Power semiconductor device

Abstract

A power semiconductor device (100) comprises: a housing (1) that has an air passage (10); a heat sink (2) that is held by the housing (1) in a state in which a plurality of fins (21) are disposed in the air passage (10); and a plurality of power modules (3). On another surface of a heat sink base (20), a relief surface (20a) is formed. The power modules (3) each have a relief part (30a) that is to be fitted to the relief surface (20a) of the heat sink base (20). The power modules (3) are disposed at intervals along the flow direction of an airflow (A) while the relief parts (30a) are fitted to the relief surface (20a) of the heat sink base (20). In power modules (3) that are adjacent to each other in the flow direction of the airflow (A), one of said power modules (3) is disposed in an offset manner with respect to the other in a direction orthogonal to the flow direction of the airflow (A).

Description

Power Semiconductor Devices

[0001] The present disclosure relates to a power semiconductor device equipped with a heat sink and a power module.

[0002] Conventionally, power semiconductor devices equipped with a heat sink and a power module have been known. For example, the power semiconductor device disclosed in Patent Document 1 includes a base, a heat sink having a plurality of fins arranged in parallel at intervals on one surface of the base, and a plurality of power semiconductor modules arranged on the other surface of the base. The power semiconductor device described in Patent Document 1 reduces temperature rise of the power semiconductor modules by blowing cooling air along the row of fins of the heat sink. The multiple power semiconductor modules are aligned diagonally with respect to the flow direction of the cooling air so that the power semiconductor modules on the downwind side are not affected by heat generated by the power semiconductor modules on the upwind side.

[0003] JP 2011-66123 A

[0004] However, in the power semiconductor device disclosed in Patent Document 1, multiple power semiconductor modules are aligned diagonally with respect to the flow direction of the cooling air, and therefore, considering the area of ​​the base on which the power semiconductor modules are mounted, it is difficult to arrange the power semiconductor modules with sufficient spacing between them, and there is a risk that the power semiconductor module on the downwind side will be affected by the heat generated by the power semiconductor module on the upwind side.

[0005] The present disclosure has been made in view of the above, and has an object to provide a power semiconductor device in which a power semiconductor module on the downwind side is less susceptible to the influence of heat generated by a power semiconductor module on the upwind side.

[0006] In order to solve the above-mentioned problems and achieve the object, the power semiconductor device according to the present disclosure includes a housing having an airflow path formed with an inlet and an outlet for an airflow facing each other, a heatsink having a flat heatsink base and a plurality of flat fins arranged in parallel at intervals on one surface of the heatsink base, the heatsink being held in the housing with the fins arranged in the airflow path, and a plurality of power modules provided on the other surface of the heatsink base. The other surface of the heatsink base has an uneven surface. The power modules have uneven portions that fit into the uneven surface of the heatsink base, and the uneven portions are fitted into the uneven surface of the heatsink base and are provided at intervals along the direction of travel of the airflow, and one power module adjacent to the direction of travel of the airflow is offset from the other adjacent power module in a direction perpendicular to the direction of travel of the airflow.

[0007] The power semiconductor device according to the present disclosure has the effect that the power semiconductor module on the downwind side is less susceptible to the influence of heat generated by the power semiconductor module on the upwind side.

[0008] 1A plan view showing a power semiconductor device according to a first embodiment; sectional view taken along the line II-II in FIG. 1; sectional view taken along the line III-III in FIG. 1A plan view showing a power semiconductor device according to a first comparative example; sectional view taken along the line V-V in FIG. 4A; sectional view showing a temperature distribution of air flowing from an inlet to an outlet in the power semiconductor device according to a first comparative example; sectional view taken along the line IX-IX in FIG. 8A; sectional view taken along the line X-X in FIG. 8A; 14A plan view showing a mounting plate of the power semiconductor device according to the second embodiment; sectional view taken along the arrows XV-XV shown in FIG. 14A plan view showing a mounting plate of the power semiconductor device according to the second embodiment; sectional view taken along the arrows XIX-XIX shown in FIG. 18A plan view showing a mounting plate of the power semiconductor device according to the third embodiment; sectional view taken along the arrows XIX-XIX shown in FIG. 18A plan view showing a mounting plate of the power semiconductor device according to the third embodiment; sectional view showing a modification of the power semiconductor device according to the third embodiment; sectional view showing a mounting plate of the modification of the power semiconductor device according to the third embodiment; sectional view showing a schematic diagram of a power semiconductor device according to the fourth embodiment; sectional view showing a schematic diagram of a modification 1 of the power semiconductor device according to the fourth embodiment; sectional view showing a schematic diagram of a modification 2 of the power semiconductor device according to the fourth embodiment.

[0009] Hereinafter, power semiconductor devices according to embodiments of the present disclosure will be described in detail with reference to the drawings.

[0010] First Embodiment Fig. 1 is a plan view of a power semiconductor device according to a first embodiment. The outline arrows in Fig. 1 indicate the direction of travel of airflow A. Fig. 2 is a cross-sectional view taken along the line II-II in Fig. 1. Fig. 3 is a cross-sectional view taken along the line III-III in Fig. 1. Note that some hatching has been omitted from the cross-sectional view to make it easier to see the components of the power module 3.

[0011] As shown in FIGS. 1 to 3, a power semiconductor device 100 according to the first embodiment includes a housing 1, a heat sink 2, a plurality of power modules 3, and a cooling fan 4.

[0012] As shown in FIGS. 1 to 3 , the housing 1 forms an air passage 10 in which an inlet 10a and an outlet 10b for an air flow A face each other, and holds a heat sink-integrated power module in which a heat sink 2 and a plurality of power modules 3 are integrated. The housing 1 is concave and has a bottom surface 11 and a pair of side surfaces 12. The housing 1 has open ends extending along the direction of travel of the air flow A, with one open end serving as the inlet 10a for the air flow A and the other open end serving as the outlet 10b for the air flow A. The air passage 10 is a space surrounded by the bottom surface 11 and the pair of side surfaces 12. In the example shown in FIG. 1 , the air flow A travels from the inlet 10a to the outlet 10b. However, this is not limited thereto. The outlet 10b may be the inlet, the inlet 10a where the cooling fan 4 is located may be the outlet, and the air flow may travel in the opposite direction from the outlet 10b to the inlet 10a.

[0013] The housing 1 is made of plated steel sheet. Plated steel sheet is a material that has the rigidity to hold the heat sink-integrated power module and can be made thin and lightweight. However, the housing 1 may be made of a material other than plated steel sheet.

[0014] The heat sink 2 is integrated with the multiple power modules 3 and dissipates heat generated by the power modules 3. As shown in Figures 2 and 3, the heat sink 2 has a flat heat sink base 20 and multiple flat fins 21 arranged in parallel at intervals on one surface of the heat sink base 20. As an example, the heat sink 2 is a crimped heat sink in which the heat sink base 20 and the fins 21 are integrated by crimping. The heat sink 2 is held in the housing 1 with the multiple fins 21 arranged in the air passage 10.

[0015] The heat sink base 20 has a rectangular shape, for example. The heat sink base 20 is made of a metal material with relatively high thermal conductivity so that heat generated by the power module 3 can be efficiently transferred to the fins 21. The heat sink base 20 is made of a corrosion-resistant metal material, for example, aluminum or an aluminum alloy. The heat sink base 20 is manufactured by a processing method such as cutting, die-casting, forging, or extrusion.

[0016] On the other surface of the heat sink base 20, an uneven surface 20a is formed in one region where the plurality of power modules 3 are provided, with recesses and protrusions extending along the direction of travel of the airflow A. The one region where the plurality of power modules 3 are provided is, for example, the entire surface of the other surface of the heat sink base 20.

[0017] With the plurality of fins 21 housed inside the concave-shaped housing 1, the heat sink base 20 is placed at its outer periphery on the upper end surface of the side surface portion 12 and fixed to the side surface portion 12 with joining members (not shown) such as screws. Note that the side surface portion 12 is provided with screw holes (not shown) for inserting screws or the like. The heat sink base 20 is also provided with screw holes or through holes (not shown) at positions corresponding to the screw holes provided in the side surface portion 12.

[0018] The fins 21 are heat dissipation components made of rectangular thin plates. The fins 21 are made of a metal material with relatively high thermal conductivity so as to be able to dissipate heat generated by the power module 3. As an example, the fins 21 are made of a metal material that is resistant to corrosion, such as aluminum or an aluminum alloy. By using a rolled material of a metal material such as aluminum for the fins 21, it is possible to achieve both workability and heat dissipation properties for the fins 21.

[0019] Each of the multiple fins 21 is inserted into a fin insertion groove (not shown) formed on one surface of the heatsink base 20 and fixed to the heatsink base 20 by crimping. If the heatsink 2 is a crimped heatsink, there are no processing restrictions on the aspect ratio in die-casting and extrusion processes, so the fins 21 can be designed freely and heat dissipation capacity can be improved. However, the heatsink 2 is not limited to a crimped heatsink and may be manufactured by other processing methods. For example, the heatsink 2 may be manufactured by integrally manufacturing the fins 21 and the heatsink base 20 by extrusion or die-casting. Furthermore, in a heatsink-integrated power module, a heatsink 2 manufactured by cutting or forging may be used.

[0020] The power module 3 is a power semiconductor module and is a resin mold type. As shown in Fig. 1, a plurality of power modules 3 are provided at intervals along the direction of travel of the air flow A. In the power semiconductor device 100 shown in Fig. 1, six power modules 3 are mounted, arranged in two columns and three rows, as an example. The number of power modules 3 is not limited to six as shown, and two or more power modules 3 may be arranged at intervals along the direction of travel of the air flow A.

[0021] 1 , in the power semiconductor device 100 according to the first embodiment, one power module 3 adjacent to the direction of travel of the air flow A is offset from the other adjacent power module 3 in a direction X perpendicular to the direction of travel of the air flow A. Specifically, of the three power modules 3 provided along the direction of travel of the air flow A, the middle power module 3 is offset from the windward-most power module 3 and the leeward-most power module 3 in the direction X perpendicular to the direction of travel of the air flow A.

[0022] As shown in Figures 1 to 3, the power module 3 includes a fin base 30, an insulating material 31, a metal conductor 32, a semiconductor element 33, a bonding material 34, a wiring wire 35, a control terminal 36, a main terminal 37, and a sealing material 38.

[0023] The fin base 30 is a rectangular flat plate smaller than the heat sink base 20, and is a connecting component for connecting the power module 3 to the heat sink 2. The fin base 30 is made of a metal material with relatively high thermal conductivity so that heat generated by the power module 3 can be efficiently transferred to the heat sink 2. The fin base 30 is made of a corrosion-resistant metal material, such as aluminum or an aluminum alloy, for example. The fin base 30 is produced by a processing method such as cutting, die-casting, forging, or extrusion.

[0024] The fin base 30 has a surface facing the heat sink base 20, on which an uneven portion 30a is formed that fits into the uneven surface 20a of the heat sink base 20. The power module 3 is integrated with the heat sink 2 by fitting the uneven portion 30a of the fin base 30 to the uneven surface 20a of the heat sink base 20 by press working. The power module 3 can be freely positioned within the area where the uneven surface 20a is formed. The power module 3 is also a greaseless power module, meaning that no thermally conductive grease is used between the power module 3 and the heat sink 2. Greaseless power modules can improve the heat dissipation performance of heat generated in the power module 3 compared to power modules that use thermally conductive grease, and are therefore suitable for use in power semiconductor devices with large power capacities. Furthermore, since no thermally conductive grease is used in the power semiconductor device 100, replacing the power module 3 does not require processes such as removing and replacing the thermally conductive grease, improving productivity and maintainability.

[0025] The materials of the heat sink base 20, the fins 21, and the fin base 30 are not limited to the aluminum-based materials described above, and may be other materials. That is, the material combination of the heat sink base 20, the fins 21, and the fin base 30 may be a combination of materials different from those described above. For example, by making the fins 21 out of a copper-based plate component having a higher thermal conductivity than an aluminum-based material, the heat dissipation capability of the fins 21 is further improved compared to when the fins 21 are plate components made of an aluminum-based material.

[0026] The insulating material 31 is an insulating sheet having heat dissipation properties. The insulating material 31 is fixed to the other surface of the fin base 30. The insulating material 31 insulates the components of the power module 3 sealed by the sealing material 38 from the heat sink base 20, and also dissipates heat generated by the semiconductor element 33 to the heat sink base 20. The insulating material 31 has heat dissipation properties equal to or greater than those of the sealing material 38.

[0027] The metal conductor 32 is a substrate on which the semiconductor element 33 is mounted, and dissipates heat generated by the semiconductor element 33 to the insulating material 31 .

[0028] The semiconductor element 33 is a semiconductor element for power control. Examples of the semiconductor element 33 include a rectifier diode, a power transistor, a thyristor, and an IGBT (Insulated Gate Bipolar Transistor). The semiconductor element 33 is exemplified by an element formed of silicon (Si) or an element formed of a wide bandgap semiconductor having a bandgap larger than that of silicon. Examples of wide bandgap semiconductors are silicon carbide (SiC), gallium nitride-based materials, and diamond. The semiconductor element 33 using a wide bandgap semiconductor has a high allowable current density and low power loss, allowing the power module 3 to be miniaturized, and therefore the heat sink 2 and the power semiconductor device 100 to be miniaturized.

[0029] The bonding material 34 is, for example, solder, and bonds the metal conductor 32 and the semiconductor element 33. The semiconductor element 33 is die-bonded to the metal conductor 32 using the bonding material 34. Note that the bonding material 34 is not limited to solder, and may have other configurations.

[0030] The wiring wires 35 electrically connect the semiconductor elements 33 to each other and also electrically connect the semiconductor elements 33 to the main terminals 37 .

[0031] The control terminal 36 and the main terminal 37 are connected to the semiconductor element 33 to supply power to the semiconductor element 33 or to transmit signals between the semiconductor element 33 and an external device.

[0032] The sealing material 38 is made of a thermosetting resin such as epoxy, and ensures insulation between the components of the power module 3. The sealing material 38 is a transfer mold formed by transfer molding, for example. However, the sealing material 38 is not limited to a thermosetting resin. Furthermore, the molding method of the sealing material 38 is not limited to transfer molding.

[0033] The cooling fan 4 generates an airflow A that flows from the inlet 10a to the outlet 10b of the housing 1. The cooling fan 4 is provided at the inlet 10a of the housing 1. The cooling fan 4 may be attached to the housing 1 by providing a fan attachment structure in a part of the housing 1 and attaching the cooling fan 4 thereto, or by providing an attachment member separate from the housing 1 at the inlet 10a and attaching the cooling fan 4 thereto.

[0034] Fig. 4 is a plan view showing the power semiconductor device of Comparative Example 1. Fig. 5 is a cross-sectional view taken along the line VV shown in Fig. 4. Fig. 6 is a contour diagram showing the temperature distribution of air flowing from the inlet to the outlet in the power semiconductor device of Comparative Example 1.

[0035] 4 and 5, a plurality of power modules 3 are provided at intervals along the direction of airflow A. For example, the power modules 3 are arranged in two columns and three rows, aligned along the direction of airflow A. In this case, as shown in FIG. 6, the temperature of the air flowing between the fins 21 of the heat sink 2 increases continuously from the upwind side to the downwind side. That is, the semiconductor elements 33 of the downwind power module 3 are affected by heat generated by the semiconductor elements 33 of the upwind power module 3, resulting in a rise in the temperature of the downwind power module 3 due to thermal interference.

[0036] 1 , in the power semiconductor device 100 according to the first embodiment, one power module 3 adjacent to the direction of travel of the air flow A is arranged offset in a direction X perpendicular to the direction of travel of the air flow A relative to the other adjacent power module 3. Specifically, of the three power modules 3 arranged along the direction of travel of the air flow A, the middle power module 3 is arranged offset in the direction X perpendicular to the direction of travel of the air flow A relative to the power module 3 on the windward side and the power module 3 on the leeward side.

[0037] 7 is a contour diagram showing the temperature distribution of air flowing from the inlet to the outlet in the power semiconductor device according to the first embodiment. As shown in FIG. 7, the power semiconductor device 100 according to the first embodiment can reduce cumulative thermal interference, so that the semiconductor elements 33 of the power module 3 on the downwind side are less susceptible to the heat generated by the semiconductor elements 33 of the power module 3 on the upwind side, and low-temperature air can be sent to the downwind side. Therefore, the power semiconductor device 100 according to the first embodiment can effectively suppress the temperature rise of the power module 3.

[0038] Fig. 8 is a plan view showing the power semiconductor device of Comparative Example 2. Fig. 9 is a cross-sectional view taken along the line IX-IX shown in Fig. 8. Fig. 10 is a cross-sectional view taken along the line XX shown in Fig. 8.

[0039] 8 to 10 , a plurality of uneven surfaces 20a, in which recesses and protrusions extend along the direction of travel of the airflow A, are formed for each power module 3 on the other surface of the heatsink base 20. The power module 3 has a fin base 30 on which uneven portions 30a are formed to fit into the uneven surface 20a of the heatsink base 20. In the power semiconductor device 100B, the positions of the power modules 3 to be installed on the heatsink base 20 are determined at the design stage of the uneven surface 20a, and therefore, if it becomes necessary to change the arrangement of the power modules 3 after the design, a new heatsink base 20 must be fabricated.

[0040] 1 , in the power semiconductor device 100 according to the first embodiment, an uneven surface 20a is formed on the other surface of the heat sink base 20. The power module 3 has a fin base 30 on which an uneven portion 30a that fits into the uneven surface 20a of the heat sink base 20 is formed. That is, in the power semiconductor device 100 according to the first embodiment, the power module 3 can be freely arranged within the region where the uneven surface 20a of the heat sink base 20 is formed, which allows for a high degree of freedom in design and can increase the productivity of the heat sink-integrated power module.

[0041] FIG. 11 is a plan view of a power semiconductor device according to the first embodiment, showing a first modified example of the uneven surface. FIG. 12 is a plan view of a power semiconductor device according to the first embodiment, showing a second modified example of the uneven surface. FIG. 13 is a plan view of a power semiconductor device according to the first embodiment, showing a third modified example of the uneven surface. The uneven surface 20 a of the heat sink base 20 is not limited to the configuration in which the recesses and protrusions extend along the direction of travel of the air flow A as shown in FIG. 1 . As shown in FIG. 11 , the uneven surface 20 a may be configured so that the recesses and protrusions extend along a direction intersecting the direction of travel of the air flow A, such as a direction perpendicular to the direction of travel of the air flow A. Furthermore, the recesses and protrusions are not limited to the continuous configuration shown in FIG. 1 , but may be configured intermittently along the extending direction as shown in FIG. 12 . Furthermore, as shown in FIG. 13 , the uneven surface 20 a may be configured, for example, so that dot-like protrusions are aligned, or may have other configurations. In short, the uneven surface 20a may have a configuration in which the uneven portions 30a of the power module 3 fit, and the shapes, orientations, and ranges of the recesses and protrusions may be appropriately changed depending on the configuration of the power semiconductor device 100. In this case, the uneven portions 30a of the power module 3 are formed in accordance with the configuration of the uneven surface 20a.

[0042] Second Embodiment Next, a power semiconductor device 101 according to a second embodiment will be described. Fig. 14 is a plan view showing a power semiconductor device according to the second embodiment. Fig. 15 is a cross-sectional view taken along the line XV-XV in Fig. 14. Fig. 16 is a cross-sectional view taken along the line XVI-XVI in Fig. 14. Fig. 17 is a plan view showing a mounting plate of the power semiconductor device according to the second embodiment. Note that some hatching has been omitted in the cross-sectional view to make it easier to see the components of the power module 3.

[0043] 14 to 16 , the housing 1 of the power semiconductor device 101 according to the second embodiment has a configuration in which a plurality of openings 14a are formed at intervals along the direction of travel of the airflow A on one surface that forms the airflow path 10. Specifically, the housing 1 has a concave-shaped housing 13 formed by a bottom surface portion 11 and a pair of side surfaces 12, and a mounting plate 14 that is disposed opposite the bottom surface portion 11 and covers the opening of the housing 13. The housing 1 is formed into a rectangular cylindrical shape by the housing 13 and the mounting plate 14. Both ends of the housing 1 that extend along the direction of travel of the airflow A are open, with one open end serving as an inlet 10a for the airflow A blown from the cooling fan 4 and the other open end serving as an outlet 10b for the airflow A. The airflow path 10 is a space surrounded by the housing 13 and the mounting plate 14. In the example shown in Figure 14, the direction of travel of the air flow A is from the inlet 10a to the outlet 10b, but this is not limited to this.The air flow A may also travel in the opposite direction, from the outlet 10b to the inlet 10a, with the outlet 10b serving as the inlet and the inlet 10a where the cooling fan 4 is located serving as the outlet.

[0044] The housing 13 and the mounting plate 14 are made of plated steel plate. Plated steel plate is a material that has the rigidity to hold the heat sink-integrated power module and can be made thin and lightweight. However, the housing 13 and the mounting plate 14 may be made of a material other than plated steel plate.

[0045] The outer peripheral edge of the mounting plate 14 is placed on the upper end surface of the side surface portion 12, and the mounting plate 14 is fixed to the side surface portion 12 with connecting members (not shown) such as screws. The side surface portion 12 is provided with screw holes (not shown) for threading connecting members such as screws. The mounting plate 14 also has screw holes or through holes (not shown) at positions corresponding to the screw holes provided in the side surface portion 12.

[0046] 17, the mounting plate 14 has three openings 14a of the same shape and size aligned at intervals along the direction of travel of the air flow A. As an example, when the power semiconductor device 101 is viewed in plan, the openings 14a have a rectangular shape that is long in a direction X perpendicular to the direction of travel of the air flow A.

[0047] As shown in FIG. 14 , the heat sink 2 is provided individually for each opening 14 a, and as shown in FIGS. 15 and 16 , the heat sink 2 is supported by the housing 1 with the fins 21 fitted through the openings 14 a and placed in the air passage 10. The heat sink 2 is formed to fit the size and shape of the openings 14 a. With the fins 21 fitted through the openings 14 a and placed in the air passage 10, the outer peripheral edge of the heat sink base 20 is placed on the upper surface of the mounting plate 14 and fixed to the mounting plate 14 with connecting members (not shown) such as screws. The mounting plate 14 is provided with screw holes (not shown) for threading the connecting members such as screws. The heat sink base 20 also has screw holes or through holes (not shown) at positions corresponding to the screw holes provided in the mounting plate 14.

[0048] Two power modules 3 arranged side by side are integrated into the individualized heat sink 2. That is, the power semiconductor device 101 according to the second embodiment has a configuration in which the heat sink 2 is partially omitted compared to the configuration of the first embodiment, and therefore the weight of the device can be reduced. Furthermore, in the power semiconductor device 101 according to the second embodiment, if a power module 3 fails, it is only necessary to replace the heat sink 2 on which the failed power module 3 is mounted, thereby improving maintainability.

[0049] Also in the power semiconductor device 101 according to the second embodiment, one power module 3 adjacent to the direction of travel of the air flow A is arranged offset in the direction X perpendicular to the direction of travel of the air flow A relative to the other adjacent power module 3. Specifically, of the three power modules 3 provided along the direction of travel of the air flow A, the middle power module 3 is arranged offset in the direction X perpendicular to the direction of travel of the air flow A relative to the power module 3 on the windward side and the power module 3 on the leeward side.

[0050] As a result, the power semiconductor device 101 according to the second embodiment can reduce cumulative thermal interference, so that the semiconductor elements 33 of the power module 3 on the downwind side are less susceptible to the heat generated by the semiconductor elements 33 of the power module 3 on the upwind side, and low-temperature air can be sent to the downwind side. Therefore, the power semiconductor device 101 according to the second embodiment can effectively suppress the temperature rise of the power module 3.

[0051] Furthermore, in the power semiconductor device 101 according to the second embodiment, the power module 3 can be freely positioned within the area where the uneven surface 20a of the heat sink base 20 is formed, which allows for a high degree of freedom in design and can increase the productivity of the heat sink-integrated power module.

[0052] Although the housing 13 and the mounting plate 14 are formed as separate members and then joined together, they may be integrally molded as a single member. The number of openings 14 a is not limited to three as shown in the figure, and may be two, four, or more. The shape of the openings 14 a is not limited to a rectangular shape elongated in the direction X perpendicular to the direction of travel of the airflow A, and may be another shape such as a square, or may be a rectangular shape elongated along the direction of travel of the airflow A. The number of power modules 3 provided in one individualized heat sink 2 is not limited to two as shown in the figure, and may be one, or three or more.

[0053] Third Embodiment Next, power semiconductor devices 102 and 102A according to a third embodiment will be described. Fig. 18 is a plan view showing the power semiconductor device according to the third embodiment. Fig. 19 is a cross-sectional view taken along the line XIX-XIX shown in Fig. 18. Fig. 20 is a plan view showing a mounting plate of the power semiconductor device according to the third embodiment.

[0054] 18 to 20 , the housing 1 of the power semiconductor device 102 according to the third embodiment has a configuration in which a plurality of openings 14a are formed at intervals along the direction of travel of the airflow A on one surface that forms the airflow path 10. Specifically, the housing 1 has a concave-shaped housing 13 formed by a bottom surface portion 11 and a pair of side surfaces 12, and a mounting plate 14 that is disposed opposite the bottom surface portion 11 and covers the opening of the housing 13. The housing 1 is formed into a rectangular cylindrical shape by the housing 13 and the mounting plate 14. Both ends of the housing 1 that extend along the direction of travel of the airflow A are open, with one open end serving as an inlet 10a for the airflow A blown from the cooling fan 4 and the other open end serving as an outlet 10b for the airflow A. The airflow path 10 is a space surrounded by the housing 13 and the mounting plate 14. In the example shown in Figure 18, the direction of travel of the air flow A is from the inlet 10a to the outlet 10b, but this is not limited to this.The air flow A may also travel in the opposite direction, from the outlet 10b to the inlet 10a, with the outlet 10b serving as the inlet and the inlet 10a where the cooling fan 4 is located serving as the outlet.

[0055] The housing 13 and the mounting plate 14 are made of plated steel plate. Plated steel plate is a material that has the rigidity to hold the heat sink 2 integrated with the multiple power modules 3 and can be made thin and lightweight. However, the housing 13 and the mounting plate 14 may be made of a material other than plated steel plate.

[0056] The outer peripheral edge of the mounting plate 14 is placed on the upper end surface of the side surface portion 12, and the mounting plate 14 is fixed to the side surface portion 12 with connecting members (not shown) such as screws. The side surface portion 12 is provided with screw holes (not shown) for threading connecting members such as screws. The mounting plate 14 also has screw holes or through holes (not shown) at positions corresponding to the screw holes provided in the side surface portion 12.

[0057] Furthermore, a plurality of openings 14a are formed in the mounting plate 14 at intervals along the direction of travel of the air flow A. The plurality of openings 14a are arranged in a plurality of rows. In the third embodiment, the openings 14a are, for example, arranged in two columns and three rows, and are aligned along the direction of travel of the air flow A. As shown in FIG. 20 , the openings 14a are, for example, rectangular in shape and elongated in the direction X perpendicular to the direction of travel of the air flow A.

[0058] As shown in FIG. 18 , the heat sink 2 is provided individually for each opening 14 a, and as shown in FIG. 19 , the heat sink 2 is supported on the housing 1 with the fins 21 fitted through the openings 14 a and placed in the air passage 10. The heat sink 2 is formed to fit the size and shape of the openings 14 a. With the fins 21 fitted through the openings 14 a and placed in the air passage 10, the heat sink base 20 has its outer edge placed on the upper surface of the mounting plate 14 and is fixed to the mounting plate 14 with connecting members (not shown) such as screws. The mounting plate 14 has screw holes (not shown) for threading the connecting members such as screws. The heat sink base 20 also has screw holes or through holes (not shown) at positions corresponding to the screw holes provided in the mounting plate 14.

[0059] Each of the separated heat sinks 2 is provided with one power module 3 integrated therewith. That is, the power semiconductor device 102 according to the third embodiment has a configuration in which the heat sinks 2 are partially omitted compared to the configuration of the first embodiment, and therefore the weight of the device can be reduced. Furthermore, in the case of the power semiconductor device 102 according to the third embodiment, if a power module 3 fails, it is only necessary to replace the heat sink 2 on which the failed power module 3 is mounted, thereby improving maintainability.

[0060] Also in the power semiconductor device 102 according to the third embodiment, one of the power modules 3 adjacent to each other in the traveling direction of the air flow A is arranged offset from the other adjacent power module 3 in the direction X perpendicular to the traveling direction of the air flow A. Specifically, of the three power modules 3 provided along the traveling direction of the air flow A, the middle power module 3 is arranged offset from the windward-most power module 3 and the leeward-most power module 3 in the direction X perpendicular to the traveling direction of the air flow A.

[0061] As a result, the power semiconductor device 102 according to the third embodiment can reduce cumulative thermal interference, so that the semiconductor elements 33 of the power module 3 on the downwind side are less susceptible to the heat generated by the semiconductor elements 33 of the power module 3 on the upwind side, and low-temperature air can be sent to the downwind side. Therefore, the power semiconductor device 102 according to the third embodiment can effectively suppress a temperature rise in the power module 3.

[0062] Furthermore, in the power semiconductor device 102 according to the third embodiment, the power module 3 can be freely positioned within the area where the uneven surface 20a of the heat sink base 20 is formed, which allows for a high degree of freedom in design and can increase the productivity of the heat sink-integrated power module.

[0063] Although the housing 13 and the mounting plate 14 are formed as separate members and then joined together, they may also be integrally molded as a single member. The number of openings 14 a is not limited to six as shown in the figure, as long as there are two or more in each row. The shape of the openings 14 a is not limited to a rectangular shape elongated in the direction X perpendicular to the direction of travel of the air flow A, but may be another shape such as a square, or may be a rectangular shape elongated along the direction of travel of the air flow A.

[0064] 21 is a plan view showing a modification of the power semiconductor device according to the third embodiment. FIG. 22 is a plan view showing a mounting plate of the modification of the power semiconductor device according to the third embodiment. The power semiconductor device 102A shown in FIGS. 21 and 22 has a configuration in which one of the openings 14a adjacent to each other in the traveling direction of the air flow A is offset in a direction X perpendicular to the traveling direction of the air flow A relative to the other adjacent opening 14a. Specifically, of the three openings 14a formed along the path from the inlet 10a to the outlet 10b, the middle opening 14a is offset in a direction X perpendicular to the traveling direction of the air flow A relative to the windward opening 14a and the leeward opening 14a.

[0065] With this configuration, simply by fitting and installing heat sink-integrated power modules of the same structure into the opening 14a of the mounting plate 14, one power module 3 adjacent to the direction of travel of the air flow A can be offset in the direction X perpendicular to the direction of travel of the air flow A relative to the other adjacent power module 3.

[0066] Fourth Embodiment Next, power semiconductor devices 103, 103A, and 103B according to the fourth embodiment will be described. FIG. 23 is a longitudinal cross-sectional view schematically illustrating the power semiconductor device according to the fourth embodiment. As shown in FIG. 23, the power semiconductor device 103 according to the fourth embodiment differs from the configurations described in the second and third embodiments in the configuration of the bottom surface 11 of the housing 1. The other configurations are the same as those described in the second or third embodiment. The housing 1 according to the fourth embodiment has a surface forming the air passage 10, on which a plurality of openings 14a are formed at intervals along the direction of travel of the air flow A. The heat sink 2 is provided individually for each opening 14a, and the fins 21 are fitted into the openings 14a and supported by the housing 1 in a state where they are arranged in the air passage 10.

[0067] As shown in Figure 23, the housing 1 has a bottom surface 11 facing the fins 21 of the heat sink 2, with an inclined surface 11a extending from an inlet 10a, which forms one end of the direction of travel of the airflow A, toward the outlet 10b, which forms the other end, and approaching the fins 21. The inclined surface 11a extends from the inlet 10a to just before the heat sink-integrated power module on the most downwind side, and then becomes a horizontal surface 11b extending parallel to the fins 21 to the outlet 10b. That is, the air passage 10 is configured so that its cross-sectional area decreases from the upwind side to the downwind side, reaching a minimum just before the heat sink-integrated power module on the most downwind side, and then maintaining the same cross-sectional area up to the outlet 10b. Note that the horizontal surface 11b does not need to be strictly horizontal; it may be slightly inclined as long as it is roughly horizontal.

[0068] With this configuration, the airflow B, which flows between the bottom surface portion 11 and the fins 21 and experiences almost no temperature increase, can be made to flow in large amounts between the fins 21 of the heat sink 2 located on the downwind side, effectively reducing the temperature increase of the power module 3 located on the downwind side. Note that the inclined surface 11a is not limited to a configuration formed from the inlet 10a to just before the heat sink-integrated power module located furthest downwind, but may be formed up to just before the heat sink-integrated power module located in the middle. Furthermore, the inclined surface 11a may be formed continuously from the inlet 10a to the outlet 10b, for example, or may be formed in a stepped inclined configuration in combination with the horizontal surface 11b.

[0069] Fig. 24 is a longitudinal cross-sectional view schematically showing a first modification of the power semiconductor device according to the fourth embodiment. In the power semiconductor device 103A shown in Fig. 24, a bottom surface 11 facing the fins 21 of the heat sink 2 is configured to have an inclined surface 11a that approaches the fins 21 from the outlet 10b that forms one end side in the traveling direction of the air flow A toward the inlet 10a that forms the other end side. That is, the direction of the air flow A in the power semiconductor device 103A shown in Fig. 24 is opposite to that of the power semiconductor device 103 shown in Fig. 23.

[0070] In this way, even in the power semiconductor device 103A shown in Figure 24, the air that flows between the bottom surface portion 11 and the fins 21 and experiences almost no temperature increase can be made to flow in large amounts between the fins 21 of the heat sink 2 located on the downwind side, thereby effectively reducing the heat generation of the power module 3 located on the downwind side.

[0071] Fig. 25 is a longitudinal cross-sectional view schematically showing a second modification of the power semiconductor device according to the fourth embodiment. The power semiconductor device 103B shown in Fig. 25 applies the features of the fourth embodiment described with reference to Fig. 23 to the configuration of the first embodiment. That is, the power semiconductor device 103B has a configuration in which a plurality of power modules 3 are provided on one heat sink 2, and an inclined surface 11a is formed on the bottom surface 11 of the housing 1. Although not shown, the inclined surface 11a of the power semiconductor device 103A shown in Fig. 24 may be applied to the configuration of the first embodiment.

[0072] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or different embodiments may be combined with each other. It is also possible to omit or modify parts of the configurations as long as they do not deviate from the gist of the invention.

[0073] REFERENCE SIGNS LIST 1 Housing, 2 Heat sink, 3 Power module, 4 Cooling fan, 10 Air passage, 10a Inlet, 10b Outlet, 11 Bottom surface, 11a Inclined surface, 11b Horizontal surface, 12 Side surface, 13 Housing, 14 Mounting plate, 14a Opening, 20 Heat sink base, 20a Concave and convex surface, 21 Fin, 30 Fin base, 30a Concave and convex portion, 31 Insulating material, 32 Metal conductor, 33 Semiconductor element, 34 Bonding material, 35 Wiring wire, 36 Control terminal, 37 Main terminal, 38 Sealing material, 100, 100A, 100B, 101, 102, 102A, 103, 103A, 103B Power semiconductor device, A, B Air flow.

Claims

1. A power semiconductor device comprising: a housing having an air passage formed with an inlet and an outlet for an air flow facing each other; a heat sink having a flat heat sink base and a plurality of flat fins arranged in parallel at intervals on one side of the heat sink base, the heat sink being held in the housing with the plurality of fins arranged in the air passage; and a plurality of power modules provided on the other side of the heat sink base, wherein an uneven surface is formed on the other side of the heat sink base, the power modules have uneven portions that fit into the uneven surface of the heat sink base, the uneven portions are fitted into the uneven surface of the heat sink base, and the power modules are provided at intervals along the traveling direction of the air flow, and one of the power modules adjacent to each other in the traveling direction of the air flow is offset in a direction perpendicular to the traveling direction of the air flow relative to the other adjacent power module.

2. The power semiconductor device according to claim 1, characterized in that the uneven surface is formed so that the concave and convex portions extend along the direction of air flow.

3. The power semiconductor device according to claim 1, characterized in that the uneven surface is formed so that the recesses and protrusions extend in a direction intersecting the direction of travel of the air flow.

4. The power semiconductor device according to any one of claims 1 to 3, characterized in that the recesses and protrusions are formed continuously or intermittently along the extending direction.

5. The power semiconductor device according to claim 1, characterized in that the uneven surface is configured with aligned dot-shaped protrusions.

6. A power semiconductor device as claimed in any one of claims 1 to 5, characterized in that the housing has a plurality of openings formed on one side forming the air passage at intervals along the direction of travel of the air flow, the heat sink is provided as an individual piece for each opening, and the fins are fitted into the openings and positioned in the air passage and held in the housing.

7. The power semiconductor device according to claim 6, wherein the plurality of openings are aligned along the direction of travel of the air flow.

8. The power semiconductor device according to claim 6, characterized in that one of the openings adjacent to each other in the direction of travel of the air flow is formed offset in a direction perpendicular to the direction of travel of the air flow relative to the other of the openings adjacent to each other.

9. The power semiconductor device according to any one of claims 6 to 8, characterized in that the power modules are provided one by one on each of the individual heat sinks.

10. The power semiconductor device according to any one of claims 6 to 9, characterized in that the openings formed at intervals along the direction of travel of the air flow are configured in a plurality of rows.

11. A power semiconductor device as claimed in any one of claims 1 to 10, characterized in that the housing has a bottom surface facing the fins of the heat sink, the bottom surface having an inclined surface that approaches the fins from one end side to the other end side in the direction of travel of the air flow.

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