Power module, method for manufacturing power module, and power conversion device

Abstract

The purpose of the present invention is to provide a power module in which a power module unit and a heat sink are integrated, wherein an increase in contact thermal resistance and a decrease in retention strength can be suppressed. The power module comprises: a power module unit having a module base, a semiconductor element mounted on one side of the module base, and a molded section that seals the semiconductor element; a heat sink base integrated with the other side of the module base exposed from the molded section; and a plurality of heat dissipation fins protruding from the heat sink base in the direction opposite the module base and fixed to a crimping section of the heat sink base. A first uneven section is provided on the other side of the module base, and the surface on the module base-side of the heat sink base is provided with a second uneven section that interlocks with the first uneven section, and a wall section that protrudes toward the module base from a position closer to the outer periphery than the portion facing the first uneven section.

Description

Power module, power module manufacturing method, and power conversion device

[0001] The present disclosure relates to a power module, a method for manufacturing a power module, and a power conversion device.

[0002] In a typical power module, heat generated by semiconductor elements is dissipated from a heat sink connected to the power module via thermal conductive grease. However, because the thermal conductivity of thermal conductive grease is low, the thermal resistance of the entire power module increases, which causes the power module to become larger.

[0003] Therefore, in order to achieve miniaturization of the power module, a heat sink-integrated power module has been developed in which, instead of using thermally conductive grease, flat fins are integrated into a fin base that is integrated with the power module by crimping (see, for example, Patent Document 1).

[0004] International Publication No. 2018 / 097027

[0005] However, in the technology described in Patent Document 1, the outer peripheral end of the uneven portion is not fixed even after crimping, so if the outer peripheral end of the uneven portion undergoes significant plastic deformation, the surface pressure applied to the point of contact with the outer peripheral end of the uneven portion will decrease, which may result in an increase in contact thermal resistance and a decrease in holding strength.

[0006] Furthermore, when each component deforms due to thermal stress or other factors, the outer edges of the uneven portion may bend outward, potentially resulting in a similar condition to that described above. This condition is thought to occur particularly when misalignment occurs when the module base and heat sink are integrated, or when the tolerances for the uneven portions of the module base and the heat sink vary.

[0007] Therefore, an object of the present disclosure is to provide a technology that can suppress an increase in contact thermal resistance and a decrease in holding strength in a power module in which a power module section and a heat sink are integrated.

[0008] A power module according to the present disclosure comprises a module base, a power module portion having a semiconductor element mounted on one side of the module base and a molded portion that seals the semiconductor element, a heat sink base that is integrated with the other side of the module base that is exposed from the molded portion, and a plurality of heat dissipation fins that protrude from the heat sink base on the side opposite to the module base and are fixed to crimping portions of the heat sink base, wherein a first uneven portion is provided on the other side of the module base, and a second uneven portion that fits with the first uneven portion is provided on the surface of the heat sink base facing the module base, and a wall portion that protrudes toward the module base at a position outer circumferentially of the portion that faces the first uneven portion.

[0009] According to the present disclosure, the wall portion can reduce the amount of deformation at the outer peripheral end of the first uneven portion, thereby suppressing an increase in contact thermal resistance and a decrease in holding strength.

[0010] The objects, features, aspects, and advantages of the present disclosure will become more apparent from the following detailed description and the accompanying drawings.

[0011] FIG. 1 is a cross-sectional view showing a power module according to embodiment 1 before integration. FIG. 1 is a cross-sectional view of a power module according to embodiment 1. FIG. 2 is a cross-sectional view showing a power module according to a modified example of embodiment 1 before integration. FIG. 3 is a cross-sectional view showing a power module according to a modified example of embodiment 1 before integration. FIG. 4 is a cross-sectional view showing a step of performing heat sink caulking in embodiment 1. FIG. 5 is a cross-sectional view showing a power module according to a modified example of embodiment 1 before integration. FIG. 6 is a cross-sectional view showing a power module according to a modified example of embodiment 1 before integration. FIG. 7 is a cross-sectional view showing a power module according to a modified example of embodiment 1 before integration. FIG. 8 is a cross-sectional view showing a power module according to a modified example of embodiment 1 before integration. FIG. 9 is a cross-sectional view showing a method of manufacturing the power module according to embodiment 1. FIG. 10 is a cross-sectional view showing a method of manufacturing the power module according to embodiment 1. FIG. 11 is a view of a heat sink provided in the power module according to embodiment 1 as seen from below. FIG. 12 is a cross-sectional view showing another method of manufacturing the power module according to embodiment 1. FIG. 13 is a cross-sectional view showing a power module according to embodiment 2 before integration. FIG. 14 is a cross-sectional view showing a power module according to embodiment 2 before integration. FIG. 15 is a cross-sectional view showing a power module according to embodiment 3 before integration. FIG. 16 is a cross-sectional view showing a step of performing heat sink caulking in embodiment 3. FIG. 17 is a block diagram showing a configuration of a power conversion system to which a power conversion device according to embodiment 4 is applied. 10A to 10C are cross-sectional views showing steps of performing heat sink caulking in a related art;

[0012] <First Embodiment> <Structure of Power Module> A first embodiment will be described below with reference to the drawings. Fig. 1 is a cross-sectional view showing a power module 202 according to the first embodiment before integration. Fig. 2 is a cross-sectional view of the power module 202 according to the first embodiment.

[0013] 1 and 2 , the power module 202 is a heat sink-integrated power module, and includes a power module section 1 and a heat sink 2. The power module section 1 includes a plurality of semiconductor chips 5 (semiconductor elements), a lead frame 3, an insulating sheet 8, a module base 9, and a molded section 4.

[0014] A plurality of semiconductor chips 5 are mounted on the upper surface (one surface) of the lead frame 3 via solder 6. The lead frame 3 is arranged via an insulating sheet 8 attached to the upper surface (one surface) of a module base 9.

[0015] The material of the semiconductor chip 5 is, for example, silicon. However, the material of the semiconductor chip 5 is not limited to silicon, and may be, for example, a wide bandgap semiconductor material such as silicon carbide, gallium nitride, or diamond. A wide bandgap semiconductor material is a material having a bandgap wider than that of silicon. A semiconductor chip 5 made of a wide bandgap semiconductor material can operate using a large current and in a high-temperature environment. For this reason, it is preferable that the material of the semiconductor chip 5 be a wide bandgap semiconductor material.

[0016] The molded portion 4 is made of molded resin and seals the semiconductor chip 5, lead frame 3, insulating sheet 8, and module base 9 so that one end side and the other end side of the lead frame 3 and the underside (other side) of the module base 9 are exposed.

[0017] A first uneven portion 7 is provided on the lower surface (other surface) of the module base 9. The first uneven portion 7 is made up of a plurality of recesses and is provided across the width direction of the module base 9 (the left-right direction in FIG. 1 ).

[0018] The heat sink 2 has a heat sink base 13 integrated with the lower surface (other surface) of the module base 9, and a plurality of heat dissipation fins 14 protruding downward from the heat sink base 13 (the side opposite to the module base 9).

[0019] A second uneven portion 11 that can fit into the first uneven portion 7 is provided on the upper surface (the surface on the module base 9 side) of the heat sink base 13 excluding the outer periphery. The second uneven portion 11 is made up of a plurality of protrusions and is provided across the width direction (left-right direction in FIG. 1 ) of the heat sink base 13 excluding the outer periphery.

[0020] Furthermore, on the upper surface of the heat sink base 13 excluding the outer periphery, a wall portion 12 protruding toward the module base 9 is provided at a position on the outer periphery side of the portion facing the first uneven portion 7, i.e., at a position on the outer periphery side of the second uneven portion 11. As shown in Fig. 2, when the module base 9 and the heat sink 2 are integrated, the wall portion 12 is in contact with an end portion 17 on the outer periphery side of the first uneven portion 7.

[0021] As shown in Figures 1 and 2, the multiple heat dissipation fins 14 are attached to the heat sink base 13 by being inserted into multiple heat dissipation fin insertion grooves 23a (see Figure 9) formed in the heat sink base 13.

[0022] The module base 9 and the heat sink 2 are integrated by fitting the first uneven portion 7 and the second uneven portion 11 together by crimping. The first uneven portion 7 and the second uneven portion 11 may be provided continuously so as to extend in the depth direction of the module base 9 and the heat sink base 13 (the depth direction in FIG. 1 ), respectively, or may have discontinuous portions. In this specification, the process of integrating the first uneven portion 7 of the module base 9 and the second uneven portion 11 of the heat sink 2 by crimping is referred to as "heat sink crimping."

[0023] Since the power module 1 incorporating the semiconductor chip 5 and the heat sink 2 are integrated by applying pressure (heat sink crimping), there are concerns that the pressure applied during the heat sink crimping process may cause cracking of the semiconductor chip 5, damage to the semiconductor chip 5, changes in the characteristics of the semiconductor chip 5 before and after application of pressure, cracking of the molded part 4, a decrease in dielectric strength voltage, and peeling between the various components. For this reason, it is desirable that the heat sink crimping process for integrating the power module 1 and the heat sink 2 be performed with as little load as possible.

[0024] The module base 9 is made of aluminum or an aluminum alloy and is produced by cutting, die-casting, forging, extrusion, or the like.

[0025] The heat sink base 13 is made of aluminum or an aluminum alloy and is produced by cutting, die-casting, forging, extrusion, or the like.

[0026] Furthermore, by using a plate material (rolled material) such as aluminum or an aluminum alloy for the heat dissipation fins 14, it is possible to achieve both ease of processing and heat dissipation. Furthermore, by embossing the surface of the heat dissipation fins 14 to create minute depressions, the heat dissipation area of ​​the heat dissipation fins 14 is increased, thereby improving heat dissipation performance. Note that the embossing can be performed on the surface of the heat dissipation fins 14 by using the same mold used to press the heat dissipation fins 14 to the specified dimensions, so it is possible to emboss the surface of the heat dissipation fins 14 without increasing costs.

[0027] Furthermore, by applying a micro-embossing to the surface of the heat dissipation fins 14, the contact area between adjacent heat dissipation fins 14 is reduced when the heat dissipation fins 14 are stacked, thereby reducing surface friction. The reduced surface friction between adjacent heat dissipation fins 14 when stacked allows for simplification of the production equipment and shortening of the production takt time required for the fin crimping process that integrates the heat sink base 13 and the heat dissipation fins 14, thereby improving productivity. By applying an embossing process with micro-indentations to the surface of the heat dissipation fins 14, when the heat sink base 13 and the heat dissipation fins 14 are integrated by crimping, the embossed portion of the surface of the heat dissipation fin 14 between adjacent heat dissipation fins 14 on the heat sink base 13 (hereinafter referred to as the "crimped portion of the heat sink base 13") penetrates deeper into the heat dissipation fins 14 than the non-embossed portion. As a result, an anchoring effect is achieved.

[0028] This increases friction in the height direction (the up-and-down direction in FIG. 1 ), i.e., the vertical direction, between the heat dissipation fins 14 and the crimped portions of the heat sink base 13, improving the vertical tensile strength of the heat dissipation fins 14 after fin crimping. In particular, when the heat dissipation fins 14 are harder than the heat sink base 13, the crimped portions of the heat sink base 13 after fin crimping plastically deform without biting into the surfaces of the heat dissipation fins 14, and therefore, by applying embossing, the vertical tensile strength of the heat dissipation fins 14 after fin crimping is improved.

[0029] On the other hand, if the hardness of the heat sink base 13 is greater than that of the heat dissipation fins 14, the crimped portion of the heat sink base 13 after the fin crimping process will bite into the surface of the heat dissipation fins 14, and the crimped portion of the heat sink base 13 after the fin crimping process will plastically deform the heat dissipation fins 14, and an anchor effect will be exerted between the plastically deformed crimped portion of the heat sink base 13 and the heat dissipation fins 14.

[0030] Therefore, if the hardness of the heat sink base 13 is greater than that of the heat dissipation fins 14, the effect of embossing on the surface of the heat dissipation fins 14 is small. Therefore, from the perspective of the strength of the heat dissipation fins 14 after fin crimping, it is desirable to consider the following two points. The first point is to emboss the surface of the heat dissipation fins 14 to create minute depressions. The second point is to use different materials for the heat sink base 13 and the heat dissipation fins 14, and to ensure that the hardness of the heat sink base 13 is greater than the hardness of the heat dissipation fins 14. If at least one of the first and second points is satisfied, the vertical tensile strength of the heat dissipation fins 14 after fin crimping is improved. Specifically, when the material of the heat sink base 13 is aluminum 6000 series and the material of the heat dissipation fins 14 is aluminum 1000 series, the strength (vertical tensile strength) of the heat dissipation fins 14 after crimping is approximately 2.5 to 3.6 times greater than when the materials of the heat sink base 13 and the heat dissipation fins 14 are both aluminum 1000 series.

[0031] However, the materials of the module base 9, the heat sink base 13, and the heat dissipation fins 14 are not limited to aluminum, and may be a combination of different materials. For example, from the viewpoint of heat dissipation capacity, by using a copper-based plate material for the heat dissipation fins 14, which has a higher thermal conductivity than aluminum-based plate material, the heat dissipation capacity is further improved compared to when using an aluminum-based plate material.

[0032] As shown in Figures 1 and 2, in the case of a heat sink 2 in which the heat sink base 13 and the heat dissipation fins 14 are integrated by fin crimping, there are no processing restrictions (aspect ratio) that are imposed when die casting or extrusion is performed, so the heat dissipation fins 14 can be designed freely, and the heat dissipation capacity of the heat sink 2 can be improved.

[0033] However, the heat sink 2 is not limited to the crimped heat sink shown in Figures 1 and 2. Figures 3 and 4 are cross-sectional views showing the power module 202 according to a modification of the first embodiment before integration. As shown in Figure 3, the heat sink 2 may be a heat sink produced by extrusion, cutting, or forging, or as shown in Figure 4, it may be a heat sink produced by die casting.

[0034] In the power module 202, the size of the module base 9 is determined for one power module unit 1, so when the heat density increases, in other words, when the amount of heat generated from the semiconductor chip 5 increases, the heat dissipation capacity according to the respective heat density can be ensured by changing the size (width and depth directions) of the heat sink base 13 other than the thickness direction, the number of heat dissipation fins 14, and the size of the heat dissipation fins 14 according to the heat density. In other words, a heat sink 2 that can accommodate various amounts of heat generation can be configured with one power module unit 1, and the power module unit 1 can be standardized, thereby improving the productivity of the power module unit 1.

[0035] <Characteristics of the Wall> Next, the characteristics of the wall 12 will be described. Here, the difference between a case where the wall 12 is provided on the heat sink 2 (first embodiment) and a case where the wall 12 is not provided (related art) will be described. Figures 5(a) and 5(b) are cross-sectional views showing the steps of performing heat sink caulking in the first embodiment. Figures 20(a) and 20(b) are cross-sectional views showing the steps of performing heat sink caulking in the related art.

[0036] First, a case where the wall portion 12 is not provided (related art) will be described. As shown in Figures 20(a) and 20(b) , in the related art, when heat sink crimping is performed, the outer peripheral end 17 of the first uneven portion 7 of the module base 9 (hereinafter also referred to as "end 17 of the module base 9") is not fixed even after crimping, and therefore undergoes plastic deformation in accordance with the applied load. As a result, the surface pressure applied to the contact portion between the end 17 of the module base 9 and the second uneven portion 11 of the heat sink base 13 is smaller than the surface pressure applied to other portions. As a result, the portion adjacent to the end 17 of the module base 9 is subjected to surface pressure on only one side, or to a small surface pressure on both sides, which may result in increased contact thermal resistance, deterioration of heat dissipation performance, and a decrease in holding strength (vertical tensile strength).

[0037] 5 , when the wall portion 12 is provided on the surface of the heat sink base 13 facing the module base 9 at a position closer to the outer periphery than the portion facing the first uneven portion 7 (Embodiment 1), the end portion 17 of the module base 9 can be fixed by the wall portion 12 when the heat sink is crimped. This reduces the amount of deformation of the end portion 17 on the outer periphery of the first uneven portion 7, thereby maintaining the surface pressure applied to the contact portion between the end portion 17 of the module base 9 and the second uneven portion 11 of the heat sink base 13. As a result, an increase in contact thermal resistance and a decrease in holding strength can be suppressed.

[0038] In this way, the wall 12 is provided to suppress deformation of the end 17 of the module base 9. By providing the wall 12 in two locations on the heat sink 2, it is possible to ensure thermal resistance and holding strength that meet specifications without increasing the press load required to perform heat sink crimping. Note that the above effect is even greater when the hardness relationship between the module base 9 and the heat sink base 13 is such that the module base 9 is harder than the heat sink base 13. Furthermore, the same effect is achieved whether the wall 12 is provided continuously so as to extend in one direction (width or depth) of the module base 9, or if discontinuous portions are provided.

[0039] 6 to 8 are cross-sectional views showing a power module 202 according to a modification of embodiment 1 before integration. As shown in Fig. 6, the first uneven portion 7 is made up of a plurality of recesses, and the second uneven portion 11 is made up of a plurality of protrusions, and by making the depth of at least one of the plurality of recesses in the first uneven portion 7 and the height position of at least one of the plurality of protrusions in the second uneven portion 11 opposing it larger than those of the other portions, it is possible to roughly position the power module portion 1 relative to the heat sink 2 when setting the power module portion 1 on the heat sink 2 during heat sink crimping processing.

[0040] By applying pressure to the power module unit 1 and the heat sink 2, the second uneven portion 11 of the heat sink base 13 comes into contact with the tapered portion of the first uneven portion 7 of the module base 9, and then slides along the tapered portion, thereby performing the heat sink crimping process. This simplifies the positioning of the power module unit 1 and the heat sink 2 in the width direction during the heat sink crimping process. Since the heat sink crimping jig used in the heat sink crimping process can be simplified, the productivity of the heat sink crimping process is also improved.

[0041] 6, the height positions of the two recesses at both ends in the width direction among the multiple recesses of the first uneven portion 7 are formed to be greater than the height positions of the recesses at locations other than both ends in the width direction, and the height positions of the two protrusions at both ends in the width direction among the multiple protrusions of the second uneven portion 11 are formed to be greater than the height positions of the protrusions at locations other than both ends in the width direction. By setting the two recesses of the first uneven portion 7 to the two protrusions of the second uneven portion 11, it is possible to set the power module portion 1, which makes it possible to simplify the heat sink crimping jig and improve the productivity of heat sink crimping.

[0042] The press load required to perform the heat sink crimping process increases due to the provision of the wall portion 12. If the required specifications are not met, the press load required to perform the heat sink crimping process can be adjusted by adjusting the dimensions of the wall portion 12 and the second uneven portion 11.

[0043] 1 to 6, the heat sink base 13 is provided with a wall portion 12, but this is not limiting. As shown in Fig. 7, the first uneven portion 7 may be composed of a plurality of convex portions, and the second uneven portion 11 may be composed of a plurality of concave portions, and the wall portion 12 protruding toward the heat sink base 13 may be provided at a position on the outer periphery side of a portion of the underside of the module base 9 that faces the second uneven portion 11. In Fig. 7, reference numeral 17 denotes the outer periphery side end of the second uneven portion 11 of the heat sink base 13.

[0044] In this case, an even greater effect can be obtained if the hardness relationship between the module base 9 and the heat sink base 13 is such that the module base 9 is greater than the heat sink base 13. Furthermore, if the module base 9 and the heat sink base 13 have the same hardness, the width of the wall portion 12 can be increased to prevent deformation of the wall portion 12, as shown in Figure 8. In the power module 202, the same effect can be achieved whether the first uneven portion 7, the second uneven portion 11, and the wall portion 12 are provided continuously so as to extend in the depth direction, or whether discontinuous portions are provided.

[0045] <Manufacturing Method of Power Module> Next, a description will be given of a manufacturing method of the power module 202. Figures 9 to 11 are cross-sectional views showing a manufacturing method of the power module 202 according to the first embodiment.

[0046] Although not shown, first, the semiconductor chip 5 is mounted on the module base 9, and the power module 1 is formed by sealing the semiconductor chip 5 with the mold part 4 while exposing the part of the module base 9 opposite to the side on which the semiconductor chip 5 is mounted. Next, the heat sink 2 is prepared, in which a plurality of heat dissipation fin insertion grooves 23a are formed.

[0047] Next, as shown in FIG. 9 , the power module unit 1 and the heat sink base 13 are arranged so that the portion of the module base 9 exposed from the molded unit 4 faces the heat sink base 13, and multiple heat dissipation fins 14 are arranged in multiple heat dissipation fin insertion grooves 23 a.

[0048] 10 and 11 , with the fin crimping tool 15 in contact with the crimped portion of the heat sink base 13, the power module unit 1 is pressed toward the heat sink base 13 by a press load. The portion of the module base 9 exposed from the molded portion 4 is joined to the heat sink base 13, and the crimped portion of the heat sink base 13 is crimped to attach the multiple heat dissipation fins 14 to the heat sink base 13, thereby integrating the power module unit 1, the heat sink base 13, and the multiple heat dissipation fins 14.

[0049] It is also possible to use a crimped heat sink in which the heat dissipation fins 14 and the heat sink base 13 are previously integrated by fin crimping. Furthermore, when using a heat sink 2 in which the heat sink base 13 and the heat dissipation fins 14 are integrated by die-casting or extrusion instead of a crimped heat sink, it is possible to integrate the power module section 1 and the heat sink 2 by heat sink crimping using the same steps and tools as those in Figures 9 to 11 by using a fin crimping tool 15 with a flat tip.

[0050] 12A and 12B are views seen from below of the heat sink 2 provided in the power module 202 according to embodiment 1. Fig. 13 is a cross-sectional view showing another method for manufacturing the power module 202 according to embodiment 1.

[0051] 10 and 11 , the press load is received by the fin crimping tool 15, but as shown in Fig. 12( a), if the heat dissipation fins 14 do not extend across the entire depth direction of the heat sink base 13, that is, if the heat dissipation fins 14 are not arranged on the periphery of the heat sink base 13, then as shown in Fig. 12( b), a press load receiving portion 20 may be provided on the surface of the heat sink base 13 opposite to the surface on which the second uneven portion 11 is provided, that is, on the surface on which the heat dissipation fins 14 are arranged. Specifically, the press load receiving portion 20 is provided on the periphery of the underside of the heat sink base 13.

[0052] As shown in Figure 13, the heat sink 2 is set so that the heat sink setting jig 21 abuts against the press load receiving portion 20, and then the power module portion 1 is set, thereby enabling the heat sink to be crimped. The other steps are the same as those in the manufacturing method shown in Figures 9 to 11, so a description thereof will be omitted. The manufacturing method shown in Figure 13 is simpler and more productive than the manufacturing method shown in Figures 9 to 11.

[0053] <Effects> As described above, in the first embodiment, the power module 202 includes the module base 9, the power module section 1 having the semiconductor chip 5 mounted on one side of the module base 9, and the molded section 4 that seals the semiconductor chip 5, the heatsink base 13 that is integrated with the other side of the module base 9 that is exposed from the molded section 4, and a plurality of heat dissipation fins 14 that protrude from the heatsink base 13 on the side opposite to the module base 9 and are fixed to crimped sections of the heatsink base 13. The other side of the module base 9 is provided with a first uneven section 7, and the surface of the heatsink base 13 facing the module base 9 is provided with a second uneven section 11 that fits with the first uneven section 7 and a wall section 12 that protrudes toward the module base 9 at a position outer circumferentially more outer than a section that faces the first uneven section 7.

[0054] Therefore, the wall portion 12 can reduce the amount of deformation of the outer peripheral end portion 17 of the first uneven portion 7, thereby suppressing an increase in contact thermal resistance and a decrease in holding strength.

[0055] In addition, in Figure 7, the wall portion 12 is not located on the heat sink base 13, but is located on the other side of the module base 9 at a position closer to the outer periphery than the portion facing the second uneven portion 11, so as to protrude toward the heat sink base 13.

[0056] Therefore, the wall portion 12 can reduce the amount of deformation of the outer peripheral end portion of the second uneven portion 11, thereby suppressing an increase in contact thermal resistance and a decrease in holding strength.

[0057] As described above, the first uneven portion 7, the second uneven portion 11, and the wall portion 12 may be formed to extend in the same direction, or discontinuous portions may be provided in any of the first uneven portion 7, the second uneven portion 11, and the wall portion 12. In this case as well, it is possible to suppress an increase in contact thermal resistance and a decrease in holding strength.

[0058] <Second Embodiment> Next, a power module 202 according to a second embodiment will be described. Fig. 14 is a cross-sectional view showing the power module 202 according to the second embodiment before integration. Fig. 15 is a cross-sectional view of the power module 202 according to the second embodiment. Note that in the second embodiment, the same components as those described in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

[0059] 14 and 15 , in the second embodiment, the heat sink base 13 has a crimped portion 22 facing the module base 9 and a heat dissipation diffusion portion 23 provided with a plurality of heat dissipation fins 14. The heat sink base 13 is composed of the crimped portion 22 and the heat dissipation diffusion portion 23, and by changing the thickness of the crimped portion 22, it is possible to freely design the insulation distance 28 between the lead frame 3 and the heat sink 2, specifically, between the lead frame 3 and the heat dissipation diffusion portion 23. The heat sink base 13 is manufactured by cutting, forging, extrusion, or die casting, so it is possible to ensure the required insulation distance 28 without reducing productivity.

[0060] On the other hand, if the heat sink base 13 is not composed of the crimped portion 22 and the heat dissipation / diffusion portion 23, it is necessary to increase the thickness of the module base 9 of the power module portion 1 in order to ensure the necessary insulation distance. Increasing the thickness of the module base 9 increases the heat capacity and reduces the rate of temperature rise, which may reduce the productivity of the molding process for forming the power module portion 1.

[0061] As in Figure 7, the first uneven portion 7 may be composed of a plurality of convex portions, and the second uneven portion 11 may be composed of a plurality of concave portions, and a wall portion 12 protruding toward the heat sink base 13 may be provided at a position on the underside of the module base 9 that is closer to the outer periphery than the portion facing the second uneven portion 11.

[0062] As described above, in the second embodiment, the heat sink base 13 has a crimping portion 22 facing the module base 9 and a heat dissipation diffusion portion 23 provided with a plurality of heat dissipation fins 14, and the crimping portion 22 is provided with a second uneven portion 11 and a wall portion 12.

[0063] Furthermore, when the configuration of embodiment 2 is adopted for the configuration of Figure 7, the heat sink base 13 has a crimping portion 22 in the portion facing the module base 9 and a heat dissipation diffusion portion 23 provided with a plurality of heat dissipation fins 14, and the crimping portion 22 is provided with a second uneven portion 11.

[0064] Therefore, the heat dissipation and diffusion portion 23 can diffuse heat, further improving the cooling effect and ensuring the necessary insulation distance 28 between the lead frame 3 and the heat dissipation and diffusion portion 23. Furthermore, the heat dissipation and diffusion portion 23 can suppress deformation of the entire heat sink base 13 that occurs during the heat sink crimping process.

[0065] <Third Embodiment> Next, a power module 202 according to a third embodiment will be described. Fig. 16 is a cross-sectional view showing the power module 202 according to the third embodiment before integration. Fig. 17 is a cross-sectional view of the power module 202 according to the third embodiment. Fig. 18 is a cross-sectional view showing a step of performing heat sink caulking in the third embodiment. Note that in the third embodiment, the same components as those described in the first and second embodiments are designated by the same reference numerals, and description thereof will be omitted.

[0066] 16 and 17, in the third embodiment, the wall portion 12 is formed so that its width becomes smaller as it approaches the heat sink base 13, as compared to Fig. 1. Specifically, the surface of the wall portion 12 that comes into contact with the end portion 17 of the module base 9 is formed in a tapered shape so that the width of the wall portion 12 becomes smaller as it approaches the heat sink base 13.

[0067] 18, when the power module section 1 and the heat sink 2 are integrated by heat sink caulking, the end 17 of the module base 9 fits into this tapered portion. As a result, the end 17 of the module base 9 functions as an anchor.

[0068] For example, even if a force acts in the direction of detachment of the second uneven portion 11 due to a transportation error, springback when the heat sink crimping process is completed, or a change in shape due to a temperature change, the end 17 of the module base 9 will catch on the wall portion 12, making it possible to prevent a decrease in the surface pressure applied to the joint between the first uneven portion 7 and the second uneven portion 11 and to prevent the two from separating.

[0069] At this time, if the difference in hardness between the module base 9 and the heat sink base 13 is such that the module base 9 is smaller than the heat sink base 13, the end 17 of the module base 9 can be crimped without increasing the press load.

[0070] 7, the wall portion 12 may be formed so that its width decreases toward the module base 9. Specifically, the surface of the wall portion 12 that comes into contact with the outer peripheral end of the second uneven portion 11 in the heat sink base 13 may be formed in a tapered shape so that the width of the wall portion 12 decreases toward the module base 9. This provides the same effect as in the above case.

[0071] Furthermore, when the hardness difference is such that the module base 9 is approximately equal to the heat sink base 13, the same effect as described above can be obtained by reducing the thickness of the outer peripheral ends of the recesses of the first uneven portion 7 and the second uneven portion 11 and by increasing the width of the wall portion 12.

[0072] As described above, in the third embodiment, the wall portion 12 is formed so that its width becomes smaller as it approaches the heat sink base 13. In addition, the wall portion 12 is formed so that its width becomes smaller as it approaches the module base 9.

[0073] Therefore, even if a force acts in the direction of detachment of the second uneven portion 11 due to, for example, a transportation error, springback when the heat sink crimping process is completed, or a change in shape due to a temperature change, the anchor effect can prevent a decrease in the surface pressure applied to the joint between the first uneven portion 7 and the second uneven portion 11, and prevent the two from separating.

[0074] <Fourth Embodiment> In this embodiment, the power module 202 according to the above-described first to third embodiments is applied to a power conversion device. The application of the power module 202 according to the first to third embodiments is not limited to a specific power conversion device, but hereinafter, as the fourth embodiment, a case where the power module 202 according to the first to third embodiments is applied to a three-phase inverter will be described.

[0075] FIG. 19 is a block diagram showing the configuration of a power conversion system to which the power conversion device according to this embodiment is applied.

[0076] The power conversion system shown in Fig. 19 is composed of a power supply 100, a power conversion device 200, and a load 300. The power supply 100 is a DC power supply and supplies DC power to the power conversion device 200. The power supply 100 can be composed of various components, such as a DC system, a solar cell, or a storage battery, or it may be composed of a rectifier circuit connected to an AC system or an AC / DC converter. The power supply 100 may also be composed of a DC / DC converter that converts DC power output from a DC system into a predetermined power.

[0077] The power conversion device 200 is a three-phase inverter connected between the power source 100 and the load 300, and converts DC power supplied from the power source 100 into AC power and supplies the AC power to the load 300. As shown in Fig. 19 , the power conversion device 200 includes a main conversion circuit 201 that converts DC power into AC power and outputs it, and a control circuit 203 that outputs a control signal to the main conversion circuit 201 to control the main conversion circuit 201.

[0078] The load 300 is a three-phase electric motor driven by AC power supplied from the power conversion device 200. The load 300 is not limited to a specific application, but is an electric motor mounted on various electrical devices, and is used as an electric motor for, for example, a hybrid vehicle, an electric vehicle, a railroad car, an elevator, or an air conditioning device.

[0079] The power conversion device 200 will be described in detail below. The main conversion circuit 201 includes switching elements (not shown) and freewheeling diodes (not shown). The switching elements convert DC power supplied from the power source 100 into AC power, which is supplied to the load 300. While the main conversion circuit 201 can have a variety of specific circuit configurations, the main conversion circuit 201 according to this embodiment is a two-level, three-phase full-bridge circuit that can be configured with six switching elements and six freewheeling diodes connected in anti-parallel to each switching element. At least one of the switching elements and freewheeling diodes of the main conversion circuit 201 is configured with a power module 202 according to any one of the first to third embodiments. Two of the six switching elements are connected in series to form upper and lower arms, which constitute each phase (U phase, V phase, and W phase) of the full-bridge circuit. The output terminals of each upper and lower arm, i.e., the three output terminals of the main conversion circuit 201, are connected to the load 300.

[0080] The main conversion circuit 201 also includes a drive circuit (not shown) that drives each switching element. The drive circuit may be built into the power module 202, or may be provided separately from the power module 202. The drive circuit generates drive signals that drive the switching elements of the main conversion circuit 201 and supplies them to the control electrodes of the switching elements of the main conversion circuit 201. Specifically, in accordance with control signals from a control circuit 203 (described later), the drive circuit outputs to the control electrodes of each switching element a drive signal that turns the switching element on and a drive signal that turns the switching element off. When maintaining a switching element in the on state, the drive signal is a voltage signal (on signal) that is equal to or higher than the threshold voltage of the switching element, and when maintaining a switching element in the off state, the drive signal is a voltage signal (off signal) that is equal to or lower than the threshold voltage of the switching element.

[0081] The control circuit 203 controls the switching elements of the main conversion circuit 201 so that the desired power is supplied to the load 300. Specifically, it calculates the time (on time) that each switching element of the main conversion circuit 201 should be in the on state based on the power to be supplied to the load 300. For example, the main conversion circuit 201 can be controlled by PWM control, which modulates the on time of the switching elements according to the voltage to be output. The control circuit 203 then outputs a control command (control signal) to a drive circuit included in the main conversion circuit 201 so that an on signal is output to a switching element that should be in the on state at each time point, and an off signal is output to a switching element that should be in the off state at each time point. In accordance with this control signal, the drive circuit outputs an on signal or an off signal as a drive signal to the control electrode of each switching element.

[0082] In the power conversion device according to this embodiment, the power module 202 according to the first to third embodiments is applied as the switching element and the free wheel diode of the main conversion circuit 201, thereby achieving improved reliability.

[0083] In this embodiment, an example has been described in which the power module 202 according to the first to third embodiments is applied to a two-level three-phase inverter, but the application of the power module 202 according to the first to third embodiments is not limited to this and can be applied to various power conversion devices. In this embodiment, a two-level power conversion device is described, but a three-level or multi-level power conversion device may also be used, and when supplying power to a single-phase load, the power module 202 according to the first to third embodiments may be applied to a single-phase inverter. Furthermore, when supplying power to a DC load or the like, the power module 202 according to the first to third embodiments can also be applied to a DC / DC converter or an AC / DC converter.

[0084] Furthermore, the power conversion device to which the power module 202 according to the first to third embodiments is applied is not limited to the case where the load described above is an electric motor, but can also be used, for example, as a power supply device for an electric discharge machine, a laser processing machine, an induction heating cooker, or a contactless power supply system, and can also be used as a power conditioner for a solar power generation system, a power storage system, etc.

[0085] Although this disclosure has been described in detail, the above description is illustrative in all respects and is not restrictive. It is understood that countless variations not illustrated can be envisioned.

[0086] It should be noted that the embodiments can be freely combined, and each embodiment can be modified or omitted as appropriate.

[0087] Various aspects of the present disclosure are summarized below as appendices.

[0088] (Supplementary Note 1) A power module comprising: a module base; a power module portion having a semiconductor element mounted on one side of the module base; and a molded portion that seals the semiconductor element; a heat sink base that is integrated with the other side of the module base exposed from the molded portion; and a plurality of heat dissipation fins that protrude from the heat sink base on the side opposite to the module base and are fixed to a crimping portion of the heat sink base, wherein a first uneven portion is provided on the other side of the module base, and a second uneven portion that fits with the first uneven portion and a wall portion that protrudes toward the module base at a position outer circumferentially further than a portion that faces the first uneven portion are provided on the surface of the heat sink base facing the module base.

[0089] (Supplementary Note 2) A power module comprising: a module base; a power module portion having a semiconductor element mounted on one side of the module base; and a molded portion that seals the semiconductor element; a heat sink base that is integrated with the other side of the module base exposed from the molded portion; and a plurality of heat dissipation fins that protrude from the heat sink base on the side opposite to the module base and are fixed to crimping portions of the heat sink base, wherein a first uneven portion is provided on the other side of the module base, a second uneven portion that fits with the first uneven portion is provided on the surface of the heat sink base facing the module base, and a wall portion that protrudes toward the heat sink base at a position outer circumferential of a portion of the other side of the module base that faces the second uneven portion.

[0090] (Supplementary Note 3) The power module according to Supplementary Note 1, wherein the heat sink base has the crimped portion that faces the module base and a heat dissipation diffusion portion on which a plurality of the heat dissipation fins are provided, and the crimped portion is provided with the second uneven portion and the wall portion.

[0091] (Supplementary Note 4) The power module according to Supplementary Note 2, wherein the heat sink base has the crimped portion that faces the module base and a heat dissipation diffusion portion on which the plurality of heat dissipation fins are provided, and the second uneven portion is provided on the crimped portion.

[0092] (Supplementary Note 5) The power module according to Supplementary Note 1, wherein the wall portion is formed so that its width becomes smaller as it goes toward the heat sink base.

[0093] (Supplementary Note 6) The power module according to Supplementary Note 2, wherein the wall portion is formed so that its width becomes smaller as it goes toward the module base side.

[0094] (Supplementary Note 7) The power module according to any one of Supplementary Notes 1 to 6, wherein the first uneven portion, the second uneven portion, and the wall portion are formed to extend in the same direction.

[0095] (Supplementary Note 8) The power module according to any one of Supplementary Note 1 to Supplementary Note 6, wherein a discontinuous portion is provided in any one of the first uneven portion, the second uneven portion, and the wall portion.

[0096] (Supplementary Note 9) A method for manufacturing a power module, comprising: a step of mounting a semiconductor element on a module base, and forming a power module section by sealing the semiconductor element with a molded section while exposing a portion of the module base opposite to the side on which the semiconductor element is mounted; a step of preparing a heat sink base having a plurality of heat dissipation fin insertion grooves formed therein; a step of positioning the power module section and the heat sink base so that the portion of the module base exposed from the molded section faces the heat sink base, and positioning a plurality of heat dissipation fins in the plurality of heat dissipation fin insertion grooves; and a step of pressing the power module section toward the heat sink base while bringing a fin crimping tool into contact with the heat sink base, thereby joining the portion of the module base exposed from the molded section and the heat sink base, and crimping the heat sink base to attach the plurality of heat dissipation fins to the heat sink base, and integrating the power module section, the heat sink base, and the plurality of heat dissipation fins.

[0097] (Supplementary Note 10) A method for manufacturing a power module, comprising: a step of mounting a semiconductor element on a module base, and forming a power module part in which the semiconductor element is sealed in a molded part while exposing a part of the module base opposite to the side on which the semiconductor element is mounted; a step of preparing a heat sink in which a heat sink base and heat dissipation fins are integrated; and a step of positioning the power module part and the heat sink base so that the part of the module base exposed from the molded part faces the heat sink base, and pressing the power module part toward the heat sink base while a fin crimping tool is in contact with the heat sink base, thereby joining the part of the module base exposed from the molded part to the heat sink base.

[0098] (Supplementary Note 11) A method for manufacturing a power module, comprising: a step of mounting a semiconductor element on a module base, and forming a power module part in which the semiconductor element is sealed with a molded part while exposing a part of the module base opposite to the side on which the semiconductor element is mounted; a step of preparing a heat sink in which a heat sink base and heat dissipation fins are integrated; a step of setting the heat sink in a heat sink setting jig; and a step of positioning the power module part and the heat sink base so that the part of the module base exposed from the molded part faces the heat sink base, and pressing the power module part towards the heat sink base to join the part of the module base exposed from the molded part to the heat sink base.

[0099] (Supplementary Note 12) A power conversion device comprising: a main conversion circuit having the power module according to any one of Supplementary Note 1 to Supplementary Note 8, which converts input power and outputs the converted power; and a control circuit which outputs a control signal for controlling the main conversion circuit to the main conversion circuit.

[0100] REFERENCE SIGNS LIST 1 Power module portion, 2 Heat sink, 4 Molded portion, 5 Semiconductor element, 7 First uneven portion, 11 Second uneven portion, 12 Wall portion, 13 Heat sink base, 14 Heat dissipation fin, 22 Crimped portion, 23 Heat dissipation diffusion portion, 23a Heat dissipation fin insertion groove, 200 Power conversion device, 201 Main conversion circuit, 202 Power module, 203 Control circuit.

Claims

1. a power module section including a module base, a semiconductor element mounted on one surface of the module base, and a mold section that seals the semiconductor element; a heat sink base integrated with the other surface of the module base exposed from the molded portion; a plurality of heat dissipation fins protruding from the heat sink base on a side opposite to the module base and fixed to a crimped portion of the heat sink base; a first concave-convex portion is provided on the other surface of the module base; a second uneven portion that fits into the first uneven portion, and a wall portion that protrudes toward the module base at a position outer than the portion facing the first uneven portion.

2. a power module section including a module base, a semiconductor element mounted on one surface of the module base, and a mold section that seals the semiconductor element; a heat sink base integrated with the other surface of the module base exposed from the molded portion; a plurality of heat dissipation fins protruding from the heat sink base on a side opposite to the module base and fixed to a crimped portion of the heat sink base; a first concave-convex portion is provided on the other surface of the module base; a second concave-convex portion that fits into the first concave-convex portion is provided on a surface of the heat sink base that faces the module base; a wall portion that protrudes toward the heat sink base at a position on the other surface of the module base that is closer to the outer periphery than a portion that faces the second uneven portion;

3. the heat sink base has the crimping portion that faces the module base, and a heat dissipation and diffusion portion on which the plurality of heat dissipation fins are provided, The power module according to claim 1 , wherein the crimping portion is provided with the second uneven portion and the wall portion.

4. the heat sink base has the crimping portion that faces the module base, and a heat dissipation and diffusion portion on which the plurality of heat dissipation fins are provided, The power module according to claim 2 , wherein the second uneven portion is provided on the crimping portion.

5. The power module according to claim 1 , wherein the wall portion is formed so that its width decreases toward the heat sink base.

6. 3. The power module according to claim 2, wherein the wall portion is formed so that its width decreases toward the module base.

7. The power module according to claim 1 , wherein the first uneven portion, the second uneven portion, and the wall portion are formed so as to extend in the same direction.

8. The power module according to claim 1 , wherein a discontinuous portion is provided in any one of the first uneven portion, the second uneven portion, and the wall portion.

9. a step of mounting a semiconductor element on a module base and sealing the semiconductor element with a molded part in a state where a portion of the module base on which a first uneven portion is provided is exposed on the side opposite to the side on which the semiconductor element is mounted; and preparing a heat sink base having a plurality of heat dissipation fin insertion grooves formed therein and a second concave-convex portion that fits with the first concave-convex portion on the side opposite to the side on which the heat dissipation fin insertion grooves are formed; a step of arranging the power module unit and the heat sink base so that a portion of the module base exposed from the mold unit faces the heat sink base, and arranging a plurality of heat dissipation fins in a plurality of the heat dissipation fin insertion grooves; a step of pressing the power module unit toward the heat sink base with a fin crimping tool in contact with the heat sink base to join the portion of the module base exposed from the molded unit to the heat sink base, crimping the heat sink base to attach the plurality of heat dissipation fins to the heat sink base, and integrating the power module unit, the heat sink base, and the plurality of heat dissipation fins; A method for manufacturing a power module comprising:

10. a step of mounting a semiconductor element on a module base and sealing the semiconductor element with a molded part in a state where a portion of the module base on which a first uneven portion is provided is exposed on the side opposite to the side on which the semiconductor element is mounted; and preparing a heat sink in which a heat sink base and heat dissipation fins are integrated and a second concave-convex portion that fits into the first concave-convex portion is provided on the side opposite to the side having the heat dissipation fins; a step of positioning the power module unit and the heat sink base so that the portion of the module base exposed from the molded portion faces the heat sink base, and pressing the power module unit toward the heat sink base while bringing a fin crimping tool into contact with the heat sink base, thereby joining the portion of the module base exposed from the molded portion to the heat sink base; A method for manufacturing a power module comprising:

11. a step of mounting a semiconductor element on a module base and sealing the semiconductor element with a molded part in a state where a portion of the module base on which a first uneven portion is provided is exposed on the side opposite to the side on which the semiconductor element is mounted; and preparing a heat sink in which a heat sink base and heat dissipation fins are integrated and a second concave-convex portion that fits into the first concave-convex portion is provided on the side opposite to the side having the heat dissipation fins; setting the heat sink in a heat sink setting jig; a step of positioning the power module unit and the heat sink base so that a portion of the module base exposed from the molded portion faces the heat sink base, and pressing the power module unit toward the heat sink base to join the portion of the module base exposed from the molded portion to the heat sink base; A method for manufacturing a power module comprising:

12. a main conversion circuit having the power module according to any one of claims 1 to 6, which converts input power and outputs the converted power; a control circuit that outputs a control signal to the main conversion circuit to control the main conversion circuit; A power conversion device comprising: