Semiconductor device and method for producing semiconductor device

Abstract

A semiconductor device comprising: a heat sink having a flat plate-like part and a plurality of fins that protrude from the flat plate-like part; a semiconductor module joined to the flat plate-like part in a state of being laminated on the flat plate-like part; a housing for housing the fins; an inflow port for allowing a liquid to flow into the housing; an outflow port for allowing the liquid to flow out of the housing; an inflow passage for allowing the liquid to flow into between the plurality of fins from the inflow port; and an outflow passage for allowing the liquid to flow out from between the plurality of fins to the outflow port, wherein at least one of the inflow port, the outflow port, the inflow passage, and the outflow passage overlaps the fins in the lamination direction of the heat sink and the semiconductor module.

Description

Semiconductor device and method for manufacturing the same

[0001] The present invention relates to a semiconductor device and a method for manufacturing the same.

[0002] The liquid-cooling device described in Patent Document 1 includes a casing in which a coolant flow path is provided and an opening is formed in either the top wall or the bottom wall, and a radiator disposed in the casing. The radiator of this liquid-cooling device includes a heat dissipation substrate that is larger than the opening of the casing, has a first surface facing the coolant flow path, and a heat-generating body attachment portion for attaching a heat-generating body to the second surface. The radiator of the liquid-cooling device further includes a plurality of heat dissipation fins integrally provided on the first surface of the heat dissipation substrate so as to protrude into the coolant flow path. The heat dissipation substrate of the radiator of the liquid-cooling device is disposed inside the first wall having the opening among the top wall and the bottom wall of the casing so as to close the opening, and the peripheral portion of the second surface of the heat dissipation substrate is brazed to the portion around the opening on the inner surface of the first wall of the casing, and the heat-generating body attachment portion on the second surface is exposed outside the casing through the opening. Also, at least a part of the tip portions of the heat dissipation fins of the liquid-cooling device are brazed to the inner surface of the second wall that does not have an opening among the top wall and the bottom wall of the casing.

[0003] Japanese Patent Application Laid-Open No. 2017-017133

[0004] For example, in the liquid-cooling device described in Patent Document 1, the coolant inlet and the inlet header portion are located upstream of the heat dissipation fins, and the coolant outlet and the outlet header portion are located downstream of the heat dissipation fins. When the heat dissipation fins are arranged to extend in a direction intersecting the flow of the coolant with respect to the inlet or outlet of the coolant, the header portion from the inlet or outlet of the coolant to the heat dissipation fins tends to be long. When the header portion becomes long, the entire semiconductor device including the cooling device becomes large. An object of the present invention is to provide a semiconductor device that can be miniaturized.

[0005] A semiconductor device to which the present invention applies comprises a heat sink having a flat plate portion and a plurality of fins protruding from the flat plate portion, a semiconductor module bonded to the flat plate portion in a stacked state, a housing for housing the fins, an inlet for liquid to flow into the housing, an outlet for liquid to flow out of the housing, an inlet passage for liquid to flow from the inlet to the plurality of fins, and an outlet passage for liquid to flow from the plurality of fins to the outlet, wherein at least one of the inlet, the outlet, the inlet passage and the outlet passage overlaps with the fins in the stacking direction of the heat sink and the semiconductor module. Here, the housing comprises a concave case for housing the fins and a flat plate-shaped cover to which the heat sink is bonded and which covers the opening of the case together with the heat sink, and the cover may be bonded to the case by irradiating it with a laser in a direction parallel to the plate surface after it has been placed on top of the case. Furthermore, the housing has a concave case for housing the fins, and the flat plate portion of the heat sink covers the opening of the case and may be joined to the case by irradiating it with a laser in a direction parallel to the plate surface after it is placed on the case. The case also has a mounting surface on which the cover or the flat plate portion of the heat sink is placed, an opposing surface that is recessed from the mounting surface in the direction of the protrusion of the plurality of fins and faces the tips of at least some of the fins, and a recess formed between the mounting surface and the opposing surface and recessed from the opposing surface in the direction of the protrusion of the plurality of fins, and the inflow passage or outflow passage is formed in the recess, and the recess may overlap with at least some of the plurality of fins in the stacking direction. Furthermore, the area of ​​the recess that overlaps with the plurality of fins in the stacking direction may be larger than the area that does not overlap with the plurality of fins.Furthermore, the semiconductor module comprises an insulating substrate, a semiconductor element, a sealing resin portion covering the insulating substrate and the semiconductor element, and a lead frame whose tip is exposed from the sealing resin portion, and the joint between the cover or the flat plate portion of the heat sink and the case may be located on the fin side of the lead frame. Furthermore, the semiconductor module comprises an insulating substrate, a semiconductor element, and a sealing resin portion covering the insulating substrate and the semiconductor element, and when viewed from the semiconductor module side in the stacking direction, the end of the joint between the cover or the flat plate portion of the heat sink and the case in the direction of liquid flow in the plurality of fins may not extend outside the sealing resin portion of the semiconductor module. Furthermore, the flat plate portion of the heat sink and the semiconductor module may be sintered.

[0006] From another perspective, the present invention relates to a method for manufacturing a semiconductor device, comprising: a semiconductor module; a heat sink having a plurality of fins for dissipating heat generated by the semiconductor module; and a housing having a concave case and a flat plate-shaped cover covering the opening of the case, the method for manufacturing a semiconductor device comprising: a joining step of joining the heat sink and the cover; a sintering step of sintering the semiconductor module and the heat sink after the joining step; and a welding step of welding the cover and the case by irradiating the cover with a laser in a direction parallel to the plate surface of the cover while the cover is placed on the case, after the sintering step.

[0007] Furthermore, from another perspective, a method for manufacturing a semiconductor device to which the present invention applies comprises a semiconductor module, a heat sink having a flat plate-shaped portion and a plurality of fins protruding from the flat plate-shaped portion to dissipate heat generated by the semiconductor module, and a concave case for housing the fins, comprising a sintering step of sintering the semiconductor module and the flat plate-shaped portion of the heat sink, and a step after the sintering step of welding the flat plate-shaped portion and the case by irradiating the flat plate-shaped portion of the heat sink with a laser in a direction parallel to the plate surface of the flat plate-shaped portion while the flat plate-shaped portion is placed on the case. Here, the semiconductor device comprises an inlet for introducing liquid into the housing or case, an outlet for introducing liquid from the housing or case, an inlet passage for introducing liquid between the plurality of fins from the inlet, and an outlet passage for introducing liquid from between the plurality of fins to the outlet, wherein at least one of the inlet, the outlet, the inlet passage, and the outlet passage overlaps with the fins in the stacking direction of the heat sink and the semiconductor module, and the sintering step may be a step of pressurizing and heating the plurality of fins and the semiconductor module with the semiconductor module placed on the heat sink.

[0008] According to the present invention, it is possible to provide a semiconductor device that can be miniaturized.

[0009] This figure shows an example of a semiconductor device according to the first embodiment. This is a view of the case from the first side in the stacking direction. This is a cross-sectional view of the case (section III-III in Figure 2). This is a diagram for explaining a semiconductor module and is a cross-sectional view for explaining the bonding position of the semiconductor device. This is a diagram for explaining an example of the process of welding the heat sink and the cover. This is a diagram for explaining an example of the process of sintering the heat sink and the semiconductor module. This is a diagram for explaining an example of the process of welding the cover and the case. This is a schematic diagram of the case for explaining the flow of the coolant. This is a cross-sectional view showing an example of a semiconductor device. (a) and (b) are schematic diagrams for explaining modified cases. This figure shows an example of a semiconductor device according to the second embodiment. This is a diagram for explaining an example of the process of welding the heat sink and the case of the semiconductor device according to the second embodiment.

[0010] Embodiments of the present invention will be described in detail below with reference to the attached drawings. <First Embodiment> Figure 1 is a diagram showing an example of a semiconductor device 1 according to the first embodiment. The semiconductor device 1 according to the first embodiment comprises a plurality of semiconductor modules 10 and a cooling device 2 for cooling the semiconductor modules 10. In the semiconductor device 1, the semiconductor modules 10 and the cooling device 2 are stacked. Hereinafter, the stacking direction of the semiconductor modules 10 and the cooling device 2 may be simply referred to as the "stacking direction". Also, the semiconductor module 10 side in the stacking direction (upper side in Figure 1) may be referred to as the "first side", and the cooling device 2 side in the stacking direction (lower side in Figure 1) may be referred to as the "second side". Furthermore, the semiconductor device 1 is a rectangular parallelepiped when viewed in the stacking direction, and hereafter, the longitudinal direction when the semiconductor device 1 is viewed in the stacking direction will be simply referred to as the "longitudinal direction", the front side in the longitudinal direction in Figure 1 may be referred to as the "front side", and the side opposite to the "front" in the longitudinal direction may be referred to as the "back side". Furthermore, the direction perpendicular to the stacking direction and the longitudinal direction is sometimes simply referred to as the short direction. Also, when viewing case 40 with the first side in the stacking direction facing upwards, from the front to the back in the longitudinal direction, the direction on the right is sometimes referred to as the "third side" of the short direction, and the direction on the left is sometimes referred to as the "fourth side" of the short direction.

[0011] The cooling device 2 comprises a heat sink 20 and a housing 60. The cooling device 2 brings the semiconductor module 10 into contact with the heat sink 20 and dissipates heat to a cooling liquid flowing inside the housing 60 via the heat sink 20.

[0012] (Heat sink 20) ​​The heat sink 20 comprises a flat plate portion 21, a plurality of mounting surfaces 22, and a plurality of fins 23. The flat plate portion 21 has a rectangular shape when viewed in the stacking direction. The flat plate portion 21 has a fin side surface 211, which is the side from which the plurality of fins 23 protrude, and an outer surface 212, which is the surface facing the semiconductor module 10. The mounting surfaces 22 are arranged on the outer surface 212 side of the flat plate portion 21 and are used for alignment when attaching the semiconductor module 10 to the heat sink 20. In the illustrated example, three mounting surfaces 22 are arranged with gaps in the longitudinal direction.

[0013] Multiple fins 23 protrude from the fin side surfaces 211 of the flat plate portion 21 in a direction perpendicular to the plate surface of the flat plate portion 21. Multiple fins 23 are provided for each mounting surface 22, and are arranged in the region opposite the mounting surface 22, sandwiching the flat plate portion 21. The shape of each of the multiple fins 23 is columnar, and the cross-sectional shape of the fin 23 on a plane perpendicular to the protrusion direction can be a circle, ellipse, or other circular shape. Alternatively, the cross-sectional shape of the fin 23 on a plane perpendicular to the protrusion direction can be a square, rectangle, rhombus, or other quadrilateral shape. Furthermore, each fin 23 may be flat. Also, multiple fins 23 may be a combination of fins 23 of different shapes. In the illustrated example, the multiple fins 23 are columnar, and the cross-sectional shape of the fin 23 on a plane perpendicular to the protrusion direction is rectangular. The material of the heat sink 20 is not particularly limited, but examples include aluminum, aluminum alloy, copper, and copper alloy.

[0014] (Housing 60) The housing 60 comprises a case 40 having an opening for accommodating the fins 23 of the heat sink 20, a cover 30 to which the heat sink 20 is attached and which covers the opening of the case 40 together with the heat sink 20, a through hole 61 (see Figure 2) for allowing coolant to flow into the inside of the housing 60, and a through hole 62 (see Figure 2) for allowing coolant to flow out to the outside of the housing 60.

[0015] [Cover 30] The cover 30 is a plate-shaped member whose plate surface faces the stacking direction, and its shape when viewed in the stacking direction is a rectangular annular shape. The cover 30 has a lower surface 311 facing the second side in the stacking direction and an upper surface 312 facing the first side in the stacking direction. The outer peripheral edge of the lower surface 311 is shaped to overlap the mounting surface 47 of the side wall 46 of the case 40, which will be described later. The inner peripheral edge of the upper surface 312 overlaps the outer peripheral edge of the fin side surface 211 of the flat plate portion 21 of the heat sink 20. The material of the cover 30 is not particularly limited, but examples include aluminum, aluminum alloy, copper, and copper alloy.

[0016] [Case 40] Next, Case 40 will be explained with reference to Figures 2 and 3 along with Figure 1. Figure 2 is a view of Case 40 from the first side in the stacking direction. Figure 3 is a cross-sectional view of Case 40 (cross-sectional view III-III in Figure 2). Case 40 is a rectangular parallelepiped when viewed in the stacking direction, and is a concave box shape.

[0017] The case 40 comprises a bottom portion 41 (see Figure 3) which forms the bottom of a rectangular box, a side wall 46 extending from the bottom portion 41 toward the first side along the stacking direction, and flow path walls 48 and 49 which constitute part of the flow path for the coolant flowing in the short direction. The bottom portion 41 comprises a convex portion 42 projecting toward the first side in the stacking direction from the front end to the rear end in the longitudinal direction of the case 40 at the center in the short direction, and a bottom surface 431 and a bottom surface 441. The convex portion 42 forms recesses 43 and 44 at the short end of the case 40, recessed toward the second side in the stacking direction and extending in the longitudinal direction. In the illustrated example, recess 43 is formed on the third side in the short direction, and recess 44 is formed on the fourth side in the short direction.

[0018] The protrusion 42 comprises a protrusion end face 421, a protrusion side face 422, and a protrusion side face 423. The protrusion end face 421 has a rectangular shape when viewed from the stacking direction and is the surface facing the first side in the stacking direction. When the heat sink 20 is housed in the case 40, the protrusion end face 421 is positioned to face the tips of at least some of the fins 23 of the heat sink 20. The protrusion end face 421 is an example of an opposing surface. The protrusion side face 422 and the protrusion side face 423 are the sides of the protrusion 42. More specifically, the protrusion side face 422 is the surface facing the third side in the short direction, and the protrusion side face 423 is the surface facing the fourth side in the short direction. Furthermore, when the case 40 is viewed from the second side in the stacking direction, the protrusion 42 has a shape that is recessed toward the first side in the stacking direction, extending from the front end to the rear end in the longitudinal direction of the case 40 at the center in the short direction.

[0019] Bottom surfaces 431 and 441 are rectangular in shape when viewed from the first side in the stacking direction of the bottom portion 41. Bottom surface 431 is located on the third side in the short direction, and bottom surface 441 is located on the fourth side in the short direction, with the convex end face 421 in between. A through hole 61 is provided on the front side in the longitudinal direction of bottom surface 431. A through hole 62 is provided on the front side in the longitudinal direction of bottom surface 441.

[0020] The side wall 46 extends from around the bottom portion 41 toward the first side along the stacking direction. The leading edge of the side wall 46 faces toward the first side in the stacking direction and becomes a mounting surface 47 on which the outer edge of the cover 30 rests. The material of the case 40 is not particularly limited, but examples include aluminum, aluminum alloy, copper, and copper alloy.

[0021] The channel walls 48 and 49 protrude from the convex end face 421 toward the first side in the stacking direction and extend along the short side from the third end to the fourth end of the convex end face 421. The channel walls 48 and 49 are arranged to form coolant channels at positions corresponding to the semiconductor module 10 when the semiconductor device 1 is assembled.

[0022] Figure 4 is a diagram illustrating the semiconductor module 10 and is a cross-sectional view illustrating the bonding position of the semiconductor device 1. Figure 4 shows a cross-section of the semiconductor device 1 at the position of the III-III cross-section in Figure 2. The semiconductor module 10 comprises an insulating substrate 11, a semiconductor element 12, and a lead frame 13. The semiconductor module 10 also includes a sealing resin portion 14 that covers the periphery of the insulating substrate 11 and the semiconductor element 12. The second side surface of the insulating substrate 11 is exposed from the sealing resin portion 14.

[0023] The insulating substrate 11 comprises an insulating layer 111 that insulates the semiconductor element 12 from the heat sink 20, a wiring layer 112 formed on the first side surface of the insulating layer 111 and including wiring for supplying power to the semiconductor element 12, and a heat transfer layer 113 formed on the second side surface of the insulating layer 111 and transferring heat generated from the semiconductor element 12 to the heat sink 20. The semiconductor element 12 is, for example, a power semiconductor such as a transistor, thyristor, or diode used for power control. The semiconductor element 12 is arranged on the first side of the insulating substrate 11.

[0024] The lead frame 13 is a terminal used to connect the semiconductor element 12 to an external device. The lead frame 13 is a plate-shaped terminal extending in one direction, and one end of the lead frame 13 is connected to the wiring layer 112. The lead frame 13 and the wiring layer 112 are connected, for example, via an electrically conductive metal fine wire. The sealing resin part 14 is, for example, a molding resin.

[0025] The semiconductor device 1 is formed by joining a semiconductor module 10, a heat sink 20, a cover 30, and a case 40 by a manufacturing method described later. In the example shown in Figure 4, the semiconductor module 10 and the heat sink 20 are joined by a sintered layer 154 formed in the second step of the manufacturing process described later. The heat sink 20 and the cover 30 are joined by a molten portion Y1 formed in the first step of the manufacturing process. The cover 30 and the case 40 are joined by a molten portion Y3 formed in the third step of the manufacturing process.

[0026] The molten portion Y1 is formed on the outer edge of the flat plate portion 21 of the heat sink 20. In the short direction, the molten portion Y1 is located outside the multiple fins 23 of the heat sink 20 and inside the end of the sealing resin portion 14. More specifically, the molten portion Y1 is located inside the outer end of the lead frame 13. In addition, the molten portion Y3 is formed on the mounting surface 47 of the case 40. In the short direction, the molten portion Y3 is located outside the multiple fins 23 of the heat sink 20 and inside the end of the sealing resin portion 14. More specifically, the molten portion Y3 is located inside the outer end of the lead frame 13.

[0027] <Manufacturing Method> Next, an example of a method for manufacturing a semiconductor device 1 by joining the semiconductor module 10, heat sink 20, cover 30, and case 40 described above will be explained. The manufacturing method of the semiconductor device 1 comprises a first step of welding the heat sink 20 and the cover 30, a second step of sintering the heat sink 20 and the semiconductor module 10, and a third step of welding the cover 30 and the case 40.

[0028] (First Step) Figure 5 is a diagram illustrating an example of the process of welding the heat sink 20 and the cover 30. In the first step, first, the inner peripheral edge of the upper surface 312 of the cover 30 is brought into contact with the outer peripheral edge of the fin side surface 211 (see Figure 1) of the flat plate portion 21 of the heat sink 20. Then, with the cover 30 and the flat plate portion 21 in contact, a laser 152 is irradiated from the first side in the stacking direction onto the outer peripheral edge of the outer surface 212 of the flat plate portion 21 to melt the heat sink 20 and the cover 30. The laser 152 is irradiated from a movable laser head 151, and while the laser 152 is irradiated in the stacking direction, the laser head 151 is moved one full turn along the outer peripheral edge of the flat plate portion 21. In Figure 5, the position where the laser 152 is irradiated is indicated by a dashed arrow. This welds the inner peripheral edge of the upper surface 312 of the cover 30 to the outer peripheral edge of the flat plate portion 21 of the heat sink 20.

[0029] (Second Step) Figure 6 is a diagram illustrating an example of the process of sintering the heat sink 20 and the semiconductor module 10. The second step of sintering the heat sink 20 and the semiconductor module 10 includes a coating step, a pressurizing step, and a heating step. [Coating Step] In the coating step, a metal paste layer 153 is formed by coating a metal paste containing dispersed metal particles in layers onto the mounting surface 22 located on the flat plate portion 21 of the heat sink 20. As metal particles used in the metal paste, for example, particles of metal selected from copper (Cu), silver (Ag), and an alloy of copper and silver (Cu-Ag) can be used. In the coating step, there are no particular limitations on the method of coating the metal paste, but examples include screen printing, transfer printing, offset printing, inkjet printing, and printing methods using various dispensers and coaters.

[0030] [Pressurization Process] In the pressurization process, first, the heat transfer layer 113 (see Figure 4) of the semiconductor module 10 is laminated onto the mounting surface 22 to which the metal paste layer 153 is applied. Then, pressure is applied in the direction of the arrow shown in Figure 6 to compress the metal paste layer 153. More specifically, pressure is applied to the semiconductor module 10 from the first side to the second side, and pressure is applied to the tips of the multiple fins 23 of the heat sink 20 from the second side to the first side. This compresses the metal paste layer 153 sandwiched between the mounting surface 22 of the heat sink 20 and the heat transfer layer 113 of the semiconductor module 10. The pressure applied to the metal paste layer 153 varies depending on the viscosity of the metal paste used in the metal paste layer 153, but for example, a pressure of 15 MPa can be exemplified. Furthermore, there are no particular limitations on the method of applying force, but examples include using a servo motor press or a hydraulic press. Additionally, a plate can be placed at the tips of the multiple fins 23, and pressure can be applied to the tips of the multiple fins 23 via the plate.

[0031] [Heating Process] In the heating process, heat is applied to the metal paste layer 153 to sinter the metal paste and bond the semiconductor module 10 and the heat sink 20. In the heating process, sintering may be performed by raising the temperature under pressure, or without applying pressure. The sintering temperature will vary depending on the viscosity of the metal paste, but a temperature of 250°C can be used as an example.

[0032] (Third Step) Figure 7 is a diagram illustrating an example of the process of welding the cover 30 and the case 40. Figure 7 is a schematic diagram of the semiconductor device 1 viewed from the front in the longitudinal direction. In the third step, laser welding is performed with the outer edge of the cover 30 placed on the mounting surface 47 of the case 40. In laser welding, a laser 152 is irradiated from the laser head 151 in a direction parallel to the plate surface of the cover 30 (the short direction in the illustrated example) so that a molten area is formed in both the area of ​​the cover 30 placed on the mounting surface 47 of the case 40 and the case 40. Then, while irradiating with the laser 152, the laser head 151 moves around the semiconductor device 1 once, melting the case 40 and the cover 30. In addition, to prevent the relative positional relationship between the cover 30 and the case 40 from shifting when the laser 152 is irradiated, the semiconductor device 1 may be held by sandwiching the first side of the semiconductor module 10 and the opposite side of the protruding end face 421 of the protrusion 42. In the illustrated example, since some of the fins 23 among the multiple fins 23 are in contact with the convex end face 421, pressure is generated between the tips of the multiple fins 23 and the convex end face 421, suppressing a change in the positional relationship between the tips of the multiple fins 23 and the convex end face 421. In addition, since the heat sink 20 is already joined to the cover 30, misalignment of the positional relationship between the cover 30 and the case 40 is suppressed. When irradiating with the laser 152, pressure may be applied to the side wall 46 from the second side in the stacking direction toward the first side, and pressure may also be applied to the outer edge of the cover 30 from the first side in the stacking direction toward the second side to suppress misalignment of the positional relationship between the cover 30 and the case 40. Furthermore, although in the illustrated example some of the multiple fins 23 are in contact with the convex end face 421, some of the multiple fins 23 do not need to be in contact with the convex end face 421. For example, when fin height tolerances are taken into account, depending on the relationship with the depth of the case, the tip of the fin 23 may interfere with the protruding end face 421, creating a gap between the cover 30 and the case 40. Therefore, the design may be such that a gap is created between the tip of the fin 23 and the protruding end face 421.In this case, by applying pressure to the side wall 46 from the second side to the first side in the stacking direction, and by applying pressure to the outer edge of the cover 30 from the first side to the second side in the stacking direction, it is possible to suppress misalignment of the positional relationship between the cover 30 and the case 40.

[0033] <Coolant Flow> Figure 8 is a schematic diagram of case 40 to explain the coolant flow. Figure 8 shows case 40 as viewed from the first side in the stacking direction, and a dotted line indicates the region R where multiple fins 23 (see Figure 1) are arranged. Arrows also indicate the direction in which the coolant flows within case 40. In the semiconductor device 1 manufactured as described above (see Figure 7), the coolant flows into case 40 from a through hole 61, which is an example of an inlet. The coolant that flows into case 40 flows through a recess 43 surrounded by the bottom surface 431, the protruding side surface 422, and a part of the inner surface 461 of the side wall 46. The recess 43 extends along the longitudinal direction, and the coolant flowing through the recess 43 flows from the front to the back in the longitudinal direction and also flows towards the first side in the stacking direction.

[0034] The coolant flowing through the recess 43 moves to the protruding end face 421 of the protrusion 42 in the stacking direction, and then flows from the third side to the fourth side in the short direction along the protrusion end face 421. As described above, since a flow channel wall 48 and a flow channel wall 49 are formed on the protruding end face 421, the flow channel that flows along the protruding end face 421 in the short direction is divided into three flow channels. Here, the flow channel on the near side of the flow channel wall 48 in the longitudinal direction is called the first flow channel 103a, the flow channel between the flow channel wall 48 and the flow channel wall 49 in the longitudinal direction is called the second flow channel 103b, and the flow channel on the far side of the flow channel wall 49 in the longitudinal direction is called the third flow channel 103c. Multiple fins 23 protrude in the region R shown in the figure, and the coolant passing through this first flow channel 103a passes between the multiple fins 23, between the fins 23 and the side wall 46, and between the fins 23 and the flow channel wall 48. Furthermore, the coolant passing through the second flow path 103b passes between multiple fins 23, between fins 23 and the flow path wall 48, and between fins 23 and the flow path wall 49. Also, the coolant passing through the third flow path 103c passes between multiple fins 23, between fins 23 and the side wall 46, and between fins 23 and the flow path wall 49.

[0035] Coolant flowing from the third side in the short direction to the fourth side through any of the first flow path 103a, the second flow path 103b, or the third flow path 103c flows into a recess 44 surrounded by the bottom surface 441, the protruding side surface 423, and a part of the inner surface 461 of the side wall 46. The recess 44 has a through hole 62, which is an example of an outlet, located on the front side in the longitudinal direction. As the coolant is discharged to the outside of the case 40 from the through hole 62, the coolant in the recess 44 flows from the back side in the longitudinal direction to the front side.

[0036] In the cooling device 2 through which the coolant flows, the recess 43 directs the coolant flowing in from the through hole 61 into the space between the multiple fins 23 located in one of the first flow path 103a, the second flow path 103b, or the third flow path 103c. Hereinafter, the recess 43 may be referred to as the inflow passage 101. The recess 44 directs the coolant that has flowed out from between the multiple fins 23 located in one of the first flow path 103a, the second flow path 103b, or the third flow path 103c out through the through hole 62. Hereinafter, the recess 44 may be referred to as the outflow passage 102.

[0037] <Positional Relationship> The positional relationship between the multiple fins 23 of the semiconductor device 1 manufactured in this manner and the inlet passage 101 and outlet passage 102 will now be explained. Figure 9 is a cross-sectional view showing an example of the semiconductor device 1. Note that the internal structure of the semiconductor module 10 is omitted in Figure 9. In Figure 9, the molten portion Y1 formed by welding the heat sink 20 and the cover 30 is shown. The molten portion Y3 formed by welding the cover 30 and the case 40 is also shown. The length L2 in the short direction of the protruding end face 421 is also shown, and the length L1 in the short direction of the region where the multiple fins 23 protrude is also shown. In the illustrated example, the length L1 is greater than the length L2, and at least a portion of the multiple fins 23 are not in contact with the protruding end face 421. In other words, at least a portion of the multiple fins 23 overlap in the stacking direction in the recess 43 or recess 44.

[0038] In the illustrated example, some of the multiple fins 23 overlap in the stacking direction in the recess 43, and other parts of the multiple fins 23 overlap in the stacking direction in the recess 44. The length of the region in the recess 43 that overlaps with the multiple fins 23 in the stacking direction is denoted as D1, and the length of the region that does not overlap with the multiple fins 23 in the stacking direction is denoted as D2. In the illustrated example, D1 > D2, meaning that the region in the recess 43 that overlaps with the multiple fins 23 in the stacking direction is larger than the region that does not overlap with the multiple fins 23. Similarly, the region in the recess 44 that overlaps with the multiple fins 23 in the stacking direction is larger than the region that does not overlap with the multiple fins 23.

[0039] The semiconductor device 1 formed as described above comprises a heat sink 20 having a flat plate portion 21 and a plurality of fins 23 protruding from the flat plate portion 21; a semiconductor module 10 joined to the flat plate portion 21 in a stacked state on the flat plate portion 21; a housing 60 for housing the fins 23; a through hole 61 for liquid to flow into the housing 60; a through hole 62 for liquid to flow out of the housing 60; an inlet passage 101 for liquid to flow from the through hole 61 to the plurality of fins 23; and an outlet passage 102 for liquid to flow from between the plurality of fins 23 to the through hole 62. At least one of the inlet passage 101 and the outlet passage 102 overlaps with some of the plurality of fins 23 in the stacking direction between the heat sink 20 and the semiconductor module 10. In the semiconductor device 1 formed in this way, at least one of the inlet passage 101 and the outlet passage 102 overlaps with the fins 23 in the stacking direction between the heat sink 20 and the semiconductor module 10. For example, if the inflow passage 101 is not arranged to overlap with at least a portion of the multiple fins 23 in the stacking direction, the inflow passage 101 will be arranged on the third side in the short direction relative to the multiple fins 23, in which case the size of the case 40 in the short direction will be large. In the semiconductor device 1 of the first embodiment, the size of the semiconductor device 1 in the short direction can be reduced by arranging the inflow passage 101 and the outflow passage 102 to overlap with at least a portion of the multiple fins 23 in the stacking direction.

[0040] Furthermore, the housing 60 has a concave case 40 that houses the fins 23 and a flat plate-shaped cover 30 to which the heat sink 20 is joined and which covers the opening of the case 40 together with the heat sink 20. The cover 30 is joined to the case 40 by being placed on top of the case 40 and then irradiated with a laser 152 in a direction parallel to the plate surface. The semiconductor device 1 manufactured in this way allows for miniaturization of the housing 60 compared to when the laser 152 is irradiated in the stacking direction. For example, when welding the cover 30 and the case 40 after attaching the semiconductor module 10 to the heat sink 20, if the laser 152 is irradiated from the first side in the stacking direction, the size of the case 40 as seen from the first side in the stacking direction must be larger than the size of the semiconductor module 10 as seen from the first side in the stacking direction. In the semiconductor device 1 according to the first embodiment, since the laser 152 is irradiated in a direction parallel to the plate surface of the cover 30, the size of the case 40 as seen from the first side in the stacking direction can be made smaller than the size of the semiconductor module 10.

[0041] The case 40 has a mounting surface 47 on which the cover 30 is placed, a convex end surface 421 recessed from the mounting surface 47 in the direction of the protrusion of the plurality of fins 23, and contact with the tips of at least some of the fins 23, and recesses 43 and 44 formed between the mounting surface 47 and the convex end surface 421 and recessed from the convex end surface 421 in the direction of the protrusion of the plurality of fins 23, the inlet passage 101 is made up of the recess 43 and the outlet passage 102 is made up of the recess 44, and the recesses 43 and 44 overlap with at least some of the plurality of fins 23 in the stacking direction. In a semiconductor device 1 formed in this way, for example, if there are many semiconductor modules 10 arranged in the longitudinal direction, the flow rate of the coolant to the semiconductor modules 10 located on the far side in the longitudinal direction tends to be less than the flow rate of the coolant to the semiconductor modules 10 located on the near side. However, the inlet passage 101 of the semiconductor device 1 is made up of a recess 43, and by increasing the depth of the recess 43 in the stacking direction, it is possible to suppress variations in the flow rate of the coolant to the semiconductor modules 10 arranged in the longitudinal direction. As a result, even if there are many semiconductor modules 10 arranged in the longitudinal direction, for example, the length (width) of the recess 43 in the short direction can be shortened, and the size of the case 40 in the short direction can be reduced.

[0042] Furthermore, in the semiconductor device 1 according to this embodiment, the area in the recesses 43 and 44 that overlaps with the multiple fins 23 in the stacking direction is larger than the area that does not overlap with the multiple fins 23. For example, as shown in Figure 9, if the area in which the recesses 43 and the multiple fins 23 overlap increases in the short-side direction, the length of D2 becomes shorter than the length of the multiple fins 23 in the short-side direction, and the size of the case 40 in the short-side direction can be reduced.

[0043] In the semiconductor device 1 of the first embodiment, the semiconductor module 10 includes an insulating substrate 11, a semiconductor element 12, a sealing resin portion 14 that covers the periphery of the insulating substrate 11 and the semiconductor element 12, and a lead frame 13 whose tip is exposed from the sealing resin portion 14. The molten portion Y3 that joins the cover 30 and the case 40 is located on the side of the multiple fins 23 beyond the tip of the lead frame 13. This makes it possible to reduce the size of the cooling device 2 of the semiconductor device 1 when viewed from the stacking direction, compared to, for example, a case where the molten portion Y3 that joins the cover 30 and the case 40 is not located on the side of the multiple fins 23 beyond the tip of the lead frame 13. In the first embodiment, the cover 30 and the case 40 are irradiated with a laser 152 in a direction parallel to the plate surface of the cover 30, so the cooling device 2 can be assembled regardless of the size of the lead frame 13. For example, if the welding position between the cover 30 and the case 40 is located on the side of the multiple fins 23 rather than the tip of the lead frame 13, irradiating the laser 152 from the stacking direction will cause the lead frame 13 to overlap with the welding position in the stacking direction, making it difficult to irradiate the cover 30 with the laser 152. In the first embodiment, since the laser 152 is irradiated in a direction parallel to the plate surface with the cover 30 placed on the case 40, even when laser welding the cover 30 and the case 40 with the semiconductor module 10 attached to the heat sink 20, the size of the cooling device 2 relative to the protruding direction of the lead frame 13 can be made smaller than the tip of the lead frame 13.

[0044] In the semiconductor device 1 of the first embodiment, the semiconductor module 10 includes an insulating substrate 11, a semiconductor element 12, and a sealing resin portion 14 that covers the periphery of the insulating substrate 11 and the semiconductor element 12. When viewed in the stacking direction from the semiconductor module 10 side, the ends of the melting portion Y3 of the cover 30 and the case 40 in the short side direction, which is the liquid flow direction in the plurality of fins 23, do not protrude outside the sealing resin portion 14 of the semiconductor module 10. Thereby, for example, compared with the case where the melting portion Y3 joining the cover 30 and the case 40 protrudes outside the sealing resin portion 14, the size of the cooling device 2 of the semiconductor device 1 when viewed from the stacking direction can be reduced. In the first embodiment, since the laser 152 is irradiated in a direction parallel to the plate surface of the cover 30 for the cover 30 and the case 40, the cooling device 2 can be assembled regardless of the length in the short side direction of the sealing resin portion 14. For example, when the position where the cover 30 and the case 40 are welded is located inside the sealing resin portion 14, when the laser 152 is irradiated from the stacking direction, the sealing resin portion 14 overlaps with the welding position in the stacking direction, and it may be more difficult to irradiate the laser 152 to the cover 30. In the first embodiment, with the cover 30 placed on the case 40, the laser 152 is irradiated in a direction parallel to the plate surface. Thereby, even in the case where the cover 30 and the case 40 are laser welded in a state where the semiconductor module 10 is attached to the cover 30 via the heat sink 20, a cooling device 2 is formed in which the ends of the melting portion Y3 of the cover 30 and the case 40 do not protrude outside the sealing resin portion 14. That is, the semiconductor device 1 can be made smaller compared with a semiconductor device in which the ends of the melting portion Y3 protrude outside the sealing resin portion 14.

[0045] In the first embodiment, the flat plate portion 21 of the heat sink 20 and the semiconductor module 10 are sintered. By joining by sintering, the thermal conductivity between the heat sink 20 and the semiconductor module 10 is increased, and the heat dissipation efficiency of the cooling device 2 is increased.

[0046] The first embodiment of the semiconductor device 1 is a method for manufacturing a semiconductor device 1 comprising a semiconductor module 10, a heat sink 20 having a plurality of fins 23 for dissipating heat generated by the semiconductor module 10, and a housing 60 having a concave case 40 and a flat plate-shaped cover 30 that covers the opening of the case 40 for housing the fins 23. The manufacturing method is performed by a joining step of joining the heat sink 20 and the cover 30, a sintering step of sintering the semiconductor module 10 and the heat sink 20 after the joining step, and a welding step of welding the cover 30 and the case 40 by irradiating the cover 30 with a laser in a direction parallel to the plate surface of the cover 30 with the cover 30 placed on top of the case 40. For example, consider the case in which a cooling device 2 is manufactured by joining the heat sink 20, the cover 30 and the case 40, and then the semiconductor module 10 is sintered against the cooling device 2. In the cooling device 2, some of the fins 23 among the plurality of fins 23 overlap with the inlet passage 101 or the outlet passage 102 in the stacking direction. Therefore, when attempting to sinter the semiconductor module 10 in the cooling device 2, it is not possible to apply pressure toward the first side in the stacking direction to the tips of some of the fins 23 that overlap with the inlet passage 101 or outlet passage 102 in the stacking direction, making it easy for variations in the pressure applied to the metal paste layer 153 to occur. On the other hand, even if the semiconductor device 1 manufactured by the above-described manufacturing method is configured such that the inlet passage 101 and outlet passage 102 are positioned under some of the fins 23 among the plurality of fins 23, by joining the semiconductor module 10 and the heat sink 20 before housing the heat sink 20 in the case 40, the entire metal paste layer 153 for sintering can be sintered while applying pressure from both sides. This allows the semiconductor module 10 and the heat sink 20 to be sintered well.

[0047] Furthermore, the semiconductor device 1 of the first embodiment includes a through hole 61 through which liquid flows into the housing 60, a through hole 62 through which liquid flows out of the housing 60, an inlet passage 101 through which liquid flows from the through hole 61 to the space between the fins 23, and an outlet passage 102 through which liquid flows from between the fins 23 to the through hole 62. At least one of the inlet passage 101 and the outlet passage 102 overlaps with the fins 23 in the stacking direction of the heat sink 20 and the semiconductor module 10. The welding process involves placing the semiconductor module 10 on the heat sink 20, applying pressure to the fins 23 from the back side of the protruding end face 421 of the protruding portion 42, and laser welding the semiconductor module 10 while applying pressure from the first side in the stacking direction. In this way, the semiconductor device 1 being manufactured is pressurized by the protruding end face 421 of the protrusion 42 of the case 40, and by pressurizing the semiconductor module 10 to press the fins 23 against the protruding end face 421, relative movement between the heat sink 20 and the case 40 is suppressed. The cover 30 is welded to the heat sink 20, and relative movement between the cover 30 and the case 40 is also suppressed. Therefore, when welding the cover 30 and the case 40, for example, misalignment of the positional relationship between the cover 30 and the case 40, which could result in welding defects, is suppressed. If a gap is provided between the tips of the fins 23 and the protruding end face 421, relative movement between the cover 30 and the case 40 is suppressed by applying pressure to the side wall 46 from the second side in the stacking direction toward the first side, and by applying pressure to the outer edge of the cover 30 from the first side in the stacking direction toward the second side. This prevents welding defects from occurring when welding the cover 30 and the case 40, for example, due to misalignment of the positional relationship between the cover 30 and the case 40.

[0048] <Modification Example of the First Embodiment>Next, a modification example of the case 40 of the first embodiment will be described. FIG. 10 is a schematic diagram for explaining a modification example of the case 40. FIG. 10(a) is a schematic diagram for explaining the case 140 of the first modification example, and FIG. 10(b) is a schematic diagram for explaining the case 240 of the second modification example. Note that the same reference numerals are used for the same functions as those in the first embodiment, and the description thereof will be omitted here. The case 140 according to the first modification example is different from the case 40 of the first embodiment in the arrangement of the through hole 62. More specifically, in the case 40 of the first embodiment, the through hole 62 is arranged on the front side in the longitudinal direction, whereas in the case 140 according to the first modification example, it is arranged on the back side in the longitudinal direction.

[0049] (Regarding the flow of the coolant in the case 140)In the case 140 with such an arrangement, the coolant first flows into the case 40 from the through hole 61. The coolant that has flowed into the case 40 flows from the front side to the back side in the longitudinal direction through the inflow path 101. When the coolant flowing through the inflow path 101 moves to the convex end face 421 of the convex portion 42 in the stacking direction, it flows from the third side to the fourth side in the short direction through any one of the first flow path 103a, the second flow path 103b, and the third flow path 103c. The coolant that has flowed to the fourth side from any one of the first flow path 103a, the second flow path 103b, and the third flow path 103c flows into the outflow path 102 and flows from the front side to the back side in the longitudinal direction through the outflow path 102. The coolant that has flowed to the back end of the outflow path 102 is discharged from the through hole 62 to the outside of the case 140.

[0050] In the case 140 in which the through hole 62 is arranged in this way, for example, if the shape of the fins 23 is such that the flow path between the plurality of fins 23 is likely to move from the third side to the fourth side in the short direction and from the front side to the back side in the longitudinal direction, the pressure for flowing the coolant can be reduced.

[0051] Next, using Figure 10(b), we will explain Case 240 according to Modification 2. As shown in Figure 10(b), Case 240 does not have recesses 43 (see Figure 1) and 44 (see Figure 1), and the bottom surface 250 of Case 240 is flat. Furthermore, Case 240 does not have the flow path walls 48 and 49 (see Figure 1) that constituted the flow path in the short direction in Case 40. In Case 240, through holes 61 and 62 are located in the center in the short direction, with through hole 61 located on the front side in the longitudinal direction and through hole 62 located on the back side in the longitudinal direction. Also, through holes 61 and 62 partially overlap with the region R where multiple fins 23 are provided in the stacking direction.

[0052] (Regarding the flow of coolant within the case 240) The coolant that flows into the case 240 from the through hole 61 flows longitudinally through the space enclosed by the bottom surface 250, which is in contact with the tips of the multiple fins 23 (see Figure 1), and the inner surface 461 of the side wall 46. The coolant flowing longitudinally flows between the multiple fins 23 in the region R where the multiple fins 23 are arranged, and receives heat from the multiple fins 23. The coolant that has flowed to the far end in the longitudinal direction is discharged to the outside of the case 240 from the through hole 62.

[0053] In the case 240 in which the through holes 61 and 62 are arranged in this manner, the length in the longitudinal direction can be reduced compared to, for example, the case in which the through hole 61 is positioned in front of the multiple fins 23 in the longitudinal direction and the through hole 62 is positioned behind the multiple fins 23 in the longitudinal direction. This makes it possible to reduce the size of the case 240 in the longitudinal direction.

[0054] <Second Embodiment> In the first embodiment, the opening of the case 40 was closed by the heat sink 20 and the cover 30, but in the second embodiment, the opening of the case 40 is closed by the heat sink 80 (described later) without the cover 30. Note that the same reference numerals are used for functions similar to those in the first embodiment, and their explanation is omitted here. Figure 11 is a diagram showing an example of a semiconductor device 5 according to the second embodiment.

[0055] The semiconductor device 5 comprises a semiconductor module 10 and a cooling device 6. The cooling device 6 comprises a heat sink 80 and a case 40. The heat sink 80 comprises a flat plate portion 81, a plurality of mounting surfaces 22, and a plurality of fins 23 (see Figure 1) that protrude from the area opposite the mounting surfaces 22, sandwiching the flat plate portion 81. The flat plate portion 81 has a rectangular shape when viewed in the stacking direction, and the outer edge of the flat plate portion 81 is shaped to overlap the mounting surface 47 of the side wall 46 of the case 40. The flat plate portion 81 has a fin side surface 211, which is the side from which the plurality of fins 23 protrude, and an outer surface 212, which is the surface facing the semiconductor module 10.

[0056] <Manufacturing Method> Next, an example of a method for manufacturing a semiconductor device 5 by joining the semiconductor module 10, heat sink 80, and case 40 described above will be explained. The manufacturing method of the semiconductor device 5 comprises a first step of sintering the heat sink 80 and the semiconductor module 10, and a second step of welding the heat sink 80 and the case 40. Figure 12 is a diagram illustrating the process of welding the semiconductor module 10, the heat sink 80, and the case 40. Figure 12 is a schematic diagram of the semiconductor device 1 viewed from the front in the longitudinal direction, showing that after sintering the heat sink 80 and the semiconductor module 10, a laser 152 is irradiated onto the heat sink 80 and the case 40 to form a molten portion Y4.

[0057] (First step) The first step includes a coating step, a pressurizing step, and a heating step. [Coating step] In the coating step, a metal paste in which metal particles are dispersed is applied between the second side of the semiconductor module 10 and the mounting surface 22 of the heat sink 80 to form a metal paste layer 153, which is a layer of metal paste.

[0058] [Pressurization Process] In the pressurization process, the insulating substrate 11 (see Figure 4) of the semiconductor module 10 is brought close to the mounting surface 22 from the first side in the stacking direction, and the mounting surface 22 and the insulating substrate 11 are stacked with the metal paste layer 153 in between. Then, pressure is applied from the first side to the second side in the stacking direction of the sealing resin portion 14 of the semiconductor module 10, and pressure is also applied to the tips of the multiple fins 23 of the heat sink 80 from the second side in the stacking direction toward the first side. This applies pressure to the metal paste layer 153 sandwiched between the heat sink 20 and the semiconductor module 10. Note that in the pressurization process, applying pressure to the tips of the multiple fins 23 without attaching the case 40 can more effectively apply pressure to the metal paste layer 153.

[0059] [Heating Process] In the heating process, heat is applied to the metal paste layer 153, causing it to harden and form a sintered layer 154. The sintered layer 154 joins the semiconductor module 10 to the mounting surface 22 of the heat sink 80. In the heating process, the temperature may be raised under pressure to cause sintering, or the sintering may be carried out without applying pressure.

[0060] (Second Step) In the second step, with the fin side surface 211 of the flat plate portion 81 of the heat sink 80 placed on the mounting surface 47 of the side wall 46 of the case 40, the laser 152 is irradiated in a direction parallel to the plate surface of the flat plate portion 81 at the position where the mounting surface 47 of the case 40 and the fin side surface 211 of the flat plate portion 81 of the heat sink 80 are in contact, thereby forming a molten portion Y4 in the heat sink 80 and the case 40. Then, while irradiating with the laser 152, the laser head 151 is moved around the case 40 once to melt the case 40 and the heat sink 80. Note that, as in the first embodiment, the semiconductor device 5 may be held by sandwiching the first side of the semiconductor module 10 and the opposite side of the convex end face 421 of the convex portion 42 so that the relative positional relationship between the heat sink 80 and the case 40 does not shift when the laser 152 is irradiated. Furthermore, when irradiating with the laser 152, pressure may be applied to the side wall 46 from the second side to the first side in the stacking direction, and pressure may also be applied to the outer edge of the heat sink 80 from the first side to the second side in the stacking direction to suppress misalignment of the positional relationship between the heat sink 80 and the case 40. In addition, in the illustrated example, some of the fins 23 among the multiple fins 23 are in contact with the convex end face 421, but some of the fins 23 among the multiple fins 23 do not have to be in contact with the convex end face 421. For example, when fin height tolerance is taken into account, depending on the relationship with the depth of the case, the tip of the fin 23 may interfere with the convex end face 421, and a gap may be created between the fin side surface 211 of the flat plate portion 81 of the heat sink 80 and the mounting surface 47 of the side wall 46 of the case 40. For this reason, the design may create a gap between the tip of the fin 23 and the convex end face 421. In this case, by applying pressure to the side wall 46 from the second side to the first side in the stacking direction, and by applying pressure to the outer edge of the flat plate portion 81 from the first side to the second side in the stacking direction, it is possible to suppress misalignment of the positional relationship between the heat sink 80 and the case 40.

[0061] The semiconductor device 5 formed as described above includes a heat sink 80 having a flat plate portion 81 and a plurality of fins 23 protruding from the flat plate portion 81, a semiconductor module 10 joined to the flat plate portion 81 in a stacked state on the flat plate portion 81, a case 40 housing the fins 23, a through hole 61 for liquid to flow into the case 40, a through hole 62 for liquid to flow out of the case 40, an inlet passage 101 for liquid to flow from the inlet to the plurality of fins 23, and an outlet passage 102 for liquid to flow from between the plurality of fins 23 to the outlet, wherein at least one of the inlet passage 101 and the outlet passage 102 overlaps with the fins 23 in the stacking direction of the heat sink 80 and the semiconductor module 10. In the semiconductor device 5 of the second embodiment formed in this way, the size of the semiconductor device 5 in the short side can be reduced by arranging the inlet passage 101 and the outlet passage 102 to overlap with at least a portion of the plurality of fins 23 in the stacking direction. Furthermore, compared to the semiconductor device 1 of the first embodiment, the semiconductor device 5 does not have a cover 30, so for example, the cover 30 and the heat sink 80 do not need to be welded together, and the manufacturing process can be shortened. Also, in the semiconductor device 5, at least one of the inflow passage 101 and the outflow passage 102 overlaps the fins 23 in the stacking direction between the heat sink 80 and the semiconductor module 10. For example, if the inflow passage 101 is not arranged to overlap at least a portion of the multiple fins 23 in the stacking direction, the inflow passage 101 will be arranged on the third side in the short direction relative to the multiple fins 23, but in this case the size of the case 40 in the short direction will be larger. In the semiconductor device 5 of the second embodiment, the size of the semiconductor device 5 in the short direction can be reduced by arranging the inflow passage 101 and the outflow passage 102 to overlap at least a portion of the multiple fins 23 in the stacking direction.

[0062] A semiconductor device 5 comprising a semiconductor module 10, a heat sink 80 having a flat plate portion 81 and a plurality of fins 23 protruding from the flat plate portion 81 to dissipate heat generated by the semiconductor module 10, and a concave case 40 for housing the fins 23 is manufactured by a sintering step of sintering the semiconductor module 10 and the flat plate portion 81 of the heat sink 80, and a step after the sintering step of welding the flat plate portion 81 and the case 40 by irradiating the flat plate portion 81 of the heat sink 80 with a laser 152 in a direction parallel to the plate surface of the flat plate portion 81 while the flat plate portion 81 of the heat sink 80 is placed on the case 40. For example, consider the case in which a cooling device 6 is manufactured by joining the heat sink 80 and the case 40, and then the semiconductor module 10 is sintered against the cooling device 6. In the cooling device 6, some of the fins 23 among the plurality of fins 23 overlap with the inlet passage 101 or the outlet passage 102 in the stacking direction. Therefore, when attempting to sinter the semiconductor module 10 in the cooling device 6, it is not possible to apply pressure toward the first side in the stacking direction to the tips of some of the fins 23 that overlap with the inlet passage 101 or outlet passage 102 in the stacking direction, making it easy for variations in the pressure applied to the metal paste layer 153 to occur. On the other hand, even if the semiconductor device 5 manufactured by the above-described manufacturing method is configured such that the inlet passage 101 and outlet passage 102 are arranged under some of the fins 23 among the plurality of fins 23, the semiconductor module 10 and the heat sink 80 can be joined together before housing the heat sink 80 in the case 40, allowing the metal paste layer 153 for sintering to be sintered while applying pressure from both sides. This enables good sintering of the semiconductor module 10 and the heat sink 80.

[0063] Furthermore, the semiconductor device 5 of the second embodiment includes a through hole 61 through which liquid flows into the case 40, a through hole 62 through which liquid flows out of the case 40, an inlet passage 101 through which liquid flows from the through hole 61 to the space between the fins 23, and an outlet passage 102 through which liquid flows from between the fins 23 to the through hole 62. At least one of the inlet passage 101 and the outlet passage 102 overlaps with the fins 23 in the stacking direction of the heat sink 80 and the semiconductor module 10. The welding process involves placing the semiconductor module 10 on the heat sink 80, applying pressure to the fins 23 from the back side of the protruding end face 421 of the protrusion 42, and laser welding the semiconductor module 10 while applying pressure from the first side in the stacking direction. In this way, when the semiconductor device 5 is manufactured, the multiple fins 23 are pressed against the protruding end face 421 of the protruding portion 42 of the case 40, and the semiconductor module 10 is pressed to press the multiple fins 23 against the protruding end face 421, thereby suppressing misalignment between the heat sink 80 and the case 40. When welding the heat sink 80 and the case 40, for example, welding defects due to misalignment are suppressed. If a gap is provided between the tips of the multiple fins 23 and the protruding end face 421, pressure is applied to the side wall 46 from the second side in the stacking direction toward the first side, and pressure is also applied to the outer peripheral edge of the flat plate portion 81 of the heat sink 80 from the first side in the stacking direction toward the second side, thereby suppressing relative movement between the heat sink 80 and the case 40. As a result, when welding the heat sink 80 and the case 40, for example, misalignment between the heat sink 80 and the case 40 and resulting welding defects are suppressed.

[0064] 1, 5... Semiconductor device, 2, 6... Cooling device, 10... Semiconductor module, 13... Lead frame, 14... Sealing resin part, 20, 80... Heat sink, 21, 81... Flat plate part, 23... Fin, 30... Cover, 40, 140, 240... Case, 41... Bottom, 42... Convex part, 43... Recess, 44... Recess, 46... Side wall, 47... Mounting surface, 48, 49... Flow channel wall, 60... Housing, 61... Through hole, 62... Through hole, 101... Inflow channel, 102... Outflow channel, 103a... First flow channel, 103b... Second flow channel, 103c... Third flow channel, 421... End face of convex part, 422... Side surface of convex part, 423... Side surface of convex part, 431, 441... Bottom surface, 461... Inner surface, Y1, Y3, Y4... Molten part

Claims

1. A semiconductor device comprising: a heat sink having a flat plate-shaped portion and a plurality of fins protruding from the flat plate-shaped portion; a semiconductor module bonded to the flat plate-shaped portion in a stacked state on the flat plate-shaped portion; a housing for housing the fins; an inlet for liquid to flow into the housing; an outlet for liquid to flow out of the housing; an inlet passage for liquid to flow from the inlet to the plurality of fins; and an outlet passage for liquid to flow from the plurality of fins to the outlet, wherein at least one of the inlet, the outlet, the inlet passage and the outlet passage overlaps with the fins in the stacking direction of the heat sink and the semiconductor module.

2. The semiconductor device according to claim 1, wherein the housing comprises a concave case for housing the fins and a flat plate-shaped cover to which the heat sink is joined and which covers the opening of the case together with the heat sink, and the cover is joined to the case by being placed on the case and then irradiated with a laser in a direction parallel to the plate surface.

3. The semiconductor device according to claim 1, wherein the housing has a concave case for housing the fins, and the flat portion of the heat sink covers the opening of the case and is joined to the case by being irradiated with a laser in a direction parallel to the plate surface after being placed on the case.

4. The semiconductor device according to claim 2 or 3, wherein the case has a mounting surface on which the flat plate portion of the cover or the heat sink is placed, a facing surface recessed from the mounting surface in the direction of the protrusion of the plurality of fins and facing the tips of at least some of the fins among the plurality of fins, and a recess formed between the mounting surface and the facing surface and recessed from the facing surface in the direction of the protrusion of the plurality of fins, the inlet passage or the outlet passage is formed in the recess, and the recess overlaps with at least some of the plurality of fins in the stacking direction.

5. The semiconductor device according to claim 4, wherein the region in the recess that overlaps with the plurality of fins in the stacking direction is larger than the region that does not overlap with the plurality of fins.

6. The semiconductor device according to claim 2 or 3, wherein the semiconductor module comprises an insulating substrate, a semiconductor element, a sealing resin portion covering the insulating substrate and the semiconductor element, and a lead frame whose tip is exposed from the sealing resin portion, and the joint between the cover or the flat plate portion of the heat sink and the case is located on the fin side of the lead frame than the tip.

7. The semiconductor device according to claim 2 or 3, wherein the semiconductor module comprises an insulating substrate, a semiconductor element, and a sealing resin portion covering the insulating substrate and the semiconductor element, and when viewed from the semiconductor module side in the stacking direction, the ends of the joints between the cover or the flat plate portion of the heat sink and the case in the liquid flow direction of the plurality of fins do not extend outside the sealing resin portion of the semiconductor module.

8. The semiconductor device according to claim 1, wherein the flat plate portion of the heat sink and the semiconductor module are sintered.

9. A method for manufacturing a semiconductor device, comprising: a semiconductor module; a heat sink having a plurality of fins for dissipating heat generated by the semiconductor module; and a housing having a concave case and a flat plate-shaped cover covering the opening of the case, the method comprising: a bonding step of joining the heat sink and the cover; a sintering step of sintering the semiconductor module and the heat sink after the bonding step; and a welding step of welding the cover and the case by irradiating the cover with a laser in a direction parallel to the plate surface of the cover while the cover is placed on the case after the sintering step.

10. A method for manufacturing a semiconductor device comprising a semiconductor module, a heat sink having a flat plate-shaped portion and a plurality of fins protruding from the flat plate-shaped portion to dissipate heat generated by the semiconductor module, and a concave case for housing the fins, comprising: a sintering step of sintering the semiconductor module and the flat plate-shaped portion of the heat sink; and, after the sintering step, a step of welding the flat plate-shaped portion and the case by irradiating the flat plate-shaped portion with a laser in a direction parallel to the plate surface of the flat plate-shaped portion while the flat plate-shaped portion of the heat sink is placed on the case.

11. The semiconductor device comprises an inlet for introducing liquid into the housing or case, an outlet for discharging liquid from the housing or case, an inlet passage for introducing liquid between the plurality of fins from the inlet, and an outlet passage for discharging liquid from between the plurality of fins to the outlet, wherein at least one of the inlet, the outlet, the inlet passage, and the outlet passage overlaps with the fins in the stacking direction of the heat sink and the semiconductor module, and the sintering step is a step of pressurizing and heating the plurality of fins and the semiconductor module with the semiconductor module placed on the heat sink, the method for manufacturing a semiconductor device according to claim 9 or 10.

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