Power module, manufacturing method and electronic equipment

Abstract

The invention provides a power module, a manufacturing method and electronic equipment, the power module comprises a heat dissipation plate, a substrate and a chip which are sequentially stacked, the surface of the heat dissipation plate is provided with a first area and a second area, the second area is at least arranged at the corner of the first area, and the surface roughness of the second area is greater than that of the first area; the projection of the substrate in the thickness direction of the heat dissipation plate is overlapped with the first area; a third area is arranged on the surface of the side, away from the heat dissipation plate, of the substrate. The projection of the chip in the thickness direction of the heat dissipation plate is overlapped with the third area. The molding compound encapsulates the substrate and the chip, and the second area is in contact with the molding compound. Therefore, when the surface roughness of the second area is large, the bonding area of the plastic package material and the heat dissipation plate can be increased, the bonding strength of the plastic package material and the heat dissipation plate is further increased, layering of the bonding surface is avoided, and the plastic package effect is improved.

Description

Technical Field

[0001] The present application relates to the field of electronic technology, and in particular to a power module, a manufacturing method and an electronic device. Background Art

[0002] As power modules in electronic devices evolve towards high power density and high reliability, power modules can be packaged in a three-dimensional (3D) plastic packaging method to improve the heat dissipation, power density and reliability of power modules in electronic devices.

[0003] When packaging the power module, the chip is welded to a substrate such as a direct bonded copper (DBC) substrate, and the substrate is then welded to a heat sink or a heat dissipation plate, and finally packaged with a plastic encapsulation material. During packaging, the bonding strength between the plastic encapsulation material and the heat sink or heat dissipation plate, and between the plastic encapsulation material and the substrate must be considered to avoid delamination of the bonding surface and improve the plastic encapsulation effect.

[0004] In view of this, how to improve the plastic sealing effect is an urgent problem to be solved. Summary of the invention

[0005] The present application provides a power module, a manufacturing method and an electronic device to improve the plastic sealing effect.

[0006] In the first aspect, the embodiment of the present application provides a power module, which may include: a heat sink, a substrate and a chip stacked in sequence; the heat sink surface is provided with: a first area and a second area, the second area is at least provided at the corner of the first area, and the surface roughness of the second area is greater than the surface roughness of the first area; the projection of the substrate along the thickness direction of the heat sink overlaps with the first area; the surface of the substrate facing away from the heat sink is provided with a third area, and the projection of the chip along the thickness direction of the heat sink overlaps with the third area; wherein the plastic encapsulation material encapsulates the substrate and the chip, and the second area is in contact with the plastic encapsulation material. In addition, a first solder is provided in the first area, and the substrate is fixed to the heat sink through the first solder, and a second solder is provided in the third area, and the chip is fixed to the substrate through the second solder. Therefore, when the surface roughness of the second area is greater than the surface roughness of the first area, the bonding area between the plastic encapsulation material and the second area in the heat sink can be increased, thereby increasing the bonding strength between the plastic encapsulation material and the heat sink, avoiding stratification of the bonding surface, and improving the plastic encapsulation effect.

[0007] Optionally, the setting of the positions of the first area and the second area may further include at least one of the following:

[0008] The first type: the second area at least partially surrounds the first area, which can increase the area of ​​the second area, thereby increasing the bonding area with the plastic packaging material, thereby improving the plastic packaging strength, and when the second area has a solder resistance effect, the second area can act as a solder resistance for the first solder in the first area, preventing the first solder from overflowing from the first area, while improving the welding effect and avoiding the impact on other structures; in addition, it can also achieve the function of fixing the substrate to prevent the substrate from shifting during welding.

[0009] The second type: there are multiple first areas, and the second areas corresponding to two adjacent first areas are at least partially connected, so that the area of ​​the second area on the surface of the heat sink can be increased, thereby increasing the bonding area between the plastic encapsulation material and the second area, thereby increasing the plastic encapsulation strength and plastic encapsulation effect. Among them, the number of first areas can be one, two or more, which can be set according to actual needs and is not limited here.

[0010] The third type: all areas on the heat sink surface except the first area are the second area, that is, all areas on the heat sink surface except the first area are the second area. This can maximize the area of ​​the second area and further increase the contact area with the plastic packaging material, thereby further improving the plastic packaging strength.

[0011] The fourth type: the second area overlaps with the orthographic projection of the substrate on the heat sink, which can increase the flexibility of setting the second area and improve the flexibility of power module design.

[0012] The fifth type: the projection of the substrate on the heat sink is located in the first area, and the area of ​​the first area is larger than the projection area of ​​the substrate on the heat sink, so that the area of ​​the first area is larger and the projection area of ​​the substrate on the heat sink is smaller. In this way, since the first solder is generally applied to the welding area with the substrate and will not cover the entire first area, it is more difficult for the first solder in the larger area of ​​the first area to overflow, so as to avoid the first solder overflowing to the second area and affecting the bonding strength between the plastic sealing material and the second area, thereby further improving the plastic sealing strength.

[0013] The sixth type: the first area is located within the projection of the substrate on the heat sink, and the projection area of ​​the substrate on the heat sink is larger than the area of ​​the first area, so that the projection area of ​​the substrate on the heat sink is larger and the area of ​​the first area is smaller. In this case, there is a gap between the second area and the corresponding first area. The size of the gap can be set according to actual needs and is not limited here. In this way, when the first solder is applied to the first area, even if the first solder overflows, since there is a part of the area between the substrate and the heat sink that is different from the first area (that is, the area corresponding to the gap), this area can be used as an overflow area to prevent the first solder from overflowing into the second area, thereby preventing the first solder from overflowing into the second area and affecting the bonding strength between the plastic encapsulation material and the second area, thereby further improving the plastic encapsulation strength.

[0014] It should be understood that the shape of the second area can be set according to actual conditions as long as it can satisfy the above-mentioned positional relationship, and is not limited here.

[0015] Optionally, the second region may conform to the following settings:

[0016] Setting 1: The second area is provided with a concave-convex structure, and the concave-convex structure can be at least one of the following structures: a fin structure, a pit structure, and a protrusion structure. The specific combination can be set according to actual needs and is not limited here. In addition, the specific shape and setting density of each fin pin, pit, and protrusion in the fin structure can be set according to actual needs and are not limited here. In this way, by providing a concave-convex structure in the demarcated second area, the bonding area between the molding compound and the heat sink in the second area can be further increased, and the bonding strength between the molding compound and the heat sink can be further increased, thereby further improving the molding effect.

[0017] Setting 2: The material of the second area is different from that of the first area, so that the second area can serve as a solder resist layer to the first solder in the first area, thereby preventing the first solder from overflowing from the first area, thereby improving the welding effect and avoiding the impact on other structures; and can also achieve the function of fixing the substrate to avoid the substrate from shifting during welding.

[0018] Setting 3: The second area is formed by sandblasting, that is, the second area is bombarded by sandblasting to improve the surface roughness of the second area, so that the second area has a higher surface roughness, thereby improving the plastic sealing effect.

[0019] Setting 4: The material of the surface of the heat sink that is welded to the substrate contains copper, and the heat sink can be called a bare copper setting. The surface of the heat sink that is welded to the substrate can also be called the welding surface of the heat sink, that is, the material of the welding surface of the heat sink contains copper. For example, the material of the welding surface of the heat sink can be single copper, and the heat sink can be a copper plate, or a plate with single copper plated on the welding surface; the material of the welding surface of the heat sink can also be copper oxide, and the heat sink can be a copper oxide plate, or a plate with copper oxide plated on the welding surface; the material of the welding surface of the heat sink can also be copper alloy, and the heat sink can be a copper alloy plate, or a plate with copper alloy plated on the welding surface. Taking the heat sink as a copper plate as an example, after the copper plate is manufactured, the surface roughness of different areas on the surface of the copper plate is different, so the surface roughness of the copper plate surface itself can be used to delineate the first area and the second area, so that the surface roughness of the delineated second area is greater than the surface roughness of the first area.

[0020] It should be understood that the structure of the second area can also be a combination of the above-mentioned multiple settings, such as a setting method combining bare copper with local sandblasting, a setting method combining bare copper with a local concave-convex structure, a setting method combining different forming materials with a local concave-convex structure, and other combinations, which are not listed one by one here.

[0021] Optionally, the second surface of the substrate may also be provided with: a fourth region at least provided at the corner of the third region, the surface roughness of the fourth region being greater than the surface roughness of the third region, and the fourth region being in contact with the molding compound. In this way, the bonding area between the molding compound and the fourth region of the substrate may be increased, thereby increasing the bonding strength between the molding compound and the substrate, avoiding stratification of the bonding surface, and further improving the molding effect.

[0022] The settings of the positions of the third area and the fourth area may include at least one of the following:

[0023] The first type: the fourth region at least partially surrounds the third region, which can increase the area of ​​the fourth region, thereby increasing the bonding area with the plastic packaging material, thereby improving the plastic packaging strength; and when the fourth region has a solder resistance effect, the fourth region can act as a solder resistance for the second solder in the third region, thereby preventing the second solder from overflowing from the third region, thereby improving the welding effect and avoiding the impact on other structures; in addition, it can also achieve the function of fixing the chip to prevent the chip from shifting during welding.

[0024] The second type: the area except the third area on the side of the substrate facing away from the heat sink is the fourth area, which can maximize the area of ​​the fourth area, further increase the contact area with the plastic packaging material, and thus further improve the plastic packaging strength.

[0025] The third type: the orthographic projection of the chip on the substrate is located in the third area, and the area of ​​the third area is larger than the orthographic projection area of ​​the chip on the substrate. In this way, since the second solder is generally applied to the welding area with the chip and will not cover the entire third area, the second solder in the larger area of ​​the third area is less likely to overflow, avoiding the second solder overflowing to the fourth area to affect the bonding strength between the plastic encapsulation material and the fourth area, thereby further improving the plastic encapsulation strength.

[0026] The fourth type: the third area is located within the orthographic projection of the chip on the substrate, and the orthographic projection area of ​​the chip on the substrate is larger than the area of ​​the third area. In this case, there is a gap between the fourth area and the corresponding third area. The size of the gap can be set according to actual needs and is not limited here. In this way, when the second solder is applied to the third area, even if the second solder overflows, since there is a part of the area between the chip and the substrate that is different from the third area (that is, the area corresponding to the gap), this area can be used as an overflow area to prevent the second solder from overflowing into the fourth area, thereby preventing the second solder from overflowing into the fourth area and affecting the bonding strength between the plastic encapsulation material and the fourth area, thereby further improving the plastic encapsulation strength.

[0027] It should be understood that the shape of the fourth area can be set according to actual conditions as long as it can satisfy the above-mentioned positional relationship, and is not limited here.

[0028] And, the fourth area can meet the following settings:

[0029] Setting 1: The material formed by the fourth area is different from the material formed by the third area, so that the fourth area can serve as a solder mask to the second solder in the third area, thereby preventing the second solder from overflowing from the third area, thereby improving the welding effect and avoiding the impact on other structures; and can also achieve the function of fixing the chip to avoid chip displacement during welding.

[0030] Setting 2: The fourth area can be formed by sandblasting, that is, the fourth area is bombarded by sandblasting to improve the surface roughness of the fourth area, so that the fourth area has a higher surface roughness, thereby improving the plastic sealing effect.

[0031] It should be understood that for the setting of the fourth area, any one of the above settings can be adopted, or a combination of the above settings can be adopted to further increase the bonding area between the plastic encapsulation material and the heat sink in the fourth area, further increase the bonding strength between the plastic encapsulation material and the heat sink, thereby further improving the plastic encapsulation effect.

[0032] In the second aspect, the embodiment of the present application also provides a method for manufacturing a power module, which is used to manufacture the power module as described in the first aspect and any one of the embodiments of the first aspect. The manufacturing method may include: forming a second area at least at the corner of the first area on the surface of the heat sink, and the surface roughness of the second area is greater than the surface roughness of the first area; fixing the substrate to the heat sink through the first area, and fixing the chip to the substrate through the third area, so that the projection of the substrate along the thickness direction of the heat sink overlaps with the first area, and the projection of the chip along the thickness direction of the heat sink overlaps with the third area; using a plastic encapsulation material to encapsulate the substrate and the chip, so that the second area is in contact with the plastic encapsulation material to obtain a power module. In this way, when the surface roughness of the second area is greater than the surface roughness of the first area, the bonding area between the plastic encapsulation material and the second area in the heat sink can be increased, thereby increasing the bonding strength between the plastic encapsulation material and the heat sink, avoiding stratification of the bonding surface, and improving the plastic encapsulation effect.

[0033] Optionally, when forming the second region, at least one of the following methods may be used: a laser ablation method, a mold pressing method, a sandblasting method, or a concave-convex structure manufacturing method.

[0034] As for laser ablation, its working principle is: using laser to irradiate the second area demarcated, so that the surface material of the second area is heated up, melted instantly, or even vaporized, ionized mixed steam and other physical phenomena occur, thus leaving permanent burn marks. Therefore, after laser ablation, the material formed in the second area is different from the material formed in the first area, so that the second area can act as a solder mask to resist the first solder in the first area, preventing the first solder from overflowing from the first area, and avoiding the impact on other structures on the basis of improving the welding effect; and it can also achieve the function of fixing the substrate to prevent the substrate from shifting during welding.

[0035] For mold pressing, a mold with patterns is used to press the demarcated second area to increase the surface roughness of the second area. This method is simple to operate and easy to implement, and can improve the plastic sealing effect while reducing the production cost of the power module. When the mold is pressed, the patterns in the mold can be mesh, triangular, quadrilateral or special-shaped, etc., which can be designed according to actual needs, and there is no specific requirement for the depth of mold pressing.

[0036] As for sandblasting, its working principle is: spraying sand particles onto the surface of the heat sink, bombarding the surface of the heat sink with sand particles to form the second area; so when sandblasting, the surface roughness of the second area can be controlled by selecting the size of the sand particles to meet the requirements of plastic sealing, and then the size of the sand particles can be selected according to the requirements of the surface roughness of the second area, which is not limited here. In addition, the material of the welding surface of the heat sink contains copper elements, for example: the material of the welding surface of the heat sink can be single copper, in which case the heat sink can be a copper plate, or a plate with single copper plated on the welding surface; the material of the welding surface of the heat sink can also be copper oxide, in which case the heat sink can be a copper oxide plate, or a plate with copper oxide plated on the welding surface; the material of the welding surface of the heat sink can also be copper alloy, in which case the heat sink can be a copper alloy plate, or a plate with copper alloy plated on the welding surface. In this way, the second area is formed by combining bare copper with local sandblasting. This method is simple to operate and easy to implement, and can reduce the production cost of the power module on the basis of improving the plastic sealing effect.

[0037] For making the concavo-convex structure, the concavo-convex structure can be at least one of the following structures: a fin structure, a pit structure and a protrusion structure, and the specific combination can be set according to actual needs and is not limited here. In addition, the specific shape and setting density of each fin pin, pit and protrusion in the fin structure can be set according to actual needs and are not limited here.

[0038] Of course, taking the heat sink as a copper plate as an example, after the copper plate is manufactured, the surface roughness of different areas on the copper plate surface is different, so the surface roughness of the copper plate surface itself can be used to delineate the first area and the second area, so that the surface roughness of the delineated second area is greater than the surface roughness of the first area. Compared with using a copper plate with nickel plated on the surface as a heat sink, using a copper plate as a heat sink can obtain the first area and the second area without any treatment on the copper plate surface. This method can greatly reduce production costs, increase production capacity, and reduce nickel plating processes.

[0039] In addition, the specific size of the surface roughness of the second area can be set according to the requirements for plastic sealing. For example, if the requirements for plastic sealing are high, the surface roughness of the second area can be set larger. If the requirements for plastic sealing are low, the surface roughness of the second area can be set smaller.

[0040] Optionally, the manufacturing method further includes: before the chip is fixed to the substrate via the third region, forming a fourth region at least at the corner of the third region, wherein the surface roughness of the fourth region is greater than the surface roughness of the third region. In this way, the bonding area between the molding compound and the fourth region in the substrate can be increased, thereby increasing the bonding strength between the molding compound and the substrate, avoiding stratification of the bonding surface, and further improving the molding effect.

[0041] Among them, when forming the fourth area, at least one of the following methods can be adopted: laser ablation method, mold pressing method, and sand blasting method. The specific implementation methods of laser ablation, mold pressing and sand blasting are the same as the specific implementation methods of the corresponding methods when forming the second area. For details, please refer to the relevant introduction when forming the second area, and the repeated parts will not be repeated.

[0042] It should be understood that since the principle of solving the problem by the power module manufactured by this manufacturing method is similar to the principle of solving the problem by the aforementioned power module, the implementation and technical effects of this manufacturing method can refer to the implementation and technical effects of the aforementioned power module, and the repeated parts will not be repeated.

[0043] In a third aspect, an embodiment of the present application further provides an electronic device, comprising: a housing, and a power module as described in the first aspect and any one of the embodiments of the first aspect, wherein the power module is disposed in the housing, and the reliability of the electronic device and the safety of use can be increased based on the improved plastic sealing effect of the power module.

[0044] Since the principle of solving the problem by the electronic device is similar to the principle of solving the problem by the aforementioned power module, the implementation and technical effects of the electronic device can refer to the implementation and technical effects of the aforementioned power module, and the repeated parts will not be repeated. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application;

[0046] Figure 2 A schematic diagram of the structure of a power module provided in an embodiment of the present application;

[0047] Figure 3 A schematic diagram of the positional relationship between a first area and a second area provided in an embodiment of the present application;

[0048] Figure 4 A schematic diagram of another positional relationship between a first area and a second area provided in an embodiment of the present application;

[0049] Figure 5 A schematic diagram of a positional relationship between a first area and a second area provided in another embodiment of the present application;

[0050] Figure 6 A schematic diagram of a positional relationship between a first area and a second area provided in another embodiment of the present application;

[0051] Figure 7 A schematic diagram of a positional relationship between a first area and a second area provided in another embodiment of the present application;

[0052] Figure 8 A schematic diagram of a positional relationship between a first area and a second area provided in another embodiment of the present application;

[0053] Fig. 9 A schematic diagram of the positional relationship between a third area and a fourth area provided in an embodiment of the present application;

[0054] Fig.10 A schematic diagram of another positional relationship between a third area and a fourth area provided in an embodiment of the present application;

[0055] Fig.11 A schematic diagram of a positional relationship between a third area and a fourth area provided in another embodiment of the present application;

[0056] Fig.12 A flowchart of a method for manufacturing a power module provided in an embodiment of the present application;

[0057] Fig.13 A flowchart of another method for manufacturing a power module provided in an embodiment of the present application. DETAILED DESCRIPTION

[0058] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings.

[0059] It should be noted that the same reference numerals in the drawings of this application represent the same or similar structures, and thus their repeated description will be omitted. The words expressing positions and directions described in this application are all explained using the drawings as examples, but they can be changed as needed, and the changes are included in the protection scope of this application. The drawings of this application are only used to illustrate the relative position relationship and do not represent the true proportion.

[0060] In order to facilitate understanding of the technical solution provided by the embodiments of the present application, its application scenario is first described below.

[0061] The power module provided in the embodiment of the present application can be widely used in various electronic devices, and the electronic devices provided in the embodiment of the present application may include various terminal devices and electronic devices. Among them, the terminal devices may include but are not limited to: smart phones, smart TVs, smart TV set-top boxes, smart watches, personal computers (PCs), wearable devices, smart broadband and other devices. Electronic devices may include but are not limited to: inverters in photovoltaic power generation systems, etc., which are not listed here one by one.

[0062] Figure 1 The schematic diagram of the structure of the power module when it is used in an electronic device is shown as an example. Figure 1As shown, the electronic device includes: a housing 100 and a circuit board 200 disposed in the housing 100, and a power module 300 is disposed on the circuit board 200. Taking the electronic device as an inverter as an example, the inverter is the core equipment in the photovoltaic power generation system, and its main functions include converting the direct current generated by the photovoltaic module into alternating current for output; the power device is an important part of the inverter, and it plays the role of power conversion and energy transmission in the inverter, and the power module 300 is one of the power devices.

[0063] When forming the power module 300, the chip is welded to the substrate (the substrate may be a copper-clad ceramic substrate), and then the substrate is welded to the heat sink or heat dissipation plate, and finally the heat sink or heat dissipation plate is encapsulated with a plastic encapsulation material to form the power module 300. During encapsulation, the bonding strength between the plastic encapsulation material and the heat sink or heat dissipation plate, and between the plastic encapsulation material and the substrate needs to be considered to avoid delamination of the bonding surface, so as to improve the plastic encapsulation effect.

[0064] Based on this, the present application provides a power module, a manufacturing method and an electronic device to improve the plastic sealing effect. The specific structure and construction of the power module are described in detail below in conjunction with specific embodiments.

[0065] Figures 2 to 8 The schematic diagram of the structure of the power module provided by the present application is shown as an example. Figure 2 As shown, the power module may include: a heat sink 10, a substrate 20 disposed on the heat sink 10, and a chip 30 disposed on the substrate 20; the substrate 20 may be a copper-clad ceramic substrate, that is, a copper layer is disposed on the upper and lower sides of the ceramic plate, thereby forming a three-layer stacked structure. Figures 3 to 8 As shown, the surface of the heat sink 10 (i.e., the soldering surface b0 of the heat sink 10) is provided with: a first region 11, and a second region 12 at least provided at the corner of the first region 11, the surface roughness of the second region 12 is greater than the surface roughness of the first region 11; a first solder 41 is provided in the first region 11. The substrate 20 has a first surface b1 and a second surface b2 opposite to each other, the first surface b1 of the substrate 20 is fixed to the heat sink 10 by the first solder 41, and the second surface b2 of the substrate 20 is provided with a third region ( Figures 2 to 8 ), a second solder ( Figures 2 to 8(not shown in the figure), the chip 30 is fixed to the second surface b2 by a second solder; the molding compound 50 encapsulates the substrate 20 and the chip 30, and the molding compound 50 is in contact with the second area 12. Thus, when the surface roughness of the second area 12 is greater than the surface roughness of the first area 11, the bonding area between the molding compound 50 and the second area 12 in the heat sink 10 can be increased, thereby increasing the bonding strength between the molding compound 50 and the heat sink 10, avoiding stratification of the bonding surface, and improving the molding effect. It should be understood that the number of chips 30 arranged on the substrate 20 can be one or at least two, which can be specifically designed according to actual conditions and is not limited here. In addition, the number of substrates 20 arranged on the heat sink 10 can be one or at least two, which can be specifically designed according to actual conditions and is not limited here.

[0066] The positional relationship between the first area 11 and the second area 12 may include at least one of the following:

[0067] like Figure 3 As shown, the second area 12 is arranged at least partially at the corner of the first area 11, and when there are multiple first areas 11, the second areas 12 located at the corners of two adjacent first areas 11 can be connected, as shown in FIG. Figure 3 As shown in (b) in the figure, the area of ​​the second region 12 on the surface of the heat sink can be increased, thereby increasing the bonding area between the plastic encapsulation material and the second region 12, thereby increasing the plastic encapsulation strength; of course, the second region 12 located at the corner position of two adjacent first regions 11 can also be unconnected, such as Figure 3 As shown in (a) in FIG. 1 , this can reduce the difficulty of manufacturing the second region 12 and reduce the manufacturing cost of the power module.

[0068] like Figure 4 As shown, the second area 12 surrounds part of the peripheral area of ​​the first area 11. When there are multiple first areas 11, the second areas 12 corresponding to two adjacent first areas 11 can be connected, so that the area of ​​the second area 12 on the surface of the heat sink can be increased, thereby increasing the bonding area between the plastic encapsulation material and the second area 12, thereby increasing the plastic encapsulation strength; wherein, when the second areas 12 corresponding to two adjacent first areas 11 are connected, as shown in FIG. Figure 4 As shown in (a) of the two first regions 11, the second region 12 is not provided at some corner positions; or as shown in Figure 4 As shown in (b), even if the second area 12 surrounds part of the peripheral area of ​​the first area 11, the second area 12 is provided at each corner position in the two first areas 11. Of course, the second areas 12 corresponding to two adjacent first areas 11 may also be unconnected, which can reduce the difficulty of manufacturing the second area 12 and reduce the manufacturing cost of the power module.

[0069] like Figure 5 As shown, the second region 12 completely surrounds the peripheral region of the first region 11, and the second region 12 can be arranged in a partial region of the welding surface b0 except the first region 11, as shown in FIG. Figure 5 Alternatively, the second region 12 may be disposed in the entire region of the welding surface b0 except the first region 11, as shown in FIG. Figure 5 As shown in (b), that is, the area except the first area 11 in the welding surface b0 is the second area 12, which can maximize the area of ​​the second area 12, further increase the contact area with the plastic packaging material, and thus further improve the plastic packaging strength.

[0070] like Figure 6 As shown, the second region 12 overlaps with an orthographic projection 20 a of the substrate 20 on the heat sink 10 .

[0071] like Figure 7 As shown, the orthographic projection 20a of the substrate 20 on the heat sink 10 is located in the first region 11, and the area of ​​the first region 11 is larger than the orthographic projection 20a of the substrate 20 on the heat sink 10. Figure 7 The first solder (not shown) is generally applied to the welding area with the substrate 20 (such as the area indicated by 20a), and will not cover the entire first area 11. Therefore, it is difficult for the first solder in the first area 11 with a larger area to overflow, thereby preventing the first solder from overflowing to the second area 12 and affecting the bonding strength between the plastic packaging material and the second area 12, thereby further improving the plastic packaging strength.

[0072] like Figure 8 As shown, the first region 11 is located within the orthographic projection 20a of the substrate 20 on the heat sink 10, and the orthographic projection 20a of the substrate 20 on the heat sink 10 is larger than the area of ​​the first region 11. At this time, there is a gap d1 between the second region 12 and the corresponding first region 11. The size of the gap d1 can be set according to actual needs, for example but not limited to, the gap d1 is set to the distance between the edge of the first region 11 and the corresponding edge of the substrate 20. In this way, in the first solder ( Figure 8 When the first solder is applied to the first area 11 (not shown in the figure), even if the first solder overflows, since there is a part of the area different from the first area 11 between the substrate 20 and the heat sink 10 (that is, the area indicated by d1), this area can be used as an overflow area to prevent the first solder from overflowing into the second area 12, thereby preventing the first solder from overflowing into the second area 12 and affecting the bonding strength between the plastic packaging material and the second area 12, thereby further improving the plastic packaging strength.

[0073] It should be understood that the shape of the second area 12 can be set according to actual conditions as long as it can satisfy the above-mentioned positional relationship, and is not limited here.

[0074] Furthermore, the second area 12 may conform to the following configuration:

[0075] Setting 1: The material forming the second area 12 can be set to be different from the material forming the first area 11, so that the second area 12 can serve as a solder resist layer to the first solder 41 in the first area 11, thereby preventing the first solder 41 from overflowing from the first area 11, thereby improving the welding effect and avoiding the impact on other structures; and it can also achieve the function of fixing the substrate to avoid the substrate from shifting during welding.

[0076] Setting 2: The second region 12 is formed by sandblasting, that is, the second region 12 is bombarded by sandblasting to improve the surface roughness of the second region 12. In this way, the second region 12 has a higher surface roughness, thereby improving the plastic sealing effect.

[0077] Setting 3: The second area 12 is provided with a concave-convex structure, and the concave-convex structure can be at least one of the following structures: a fin structure, a pit structure and a protrusion structure. The specific combination can be set according to actual needs and is not limited here. In addition, the specific shape and setting density of each fin pin, pit and protrusion in the fin structure can be set according to actual needs and are not limited here. In this way, by providing a concave-convex structure in the demarcated second area 12, the bonding area between the molding compound 50 and the heat sink 10 in the second area 12 can be further increased, and the bonding strength between the molding compound 50 and the heat sink 10 can be further increased, thereby further improving the molding effect.

[0078] Setting 4: The material of the welding surface b0 in the heat sink 10 contains copper element, and the heat sink 10 can be called a bare copper setting; for example: the material of the welding surface b0 can be single copper, and the heat sink 10 can be a copper plate, or a plate with single copper plated on the welding surface b0. The material of the welding surface b0 can also be copper oxide, and the heat sink 10 can be a copper oxide plate, or a plate with copper oxide plated on the welding surface b0. The material of the welding surface b0 can also be copper alloy, and the heat sink 10 can be a copper alloy plate, or a plate with copper alloy plated on the welding surface b0. Taking the heat sink 10 as a copper plate as an example, after the copper plate is manufactured, the surface roughness of different areas on the surface of the copper plate is different, so the surface roughness of the copper plate surface itself can be used to delineate the first area 11 and the second area 12, so that the surface roughness of the delineated second area 12 is greater than the surface roughness of the first area 11.

[0079] It should be understood that for the setting of the second area 12, any one of the above four settings can be adopted, and a combination of at least two of the above four settings can be adopted to further increase the bonding area between the plastic encapsulation material 50 and the heat sink 10 in the second area 12, and further increase the bonding strength between the plastic encapsulation material 50 and the heat sink 10, thereby further improving the plastic encapsulation effect, such as: the combination of setting 4 and setting 2, that is, the combination setting of bare copper and local sandblasting; or the combination of setting 4 and setting 3, that is, the combination setting of bare copper and a local concave-convex structure; or the combination of setting 1 and setting 4, that is, the combination setting of different forming materials and a local concave-convex structure, and so on. The above four settings can be combined according to actual conditions and are not listed one by one here.

[0080] In addition, when the heat sink 10 includes two surfaces facing each other, one of the surfaces can be used as a welding surface b0, and the other surface can be used as a non-welding surface b0, in which case the non-welding surface b0 can be a smooth surface. Of course, when the other surface is also used as a welding surface b0, both surfaces of the heat sink 10 are welded to other structures, so the second areas 12 of both surfaces can adopt the above-mentioned setting method, so as to increase the bonding strength between the plastic encapsulation material 50 and the two surfaces and increase the plastic encapsulation effect.

[0081] Figures 9 to 11 The schematic diagram of the structure of the power module provided by the present application is shown as an example. Figures 9 to 11 As shown, the structure of the power module of this embodiment is similar to that of the above embodiment. Figures 2 to 8 The structure of the power module introduced in is basically similar, except that: the second surface b2 of the substrate is also provided with a fourth area 22. Optionally, the second surface b2 is further provided with: a fourth area 22 at least provided at the corner of the third area 21, the surface roughness of the fourth area 22 is greater than the surface roughness of the third area 21, and the fourth area 22 is in contact with the molding compound. In this way, the bonding area between the molding compound and the fourth area 22 in the substrate can be increased, thereby increasing the bonding strength between the molding compound and the substrate, avoiding stratification of the bonding surface, and further improving the molding effect.

[0082] The positional relationship between the third area 21 and the fourth area 22 may include at least one of the following:

[0083] like Fig. 9 As shown in (a) and (b) of FIG. 1 , the fourth region 22 is disposed at least partially at the corner of the third region 21, and when there are multiple third regions 21, the fourth regions 22 located at the corners of two adjacent third regions 21 can be connected, such as Fig. 9As shown in (a) in the figure, the area of ​​the fourth region 22 on the surface of the substrate can be increased, thereby increasing the bonding area between the molding material and the fourth region 22, thereby increasing the molding strength; of course, the fourth region 22 located at the corner position of two adjacent third regions 21 can also be unconnected, such as Fig. 9 As shown in (b) in FIG. 1 , this can reduce the difficulty of manufacturing the fourth region 22 and reduce the manufacturing cost of the power module.

[0084] like Fig.10 As shown in (a), the fourth area 22 surrounds part of the peripheral area of ​​the third area 21, and when there are multiple third areas 21, the fourth areas 22 corresponding to two adjacent third areas 21 can be connected, so that the area of ​​the fourth area 22 on the surface of the heat sink can be increased, thereby increasing the bonding area between the plastic packaging material and the fourth area 22, thereby increasing the plastic packaging strength; wherein, when the fourth areas 22 corresponding to two adjacent third areas 21 are connected, in the two third areas 21, the fourth areas 22 are not set at some corners, and no figure is shown; or as shown in Fig.10 As shown in (a), even if the fourth region 22 surrounds part of the peripheral area of ​​the third region 21, the fourth region 22 is provided at each corner position in the two third regions 21. Of course, the fourth regions 22 corresponding to two adjacent third regions 21 may also be unconnected, which can reduce the difficulty of manufacturing the fourth region 22 and reduce the manufacturing cost of the power module.

[0085] like Fig.10 As shown in (b) in FIG. 1 , the fourth region 22 completely surrounds the peripheral region of the third region 21, and the fourth region 22 can be set in a partial region of the second surface b2 except the third region 21, which is not shown in the figure; or, the fourth region 22 can be set in the entire region of the second surface b2 except the third region 21, as shown in FIG. Fig.10 As shown in (b), that is, the areas except the third area 21 in the second surface b2 are all fourth areas 22, which can maximize the area of ​​the fourth area 22, further increase the contact area with the molding material, and thus further improve the molding strength.

[0086] like Fig. 9 As shown in (b) in FIG. 1 , the fourth region 22 overlaps with the orthographic projection 30 a of the chip on the substrate.

[0087] like Fig.11 As shown in (a) of FIG. 1 , the orthographic projection 30a of the chip 30 on the substrate 20 is located in the third region 21, and the area of ​​the third region 21 is larger than the orthographic projection 30a of the chip 30 on the substrate 20. Fig.11The second solder (not shown) is generally applied to the welding area with the chip 30 (such as the area indicated by 30a), and will not cover the entire third area 21. Therefore, it is difficult for the second solder in the larger area of ​​the third area 21 to overflow, thereby preventing the second solder from overflowing to the fourth area 22 and affecting the bonding strength between the plastic packaging material and the fourth area 22, thereby further improving the plastic packaging strength.

[0088] like Fig.11 As shown in (b), the third region 21 is located within the orthographic projection 30a of the chip 30 on the substrate 20, and the orthographic projection 30a of the chip 30 on the substrate 20 is larger than the area of ​​the third region 21. At this time, there is a gap d2 between the fourth region 22 and the corresponding third region 21. The size of the gap d2 can be set according to actual needs, such as but not limited to, setting the gap d2 to the distance between the edge of the third region 21 and the corresponding edge of the chip 30. In this way, in the second solder ( Fig.11 When the second solder is applied to the third area 21 (not shown in the figure), even if the second solder overflows, since there is a part of the area different from the third area 21 between the chip 30 and the substrate 20 (that is, the area indicated by d2), this area can be used as an overflow area to prevent the second solder from overflowing to the fourth area 22, thereby preventing the second solder from overflowing to the fourth area 22 and affecting the bonding strength between the plastic packaging material and the fourth area 22, thereby further improving the plastic packaging strength.

[0089] It should be understood that the shape of the fourth area 22 can be set according to actual conditions as long as it can satisfy the above-mentioned positional relationship, and is not limited here.

[0090] Furthermore, the fourth area 22 may conform to the following configuration:

[0091] Setting 1: The material forming the fourth area 22 can be set to be different from the material forming the third area 21, so that the fourth area 22 can serve as a solder resist layer to the second solder in the third area 21, thereby preventing the second solder from overflowing from the third area 21, thereby improving the welding effect and avoiding the impact on other structures; and it can also achieve the function of fixing the chip to avoid chip displacement during welding.

[0092] Setting 2: The fourth region 22 is formed by sandblasting, that is, the fourth region 22 is bombarded by sandblasting to improve the surface roughness of the fourth region 22. In this way, the fourth region 22 has a higher surface roughness, thereby improving the plastic sealing effect.

[0093] It should be understood that the fourth region 22 may be configured by any one of the above two configurations, or by a combination of the above two configurations, so as to further increase the bonding area of ​​the molding compound and the heat sink in the fourth region 22, further increase the bonding strength of the molding compound and the heat sink, and thus further improve the molding effect. Figures 9 to 11 In the figure, 42 represents the second solder located in the third region 21 .

[0094] It should also be understood that the structure of the power module in this embodiment is similar to that in the above embodiment. Figures 2 to 8 The structure of the power module described in the above embodiment is similar to that of the power module described in the above embodiment. Figures 2 to 8 The relevant introduction in , the repeated parts will not be repeated.

[0095] Fig.12 The schematic diagram of the method for manufacturing the power module provided by the present application is exemplarily shown, referring to Fig.12 As shown, the method for manufacturing a power module may include:

[0096] S1201, forming a second region at least at the corner of the first region demarcated on the surface of the heat sink, and disposing a first solder in the first region, wherein the surface roughness of the second region is greater than the surface roughness of the first region;

[0097] When realizing the second area in S1201, at least one of the following methods may be used: using a laser ablation method, using a mold pressing method, using a sandblasting method, or making a concave-convex structure.

[0098] For laser ablation, its working principle is: the second area demarcated by laser irradiation causes the surface material of the second area to increase in temperature, melt instantly, or even vaporize, ionize the mixed steam, and other physical phenomena, thereby leaving permanent burn marks. Therefore, after laser ablation, the material formed in the second area is different from the material formed in the first area, so that the second area can act as a solder mask to the first solder in the first area, thereby preventing the first solder from overflowing from the first area, and avoiding the impact on other structures while improving the welding effect; and it can also achieve the function of fixing the substrate to prevent the substrate from shifting during welding. Among them, when the second area demarcated by laser irradiation, multiple ablation lines will be left in the second area, and the spacing between adjacent ablation lines can be small or even zero, so that the surface roughness of different positions in the second area can be more uniform, thereby improving the reliability of the plastic package.

[0099] For mold pressing, a mold with patterns is used to press the demarcated second area to increase the surface roughness of the second area. This method is simple to operate and easy to implement, and can improve the plastic sealing effect while reducing the production cost of the power module. When the mold is pressed, the patterns in the mold can be mesh, triangular, quadrilateral or special-shaped, etc., which can be designed according to actual needs, and there is no specific requirement for the depth of mold pressing.

[0100] As for sandblasting, its working principle is: spraying sand particles onto the surface of the heat sink, bombarding the surface of the heat sink with sand particles to form the second area; so when sandblasting, the surface roughness of the second area can be controlled by selecting the size of the sand particles to meet the requirements of plastic sealing, and then the size of the sand particles can be selected according to the requirements of the surface roughness of the second area, which is not limited here. In addition, the material of the welding surface of the heat sink contains copper elements, for example: the material of the welding surface of the heat sink can be single copper, in which case the heat sink can be a copper plate, or a plate with single copper plated on the welding surface; the material of the welding surface of the heat sink can also be copper oxide, in which case the heat sink can be a copper oxide plate, or a plate with copper oxide plated on the welding surface; the material of the welding surface of the heat sink can also be copper alloy, in which case the heat sink can be a copper alloy plate, or a plate with copper alloy plated on the welding surface. In this way, the second area is formed by combining bare copper with local sandblasting. This method is simple to operate and easy to implement, and can reduce the production cost of the power module on the basis of improving the plastic sealing effect.

[0101] For making the concavo-convex structure, the concavo-convex structure can be at least one of the following structures: a fin structure, a pit structure and a protrusion structure, and the specific combination can be set according to actual needs and is not limited here. In addition, the specific shape and setting density of each fin pin, pit and protrusion in the fin structure can be set according to actual needs and are not limited here.

[0102] Of course, taking the heat sink as a copper plate as an example, after the copper plate is manufactured, the surface roughness of different areas on the copper plate surface is different, so the surface roughness of the copper plate surface itself can be used to delineate the first area and the second area, so that the surface roughness of the delineated second area is greater than the surface roughness of the first area. Compared with using a copper plate with nickel plated on the surface as a heat sink, using a copper plate as a heat sink can obtain the first area and the second area without any treatment on the copper plate surface. This method can greatly reduce production costs, increase production capacity, and reduce nickel plating processes.

[0103] In addition, the specific size of the surface roughness of the second area can be set according to the requirements for plastic sealing. For example, if the requirements for plastic sealing are high, the surface roughness of the second area can be set larger. If the requirements for plastic sealing are low, the surface roughness of the second area can be set smaller.

[0104] S1202, disposing a second solder in a third area defined on one surface of the substrate;

[0105] S1203, using a reflow soldering method, fixing another surface of the substrate opposite to one of the surfaces to the heat sink through a first solder, and fixing the chip to one of the surfaces through a second solder;

[0106] Among them, the reflow soldering method is a method in which gas (such as but not limited to nitrogen) circulates in a welding machine to generate high temperature to achieve the purpose of soldering; therefore, the chip and the substrate, and the substrate and the heat sink are soldered together at the same time.

[0107] Of course, when other welding methods are used, the chip can be welded to the substrate first, and then the substrate with the chip welded thereon can be welded to the heat sink, or the substrate can be welded to the heat sink first, and then the chip can be welded to the substrate. As long as the welding of the chip to the substrate and the welding of the substrate to the heat sink can be achieved, the specific welding sequence and welding method are not limited here.

[0108] S1204, encapsulating the substrate and the chip with a plastic encapsulation material to obtain a power module.

[0109] Thus, when the surface roughness of the second region is greater than that of the first region, the bonding area between the molding compound and the second region of the heat sink can be increased, thereby increasing the bonding strength between the molding compound and the heat sink, avoiding stratification of the bonding surface, and improving the molding effect.

[0110] Fig.13 The schematic diagram of the method for manufacturing the power module provided by the present application is exemplarily shown, referring to Fig.13 As shown, the manufacturing method of the power module of this embodiment is the same as that of the above Fig.12 The manufacturing method of the power module in the illustrated embodiment is basically similar, except that: step S1 is added between the above S1201 and S1202. Optionally, step S1 is: forming a fourth region at least at the corner of the third region, and the surface roughness of the fourth region is greater than the surface roughness of the third region. In this way, the bonding area between the molding compound and the fourth region in the substrate can be increased, thereby increasing the bonding strength between the molding compound and the substrate, avoiding stratification of the bonding surface, and further improving the molding effect.

[0111] When implementing the fourth area in S1, at least one of the following methods may be used: a laser ablation method, a mold pressing method, or a sandblasting method, and the specific implementation methods of laser ablation, mold pressing, and sandblasting are the same as those described above. Fig.12 The specific implementation methods of the related methods mentioned in the embodiments shown are the same, and the details can be referred to above Fig.12 The related introduction in the illustrated embodiment will not be repeated any more.

[0112] It should be understood that the method for manufacturing the power module in this embodiment is similar to the method described above. Fig.12 The similarities between the manufacturing methods of the power modules in the embodiments shown are as follows: Fig.13 S1201 and Fig.12 Similar to S1201 in Fig.13 S1202 and Fig.12 Similar to S1202, Fig.13 S1203 and Fig.12 Similar to S1203 in Fig.13 S1204 and Fig.12 Similar to S1204 in the above Fig.12 The related introduction in the illustrated embodiment will not be repeated any more.

[0113] Obviously, those skilled in the art can make various changes and modifications to the embodiments of the present application without departing from the spirit and scope of the embodiments of the present application. Thus, if these modifications and variations of the embodiments of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A power module, It is characterized in that include: A heat sink, a substrate and a chip are stacked in sequence; The surface of the heat sink is provided with: a first area and a second area, the second area is at least provided at the corner of the first area, and the surface roughness of the second area is greater than the surface roughness of the first area; the projection of the substrate along the thickness direction of the heat sink overlaps with the first area; A third area is provided on a surface of the substrate facing away from the heat sink, and a projection of the chip along the thickness direction of the heat sink overlaps with the third area; The molding compound encapsulates the substrate and the chip, and the second region is in contact with the molding compound.

2. The power module according to claim 1, It is characterized in that A plurality of the first regions are provided, and the second regions corresponding to two adjacent first regions are at least partially connected.

3. The power module according to claim 1 or 2, It is characterized in that All areas on the surface of the heat sink except the first area are the second area.

4. The power module according to any one of claims 1 to 3, It is characterized in that The second area overlaps with an orthographic projection of the substrate on the heat dissipation plate.

5. The power module according to any one of claims 1 to 4, It is characterized in that The projection of the substrate on the heat dissipation plate is located in the first region, and the area of ​​the first region is larger than the projection area of ​​the substrate on the heat dissipation plate.

6. The power module according to any one of claims 1 to 4, It is characterized in that The first region is located within a projection of the substrate on the heat sink, and an area of ​​the projection of the substrate on the heat sink is larger than an area of ​​the first region; There is a gap between the second area and the corresponding first area.

7. The power module according to any one of claims 1 to 6, It is characterized in that The second region is provided with a concavo-convex structure.

8. The power module according to claim 7, It is characterized in that The concave-convex structure is at least one of the following structures: a fin structure, a pit structure and a convex structure.

9. The power module according to any one of claims 1 to 8, It is characterized in that A fourth region is also provided on the surface of the substrate facing away from the heat sink. The fourth region is at least provided at the corner of the third region. The surface roughness of the fourth region is greater than that of the third region. The fourth region contacts the molding compound.

10. The power module according to claim 9, It is characterized in that The fourth area at least partially surrounds the third area; Alternatively, the second region at least partially surrounds the first region.

11. The power module according to claim 9 or 10, It is characterized in that Areas other than the third area on the surface of the substrate facing away from the heat dissipation plate are all fourth areas.

12. The power module according to any one of claims 9 to 11, It is characterized in that The fourth region is formed of a material different from the third region; Alternatively, the second region is formed of a material different from the first region.

13. The power module according to any one of claims 9 to 12, It is characterized in that The second region or the fourth region is formed by sandblasting.

14. A method for manufacturing a power module according to any one of claims 1 to 13, It is characterized in that include: A second region is formed at least at the corner of the first region on the surface of the heat sink, and the surface roughness of the second region is greater than the surface roughness of the first region; Fixing the substrate to the heat sink through the first region, and fixing the chip to the substrate through the third region, so that the projection of the substrate along the thickness direction of the heat sink overlaps with the first region, and the projection of the chip along the thickness direction of the heat sink overlaps with the third region; The substrate and the chip are encapsulated with a plastic encapsulation material so that the second region is in contact with the plastic encapsulation material, thereby obtaining the power module.

15. An electronic device, It is characterized in that include: A shell, and a power module according to any one of claims 1 to 13, wherein the power module is arranged in the shell.

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