Power module and inverter

Abstract

The power module and the inverter, the power module includes a package and a plurality of copper sheet groups, the package is used for packaging power chips, each copper sheet group includes a plurality of copper sheets, along the extension direction of the plurality of copper sheets, one end of the plurality of copper sheets is located in the package, the other end of the plurality of copper sheets extends out of the package, and the end of the plurality of copper sheets extending out of the package includes a first hardened area, and the first hardened area is used for being connected with a circuit board. By the plastic deformation of the plurality of copper sheets, the stress generated by the relative displacement between the circuit board and the direct copper bonded ceramic substrate (DBC) is absorbed, the friction and wear at the connection between the first hardened area and the circuit board are reduced, and the service life of the power module is improved.

Description

Technical Field

[0001] This application relates to the field of power electronics, and more particularly to a power module and an inverter. Background Technology

[0002] When power modules are used in inverters, the air-cooling structure (such as a fan) dissipates heat from power devices such as Insulated Gate Bipolar Transistors (IGBTs), Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs), and capacitors during operation. However, the air-cooling structure vibrates during operation, which can cause displacement of the printed circuit board (PCB) relative to the power module or introduce additional forces between them. The electrical connection between the power module and the PCB is achieved through pins, and the most widely used connection method is crimp pins, which provide a rigid connection. Under the influence of air-cooling vibration, the connection between the pins and the vias on the PCB may shift or even detach from the vias, affecting the reliability of the connection. In addition, changes in temperature or humidity inside the inverter can also degrade the contact performance between the pins and the vias. Meanwhile, with prolonged use, since the pin tips are rigidly connected to the printed circuit board and the pin bottoms are rigidly connected to the direct-bonded ceramic (DBC) substrate, any external stress will be transmitted to the pin tips. This will further exacerbate the degradation of the connection between the pin tips and the printed circuit board, resulting in increased contact resistance, decreased current carrying capacity, and consequently affecting the stability and lifespan of the entire inverter system. Utility Model Content

[0003] This application provides a power module that absorbs the stress generated by the relative displacement between the circuit board and the direct copper-clad ceramic substrate (DBC) through plastic deformation of multilayer copper sheets, thereby reducing friction and wear at the connection between the first hardened area and the circuit board and improving the service life of the power module.

[0004] Firstly, this application provides a power module, which includes a package and multiple copper sheet groups. The package is used to encapsulate a power chip. Each copper sheet group includes multiple layers of copper sheets. Along the extension direction of the multiple copper sheets, one end of each layer is located inside the package, and the other end extends out of the package. The end of the multiple copper sheets extending out of the package includes a first hardened region for connection with a circuit board. The multiple copper sheets can undergo plastic deformation under external force without breaking. Therefore, when relative displacement occurs between the circuit board and the direct copper-clad ceramic substrate (DBC), local stress concentration occurs. This stress is transmitted to the multiple copper sheets extending out of the package through the connection between the first hardened region and the circuit board. Because the multiple copper sheets have good plastic deformation capabilities, they can undergo a certain degree of plastic deformation under external force, thereby effectively absorbing and dispersing stress. This process not only alleviates the mechanical impact caused by displacement but also correspondingly reduces friction and wear at the connection between the first hardened region and the circuit board, thereby reducing the possibility of increased contact resistance, ensuring stable current transmission, maintaining good current carrying capacity, improving the overall operational stability of the power module and inverter, and extending service life.

[0005] In one possible implementation, each layer of copper sheet in the multilayer copper sheet has the same thickness. By setting each layer of copper sheet in the multilayer copper sheet to have the same thickness, the multilayer copper sheet with equal thickness can provide uniform structural support and consistent mechanical properties. This is suitable for scenarios with high requirements for the mechanical stability, safety and consistency of power modules, and effectively avoids the risk of local overheating or breakage.

[0006] In one possible implementation, in some special designs, to achieve specific mechanical properties, such as directional bending, reducing the stiffness of a certain part, or enhancing the strength of a certain area, embodiments of this application configure the multilayer copper sheets along the stacking direction. The multilayer copper sheets include a first part and a second part, where the thickness of the copper sheet in the first part is greater than the thickness of the copper sheet in the second part. That is, the first part is a high-stiffness region, and the second part is a low-stiffness region. When a copper sheet is subjected to bending force, the moment of inertia of its cross-section determines its ability to resist bending. The larger the moment of inertia, the less likely it is to bend, and vice versa. The moment of inertia is proportional to the cube of the thickness of the copper sheet. Therefore, the larger the thickness of the copper sheet, the larger the moment of inertia, the stronger the bending resistance, and the less likely it is to deform; the smaller the thickness of the copper sheet, the smaller the moment of inertia, and the easier it is to bend. Along the stacking direction of the multilayer copper sheets, the second part can be located on one side of the first part. The second part is more prone to plastic deformation, so the multilayer copper sheets will naturally bend towards the first part. In other embodiments, along the stacking direction of the multilayer copper sheets, the second part can be located on the opposite side of the first part. The second part is more prone to plastic deformation, so the multilayer copper sheets will naturally bend towards the opposite side of the first part. This application embodiment controls the bending direction of the multilayer copper sheets by controlling the thickness difference between the copper sheets in the first and second parts, adapting to various assembly requirements, improving the adaptability of the multilayer copper sheets, and optimizing space utilization within the power module.

[0007] In one possible implementation, the multilayer copper sheet further includes multiple second hardened regions. These second hardened regions are spaced apart along the extension direction and / or a first direction of the multilayer copper sheet, where the first direction is perpendicular to both the extension direction and the stacking direction of the multilayer copper sheet. The resistance of a copper sheet is related to its cross-sectional area; the smaller the cross-sectional area, the greater the resistance and the worse the current-carrying capacity. For example, the multiple second hardened regions can be formed by hot-pressing a portion of the multilayer copper sheet. The cross-sectional area of ​​the second hardened region is larger than that of the single-layer copper sheet, therefore the resistance of the second hardened region is less than that of the single-layer copper sheet, and the current-carrying capacity of the second hardened region is superior to that of the single-layer copper sheet. This embodiment of the application ensures the current-carrying capacity of the multilayer copper sheet by providing multiple second hardened regions. Furthermore, the second hardened regions have a certain hardness or strength, providing a certain supporting force during power module assembly, improving the stability of the internal structure of the power module, and adapting to various assembly requirements.

[0008] In one possible implementation, the first hardened region is formed by hot pressing a portion of a multilayer copper sheet. Under high temperature and high pressure, localized melting, diffusion, or plastic deformation occurs in certain areas of the multilayer copper sheet. These changes increase the hardness and strength of these areas, forming a first hardened region with a certain hardness or strength.

[0009] In one possible implementation, the second hardened region is formed by hot pressing a portion of a multilayer copper sheet. Under high temperature and high pressure, localized melting, diffusion, or plastic deformation occurs in certain areas of the multilayer copper sheet. These changes increase the hardness and strength of these areas, forming a second hardened region with a certain hardness or strength.

[0010] In one possible implementation, the power module further includes a direct copper-clad ceramic substrate (DBC), with the power chip disposed on the DBC. One end of a multilayer copper strip within the package is connected to the DBC. Drive signals from the power module are transmitted to the circuit board via the multilayer copper strip, and control signals from the circuit board are fed back to the power module via the multilayer copper strip. Power is transmitted from the circuit board to the power device disposed on the DBC via the multilayer copper strip. Exemplarily, the power device may be a power chip.

[0011] In one possible implementation, one end of the multilayer copper sheet within the package is a bent structure, which connects to the DBC (Diverterless Core Compactor). During the operation of the power module, the multilayer copper sheet and the DBC will have different coefficients of thermal expansion (CTE) due to temperature changes. When the thermal expansion is inconsistent, significant thermal stress is generated at the connection between the end of the multilayer copper sheet within the package and the DBC. Therefore, in this embodiment, the other end of the multilayer copper sheet can be configured as a bent structure. This bent structure acts as a buffer, absorbing some of the thermal stress and reducing the risk of breakage. Furthermore, during the molding process of the encapsulation section, there will be pressure from both above and below. The bent structure can absorb some of this pressure stress, preventing structural cracking or package failure due to stress concentration.

[0012] In one possible implementation, the first hardened area is used for locking to the circuit board. Locking refers to the first hardened area being mechanically fixed to the circuit board, resulting in a strong connection with high resistance to vibration and impact. Exemplarily, the mechanical locking method can be a snap-fit ​​locking, a pin locking, or a threaded locking. Furthermore, since the locking method lacks a solder layer, it is not affected by solder aging or melting, making it suitable for long-term use in high and low temperature cycling and high temperature environments. Additionally, the locking structure allows for convenient and quick disassembly when the power module needs to be replaced or repaired.

[0013] In one possible implementation, the power module further includes a plurality of rigid pins, one end of which extends out of the package along the extension direction of the rigid pins and is used to insert into a through hole in the circuit board, and the other end of which is disposed within the package.

[0014] In one possible implementation, a rigid pin is located at the other end of the package and connected to the DBC.

[0015] Secondly, this application provides an inverter, which includes a circuit board and a power module as described in any embodiment of the first aspect. The multilayer copper sheets can undergo plastic deformation under external force without breaking. Therefore, when relative displacement occurs between the circuit board and the direct copper-clad ceramic substrate (DBC), local stress concentration occurs. This stress is transmitted to the multilayer copper sheets extending from the package through the connection between the first hardened area and the circuit board. Because the multilayer copper sheets possess good plastic deformation capabilities, they can undergo a certain degree of plastic deformation under external force, thereby effectively absorbing and dispersing stress. This process not only alleviates the mechanical impact caused by displacement but also correspondingly reduces friction and wear at the connection between the first hardened area and the circuit board, thereby reducing the possibility of increased contact resistance, ensuring stable current transmission, maintaining good current carrying capacity, improving the overall operational stability of the power module and inverter, and extending service life. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the embodiments of this application will be described below.

[0017] Figure 1 A schematic diagram of a power module provided in an embodiment of this application;

[0018] Figure 2 A schematic diagram of yet another power module provided in the embodiments of this application;

[0019] Figure 3 A schematic diagram of another power module provided in an embodiment of this application;

[0020] Figure 4(a) is a side view of a multilayer copper sheet and circuit board connection method provided in an embodiment of this application;

[0021] Figure 4(b) is a partial enlarged view of region A in Figure 4(a) of the embodiment of this application;

[0022] Figure 5(a) is a side view of another multilayer copper sheet provided in an embodiment of this application;

[0023] Figure 5(b) is a partial enlarged view of region B in Figure 5(a) of an embodiment of this application;

[0024] Figure 5(c) is another enlarged view of region B in Figure 5(a) of the embodiment of this application;

[0025] Figure 6(a) is a perspective view of a multilayer copper sheet provided in an embodiment of this application;

[0026] Figure 6(b) is a cross-sectional view of the hardened region along the AA' direction in region C of the embodiment of this application in Figure 6(a);

[0027] Figure 6(c) is a cross-sectional view of a single-layer copper sheet along the BB' direction in region D of Figure 6(a) of this application embodiment;

[0028] Figure 7 (a) is a front view of a multilayer copper sheet provided in an embodiment of this application;

[0029] Figure 7 (b) is a front view of another multilayer copper sheet provided in an embodiment of this application;

[0030] Figure 7 (c) is a front view of yet another multilayer copper sheet provided in the embodiments of this application;

[0031] Figure 8 A side view of another method for connecting multilayer copper sheets to a circuit board, provided in an embodiment of this application;

[0032] Figure 9 This is a perspective view of another method of connecting a multilayer copper sheet to a circuit board, as provided in an embodiment of this application.

[0033] Explanation of reference numerals in the attached figures:

[0034] Power module 1000;

[0035] Copper substrate 1001; DBC 1002; Chip 1003; Pin 1004; Bonding wire 1005; Housing 1006; Silicon gel 1007;

[0036] Power module 2000;

[0037] Copper substrate 2001; DBC 2002; Chip 2003; Pin 2004; Bonding wire 2005; Cover plate 2006; Silicone pad 2007;

[0038] Power module 3000;

[0039] Package 3001; DBC 3002; Copper substrate 3003; Power chip 3004; Bonding wire 3005;

[0040] Copper sheet group 300;

[0041] Multilayer copper sheet 310; copper sheet 311; first part 312; second part 313; bent structure 314; first hardened region 320; second hardened region 330;

[0042] Circuit board 4000;

[0043] Bolt 5000;

[0044] The extension direction of the multilayer copper sheet 310 is X; the stacking direction of the multilayer copper sheet 310 is Y; the first direction is Z. Detailed Implementation

[0045] 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.

[0046] Power modules are core components of power electronic systems, typically composed of power semiconductor devices such as IGBTs, MOSFETs, or SiC, used for switching, converting, and controlling power. In practical applications, multiple power modules are combined into power board systems to improve the system's power density, efficiency, and reliability. Power board systems are widely used in various scenarios requiring power conversion. For example, in inverters, power modules are responsible for converting DC to AC, making them key components in photovoltaic systems, electric vehicles, and industrial frequency converters. In charging stations, such as fast-charging stations for electric vehicles, power modules are used to achieve efficient AC to DC conversion to meet the demands of high-power charging. Furthermore, power modules can also be applied to servo motors, frequency converters, energy storage systems, uninterruptible power supplies (UPS), and industrial motor control.

[0047] Please see Figure 1 , Figure 1 This is a schematic diagram of a power module 1000 provided in an embodiment of this application. The power module 1000 generally includes a copper substrate 1001, a direct copper-clad ceramic substrate DBC 1002, a power semiconductor chip 1003, and pins 1004 (also referred to as "pins"). Sometimes, the direct copper-clad ceramic substrate can also be called a direct-bonded copper substrate; in this document, it is uniformly referred to as the direct copper-clad ceramic substrate DBC. For ease of description, the power semiconductor chip will be referred to as "chip 1003" below. The DBC 1002 is disposed on the copper substrate 1001, and the two can be connected by methods such as soldering, sintering, or diffusion. The chip 1003 is mounted on the surface of the DBC 1002, electrically connected to the DBC 1002 via bonding wires 1005, and mechanically connected to the DBC 1002 by methods such as reflow soldering, silver sintering, eutectic bonding, or laser welding. Meanwhile, the bottom of pin 1004 is connected to DBC1002, and the connection method also includes welding, pressing, sintering, or laser welding to ensure good conductivity and structural stability. For example, chip 1003 can be an IGBT, MOSFET, SiC power transistor, etc.

[0048] Currently, power modules 1000 are generally packaged using a "housing" method. After assembling and soldering components such as the copper substrate 1001, DBC 1002, chip 1003, and pins 1004, the entire structure is placed inside the housing 1006, with the tips of the pins 1004 extending out of the housing 1006. Silicone gel 1007 is then injected to completely fill all gaps within the housing 1006, ensuring that the internal components are completely covered by the silicone gel 1007. Once the silicone gel 1007 has cured, the encapsulation of the power module 1000 is complete. Silicone gel 1007 is an elastic material between liquid and solid, possessing excellent insulation, temperature resistance, and shock resistance. Encapsulating the power module 1000 with silicone gel 1007 effectively isolates it from the influence of external environmental factors such as moisture, dust, and vibration, improving the power module 1000's waterproof and moisture-proof capabilities. In addition, silicone gel 1007 also possesses certain thermal conductivity, which helps dissipate heat from the power module 1000 during operation and improves heat dissipation. However, due to the soft texture and relatively loose structure of silicone gel 1007, bubbles may form or deteriorate within it during temperature changes, affecting its physical and electrical properties and leading to a decrease in insulation performance. This, in turn, adversely impacts the stability and lifespan of the power module 1000.

[0049] With technological advancements, traditional housing packaging, limited by the properties of silicone gel materials, is gradually being replaced by a new type of molding compound packaging technology. This technology uses molding compound instead of silicone gel to achieve the protection function of the power module. For example, the molding compound can be materials such as epoxy molding compound (EMC) or epoxy resin. This packaging method not only improves the stability of the various electrical structures within the power module but also enhances the durability of the power module.

[0050] Please see Figure 2 , Figure 2This is a schematic diagram of another power module 2000 provided in an embodiment of this application. The power module 2000 includes components such as a copper substrate 2001, a DBC 2002, a chip 2003, and pins 2004. The DBC 2002 is disposed on the copper substrate 2001, the chip 2003 is mounted on the surface of the DBC 2002, and the chip 2003 is electrically connected to the DBC 2002 via bonding wires 2005. The bottom end of the pins 2004 is connected to the DBC 2002. After assembling and soldering the components such as the copper substrate 2001, DBC 2002, chip 2003, and pins 2004, the power module 2000 is encapsulated. First, the electrical structures in the power module 2000 are pressed together using an injection mold. A cover plate 2006 fixes a silicone pad 2007 to cooperate with the injection mold to form an injection cavity. In this design, the bottom of pin 2004 is located inside the injection cavity and connects to DBC2002; the top of pin 2004 is located outside the injection cavity and is used to connect to external electrical structures (such as printed circuit boards). To prevent the molding compound from completely encapsulating pin 2004 during injection molding, thus preventing electrical interconnection with external electrical structures, a silicone pad 2007 secures the portion of pin 2004 outside the injection cavity. After the injection cavity is constructed, the molding compound is heated to a suitable temperature and injected into the cavity. Once the molding compound has fully cured, a complete molding body 2008 is formed. The mold is then removed, completing the encapsulation process. Compared to silicone gel encapsulation, molding encapsulation is formed through a mold, eliminating the need for an additional shell structure. It has a more rigid overall texture and a more compact shape, making it suitable for applications requiring higher structural strength and protection.

[0051] Furthermore, regardless of whether the power module 1000 uses plastic or silicone gel encapsulation, it typically employs a top-pin design for electrical connections. Specifically, the bottom of pin 2004 inside the power module 2000 is connected to DBC2002, while its top is connected to a printed circuit board (not shown). The printed circuit board handles the input and output of electrical signals. After the power module 2000 is assembled and powered on, all electrical input and output signals first enter the printed circuit board for processing or distribution, and then are transmitted to the power module 2000 to perform the corresponding power conversion functions. The connection methods between the top of pin 2004 and the external electrical structure include press-fit pins, solder pins, and Xenon Terminal (XT). Among these, in practical applications, press-fit pin connections have become the mainstream choice due to their advantages such as convenient installation, no soldering required, and reusability.

[0052] Taking the power module 2000 in an inverter as an example, during inverter operation, power devices such as IGBTs, MOSFETs, and capacitors generate heat. If heat dissipation is ineffective, these power devices will age faster, experience performance degradation, and may even lead to thermal runaway. Therefore, inverters typically incorporate air-cooling structures (such as fans) to rapidly dissipate heat through forced airflow, maintaining the power devices within a safe operating temperature range. However, these air-cooling structures vibrate during operation, potentially causing displacement of the printed circuit board relative to the power module 2000 or introducing additional forces between them. As mentioned earlier, the electrical connection between the power module 2000 and the printed circuit board is achieved through pin 2004, currently widely using press-fit pins, which are rigid connections. Under the influence of air-cooling vibration, the connection between pin 2004 and the via on the printed circuit board may shift or even detach, affecting connection reliability. Furthermore, changes in temperature or humidity inside the inverter can also degrade the contact performance between pin 2004 and the via. Meanwhile, with prolonged use, since the top of pin 2004 is rigidly connected to the printed circuit board and the bottom of pin 2004 is rigidly connected to DBC2002, any external stress will be transmitted to the top of pin 2004. This will further exacerbate the deterioration of the connection between the top of pin 2004 and the printed circuit board, resulting in increased contact resistance, decreased current carrying capacity, and consequently affecting the stability and lifespan of the entire inverter system.

[0053] To address the degradation of the connection between the pins and the PCB printed circuit board, this application modifies the power module. Please refer to... Figure 3 , Figure 3 This is a schematic diagram of another power module 3000 provided in an embodiment of this application. The inverter (not shown) includes a power module 3000 and a circuit board 4000. The power module 3000 includes a package 3001, a DBC 3002, and multiple copper sheet groups 300. The package 3001 encapsulates a power chip 3004, which is disposed on the DBC 3002. Each copper sheet group 300 includes multiple layers of copper sheets 310. Along the extending direction X of the multiple layers of copper sheets 310, one end of the multiple layers of copper sheets 310 is located within the package 3001, and the other end of the multiple layers of copper sheets 310 extends out of the package 3001. The end of the multiple layers of copper sheets 310 extending out of the package 3001 includes a first hardened region 320, which is connected to the circuit board 4000 (also referred to as a "PCB").

[0054] The multilayer copper sheet 310 can undergo plastic deformation under external force without breaking itself. Therefore, when relative displacement occurs between the circuit board 4000 and DBC3002, local stress concentration occurs. This stress is transmitted to the multilayer copper sheet 310 extending from the package 3001 through the connection between the first hardened region 320 and the circuit board 4000. Because the multilayer copper sheet 310 has good plastic deformation capability, it can undergo a certain degree of plastic deformation under external force, thereby effectively absorbing and dispersing stress. This process not only alleviates the mechanical impact caused by displacement but also correspondingly reduces the friction and wear at the connection between the first hardened region 320 and the circuit board 4000, thereby reducing the possibility of increased contact resistance, ensuring stable current transmission, maintaining good current carrying capacity, improving the overall operational stability of the power module 3000 and the inverter, and extending service life.

[0055] In one embodiment, the first hardened region 320 is formed by hot pressing a portion of a multilayer copper sheet 310. Under high temperature and high pressure, a portion of the multilayer copper sheet 310 undergoes localized melting, diffusion, or plastic deformation. These changes increase the hardness and strength of the portion of the sheet, forming the first hardened region 320 with a certain hardness or strength. It should be noted that in other embodiments, the first hardened region 320 can also be formed from a portion of the multilayer copper sheet 310 through processes such as extrusion molding, laser welding, or stamping.

[0056] In one embodiment, please also refer to Figures 3 to 4(b) Figure 4(a) is a side view of a connection method between a multilayer copper sheet 310 and a circuit board 4000 provided in an embodiment of this application, and Figure 4(b) is a partial enlarged view of area A in Figure 4(a) of an embodiment of this application. In this embodiment of the application, the thickness d of each copper sheet 311 in the multilayer copper sheet 310 is the same. The multilayer copper sheet 310 with equal thickness d can provide uniform structural support and consistent mechanical properties, which is suitable for scenarios with high requirements for the mechanical stability, safety and consistency of the power module 3000, and effectively avoids the risk of local overheating or breakage.

[0057] In one embodiment, please also refer to Figure 3Figures 5(a) and 5(b) are provided. Figure 5(a) is a side view of another multilayer copper sheet 310 provided in this embodiment, and Figure 5(b) is a partial enlarged view of region B in Figure 5(a) of this embodiment. In some special designs, to achieve specific mechanical properties, such as directional bending, reducing the stiffness of a certain part, or enhancing the strength of a certain area, this embodiment sets the multilayer copper sheet 310 along the stacking direction Y. The multilayer copper sheet 310 includes a first part 312 and a second part 313. The thickness of the copper sheet 311 in the first part 312 is greater than the thickness of the copper sheet 311 in the second part 313. That is, the first part 312 is a high-stiffness region, and the second part 313 is a low-stiffness region. When the copper sheet 311 is subjected to bending force, the moment of inertia of its cross section determines its ability to resist bending. The larger the moment of inertia, the less likely it is to bend, and vice versa. The moment of inertia is proportional to the cube of the thickness of the copper sheet 311. Therefore, the larger the thickness of the copper sheet 311, the larger the moment of inertia, the stronger the bending resistance, and the less prone it is to deformation; the smaller the thickness of the copper sheet 311, the smaller the moment of inertia, and the easier it is to bend. For example, the positional relationship between the first part 312 and the second part 313 can be shown in Figure 5(b). Along the stacking direction Y of the multilayer copper sheets 310, the second part 313 is located on one side of the first part 312. The second part 313 is more prone to plastic deformation, so the multilayer copper sheets 320 will naturally bend towards the side of the first part 312. In other embodiments, the positional relationship between the first part 312 and the second part 313 can be shown in Figure 5(c), which is another enlarged view of region B in Figure 5(a) of this embodiment. Along the stacking direction Y of the multilayer copper sheets 310, the second part 313 can be located on the other side of the first part 312. Since the second part 313 is more prone to plastic deformation, the multilayer copper sheets 320 will naturally bend towards the other side of the first part 312. This embodiment controls the bending direction of the multilayer copper sheets 320 by controlling the thickness difference of the copper sheets 311 in the first part 312 and the second part 313, adapting to various assembly requirements, improving the adaptability of the multilayer copper sheets 320, and optimizing space utilization within the power module 3000.

[0058] In one embodiment, the resistance of the copper sheet 311 is related to its cross-sectional area; the smaller the cross-sectional area, the greater the resistance of the copper sheet 311 and the worse its current-carrying capacity. Therefore, embodiments of this application may include a plurality of second hardened regions 330 within the multilayer copper sheet 310. Exemplarily, the plurality of second hardened regions 330 may be formed by hot pressing partial areas of the multilayer copper sheet 310. Under high temperature and high pressure, partial areas of the multilayer copper sheet 310 undergo localized melting, diffusion, or plastic deformation. These changes increase the hardness and strength of these partial areas, forming second hardened regions 330 with a certain hardness or strength. Figures 6(a) to 6(c)As shown, Figure 6(a) is a perspective view of a multilayer copper sheet 310 provided in an embodiment of this application; Figure 6(b) is a cross-sectional view of the hardened region in region C of Figure 6(a) along the AA' direction in an embodiment of this application; and Figure 6(c) is a cross-sectional view of a single-layer copper sheet 311 in region D of Figure 6(a) along the BB' direction in an embodiment of this application. The hardened region in region C is formed by the multilayer copper sheet 310 through processes such as hot pressing, extrusion molding, laser welding, or stamping. Referring to Figures 6(b) and 6(c), the cross-sectional area S1 of the hardened region is larger than the cross-sectional area S2 of the single-layer copper sheet 311. Similarly, the cross-sectional area of ​​the second hardened region 330 is larger than the cross-sectional area of ​​the single-layer copper sheet 311. Therefore, the resistance of the second hardened region 330 is less than the resistance of the single-layer copper sheet 311, and the current-carrying capacity of the second hardened region 330 is superior to that of the single-layer copper sheet 311. This embodiment of the application ensures the current-carrying capacity of the multilayer copper sheet 310 by setting multiple second hardened regions 330. Furthermore, the second hardened region 330 possesses a certain degree of hardness or strength, providing support during the assembly of the power module 3000, thereby improving the stability of the internal structure of the power module 3000 and adapting to various assembly requirements. For example, multiple second hardened regions 330 can be configured as follows: Figure 7 As shown in (a), the layers of copper sheets 310 are spaced apart along the extension direction X. Alternatively, they can be arranged as shown in (a). Figure 7 As shown in (b), the spacing is arranged along the first direction Z, and it can also be as follows: Figure 7 As shown in (c), the multilayer copper sheet 310 is spaced apart along the extension direction X and the first direction Z. The first direction Z is perpendicular to the extension direction X of the multilayer copper sheet 310 and perpendicular to the stacking direction Y of the multilayer copper sheet 310. Figure 7 (a) is a front view of a multilayer copper sheet 310 provided in an embodiment of this application. Figure 7 (b) is a front view of another multilayer copper sheet 310 provided in an embodiment of this application. Figure 7 Image (c) is a front view of another multilayer copper sheet 310 provided in an embodiment of this application. In other embodiments, the second hardened region 330 can also be formed by extrusion molding, laser welding, or stamping of a portion of the multilayer copper sheet 310. It should be noted that the shape of the second hardened region 330 can be as follows: Figure 7 The regular shape shown in (a) is, for example, a rectangle, a circle, etc., and the shape of the second hardened region 330 can also be an irregular shape.

[0059] In one embodiment, see Figure 3 The power module 3000 also includes a copper substrate 3003 and a bonding wire 3005. The DBC 3002 is disposed on the copper substrate 3003, and the power chip 3004 is electrically connected to the DBC 3002 through the bonding wire 3005.

[0060] In one embodiment, see Figure 3 One end of the multilayer copper strip 310 located within the package 3001 is connected to the DBC 3002. As described above, the multilayer copper strip 310 extends beyond the first hardened region 320 of the package 3001 for connection to the circuit board 4000. Drive signals from the power module 3000 are transmitted to the circuit board 4000 via the multilayer copper strip 310, and control signals from the circuit board 4000 are fed back to the power module 3000 via the multilayer copper strip 310. Power is transmitted from the circuit board 4000 to the power device mounted on the DBC 3002 via the multilayer copper strip 310. For example, the power device may be a power chip 3004.

[0061] In one embodiment, see Figure 3 As shown in Figure 4(a), one end of the multilayer copper sheet 310 located within the package 3001 is a bent structure 314, which is connected to the DBC 3002. Exemplarily, the bent structure 314 can be a "U-shaped bend" as shown in Figure 4(a). In other embodiments, the bent structure 314 can also be an "S-shaped bend" or a bend of other shapes. During the operation of the power module 3000, the multilayer copper sheet 310 and the DBC 3002 will have different coefficients of thermal expansion (CTE) due to temperature changes. When the thermal expansion is inconsistent, a large thermal stress will be generated at the connection between the end of the multilayer copper sheet 310 located within the package 3001 and the DBC 3002. Therefore, in this embodiment, the end of the multilayer copper sheet 310 located within the package 3001 can be set as a bent structure 314. The bent structure 314 plays a certain buffering role, absorbing some of the thermal stress and reducing the risk of breakage. In addition, there will be pressure from the upper and lower parts when the molding section is closed. The bending structure 314 can absorb some of the pressure stress, avoiding structural cracking or encapsulation failure caused by stress concentration.

[0062] In one embodiment, the first hardened region 320 is locked to the circuit board 4000. Locking means that the first hardened region 320 and the circuit board 4000 are fixed together by mechanical locking, resulting in a strong connection with high resistance to vibration and impact. Exemplarily, the mechanical locking method can be a snap-fit ​​locking, a pin locking, or a threaded locking. Exemplarily, the first hardened region 320 can be as follows: Figure 8 As shown, it is connected to circuit board 4000 via bolt 5000. Figure 8This is a side view of another connection method between the multilayer copper sheet 310 and the circuit board 4000 provided in an embodiment of this application. Since the locking method has no solder layer, it is not affected by solder aging or melting, making it suitable for long-term use in high and low temperature cycling and high temperature environments. Furthermore, the locking structure allows for convenient and quick disassembly when the power module 3000 needs to be replaced or repaired. It should be noted that in other embodiments, the first hardened area 320 can also be soldered to the circuit board 4000 (as shown in Figure 4(a)), or connected through a through-hole in the circuit board 4000 (e.g., ...). Figure 9 (as shown), Figure 9 A perspective view of another connection method between a multilayer copper sheet 310 and a circuit board 4000 provided in an embodiment of this application.

[0063] In one embodiment, as mentioned above, the optimal connection between the first hardened region 320 of the multilayer copper sheet 310 and the circuit board 4000 is a locking connection. However, in some cases, the circuit board 4000 does not meet the conditions for locking, making it impossible to connect the multilayer copper sheet 310 and the circuit board 4000. Therefore, the power module 3000 in this embodiment further includes multiple rigid pins (not shown in the figure). Along the extension direction of the rigid pins, one end of the multiple rigid pins extends out of the package 3001 and is used to insert into the through hole of the circuit board 4000. The other end of the multiple rigid pins is disposed within the package 3001. When the power module 3000 cannot be connected to the circuit board 4000 through the multilayer copper sheet 310, it can still be electrically connected to the circuit board 4000 through the multiple rigid pins.

[0064] In one embodiment, the other end of the rigid pin located within the package 3001 is connected to the DBC 3002. Drive signals from the power module 3000 are transmitted to the circuit board 4000 via multiple rigid pins. Control signals from the circuit board 4000 are then fed back to the power module 3000 via multiple rigid pins. Power is transmitted from the circuit board 4000 to the power device located on the DBC 3002 via multiple rigid pins. Exemplarily, the power device may be a power chip 3004.

[0065] 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 power module includes a package and multiple copper sheet groups. The package is used to package the power chip. Each copper sheet group includes multiple layers of copper sheets. Along the extension direction of the multiple layers of copper sheets, one end of the multiple layers of copper sheets is located inside the package, and the other end of the multiple layers of copper sheets extends out of the package. The end of the multiple layers of copper sheets extending out of the package includes a first hardened area, which is used to connect to a circuit board.

2. The power module according to claim 1, characterized in that, Each layer of copper sheet in the multilayer copper sheet has the same thickness.

3. The power module according to claim 1, characterized in that, Along the stacking direction of the multilayer copper sheets, the multilayer copper sheets include a first part and a second part, wherein the thickness of the copper sheet in the first part is greater than the thickness of the copper sheet in the second part.

4. The power module according to claim 1, characterized in that, The multilayer copper sheet further includes multiple second hardened regions. The multiple second hardened regions are spaced apart along the extension direction and / or the first direction of the multilayer copper sheet. The first direction is perpendicular to the extension direction of the multilayer copper sheet and perpendicular to the stacking direction of the multilayer copper sheet.

5. The power module according to claim 1, characterized in that, The first hardened region is formed by hot pressing a portion of the multilayer copper sheet.

6. The power module according to claim 1, characterized in that, The power module also includes a direct copper-clad ceramic substrate (DBC), the power chip is disposed on the DBC, and one end of the multilayer copper sheet located within the package is connected to the DBC.

7. The power module according to claim 6, characterized in that, The multilayer copper sheet has a bent structure at one end within the package, and the bent structure is connected to the DBC.

8. The power module according to claim 1, characterized in that, The power module also includes a plurality of rigid pins. Along the extension direction of the rigid pins, one end of the plurality of rigid pins extends out of the package and is used to insert into a through hole of the circuit board. The other end of the plurality of rigid pins is disposed inside the package.

9. The power module according to claim 8, characterized in that, The rigid pin is located at the other end of the package and is connected to the DBC.

10. An inverter, characterized in that, The inverter includes a circuit board and a power module as described in any one of claims 1-9.

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