant 23 can cover the side of the ceramic substrate 25 and the side facing the heat-conducting base plate 26 as much as possible, further reducing the risk of delamination or cracking of the insulating layer 252.

[0068] The heat-conducting base plate 26 is made of high thermal conductivity metal materials such as copper and aluminum, which helps to improve the heat dissipation capacity of the power module 20.

[0069] In this application, one or more ceramic substrates 25 may be connected to each heat-conducting base plate 26. When multiple ceramic substrates 25 are connected to the heat-conducting base plate 26, the multiple ceramic substrates 25 are spaced apart on the heat-conducting base plate 26, and the number of ceramic substrates 25 can be determined according to the electrical and structural design.

[0070] Please combine Figure 4 and Figure 5 , Figure 4 This is a schematic diagram of the structure of a heat-conducting base plate 26 provided in an embodiment of this application; Figure 5 This is a schematic diagram of a heat-conducting base plate 26 provided in another embodiment of this application. The reinforcing structure 261 is disposed at the outer edge (i.e., side) of the connecting layer 24, and the reinforcing structure 261 is distributed circumferentially along the outer edge of the connecting layer 24. For example, when there is only one reinforcing structure 261, the reinforcing structure 261 extends circumferentially along the outer edge of the connecting layer 24 and forms a closed-loop structure, and the reinforcing structure 261 has a fully enclosed structure, such as... Figure 4 As shown; or, the reinforcing structure 261 extends circumferentially along the outer edge of the connecting layer 24 and forms an annular structure with an opening. For example, there may be multiple reinforcing structures 261, which are spaced apart circumferentially along the outer edge of the connecting layer 24, such as... Figure 5 As shown. With this configuration, the molding compound 23 can cover the sides of the ceramic substrate 25 and the side facing the heat-conducting base plate 26 as much as possible, further reducing the risk of delamination or cracking of the insulating layer 252.

[0071] Please combine Figure 6 , Figure 6 This is a schematic diagram of the structure of the heat-conducting base plate 26 and the first metal layer 251 in a power module 20 according to an embodiment of this application. In one embodiment, when the first metal layer 251 has multiple corners 2511 and multiple reinforcing structures 261 are spaced apart on the outer edge of the connecting layer 24, each corner 2511 corresponds to one reinforcing structure 261, one end of the reinforcing structure 261 extends toward one side of the corner 2511, and the other end of the reinforcing structure 261 extends toward the other side adjacent to the corner 2511. The abrupt change in shape at the corner 2511 of the first metal layer 251 can easily lead to stress concentration, which may cause the insulating layer 252 to crack at the corresponding location. To address this, a reinforcing structure 261 is provided at the corner 2511 of the first metal layer 251, extending to the two adjacent sides of the corner 2511. This allows the encapsulant 23, which is filled between the heat-conducting base plate 26 and the first metal layer 251, to extend to the two adjacent sides of the corner 2511, reducing the risk of the insulating layer 252 delaminating or cracking at the corner 2511 and improving the reliability of the power module 20.

[0072] Please combine Figure 3 For example, the reinforcing structure 261 partially surrounds the corner 2511 on one side facing the corner 2511. In other words, along the arrangement direction of the heat-conducting base plate 26 and the ceramic substrate 25, the outer edge of the orthographic projection of the reinforcing structure 261 on the side away from the connecting layer 24 is located outside the outer edge of the orthographic projection of the corner 2511, which includes one end of the reinforcing structure 261 (e.g., Figure 6 The first end 261b shown is located outside one side of the corner 2511, and the other end of the reinforcing structure 261 (as shown) Figure 6 The second end 261c shown (which is positioned opposite to the first end 261b) is located on the other side adjacent to the corner 2511.

[0073] Please combine Figure 7 , Figure 7 This is a schematic diagram of the structure of a power module 20 provided in one embodiment of this application. Figure 7 As shown, it can be understood that, along the arrangement direction of the heat-conducting base plate 26 and the ceramic substrate 25, the outer edge of the orthogonal projection of the reinforcing structure 261 can be located within the outer edge of the orthogonal projection of the corner 2511.

[0074] Please combine Figure 8 , Figure 8 This is a schematic diagram of the structure of a reinforcing structure 261 with different projected shapes in a heat-conducting base plate 26 provided in an embodiment of this application. (See attached diagram.) Figure 8 As shown, along the arrangement direction of the heat-conducting base plate 26 and the ceramic substrate 25, the orthographic projection outer contour shape of the reinforcing structure 261 can be any one of triangle, rectangle, circle, or a combination of the above shapes, without any specific limitation.

[0075] Please combine Figure 5 Furthermore, multiple reinforcing structures 261 are spaced apart between adjacent corners 2511, and the arrangement of the reinforcing structures 261 on the heat-conducting base plate 26 is intermittent in a ring shape. In other words, multiple reinforcing structures 261 form a discontinuous ring structure. For example, when the first metal layer 251 is a rectangular structure, multiple spaced reinforcing structures 261 are provided between adjacent corners 2511 along the long side of the first metal layer 251, such as... Figure 5 As shown; or, multiple reinforcing structures 261 are provided between two adjacent corners 2511 along the short side of the first metal layer 251; or, multiple reinforcing structures 261 are provided between any two adjacent corners 2511 along the outer edge circumferential direction of the first metal layer 251.

[0076] Please combine Figure 9 and Figure 10 , Figure 9 This is a schematic diagram of the structure of a heat-conducting base plate 26 provided in another embodiment of this application; Figure 10 This is a schematic diagram of another heat-conducting base plate 26 provided in another embodiment of this application. In another embodiment, the reinforcing structure 261 is a long strip structure, and the end of the reinforcing structure 261 is bent and partially surrounds the corner 2511 of the first metal layer 251. The structure of the reinforcing structure 261 surrounding the corner 2511 is similar to the design of the reinforcing structure 261 in the previous embodiment. In other words, the two reinforcing structures 261 at the two corners 2511 and the reinforcing structure 261 between the two corners 2511 are connected to form an integral structure. For example, when the first metal layer 251 is a rectangular structure, the integral reinforcing structure 261 can be a long-side semi-enclosed structure, such as... Figure 9 As shown; it can also be a short-side semi-enclosed structure, such as Figure 10 As shown.

[0077] When there are multiple ceramic substrates 25, each ceramic substrate 25 may have one or more reinforcing structures 261 on its outer circumference. The reinforcing structures 261 between two adjacent ceramic substrates 25 may overlap, such as... Figure 4 , Figure 9 and Figure 10 As shown. Optionally, when there are multiple ceramic substrates 25, the reinforcing structures 261 between two adjacent ceramic substrates 25 can also be spaced apart, such as... Figure 6 and Figure 8 As shown; or, the side portion between two adjacent ceramic substrates 25 is located in the middle of the heat-conducting base plate 26, where the stress is relatively low, and the heat-conducting base plate 26 portion between two adjacent ceramic substrates 25 may not have a reinforcing structure 261, as shown. Figure 5 As shown.

[0078] like Figure 7 As shown, in one embodiment, the reinforcing structure 261 includes a groove 263 filled with a molding compound 23. Specifically, the side of the heat-conducting base plate 26 facing the ceramic substrate 25 is recessed to form the groove 263, and each wall surface of the groove 263 and the side of the first metal layer 251 facing the heat-conducting base plate 26 form an accommodating space 261a. Forming the groove 263 on the heat-conducting base plate 26 is simple and easy to implement. The groove 263 allows the molding compound 23, which fills the space between the heat-conducting base plate 26 and the first metal layer 251, to extend to the outer periphery of the connecting layer 24, thereby maximizing the contact area between the molding compound 23 and the side of the first metal layer 251 facing the heat-conducting base plate 26. This increases the contact area between the molding compound 23 and the first metal layer 251, optimizes the internal stress distribution of the power module 20, reduces the risk of delamination or cracking of the insulation layer 252, and improves the reliability of the power module 20.

[0079] Meanwhile, a connecting portion 262 is formed on the heat-conducting base plate 26, protruding towards the ceramic substrate 25 relative to the bottom of the groove 263. The connecting portion 262 is used to place the connecting layer 24, and the groove 263 surrounds the connecting portion 262. This arrangement effectively limits the extension distance of the connecting layer 24 based on the outer edge of the connecting portion 262, reducing the possibility of the connecting layer 24 extending to the side of the first metal layer 251. The depth of the groove 263 can be designed based on the thickness of the heat-conducting base plate 26 and is not specifically limited.

[0080] Please combine Figure 11 , Figure 11 This is a schematic diagram of a heat-conducting base plate 26 with a groove 263 provided in an embodiment of this application. The groove 263 includes a bottom wall 2631, a first side wall 2632, and a second side wall 2633. The first side wall 2632 is connected to the edge of the bottom wall 2631 facing the connecting layer 24, and the second side wall 2633 is connected to the edge of the bottom wall 2631 away from the connecting layer 24. The first side wall 2632, the bottom wall 2631, and the second side wall 2633 together form the groove 263. The bottom wall 2631 of the groove 263 is the bottom of the groove 263.

[0081] Please combine Figure 12 , Figure 12 This is a partial structural diagram of a heat-conducting base plate 26 provided in an embodiment of this application, which has grooves 263 of different sizes. For example, the first sidewall 2632 is inclined toward the second sidewall 2633 relative to its connection with the bottom wall 2631; and / or, the second sidewall 2633 is inclined away from the first sidewall 2632 relative to its connection with the bottom wall 2631.

[0082] For example, if the first sidewall 2632 is inclined towards the second sidewall 2633 relative to its connection with the bottom wall 2631, the second sidewall 2633 can be perpendicular to the bottom wall 2631, and the groove 263 has a dovetail groove structure, such as... Figure 11 As shown; the second sidewall 2633 can also be inclined towards the first sidewall 2632 relative to its connection with the bottom wall 2631, and the groove 263 also has a dovetail groove structure. For example, when the second sidewall 2633 is inclined away from the first sidewall 2632 relative to its connection with the bottom wall 2631, the groove 263 forms a chamfered structure at the second sidewall 2633, and the first sidewall 2632 can be perpendicular to the bottom wall 2631. The groove 263 as a whole is a groove with a chamfered structure, such as... Figure 12 As shown in the right figure; the first sidewall 2632 can also be inclined away from the second sidewall 2633 relative to its connection with the bottom wall 2631, and the groove 263 forms a chamfered structure at the first sidewall 2632, so the groove 263 as a whole is a dovetail groove with a chamfered structure. Alternatively, the first sidewall 2632 can be inclined towards the second sidewall 2633 relative to its connection with the bottom wall 2631, and the second sidewall 2633 can be inclined away from the first sidewall 2632 relative to its connection with the bottom wall 2631, so the groove 263 forms a chamfered structure at the second sidewall 2633, thus the groove 263 as a whole is a dovetail groove with a chamfered structure, such as... Figure 12 As shown in the left figure.

[0083] Please combine Figure 11 and Figure 13 , Figure 13 This is a three-dimensional structural diagram of a heat-conducting base plate 26 provided in an embodiment of this application. The first sidewall 2632 is inclined towards the second sidewall 2633 relative to its connection with the bottom wall 2631. In other words, along the arrangement direction of the heat-conducting base plate 26 and the ceramic substrate 25, the outer edge of the orthographic projection of the groove 263 near the connecting layer 24 is located within the outer edge of the orthographic projection of the connecting portion 262. Figure 11As shown. With this configuration, the groove 263 has a dovetail groove structure at the first sidewall 2632. Even if there is a risk of delamination or cracking between the encapsulation body 23 and the heat-conducting base plate 26, the delamination or cracking location can be concentrated at the connection between the first sidewall 2632 and the bottom wall 2631, and it is not easy for it to extend to the connecting layer 24 and cause delamination or cracking in the connecting layer 24. This is beneficial to improving the connection reliability between the heat-conducting base plate 26 and the connecting layer 24, as well as between the first metal layer 251 and the connecting layer 24.

[0084] The second sidewall 2633 is inclined relative to the side of its connection with the bottom wall 2631 away from the first sidewall 2632. With this configuration, the groove 263 forms a chamfered structure at the second sidewall 2633. The edge of the groove 263 away from the connecting layer has a gentler transition. That is, the transition at the connection between the second sidewall 2633 and the bottom wall 2631 is gentler, and the transition between the end of the second sidewall 2633 away from the bottom wall 2631 and the surface of the heat-conducting base plate 26 closest to the first metal layer 251 is also gentler. This helps to reduce the stress on the side of the encapsulated body 23 away from the connecting layer 24 of the groove 263 and reduce the risk of cracking of the encapsulated body 23.

[0085] Furthermore, the end of the second sidewall 2633 away from the bottom wall 2631 is connected to the surface of the heat-conducting base plate 26 closest to the first metal layer 251 by an arc transition, which further reduces the stress on the encapsulated body 23 at this position and reduces the risk of cracking of the encapsulated body 23.

[0086] Please combine Figure 14 , Figure 14 This is a schematic diagram of the structure of a power module 20 according to another embodiment of this application. In another embodiment, the reinforcing structure 261 includes a boss 264, which protrudes towards the first metal layer 251 and is located on the side of the connecting layer 24. Thus, a portion of the heat-conducting base plate 26 without the boss 264 has a gap with the first metal layer 251, such that the side of the boss 264 away from the connecting layer 24, the side of the heat-conducting base plate 26 facing the first metal layer 251, and the side of the first metal layer 251 facing the heat-conducting base plate 26 together form an accommodating space 261a. The molding compound 23 can extend to the side of the first metal layer 251 facing the heat-conducting base plate 26, thereby shifting the stress concentration on the ceramic substrate 25 to the side of the first metal layer 251 facing the heat-conducting base plate 26, reducing the risk of delamination or cracking of the insulating layer 252, and improving the reliability of the power module 20.

[0087] Furthermore, the boss 264 is located on the side of the connecting layer 24. The boss 264 can limit the connecting layer 24, effectively reducing the possibility of the connecting layer 24 extending to the side of the first metal layer 251. The boss 264 is arranged in the same way as the aforementioned distribution of the reinforcing structure 261. Thus, one or more bosses 264 form a receiving space 265, in which the connecting layer 24 is placed to limit the connection layer 24.

[0088] Please combine Figure 15 , Figure 15 This is a schematic diagram of the structure of a power module 20 according to another embodiment of this application. In yet another embodiment, the reinforcing structure 261 includes a boss 264 and a groove 263, both of which are located on the side of the connecting layer 24, with the boss 264 located between the connecting layer 24 and the groove 263. Along the arrangement direction of the heat-conducting base plate 26 and the ceramic substrate 25, the orthographic projection of the boss 264 is located within the outer edge of the orthographic projection of the first metal layer 251, and the groove 263 is filled with a molding compound 23.

[0089] The boss 264 and the groove 263 are sequentially arranged around the periphery of the connecting layer 24. The side of the boss 264 facing away from the connecting layer 24, the side of the first metal layer 251 facing the heat-conducting base plate 26, and the various walls of the groove together form an accommodating space 261a. On the one hand, the boss 264 can limit the connection layer 24. On the other hand, the groove 263 further increases the depth of the accommodating space 261a, allowing the molding compound 23 to fill more of the side of the first metal layer 251 facing the heat-conducting base plate 26, enhancing the support for the ceramic substrate 25, reducing the risk of delamination or cracking of the ceramic substrate 25, and improving the reliability of the power module 20.

[0090] In an embodiment where the reinforcing structure 261 includes a boss 264, the side of the boss 264 facing the first metal layer 251 is attached to the first metal layer 251. Thus, the boss 264 provides support for the first metal layer 251 and effectively reduces the flow of the connecting layer 24 during the welding process to the side of the boss 264 away from the connecting layer 24, effectively limiting the position of the connecting layer 24. Optionally, when the thickness of the connecting layer 24 along the arrangement direction of the heat-conducting base plate 26 and the ceramic substrate 25 is greater than the height of the boss 264, there is a gap between the side of the boss 264 facing the first metal layer 251 and the first metal layer 251.

[0091] Furthermore, along the arrangement direction of the heat-conducting base plate 26 and the ceramic substrate 25, the orthographic projection of the boss 264 is located within the outer edge of the orthographic projection of the first metal layer 251. The molding compound 23 can effectively fill the space between the first metal layer 251 and the heat-conducting base plate 26 to wrap the side of the ceramic substrate 25, which is beneficial to improving the reliability of the power module 20.

[0092] Please combine Figure 16 , Figure 16 This is a schematic diagram of the structure of different shaped bosses 264 on the heat-conducting base plate 26 provided in one embodiment of this application. The cross-section of the boss 264 can be a trapezoidal structure that is wider at the top and narrower at the bottom, a trapezoidal structure that is narrower at the top and wider at the bottom, an arc-shaped structure, or a rectangular structure, etc., and is not specifically limited. The top and bottom are the two sides opposite each other along the arrangement direction of the heat-conducting base plate 26 and the ceramic substrate 25.

[0093] Please combine Figure 6 and Figure 17 , Figure 17 This is a schematic diagram of a structure provided in an embodiment of the present application, showing a heat-conducting base plate 26 with spaced semi-enclosed bosses 264. As mentioned above, the number of bosses 264 can be one or more. When there is only one boss 264, the boss 264 surrounds the connecting layer 24, forming a closed-loop structure, thus creating a fully enclosed boss 264; or, the boss 264 may have an open ring structure. When there are multiple bosses 264, the multiple bosses 264 can be four corner bosses 264 (e.g.,...). Figure 6 As shown), the spaced semi-enclosed boss 264 (as shown) Figure 16 or Figure 10 (as shown) or annular discontinuous protrusions 264, wherein the distribution and arrangement of the annular discontinuous protrusions 264 are similar to the annular discontinuous distribution and arrangement of the aforementioned reinforcing structure 261, and will not be described again.

[0094] In embodiments where the reinforcing structure 261 includes a groove 263, the groove 263 can be a dovetail groove, a rectangular groove, a triangular groove, or a groove of other shapes. Specifically, along the arrangement direction of the heat-conducting base plate 26 and the ceramic substrate 25, at least a portion of the orthographic projection of the groove 263 is located within the outer edge of the orthographic projection of the first metal layer 251. For example, a portion of the orthographic projection of the groove 263 is located within the outer edge of the orthographic projection of the first metal layer 251, while another portion is located outside the outer edge of the orthographic projection of the first metal layer 251, such as... Figure 15 As shown; for example, the orthographic projection of the groove 263 is entirely located within the outer edge of the orthographic projection of the first metal layer 251, such as... Figure 7 and Figure 11 As shown. With this configuration, the molding compound 23 can fill the space between the heat-conducting base plate 26 and the first metal layer 251 and is at least partially located within the outer edge of the first metal layer 251. This causes the stress concentration on the ceramic substrate 25 to shift to the side of the first metal layer 251 facing the heat-conducting base plate 26, reducing the risk of delamination or cracking of the insulating layer 252 and improving the reliability of the power module 20.

[0095] Please combine Figure 15 and Figure 18 , Figure 18This is a partial structural schematic diagram of the groove 263 in a heat-conducting base plate 26 provided in an embodiment of this application. For example, along the arrangement direction of the heat-conducting base plate 26 and the ceramic substrate 25, the orthographic projection of the groove 263 away from the edge of the connecting layer 24 is located outside the outer edge of the orthographic projection of the first metal layer 251. Wherein, as... Figure 18 As shown, the portion of the edge of the groove 263 that is away from the connecting layer 24 can extend to the side edge of the heat-conducting base plate 26, that is, the groove 263 has a notch 2634. By offsetting the outer edge of the groove 263 away from the connecting layer 24 from the outer edge of the first metal layer 251, the position where the side shape of the ceramic substrate 25 changes abruptly is offset from the position where the molding compound 23 changes abruptly, and the contact area between the molding compound 23 and the first metal layer 251 is increased, the stress distribution inside the power module 20 is optimized, the risk of delamination or cracking of the insulating layer 252 is reduced, and the reliability of the power module 20 is improved.

[0096] Please combine Figure 19 and Figure 20 , Figure 19 A schematic diagram of a structure in which a heat-conducting base plate 26 with four corner grooves 263 is provided in an embodiment of this application; Figure 20 This is a schematic diagram of a structure provided in an embodiment of the present application, showing a heat-conducting base plate 26 with spaced semi-enclosed grooves 263. Similarly, the number of grooves 263 can be one or more. When there is only one groove 263, it surrounds the connecting layer 24, forming a closed-loop structure, thus creating a fully enclosed groove 263. Alternatively, an open annular structure can be formed between the two ends of the groove 263. When there are multiple grooves 263, these multiple grooves 263 can be four-corner grooves 263 (e.g.,...). Figure 19 As shown), the spaced semi-enclosed groove 263 (as shown) Figure 20 or Figure 10 (as shown) or annular discontinuous groove 263, wherein the distribution and arrangement of the annular discontinuous groove 263 is similar to the annular discontinuous distribution and arrangement of the aforementioned reinforcing structure 261, and will not be described again.

[0097] In summary, the thermally conductive base plate 26 structure provided in this application effectively improves the internal stress distribution of the power module 20 under reliability testing or normal application conditions, reduces the risk of delamination or cracking of the ceramic substrate 25, and is beneficial to improving the application reliability of the ceramic substrate 25, as well as enhancing the heat dissipation performance and reliability of the power module 20. Furthermore, the reduced stress risk of the power module 20 allows for an effective increase in its area, further increasing the power limit of a single power module 20 and reducing the cost per watt of the power module 20.

[0098] In this application, unless otherwise expressly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0099] The terms "first," "second," and various numerical designations used herein are merely for descriptive convenience and are not intended to limit the scope of this application.

[0100] It should be understood that in the various embodiments of this application, the order of the above-mentioned processes does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0101] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit it. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A power module, characterized in that, The device includes a thermally conductive base plate, a ceramic substrate, a chip, a molding compound, and a connecting layer; the thermally conductive base plate, the connecting layer, the ceramic substrate, and the chip are stacked sequentially, and the molding compound encapsulates the ceramic substrate and the chip; the ceramic substrate includes an insulating layer and a first metal layer, the first metal layer being disposed between the insulating layer and the connecting layer; A reinforcing structure is formed on the side of the thermally conductive base plate facing the ceramic substrate. In a direction perpendicular to the stacking direction of the thermally conductive base plate and the connecting layer, the reinforcing structure is located on the side of the connecting layer. The wall of the reinforcing structure and the side of the first metal layer facing the thermally conductive base plate form an accommodating space, and the encapsulation fills the accommodating space.

2. The power module according to claim 1, characterized in that, The number of the reinforcing structures is multiple, and the multiple reinforcing structures are arranged around the connecting layer at intervals.

3. The power module according to claim 2, characterized in that, The first metal layer has multiple corners, each corner corresponding to a reinforcing structure, one end of the reinforcing structure extending toward one side of the corner, and the other end of the reinforcing structure extending toward the opposite side adjacent to the corner.

4. The power module according to claim 1, characterized in that, The reinforcing structure includes a groove filled with the encapsulant.

5. The power module according to claim 4, characterized in that, Along the arrangement direction of the thermally conductive base plate and the ceramic substrate, the orthographic projection of the groove is located away from the edge of the connecting layer and outside the outer edge of the orthographic projection of the first metal layer.

6. The power module according to claim 4, characterized in that, Along the arrangement direction of the thermally conductive base plate and the ceramic substrate, at least a portion of the orthographic projection of the groove is located within the outer edge of the orthographic projection of the first metal layer.

7. The power module according to claim 1, characterized in that, The reinforcing structure includes a boss that protrudes toward the first metal layer and is located on the side of the connecting layer. The side of the boss away from the connecting layer, the side of the heat-conducting base plate facing the first metal layer, and the side of the first metal layer facing the heat-conducting base plate form the accommodating space. Along the arrangement direction of the thermally conductive base plate and the ceramic substrate, the orthographic projection of the boss is located within the outer edge of the orthographic projection of the first metal layer.

8. The power module according to claim 1, characterized in that, The reinforcing structure includes a boss and a groove, both of which are arranged around the connecting layer. The boss is located between the connecting layer and the groove, along the arrangement direction of the heat-conducting base plate and the ceramic substrate. The orthographic projection of the boss is located within the outer edge of the orthographic projection of the first metal layer. The groove is filled with the encapsulant.

9. The power module according to claim 7 or 8, characterized in that, The side of the boss facing the first metal layer is attached to the first metal layer.

10. The power module according to claim 4 or 8, characterized in that, The groove includes a bottom wall, a first side wall, and a second side wall. The first side wall is connected to the edge of the bottom wall facing the connecting layer, and the second side wall is connected to the edge of the bottom wall away from the connecting layer. The first sidewall is inclined toward the second sidewall relative to the connection between the first sidewall and the bottom wall; And / or, the second sidewall is inclined away from the first sidewall at the connection between the second sidewall and the bottom wall.

11. A power conversion device, characterized in that, It includes a circuit board and a power module as described in any one of claims 1-10, wherein the power module is disposed on the circuit board.

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