Semiconductor module, method for manufacturing semiconductor module, and step difference jig

Abstract

Provided is a method for manufacturing a semiconductor module using a step difference jig of a simple structure. Provided is a method for manufacturing a semiconductor module, which is a fin-integrated semiconductor module, including a step of applying a step difference to a fin-integrated heat dissipation base by a step difference jig to perform press-fixing, and a step of welding a semiconductor assembly on the heat dissipation base. Provided is a semiconductor module including a fin-integrated heat dissipation base and a semiconductor assembly provided on the heat dissipation base, the heat dissipation base having a warping amplitude of 200 μm or less.

Description

Technical Field

[0001] The present invention relates to a semiconductor module, a method for manufacturing the semiconductor module, and a step fixture. Background Art

[0002] Conventionally, as a method for reducing warping of a heat dissipation base of a semiconductor module, there is known a method of using a curved press jig to preliminarily pressurize and fix the heat dissipation base into a curved shape (for example, see Patent Documents 1 and 2).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2015-153925

[0006] Patent Document 2: Japanese Patent Application Laid-Open No. 2013-197246 Summary of the Invention

[0007] Technical issues

[0008] However, conventional curved press jigs are difficult to process and manage.

[0009] Technical Solution

[0010] In the first embodiment of the present invention, a method for manufacturing a semiconductor module is provided, which is a method for manufacturing a fin-integrated semiconductor module, comprising: a step of applying a step difference to a fin-integrated heat dissipation base by a step-difference fixture to pressurize and fix it; and a step of soldering a semiconductor assembly on the heat dissipation base.

[0011] The step of pressurizing and fixing the heat dissipation base may include: fixing a plurality of first pressurized and fixed parts arranged in the long side direction of the heat dissipation base at a first height; and fixing a second pressurized and fixed part arranged between the plurality of first pressurized and fixed parts in the long side direction at a second height lower than the first height.

[0012] The pressurizing and fixing step may include: providing a first jig of a stepped jig; placing the heat dissipation base on the first jig; and connecting the first jig to a second jig of the stepped jig to fix the heat dissipation base at a first height and a second height.

[0013] The step of pressurizing and fixing may include the step of pressurizing and fixing the heat dissipation base by point pressurization. The heat dissipation base may include a plurality of first pressurized and fixed portions and a second pressurized and fixed portion fixed by a step jig and a free portion not fixed by the step jig.

[0014] The step of pressurizing and fixing may include pressurizing and fixing the heat dissipation base by surface pressurization. The heat dissipation base may include a plurality of first pressurizing and fixing parts and a second pressurizing and fixing part fixed by a step jig and a surface pressurizing part pressurized by a second jig surface.

[0015] The method for manufacturing a semiconductor module may further include positioning the insulating substrate using a second jig and placing the substrate on the heat dissipation base.

[0016] The method for manufacturing a semiconductor module may include a step of attaching a cooling case for accommodating cooling fins to a heat dissipation base before the step of soldering the semiconductor assembly.

[0017] The heat dissipation base may have the same linear expansion coefficient as that of the step fixture.

[0018] In a second aspect of the present invention, a semiconductor module is provided, comprising a fin-integrated heat dissipation base and a semiconductor assembly provided on the heat dissipation base, wherein the heat dissipation base has a warpage width of 200 μm or less.

[0019] The semiconductor module may further include a cooling housing for accommodating the cooling fins, and a refrigerant circulation portion having an opening provided in the cooling housing for circulating refrigerant within the cooling housing through the opening. When defining a virtual plane passing through the first end of the heat sink base and a second end of the heat sink base opposite to the first end in the longitudinal direction, the deviation of a central axis passing through the opening from a perpendicular to the virtual plane may be within 5 degrees.

[0020] In a third aspect of the present invention, a stepped jig for manufacturing semiconductor modules is provided, comprising a first jig for mounting a heat sink base on the semiconductor module, and a second jig coupled to the first jig for pressurizing and securing the heat sink base. The first jig may include a first protrusion for positioning a plurality of first pressurizing and securing portions arranged along the longitudinal direction of the heat sink base at a first height, and a second protrusion for positioning a second pressurizing and securing portion, sandwiched between the plurality of first pressurizing and securing portions along the longitudinal direction, at a second height lower than the first height. The second jig may include a first coupling portion coupled to the first protrusion for pressurizing and securing the plurality of first pressurizing and securing portions at the first height, and a second coupling portion coupled to the second protrusion for pressurizing and securing the second pressurizing and securing portion at the second height.

[0021] It should be noted that the above summary of the invention does not list all the features of the present invention. In addition, sub-combinations of these feature groups may also constitute inventions. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1A An example of a plan view of the semiconductor module 100 according to the embodiment is shown.

[0023] Figure 1B To show Figure 1A FIG. 1 is a diagram showing an example of an AA' cross section.

[0024] Figure 1C This is an example of a bottom view of the semiconductor module 100 .

[0025] Figure 1D To show Figure 1C An example of a BB' cross section.

[0026] Figure 2A FIG. 3 is an example of a top view of the first jig 310 .

[0027] Figure 2B To show Figure 2A An example of a CC' cross section.

[0028] Figure 3 An example of a side view of the heat dissipation base 10 pressurized and fixed by point pressing is shown.

[0029] Figure 4A An example of a top view of the second jig 320 is shown.

[0030] Figure 4B An example of a side view of the heat dissipation base 10 pressurized and fixed by surface pressing is shown.

[0031] Figure 5 An example of a cross-sectional view of the semiconductor module 100 after reflow is shown.

[0032] Figure 6 An example of a method for manufacturing the semiconductor module 100 is shown.

[0033] Figure 7A An example of a top view of a semiconductor module 100 according to another embodiment is shown.

[0034] Figure 7B To show Figure 7A FIG. 1 is a diagram showing an example of a D-D' cross section.

[0035] Figure 8 An example of a side view of the heat dissipation base 10 pressurized and fixed by point pressing is shown.

[0036] Figure 9A An example of a cross-sectional view of a semiconductor module 500 manufactured by a method of a comparative example is shown. Figure 9B An example of a cross-sectional view of a semiconductor module 500 manufactured by a method of a comparative example is shown.

[0037] Explanation of symbols

[0038] 10: Heat dissipation base 11: Pressurized fixing part

[0039] 12: Pressurized fixed part 13: Free part

[0040] 14: Surface pressing part 15: End

[0041] 16: Opening 20: Insulating substrate

[0042] 21: Conductive plate 22: Insulating plate

[0043] 23: Conductive plate 25: Solder portion under substrate

[0044] 30: Semiconductor chip 40: Metal wiring board

[0045] 50: Sealing resin 60: Box

[0046] 62: Main terminal 70: Fastening part

[0047] 100: Semiconductor module 110: Semiconductor assembly

[0048] 200: Cooling unit 205: Fin integrated base

[0049] 210: Cooling fins 220: Cooling shell

[0050] 222: Frame 230: Refrigerant circulation part

[0051] 232: Opening 234: Opening

[0052] 300: Step difference fixture 310: First fixture

[0053] 311: Main body 312: Protrusion

[0054] 314: protrusion 315: countersunk hole

[0055] 320: Second jig 321: Main body

[0056] 322: Connecting part 324: Connecting part

[0057] 326: Opening 328: Protrusion

[0058] 500: semiconductor module 505: base substrate

[0059] 510: Cooling fins 520: Cooling shell DETAILED DESCRIPTION

[0060] The present invention will be described below by way of embodiments of the invention, but the following embodiments do not limit the invention as defined in the claims. Furthermore, all combinations of features described in the embodiments are not necessarily essential to the technical aspects of the invention.

[0061] Figure 1A An example of a top view of the semiconductor module 100 according to the embodiment is shown. Figure 1A The long side direction of the rectangular box 60 in the top view is the X axis, and the short side direction is the Y axis. The Z axis forms a right-hand system with the X axis and the Y axis.

[0062] The semiconductor module 100 includes a heat dissipation base 10, a housing 60, and semiconductor assemblies 110. The semiconductor module 100 of this embodiment includes three semiconductor assemblies 110.

[0063] The box 60 is a terminal housing made of resin and defines a region for accommodating the semiconductor assembly 110 , and is provided so as to surround the semiconductor assembly 110 in a plan view.

[0064] The fin-integrated base 205 includes a heat sink base 10 and cooling fins 210, described later. The fin-integrated base 205 has a fin-integrated structure, integrating the heat sink base 10 and cooling fins 210. In this specification, a semiconductor module 100 equipped with a fin-integrated heat sink base 10 is referred to as a fin-integrated semiconductor module. The fin-integrated semiconductor module 100 can be pre-warped by applying a warp to the fin-integrated heat sink base 10 before reflow, thereby reducing warpage in the finished product.

[0065] The heat sink 10 is provided on the lower surface of the semiconductor module 100. The heat sink 10 may be a metal plate having a plane parallel to the XY plane. For example, the heat sink 10 may be made of a metal material including aluminum or copper. The heat sink 10 is provided so as to overlap the housing 60 in a top view.

[0066] Semiconductor assembly 110 is mounted on the upper surface of heat sink 10. Semiconductor assembly 110 is secured to the upper surface of heat sink 10 using a bonding material such as solder. This allows heat generated by semiconductor assembly 110 to be transferred to heat sink 10. In this example, three semiconductor assemblies 110 are arranged side by side in the X-axis, which is the longitudinal direction. However, this is not limiting. Semiconductor assembly 110 is an assembly comprising insulating substrate 20 and semiconductor chip 30.

[0067] The insulating substrate 20 is soldered to the heat dissipation base 10 . The insulating substrate 20 may be a DCB (Direct Copper Bonding) substrate or an AMB (Active Metal Brazing) substrate. The insulating substrate 20 includes a conductive plate 21 and an insulating plate 22 .

[0068] The insulating plate 22 is formed of an insulating material such as ceramics. For example, the insulating plate 22 is made of alumina (Al2O3), aluminum nitride (AlN), or silicon nitride (Si3N4).

[0069] Conductive plate 21 is a wiring pattern provided on the upper surface of insulating plate 22. Conductive plate 21 is made of a metal material, such as copper or a copper alloy, for example. Conductive plate 21 is soldered to semiconductor chip 30 using solder. This electrically connects conductive plate 21 and semiconductor chip 30. In semiconductor assembly 110, semiconductor chip 30, conductive plate 21, and metal wiring plate 40 can be electrically connected to form a half-bridge circuit.

[0070] The semiconductor chip 30 can be a vertical power semiconductor element including at least one of a transistor and a diode. In one example, the semiconductor chip 30 is a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) or an IGBT (Insulated Gate Bipolar Transistor). The semiconductor chip 30 can be an RC-IGBT (Reverse Conducting-IGBT) in which an IGBT and a freewheeling diode (FWD) are formed on one chip. The semiconductor chip 30 can be formed using a semiconductor substrate such as silicon, silicon carbide or gallium nitride. For each of the three semiconductor assemblies 110, two groups of four semiconductor chips 30 of this example are provided in a group of two.

[0071] The metal wiring plate 40 is electrically connected to the semiconductor chip 30. For example, the metal wiring plate 40 wires the collector or emitter of the semiconductor chip 30. One end of the metal wiring plate 40 can be connected to the electrode of the semiconductor chip 30 via solder. The other end of the metal wiring plate 40 can be connected to an external connection terminal for connecting to the outside of the semiconductor module 100. The metal wiring plate 40 can be a conductive connecting member obtained by forming a metal plate by stamping or the like. The metal plate can be a copper plate or a copper alloy plate. The metal wiring plate 40 can have a plating film such as nickel on the surface. The cross section (ZX cross section) of the metal wiring plate 40 can have a rectangular portion.

[0072] It should be noted that the housing 60 has a plurality of main terminals 62. The main terminals 62 include a U-phase terminal, a V-phase terminal, and a W-phase terminal for driving, for example, the U-phase, V-phase, and W-phase of a three-phase inverter circuit, respectively. Furthermore, the main terminals 62 include a power supply terminal for supplying power to, for example, the three-phase inverter circuit.

[0073] Figure 1B To show Figure 1A1 is a diagram showing an example of an AA′ cross section. The AA′ cross section is an XZ cross section passing through the housing 60 and the semiconductor assembly 110 . The semiconductor module 100 includes a cooling unit 200 .

[0074] The cooling unit 200 is disposed below the semiconductor assembly 110. A refrigerant can be supplied to the cooling unit 200 from the outside. The cooling unit 200 cools the semiconductor module 100 by flowing the refrigerant. The cooling unit 200 includes a fin-integrated base 205 and a cooling housing 220. Heat generated by the operation of the semiconductor chips 30 is dissipated to the outside of the semiconductor module 100 via the cooling unit 200 and the refrigerant.

[0075] The cooling fins 210 form a plurality of flow paths for circulating the refrigerant. The cooling fins 210 are arranged to extend in the Z-axis direction. One end of the cooling fin 210 on the positive side of the Z-axis is arranged to be connected to the lower surface of the heat dissipation base 10. One end of the cooling fin 210 on the negative side of the Z-axis can be in contact with the upper surface of the cooling shell 220. A plurality of cooling fins 210 are arranged at arbitrary intervals in the X-axis direction. In addition to straight fins, the cooling fins 210 can also be wavy fins, pin-shaped fins, corrugated fins or stacked fins. The cooling fins 210 can be formed of a metal having the same composition as the cooling shell 220. The cooling fins 210 are formed of, for example, a metal containing aluminum or copper. In order to reduce weight, the material of the cooling fins 210 can be a metal containing aluminum.

[0076] The heat sink 10 is integrally formed with the cooling fins 210. Specifically, the heat sink 10 is configured to be connected to the cooling fins 210. In one example, the fin-integrated heat sink 10 is manufactured by forming the fins through cutting, brazing, stamping, forging, inserting, and riveting. In an integral fin structure, warping is more difficult to control than in a monolithic heat sink. Similarly, attempting to pre-introduce warping can sometimes complicate or even render manufacturing impossible.

[0077] The cooling housing 220 houses the cooling fins 210. The cooling housing 220 covers the lower and side surfaces of the cooling fins 210. The upper surface of the cooling fins 210 is covered by the heat dissipation base 10. The cooling housing 220 can be formed from the same material as the heat dissipation base 10. The cooling housing 220 can be a box-shaped component having a bottom plate and sidewalls. The cooling housing 220 can also have flanges connected to the sidewalls. The flanges can engage with the heat dissipation base 10.

[0078] The insulating substrate 20 is soldered to the heat dissipation base 10 via the lower substrate solder portion 25 . The insulating substrate 20 includes a conductive plate 21 , an insulating plate 22 , and a conductive plate 23 .

[0079] The conductive plate 23 is provided on the lower surface of the insulating plate 22. The conductive plate 21 and the conductive plate 23 are formed of a conductive material or a metal material such as copper or a copper alloy. The conductive plate 23 is provided on substantially the entire lower surface of the insulating plate 22.

[0080] Sealing resin 50 seals the interior of housing 60. Sealing resin 50 covers the periphery of semiconductor assembly 110. Sealing resin 50 can be made of epoxy resin or silicone gel. The lower surface of sealing resin 50 can be arranged to contact the upper surface of heat sink 10. The side surface of sealing resin 50 can be arranged to contact housing 60. The upper surface of sealing resin 50 is arranged below the upper surface of housing 60.

[0081] The cooling housing 220 and the cooling fins 210 can be formed by stamping, forging, or extrusion. The cooling housing 220 and the cooling fins 210 can also be assembled by brazing. The brazing material can be formed of a metal with a lower melting point than the cooling housing 220. The brazing material can use a metal containing copper or aluminum as the low-melting-point metal.

[0082] Figure 1C This is an example of a bottom view of the semiconductor module 100. On the bottom surface of the semiconductor module 100, an opening 16 for mounting a step jig described later is provided in the heat dissipation base 10.

[0083] Cooling fins 210 are arranged inside cooling housing 220, extending along the Y-axis and arranged in the X-axis. In this example, cooling fins 210 are straight fins with their longitudinal sides extending in the Y-axis direction. The number and shape of cooling fins 210 are not limited to this example.

[0084] Refrigerant flow section 230 is provided on the lower surface of cooling housing 220. Refrigerant flow section 230 allows refrigerant to flow into cooling housing 220. In one example, refrigerant flows into cooling housing 220 through refrigerant flow section 230a and flows out of cooling housing 220 through refrigerant flow section 230b. Refrigerant flow sections 230a and 230b are provided at the ends of cooling housing 220 in the longitudinal direction, but may alternatively be provided near the center.

[0085] Figure 1D To show Figure 1C FIG. 1 is a diagram showing an example of a BB' cross section. The BB' cross section is an XZ cross section passing through the refrigerant flow portion 230a. The refrigerant flow portion 230 includes a refrigerant flow portion 230a and a refrigerant flow portion 230b.

[0086] The refrigerant flow portion 230a is connected to an external device or the like, and allows the refrigerant to flow into the interior of the cooling housing 220. The refrigerant flow portion 230a is provided with an opening 232a for allowing the refrigerant to flow in.

[0087] The refrigerant flow portion 230b is connected to an external device and allows the refrigerant to flow out from the cooling housing 220. The refrigerant flow portion 230b is provided with an opening 232b for allowing the refrigerant to flow out. The refrigerant can circulate between the external device and the cooling unit 200.

[0088] The refrigerant circulation portion 230 has a structure protruding from the lower surface of the cooling shell 220. The refrigerant circulation portion 230 may have a flange or a tube for connecting to an external device. In order to be inserted into the opening of the external device, the refrigerant circulation portion 230 is manufactured to be consistent with the opening and angle of the external device. However, if warping occurs in the heat dissipation base 10, the angle of the refrigerant circulation portion 230 is tilted, and sometimes it becomes impossible to connect to the external device. In particular, if the refrigerant circulation portion 230 has a protruding structure such as a flange or a tube, it is easy to be positionally offset due to the influence of the warping of the heat dissipation base 10. It should be noted that the warping of the heat dissipation base 10 can be regarded as the warping of the fin-integrated base 205 taking into account the influence of the cooling fins 210.

[0089] Figure 2A 1 is an example of a top view of the first jig 310 . The first jig 310 is an example of the stepped jig 300 .

[0090] The first jig 310 is used to place the heat dissipation base 10, set the steps and pressurize it. The first jig 310 includes a main body 311, a protrusion 312 and a protrusion 314. In this example, the first jig 310 has four protrusions 312 and four protrusions 314.

[0091] The protrusion 312 is provided on the upper surface of the first jig 310. The protrusion 312 extends from the upper surface of the main body 311 in the Z-axis direction. The protrusion 312 positions the heat sink 10 at a predetermined first height T1. The protrusions 312a and 312b are arranged along the longitudinal direction of the heat sink 10. The protrusions 312a and 312b are examples of the first protrusions that secure the heat sink 10 at the first height T1. The protrusion 312 may have internal threads for clamping the heat sink 10 and applying pressure to secure it.

[0092] The protrusion 314 is provided on the upper surface of the first jig 310. The protrusion 314 extends from the upper surface of the main body 311 in the Z-axis direction. The protrusion 314 positions the heat sink 10 at a second height T2, which is lower than the first height T1. The protrusion 314 is an example of a second protrusion that secures the heat sink 10 at the second height T2. The protrusion 314 may have internal threads for clamping and pressurizing the heat sink 10. The protrusion 314 may be positioned between the protrusion 312a and the protrusion 312b along the longitudinal direction of the heat sink 10.

[0093] Note that a heat transfer member, such as a carbon sheet, may be provided on the upper surface of the first jig 310. Providing a heat transfer member on the first jig 310 facilitates heat transfer from the first jig 310 to the semiconductor assembly 110 during reflow. The main body 311 may be a flat plate having a main surface and may further include a countersunk hole 315 for accommodating the refrigerant flow portion 230. The countersunk hole 315a is provided at a position corresponding to the refrigerant flow portion 230a. The countersunk hole 315b is provided at a position corresponding to the refrigerant flow portion 230b.

[0094] Figure 2B To show Figure 2A The CC' cross section is an XZ cross section passing through the protrusion 312 and the protrusion 314 of the first jig 310.

[0095] The first height T1 is the height of the protrusion 312. The second height T2 is the height of the protrusion 314. The second height T2 is lower than the first height T1. The second height T2 is determined based on the heights of the cooling fins 210 and the cooling housing 220. For example, the second height T2 is set to a height at which the cooling fins 210 can contact the main body 311. Alternatively, the second height T2 can be set to a height at which the cooling housing 220 can contact the main body 311.

[0096] The warping amplitude W is the difference between the first height T1 and the second height T2. The first jig 310 has a protrusion 312 and a protrusion 314 of different heights, and has a step difference of the warping amplitude W. The warping amplitude of the heat dissipation base 10 is adjusted by the warping amplitude W. The step-difference jig 300 reduces the warping of the heat dissipation base 10 after reflow by applying warping in a direction opposite to the direction in which the warping occurs during reflow. The warping amplitude W is adjusted to make the warping amplitude after reflow smaller. In one example, the warping amplitude W can be adjusted according to the difference in linear expansion coefficient between the heat dissipation base 10 and the insulating substrate 20. In addition, the warping amplitude W can be adjusted according to the shape of the heat dissipation base 10 and the insulating substrate 20, etc. For example, the warping amplitude W is greater than 0.2 mm and less than 2.0 mm.

[0097] Figure 3This figure shows an example of a side view of a heat sink 10 secured by point pressure. This side view shows the heat sink 10 being warped. The structures of the first jig 310 and the second jig 320 in this example are examples of securing the heat sink 10 by point pressure, but are not limited to this. The heat sink 10 includes a pressurized portion 11, a pressurized portion 12, and a free portion 13. The second jig 320 includes a connecting portion 322 and a connecting portion 324.

[0098] The connecting portion 322 is connected to the protrusion 312 to pressurize and secure the heat sink 10. The connecting portion 322 is a fixing member such as a screw. For example, the connecting portion 322 is an external thread that is inserted into the internal thread of the protrusion 312 through the opening 16. The head of the external thread is used to apply pressure to the pressurized fixing portion 11.

[0099] The connecting portion 324 is connected to the protrusion 314 to pressurize and secure the heat sink 10. The connecting portion 324 is a fixing member such as a screw. For example, the connecting portion 324 is an external thread that is inserted into the internal thread of the protrusion 314 through the opening 16. The head of the external thread is used to apply pressure to the pressurized fixing portion 12.

[0100] The press-fixed portion 11 is positioned at the first height T1 by the protrusion 312. The press-fixed portion 11 is a region press-fixed by the protrusion 312 and the connection portion 322. That is, the press-fixed portion 11 is sandwiched between the protrusion 312 and the connection portion 322.

[0101] The pressurized fixed portion 12 is positioned at the second height T2 by the protrusion 314. The pressurized fixed portion 12 is the area pressurized and fixed by the protrusion 314 and the connecting portion 324. In other words, the pressurized fixed portion 12 is sandwiched between the protrusion 314 and the connecting portion 324. The pressurized fixed portion 12 is sandwiched between the plurality of pressurized fixed portions 11 along the longitudinal direction of the heat dissipation base 10. This creates a curved surface shape of the heat dissipation base 10 that is higher at both ends in the longitudinal direction and lower in the center.

[0102] The free portion 13 is an area of ​​the heat dissipation base 10 that is not fixed by the stepped jig 300. That is, the free portion 13 does not contact the first jig 310 and the second jig 320. However, the free portion 13 is indirectly fixed because the press-fixing portion 11 and the press-fixing portion 12 are press-fixed at different heights.

[0103] Figure 4A An example of a plan view of the second jig 320 is shown. The structure of the second jig 320 of this example is an example of a case where the heat dissipation base 10 is pressurized and fixed by surface pressure.

[0104] The second jig 320 is fixed to the first jig 310 and is used to place the semiconductor chip 30 on the heat sink 10. The second jig 320 has connecting portions 322 and 324 at positions corresponding to the shape of the housing 60. In this example, the second jig 320 has four connecting portions 322 and four connecting portions 324.

[0105] Openings 326 are used to position semiconductor assembly 110 for placement on heat dissipation base 10. The second jig 320 of this example has three openings 326. In other words, the second jig 320 of this example also serves as an assembly jig for positioning insulating substrate 20 for placement on heat dissipation base 10. This allows warping of heat dissipation base 10 without increasing the number of jigs.

[0106] Protrusions 328 are provided at the ends of opening 326. Multiple protrusions 328 guide the position of insulating substrate 20 and the like to a desired location. Providing multiple protrusions 328 allows for the expansion of bonding members such as molten solder during reflow to occur between adjacent protrusions 328. The cross-sections of the multiple protrusions 328 may have a slope to guide semiconductor chip 30 and the like to a desired location. Protrusions 328 may be formed from a different material than main body 321, such as carbon.

[0107] Figure 4B An example of a side view of the heat dissipation base 10 pressurized and fixed by surface pressure is shown. The structures of the first jig 310 and the second jig 320 in this example are an example of pressurizing and fixing the heat dissipation base 10 by surface pressure, and are not limited thereto.

[0108] The second jig 320 is connected to the first jig 310 via the connecting portion 322 and the connecting portion 324. As a result, the main body 321 of the second jig 320 is deformed according to the step difference, and the surface of the heat dissipation base 10 is pressurized.

[0109] The surface pressing portion 14 is a region that is surface-pressed by the second jig 320. Specifically, the surface pressing portion 14 is a region that contacts the main body 321 but does not contact the first jig 310. The surface pressing portion 14 is pressurized by the second jig 320 when the second jig 320 is coupled to the first jig 310.

[0110] The second jig 320 of this embodiment can pressurize and fix the heat dissipation base 10 in a shape close to a curved surface without complicated processing. The second jig 320 can handle heat dissipation bases 10 of various shapes and sizes.

[0111] The stepped jig 300 may have the same linear expansion coefficient as the heat dissipation base 10 . This can suppress warping caused by the difference in linear expansion coefficient between the heat dissipation base 10 and the stepped jig 300 .

[0112] Figure 5 An example of a cross-sectional view of the semiconductor module 100 after reflow is shown. The cross-sectional view of this example corresponds to Figure 1C BB' section.

[0113] Heat sink base 10 is flat, or warped in the opposite direction to the warping imparted by step jig 300 before reflow. In other words, heat sink base 10 is deformed into a convex shape in cross section. Cooling housing 220 is similarly deformed into a convex shape, with refrigerant flow portion 230 tilted inward.

[0114] Warpage Wa represents the warpage of the heat sink 10 after reflow. By appropriately setting the warpage Wa of the step jig 300, the warpage Wa of the heat sink 10 after reflow can be adjusted. The semiconductor module 100 can have a flat heat sink 10 without warpage Wa. For example, the warpage Wa is 200 μm or less. Alternatively, the warpage Wa can be 0 μm or greater.

[0115] Virtual plane Vp is a virtual plane passing through end 15a and end 15b in the longitudinal direction of heat dissipation base 10. End 15b is the end on the opposite side of heat dissipation base 10 in the longitudinal direction of heat dissipation base 10 from end 15a. Preferably, heat dissipation base 10 has a flat surface parallel to virtual plane Vp. In this example, virtual plane Vp coincides with the XY plane.

[0116] The warp angle R is the angular deviation of the central axis Ac caused by warping of the heat dissipation base 10. The central axis Ac passes through the center of the opening of the refrigerant flow portion 230. In the absence of warping, the central axis Ac is perpendicular to the virtual plane Vp. The warp angle R is the angle between the central axis Ac and the perpendicular to the virtual plane Vp. Preferably, the warp angle R is within 5 degrees.

[0117] The use of the stepped jig 300 makes it easier to control the warpage of the semiconductor module 100 and expands the range of permissible initial warpage of the heat sink base 10. Furthermore, since the warpage of the finished product can be controlled by using the initial warpage, it is no longer necessary to use a high-strength material with low warpage for the heat sink base 10. Consequently, the range of material strength options for the heat sink base 10 is expanded.

[0118] Furthermore, if warpage control becomes easier, the constraints of the manufacturing process are reduced, and the optimal structure for improving cooling efficiency can be selected. As described above, by using the manufacturing method of this example, a semiconductor module 100 with excellent cooling efficiency can be manufactured using a simple step jig 300.

[0119] Figure 6An example of a method for manufacturing the semiconductor module 100 is shown. According to steps S100 to S110 , the semiconductor module 100 can be manufactured while reducing warpage of the finished product.

[0120] In step S100 , a first jig 310 is provided. In step S102 , the fin-integrated base 205 is placed on the first jig 310 . Furthermore, when the cooling housing 220 and the heat dissipation base 10 are integrated, the cooling housing 220 can be placed on the first jig 310 .

[0121] In step S104, the first jig 310 and the second jig 320 are connected to apply pressure to the heat dissipation base 10 by applying steps. This step of applying pressure to the heat dissipation base 10 by applying steps includes fixing the plurality of press-fixing portions 11 at a first height T1 and fixing the press-fixing portion 12 at a second height T2. The press-fixing of the heat dissipation base 10 can be performed by applying pressure to a specific point or a specific surface.

[0122] In step S106, the semiconductor assembly 110 is placed on the heat dissipation base 10. In step S106, the insulating substrate 20 can be positioned on the heat dissipation base 10 by the second jig 320. Alternatively, an assembly jig other than the second jig 320 can be used to position the semiconductor assembly 110.

[0123] In step S108, the semiconductor assembly 110 is soldered by reflow soldering. The semiconductor module 100 is reflowed with the first jig 310 and the second jig 320 mounted thereon. That is, the reflow is performed while the heat sink 10 is pressurized and secured. It should be noted that the cooling housing 220 for accommodating the cooling fins 210 may be mounted on the heat sink 10 before soldering the semiconductor assembly 110. Alternatively, the cooling unit 200, which includes the heat sink 10, cooling fins 210, and the cooling housing 220, may be placed on the first jig 310 in step S102, and the heat sink 10 may be pressurized and secured in the subsequent step S104.

[0124] In step S110 , the first jig 310 and the second jig 320 are removed. The first jig 310 and the second jig 320 may be removed after the heat dissipation base 10 is cooled. Through these steps, the warping of the semiconductor module 100 may be reduced.

[0125] Figure 7A FIG. 1 shows an example of a top view of a semiconductor module 100 according to another embodiment. Figure 1A The semiconductor module 100 of this example is different from the semiconductor module 100 of the embodiment. Figure 1AThe box body 60 is different from the embodiment, but the shape of the box body 60 is not limited to this example.

[0126] The opening 234 is provided at an end of the housing 60. The opening 234 is a through hole that penetrates the housing 60, the heat dissipation base 10, and the cooling case 220. In the semiconductor module 100 of this embodiment, two openings 234a and 234b are provided.

[0127] The fastening portion 70 is disposed within the opening 234 to securely fasten the housing 60, the heat dissipation base 10, and the cooling housing 220. The fastening portion 70 can be used to secure the semiconductor module 100 to an external device. The semiconductor module 100 in this example includes two fastening portions 70a and 70b. The fastening portions 70a and 70b are disposed within the plurality of openings 234a and 234b, respectively.

[0128] Figure 7B To show Figure 7A DD' cross section is a cross section passing through the housing 60 and the semiconductor assembly 110 and passing through the opening 234a and the opening 234b.

[0129] The fastening portion 70 fastens the housing 60, the heat dissipation base 10, and the cooling shell 220. For example, the fastening portion 70 is a region where the heat dissipation base 10 and the cooling shell 220 are directly or indirectly in close contact and overlapped in the z-axis direction, and is provided in a region formed by the opening 234 that penetrates the heat dissipation base 10 and the cooling shell 220. By providing the fastening portion 70, Figure 1B Compared with the case of the embodiment, it becomes easier to fix the cooling housing 220.

[0130] The frame portion 222 is disposed at the outer edge of the cooling housing 220. The frame portion 222 is configured to surround the cooling fins 210 in the xy plane. The frame portion 222 may be a plate-like protrusion (i.e., a flange) that surrounds the outer edge of the cooling housing 220. The upper surface of the plate-like protrusion may be parallel to the lower surface of the heat dissipation base 10. The upper surface of the frame portion 222 is configured to be in close contact with the lower surface of the heat dissipation base 10, directly or indirectly. A sealing material or other member may be provided between the upper surface of the frame portion 222 and the lower surface of the heat dissipation base 10.

[0131] Figure 8 An example of a side view of the heat dissipation base 10 fixed by point pressing is shown. This side view shows the state where the heat dissipation base 10 is being warped. Figure 6This embodiment illustrates the case where the fin-integrated base 205 is integrated with the cooling housing 220 in step S102. The fin-integrated base 205 is pressurized and secured while mounted on the cooling housing 220. This causes the cooling housing 220 to warp in response to the deformation of the fin-integrated base 205. By pre-warping the cooling housing 220, it is easier to reduce warping in the finished product.

[0132] The structure of the first fixture 310 and the second fixture 320 in this example is an example of a case where the heat dissipation base 10 is pressurized and fixed by point pressure. The fin-integrated base 205 with the cooling shell 220 can be used as shown in FIG. Figure 4B The first jig 310 and the second jig 320 are fixed by pressurization through surface pressure.

[0133] Figure 9A An example of a cross-sectional view of a semiconductor module 500 manufactured using the comparative example method is shown. This example illustrates a case where the cooling housing 520 is not installed during reflow. The cooling housing 520 is installed after the semiconductor assembly 110 is reflowed. Furthermore, since no initial warping is applied to the base substrate 505, it exhibits a convex warp after reflow. This warping occurs during cooling from the solder melting point to room temperature due to the difference in linear expansion coefficient between the base substrate 505 and the insulating substrate 20.

[0134] Gap G1 is the height difference between the cooling fins 510 caused by the warping of the base substrate 505. The presence of gap G1 increases the clearance between the cooling fins 510 and the cooling housing 520, which can alter the refrigerant flow rate and reduce cooling performance. Alternatively, it is possible to fabricate the cooling housing 520 to accommodate the warping of the base substrate 505, but this would require time and increase costs.

[0135] Figure 9B An example of a cross-sectional view of a semiconductor module 500 manufactured using the method of a comparative example is shown. This example illustrates a semiconductor module 500 with a cooling housing 520 installed during reflow. The cooling housing 520 can be integrated with the base substrate 505. Furthermore, since no initial warpage is applied to the base substrate 505, it exhibits a convex warpage after reflow.

[0136] Furthermore, the semiconductor module 500 has a structure in which the cooling housing 520 and the cooling fins 510 are integrated. The cooling housing 520 has a convex warp after reflow. If the cooling housing 520 has warp, the cooling efficiency of other components provided on the back surface of the semiconductor module 100 may be reduced.

[0137] Gap G2 is the extent of the warping of the cooling housing 520 caused by the warping of the base substrate 505. If gap G2 is present, the cooling housing 520 cannot contact external devices located on the opposite side of the cooling housing 520 from the base substrate 505. Consequently, the cooling efficiency of the cooling fins 510 for the external devices is reduced.

[0138] While the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications or improvements may be made to the above embodiments. According to the claims, such modifications or improvements are also encompassed within the technical scope of the present invention.

[0139] It should be noted that the order in which actions, processes, steps, and stages, etc., of the apparatus, system, program, and method described in the claims, specifications, and drawings may be executed in any order, unless otherwise expressly stated, such as "before" or "before," and unless the results of previous processing are used in subsequent processing. Even if the action flow in the claims, specifications, and drawings is described using the phrases "first" or "next" for convenience, it does not necessarily mean that the actions must be executed in that order.

Claims

1. A method for manufacturing a semiconductor module, characterized in that: A method for manufacturing a fin-integrated semiconductor module, the method comprising: A step of applying a step difference to the fin-integrated heat dissipation base by using a step difference fixture to pressurize and fix it; and The step of welding the semiconductor assembly on the heat dissipation base, In the step of pressurizing and fixing the heat dissipation base, the first protrusion, the second protrusion, and the connecting portion of the step jig are connected, so that the heat dissipation base is pressurized and fixed in a manner such that the heights of both ends in the long side direction of the heat dissipation base are higher than the height of the center, the first protrusion has a first height, and the second protrusion has a second height lower than the first height.

2. The method for manufacturing a semiconductor module according to claim 1, wherein: The step of pressurizing and fixing the heat dissipation base includes: A step of fixing a plurality of first pressurizing and fixing portions arranged in the longitudinal direction of the heat dissipation base at a first height; and A step of fixing a second press-and-fix portion disposed between the plurality of first press-and-fix portions in the longitudinal direction at a second height lower than the first height.

3. The method for manufacturing a semiconductor module according to claim 2, wherein: The step of pressurizing and fixing comprises: A step of providing a first jig of the step jig; The step of placing the heat dissipation base on the first fixture; and The step of connecting the first fixture to the second fixture of the step fixture to fix the heat dissipation base at the first height and the second height.

4. The method for manufacturing a semiconductor module according to claim 2, wherein: The step of pressurizing and fixing includes the step of pressurizing and fixing the heat dissipation base by point pressurization. The heat dissipation base has: the plurality of first pressurized fixing portions and the second pressurized fixing portions fixed by the step jig; and A free portion not fixed by the step jig.

5. The method for manufacturing a semiconductor module according to claim 3, wherein: The step of pressurizing and fixing includes the step of pressurizing and fixing the heat dissipation base by point pressurization. The heat dissipation base has: the plurality of first pressurized fixing portions and the second pressurized fixing portions fixed by the step jig; and A free portion not fixed by the step jig.

6. The method for manufacturing a semiconductor module according to claim 3, wherein: The step of pressurizing and fixing includes the step of pressurizing and fixing the heat dissipation base by surface pressure. The heat dissipation base has: the plurality of first pressurized fixing portions and the second pressurized fixing portions fixed by the step jig; and A surface pressing portion that is surface-pressed by the second jig.

7. The method for manufacturing a semiconductor module according to claim 6, wherein: The manufacturing method further comprises: The step of positioning the insulating substrate and placing it on the heat dissipation base using the second fixture.

8. The method for manufacturing a semiconductor module according to any one of claims 1 to 7, wherein: The manufacturing method includes, before the step of soldering the semiconductor assembly, a step of attaching a cooling case for accommodating cooling fins to the heat dissipation base.

9. The method for manufacturing a semiconductor module according to any one of claims 1 to 7, wherein: The heat dissipation base has the same linear expansion coefficient as that of the step fixture.

10. The method for manufacturing a semiconductor module according to claim 8, wherein: The heat dissipation base has the same linear expansion coefficient as that of the step fixture.

11. A step difference fixture, characterized in that A step fixture for manufacturing a semiconductor module, the step fixture comprising: A first fixture for mounting a heat dissipation base of the semiconductor module; and a second jig connected to the first jig for pressurizing and fixing the heat dissipation base; The first fixture has: Positioning a plurality of first pressurizing and fixing portions arranged in the longitudinal direction of the heat dissipation base at a first protrusion of a first height; as well as Positioning a second press-fixed portion sandwiched between the plurality of first press-fixed portions in the longitudinal direction at a second protrusion having a second height lower than the first height, The second fixture has: a first connecting portion connected to the first protrusion to pressurize and fix the plurality of first pressurizing and fixing portions to the first height; and The second protrusion is connected to the second connection portion, and the second pressurized fixing portion is pressurized and fixed to the second connection portion at the second height.

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