Semiconductor device and method for manufacturing semiconductor device

Abstract

The purpose is to provide a technology that can suppress deformation of pin fins caused by contact during assembly of a semiconductor device. A semiconductor device (100) has a base plate (1), a semiconductor element (6), and a resin component. The base plate (1) has a plurality of pin fins (2) on the lower surface. The semiconductor element (6) is mounted on the upper side of the base plate (1). The resin component covers at least the side surface of the semiconductor element (6). In addition, the resin component has a rib (9) that covers the side surface of the base plate (1), and the lower end of the rib (9) is located below the lower ends of the plurality of pin fins (2).

Description

Technical Field

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

[0002] Semiconductor devices that control power may include a base plate having pin fins for heat dissipation. Such semiconductor devices have a problem in that, since the pin fins protrude downward from the package, during assembly of the semiconductor device, the pin fins may come into contact with a workbench due to operator error and become deformed.

[0003] In particular, pin fins are made of aluminum and are easily deformed by contact. If the pin fins are deformed, it may lead to a decrease in heat dissipation, blockage of the coolant flow path, and leakage of the coolant. Therefore, semiconductor devices with deformed pin fins become defective in shape and cannot be shipped as products.

[0004] For example, Patent Document 1 discloses a structure in which, in a semiconductor device in which a cooler and a plurality of semiconductor modules to be cooled are integrated, a plurality of fins of the plurality of semiconductor modules are housed in a cooler body and the plurality of fins are protected by the cooler body.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2018-63999 Summary of the invention

[0006] However, in the technology described in Patent Document 1, a plurality of fins protrude downward from the protective mold portion of the semiconductor module before being assembled into a cooler. Therefore, the problem that the plurality of fins may be deformed by contact with a workbench due to an operator's operating error cannot be solved.

[0007] Therefore, an object of the present invention is to provide a technology capable of suppressing deformation of pin fins due to contact during assembly of a semiconductor device or the like.

[0008] The semiconductor device involved in the present invention comprises: a base plate having a plurality of pin fins on its lower surface; a semiconductor element mounted on the upper side of the base plate; and a resin component covering at least the side surfaces of the semiconductor element, the resin component having a rib covering the side surfaces of the base plate, the lower end of the rib being located below the lower ends of the plurality of pin fins.

[0009] Effects of the Invention

[0010] According to the present invention, since the plurality of pin fins do not protrude downward relative to the rib portion, deformation of the pin fins due to contact can be suppressed during assembly of the semiconductor device.

[0011] The objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description and accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a cross-sectional view of the semiconductor device according to the first embodiment.

[0013] Figure 2 This is a flowchart showing a method for manufacturing a semiconductor device according to the first embodiment.

[0014] Figure 3 It is a cross-sectional view showing the welding process.

[0015] Figure 4 It is a cross-sectional view showing a wire bonding process.

[0016] Figure 5 It is a cross-sectional view showing the lower clamp fitting step.

[0017] Figure 6 It is a cross-sectional view showing the resin molding process.

[0018] Figure 7 It is a cross-sectional view showing the lower jig demolding step.

[0019] Figure 8 This is a cross-sectional view showing the lead cutting and terminal bending process.

[0020] Fig. 9 This is a cross-sectional view showing a resin molding step in Modification 1 of Embodiment 1.

[0021] Fig.10 It is a cross-sectional view showing a resin molding step in Modification 2 of Embodiment 1.

[0022] Fig.11 This is a cross-sectional view showing the lead cutting and terminal bending steps in Modification 3 of Embodiment 1.

[0023] Fig.12 This is a cross-sectional view of a semiconductor device according to the second embodiment.

[0024] Fig.13 This is a cross-sectional view of a semiconductor device according to a third embodiment.

[0025] Fig.14 This is a bottom view showing a semiconductor device according to the third embodiment in a state before the refrigerant jacket is assembled.

[0026] Fig.15 It is a plan view showing a coolant jacket included in the semiconductor device according to the third embodiment.

[0027] Fig.16This is a cross-sectional view showing a semiconductor device according to a fourth embodiment in a state before the refrigerant jacket is assembled.

[0028] Fig.17 This is a cross-sectional view showing a semiconductor device according to the fifth embodiment in a state before the refrigerant jacket is assembled.

[0029] Fig.18 This is a cross-sectional view of a semiconductor device according to a fifth embodiment. DETAILED DESCRIPTION

[0030] <Implementation method 1>

[0031] Hereinafter, Embodiment 1 will be described using the drawings. Figure 1 It is a cross-sectional view of the semiconductor device 100 according to the first embodiment.

[0032] like Figure 1 As shown, the semiconductor device 100 is a transfer mold type, and includes a base plate 1 , an insulating sheet 3 , a heat sink 4 , a frame 5 , a molding resin 8 , and two semiconductor elements 6 .

[0033] The base plate 1 is an aluminum plate having a rectangular shape in a plan view, and has a plurality of pin fins 2 for heat dissipation protruding downward from the lower surface of the base plate 1. The plurality of pin fins 2 are made of aluminum and formed integrally with the base plate 1.

[0034] Heat sink 4 is disposed on the upper surface of base plate 1 via insulating sheet 3. Two semiconductor elements 6 are mounted on the upper surface of heat sink 4 via solder 6a. The number of semiconductor elements 6 is not limited to two, but may be one or three or more.

[0035] The frame 5 is connected to the electrode of the semiconductor element 6 via the solder 6 b or connected to the electrode of the semiconductor element 6 via the wire 7 .

[0036] The molding resin 8 is a resin component that covers at least the side of the semiconductor element 6. Specifically, the molding resin 8 is made of, for example, epoxy resin, and encapsulates the insulating sheet 3, the heat sink 4, a part of the frame 5, and the semiconductor element 6. The molding resin 8 has a rib 9 that covers the side of the base plate 1. The rib 9 is made of epoxy resin and is formed integrally with the molding resin 8. In addition, the rib 9 is formed in a manner that surrounds the side of the plurality of pin fins 2 and protrudes downward throughout the entire periphery of the molding resin 8. The lower end of the rib 9 is located lower than the lower end of the plurality of pin fins 2. That is, the plurality of pin fins 2 do not protrude relative to the lower end of the rib 9, and therefore, it is possible to prevent the operator from making the plurality of pin fins 2 contact with the workbench due to an operating error.

[0037] Next, use Figure 2 to Figure 8A method for manufacturing the semiconductor device 100 will be described.

[0038] Figure 2 1 is a flowchart showing a method for manufacturing the semiconductor device 100 according to the first embodiment.

[0039] Figure 3 It is a cross-sectional view showing the welding process. Figure 4 It is a cross-sectional view showing a wire bonding process.

[0040] Figure 5 It is a cross-sectional view showing the lower clamp fitting step. Figure 6 It is a cross-sectional view showing the resin molding process. Figure 7 It is a cross-sectional view showing the lower jig demolding step. Figure 8 This is a cross-sectional view showing the lead cutting and terminal bending process.

[0041] First, if Figure 2 and Figure 3 As shown, in the soldering process (step S1 ), after the semiconductor element 6 is arranged on the upper surface of the heat sink 4 , it is joined to the heat sink 4 and the frame 5 by solder.

[0042] Next, if Figure 2 and Figure 4 As shown, in the wire bonding step (step S2), the frame 5 and the semiconductor element 6 are wired by wire bonding.

[0043] Next, if Figure 2 and Figure 5 As shown, in the lower fixture fitting process (step S3), in the molding die, after the lower fixture 50 is fitted with the plurality of pin fins 2, the heat sink 4 is mounted on the upper surface of the base plate 1 via the insulating sheet 3 to form an assembly. The lower surface of the lower fixture 50 is a plane, and when the lower fixture 50 is fitted with the plurality of pin fins 2, the bottom surface of the assembly is flat.

[0044] Next, if Figure 2 and Figure 6 As shown, in the resin molding step (step S4), the assembly is molded and mold-sealed with epoxy resin.

[0045] Next, if Figure 2 and Figure 7 As shown, in the lower jig demolding step (step S5), the lower jig 50 is removed from the molded assembly.

[0046] Next, if Figure 2 and Figure 8 As shown, in the lead cutting and terminal bending process (step S6), the frame 5 is cut and the terminals are bent.

[0047] Here, the welding step is equivalent to the step (a) of mounting the semiconductor element 6 on the upper surface of the heat sink 4. The lower fixture fitting step is equivalent to the step (b) of mounting the heat sink 4 on the upper surface of the base plate 1 via the insulating sheet 3 to form an assembly after fitting the lower fixture 50 with the plurality of pin fins 2 in the molding die. The resin molding step is equivalent to the step (c) of molding the assembly. And, the lower fixture demolding step is equivalent to the step (d) of removing the lower fixture 50 from the assembly after molding.

[0048] As described above, the semiconductor device 100 according to the first embodiment includes: a base plate 1 having a plurality of pin fins 2 on its lower surface; a semiconductor element 6 mounted on the upper side of the base plate 1; and a resin member covering at least the side surface of the semiconductor element 6, the resin member having a rib 9 covering the side surface of the base plate 1, the lower end of the rib 9 being located below the lower ends of the plurality of pin fins 2. Here, the resin member is a molding resin 8 that further encapsulates the semiconductor element 6.

[0049] Therefore, the plurality of pin fins 2 do not protrude downward relative to the rib 9 , and thus deformation of the pin fins 2 due to contact can be suppressed during assembly of the semiconductor device 100 .

[0050] In addition, the manufacturing method of the semiconductor device 100 includes the following steps: step (a), mounting the semiconductor element 6 on the upper surface of the heat sink 4; step (b), after engaging the lower clamp 50 with the plurality of pin fins 2 in a molding die, mounting the heat sink 4 on the upper surface of the base plate 1 via the insulating sheet 3 to form an assembly; step (c), molding the assembly; and step (d), removing the lower clamp 50 from the molded assembly.

[0051] Since the bottom surface of the assembly during molding is flat, pressure during molding is evenly applied within the surface of the insulating sheet 3 and the curing reaction proceeds evenly, thereby improving the quality of the semiconductor device 100 and suppressing the occurrence of insulation failure.

[0052] Here, the lower fixture 50 may also be provided in the molding die. That is, the lower fixture 50 may also be a part of the molding die. In this case, the number of components of the assembly can be reduced, and therefore, the assemblability of the assembly is improved.

[0053] <Variation of Embodiment 1>

[0054] Next, a modification of the first embodiment will be described. Fig. 9 This is a cross-sectional view showing a resin molding step in Modification 1 of Embodiment 1. Fig.10 It is a cross-sectional view showing a resin molding step in Modification 2 of Embodiment 1. Fig.11 This is a cross-sectional view showing the lead cutting and terminal bending steps in Modification 3 of Embodiment 1.

[0055] like Fig. 9 As shown, a protrusion 51 protruding downward from the lower surface of the lower clamp 50 may also be formed. The protrusion 51 is formed all around the outer circumference of the lower surface of the lower clamp 50. Thus, in the lower clamp demolding step, the operator can easily remove the lower clamp 50 from the assembly molded with the protrusion 51 wrapped therein.

[0056] In addition, if Fig.10 As shown, in the resin molding process, a recess 9a may be formed at a portion of the lower end of the rib 9 that faces the lower jig 50. The recess 9a is formed over the entire circumference of the rib 9. When the lower jig 50 is demolded, if the lower jig is pulled in an oblique direction by mistake, a force is applied laterally to a portion of the semiconductor device 100 that fits with the lower jig 50, and thus, the portion of the lower end of the resin rib 9 that faces the lower jig 50 may be damaged. When the recess 9a is formed at a portion of the lower end of the rib 9 that faces the lower jig 50, no resin is present at that portion, and thus it is possible to suppress the resin from being damaged at that portion.

[0057] In addition, if Fig.11 As shown, a mirror surface 9b may be formed at the portion of the rib 9 that contacts the lower jig 50. Specifically, the method for manufacturing the semiconductor device 100 may further include a step of mirror finishing the portion of the rib 9 that contacts the lower jig 50 between the resin molding step and the lower jig demolding step. This can improve the demoldability of the lower jig 50 from the assembled body after molding.

[0058] <Implementation method 2>

[0059] Next, a semiconductor device 100A according to a second embodiment will be described. Fig.12 It is a cross-sectional view of a semiconductor device 100A according to Embodiment 2. In Embodiment 2, the same components as those described in Embodiment 1 are denoted by the same reference numerals, and the description thereof is omitted.

[0060] like Fig.12 As shown, in the second embodiment, the resin member covering at least the side of the semiconductor element 6 is a resin case 10, and the semiconductor device 100A further includes a sealing resin 12 filled in the resin case 10 and sealing the semiconductor element 6. The sealing resin 12 is made of silicone gel. In addition, the semiconductor device 100A includes a ceramic plate 13 instead of the insulating sheet 3. Hereinafter, the semiconductor device 100A including the resin case 10 is also referred to as a case-type semiconductor device 100A.

[0061] The resin case 10 is made of, for example, epoxy resin, and has a rib 11 that covers the side surface of the base plate 1. The rib 11 is made of epoxy resin and is formed integrally with the resin case 10. In addition, the rib 11 is formed in a manner that surrounds the side surfaces of the plurality of pin fins 2 and protrudes downward over the entire circumference of the outer periphery of the resin case 10. The lower end of the rib 11 is located lower than the lower ends of the plurality of pin fins 2. That is, the plurality of pin fins 2 do not protrude relative to the lower end of the rib 11, and therefore, it is possible to prevent the operator from making contact with the plurality of pin fins 2 and the workbench due to an operating error.

[0062] As described above, in the semiconductor device 100A according to the second embodiment, the resin member is the resin case 10 , and the semiconductor device 100A further includes the sealing resin 12 which is filled in the resin case 10 and seals the semiconductor element 6 .

[0063] The transfer molded semiconductor device 100 is suitable for a small-sized semiconductor device, and the housing-type semiconductor device 100A is suitable for a large-sized semiconductor device. Therefore, even in a large-sized semiconductor device, since the plurality of pin fins 2 do not protrude downward relative to the rib 11, deformation of the pin fins 2 due to contact can be suppressed during assembly of the semiconductor device 100A.

[0064] <Implementation method 3>

[0065] Next, a semiconductor device 100B according to a third embodiment will be described. Fig.13 It is a cross-sectional view of a semiconductor device 100B according to the third embodiment. Fig.14 This is a bottom view showing a state before the refrigerant jacket 20 is assembled with respect to the semiconductor device 100B according to the third embodiment. Fig.15 It is a plan view of the refrigerant jacket 20 included in the semiconductor device 100B according to the third embodiment. In the third embodiment, the same components as those described in the first and second embodiments are denoted by the same reference numerals, and the description thereof is omitted.

[0066] like Figure 13 to Figure 15 As shown, in the third embodiment, the semiconductor device 100B further includes a coolant jacket 20 compared to the semiconductor device 100 according to the first embodiment. That is, the semiconductor device 100B is a transfer mold type, and includes a base plate 1, an insulating sheet 3, a heat sink 4, a frame 5, a molding resin 8, a coolant jacket 20, and two semiconductor elements 6.

[0067] like Fig.13 and Fig.15As shown, the refrigerant jacket 20 is rectangular when viewed from above, and is fixed to the lower ends of the ribs 9 and the plurality of pin fins 2, and a flow path 23 of the refrigerant, i.e., cooling water, is formed between the refrigerant jacket 20 and the base plate 1. The refrigerant jacket 20 has a middle plate 21 that is T-shaped when viewed in cross section, and a main body 22 that is concave when viewed in cross section. The middle plate 21 is formed in a recessed portion of the main body 22, and the main body 22 is formed in the outer periphery of the refrigerant jacket 20, that is, closer to the outer periphery than the middle plate 21. The upper surface of the middle plate 21 is located higher than the main body 22, and therefore abuts against the lower ends of the plurality of pin fins 2, and the upper surface of the main body 22 abuts against the lower end of the ribs 9.

[0068] In addition, a groove 22a for accommodating an O-ring 24 is formed all over the inner circumference of the upper surface of the main body 22. The rectangular frame-shaped O-ring 24 is accommodated in the groove 22a. A pressing plate 30 is arranged on the upper surface of the molded resin 8 to press the molded resin 8 and the base plate 1 downward relative to the refrigerant jacket 20.

[0069] As described above, the semiconductor device 100B involved in embodiment 3 also has: a refrigerant sleeve 20, which is fixed to the lower ends of the ribs 9 and the plurality of pin fins 2, and a cooling water flow path 23 is formed between the refrigerant sleeve 20 and the base plate 1, the refrigerant sleeve 20 has a middle plate 21 abutting against the lower ends of the pin fins 2 and a main body 22 formed on the outer peripheral side than the middle plate 21 and abutting against the lower end of the ribs 9, and the upper surface of the middle plate 21 is located above the main body 22.

[0070] By forming the rib 9 protruding downward compared to the pin fin 2, the distance between the frame 5 extending from the side of the molded resin 8 to the outside and the refrigerant sleeve 20 can be lengthened, thereby ensuring the required surface distance and spatial distance for insulation between the frame 5 and the refrigerant sleeve 20.

[0071] Furthermore, by making the middle plate 21 abut against the lower ends of the plurality of pin fins 2 , the base plate 1 and the middle plate 21 are brought close to each other, thereby increasing the flow rate of cooling water flowing between the base plate 1 and the middle plate 21 , thereby improving the heat dissipation of the semiconductor device 100B.

[0072] <Implementation method 4>

[0073] Next, a semiconductor device according to a fourth embodiment will be described. Fig.16 This is a cross-sectional view showing a semiconductor device according to Embodiment 4 in a state before the refrigerant jacket 20 is assembled. In Embodiment 4, the same components as those described in Embodiments 1 to 3 are denoted by the same reference numerals, and description thereof is omitted.

[0074] like Fig.16As shown, in the fourth embodiment, the resin coating portion 25 is formed on the inner peripheral surface of the rib 9 and at the boundary between the base plate 1 and the mold resin 8 as the resin member.

[0075] Resins such as the molding resin 8 are materials that easily absorb moisture. Therefore, in the semiconductor device involved in embodiment 4, by forming a resin coating portion 25 at the portion in contact with cooling water, namely, the inner peripheral surface of the rib 9 and the boundary between the base plate 1 and the molding resin 8, moisture absorption at this portion can be suppressed.

[0076] As described above, in the semiconductor device according to the fourth embodiment, a resin coating portion 25 is formed on the inner peripheral surface of the rib 9 and at the boundary between the base plate 1 and the molded resin 8, thereby suppressing moisture absorption at this portion and cutting off the intrusion of cooling water into the interior of the molded resin 8, thereby preventing the semiconductor device from becoming poorly insulated.

[0077] <Implementation method 5>

[0078] Next, a semiconductor device 100C according to the fifth embodiment will be described. Fig.17 This is a cross-sectional view showing a state before the refrigerant jacket 20 is assembled in the semiconductor device 100C according to the fifth embodiment. Fig.18 It is a cross-sectional view of a semiconductor device 100C according to Embodiment 5. In Embodiment 5, the same components as those described in Embodiments 1 to 4 are denoted by the same reference numerals, and description thereof is omitted.

[0079] In the third embodiment, the groove 22a for accommodating the O-ring 24 is formed in the refrigerant jacket 20. Fig.17 and Fig.18 As shown, in Embodiment 5, a groove 9c for accommodating an O-ring 24 is formed at the lower end of the rib 9. The groove 9c is formed over the entire circumference of the lower end of the rib 9, and the rectangular frame-shaped O-ring 24 is accommodated in the groove 9c.

[0080] As described above, in the semiconductor device 100C according to the fifth embodiment, the groove 9c for accommodating the O-ring 24 is formed at the lower end of the rib 9. Therefore, the groove 9c can be formed in the resin molding process, and thus the man-hours associated with the groove processing can be reduced compared to the case where the groove 22a is formed in the coolant jacket 20. Similarly, since it is not necessary to form the groove 22a in the coolant jacket 20, the man-hours associated with the metal processing when manufacturing the coolant jacket 20 can be reduced.

[0081] <Other Modifications>

[0082] In the third to fifth embodiments, the transfer mold type semiconductor device has the coolant jacket 20, but the present invention is not limited thereto, and a housing type semiconductor device may have the coolant jacket 20. In this case, the same effects as those of the third to fifth embodiments are obtained.

[0083] While the present invention has been described in detail, the above description is in all aspects illustrative and the present invention is not limited thereto, and it is understood that numerous modifications not shown here are conceivable without departing from the scope of the present invention.

[0084] In addition, the various embodiments can be freely combined, or the various embodiments can be appropriately modified or omitted.

[0085] Description of the label

[0086] 1 base plate, 2 pin fin, 3 insulating sheet, 4 heat sink, 6 semiconductor element, 8 molding resin, 9 rib, 9a recess, 9c groove, 10 resin case, 12 packaging resin, 20 refrigerant jacket, 21 middle plate, 22 main body, 24 O-ring, 25 resin coating portion, 50 lower fixture, 51 protrusion, 100, 100A, 100B, 100C semiconductor device.

Claims

1. A semiconductor device comprising: a base plate having a plurality of pin fins on a lower surface; a semiconductor element mounted on an upper side of the base plate; and a resin member that covers at least the side surfaces of the semiconductor element, The resin member has a rib covering a side surface of the base plate, The lower end of the rib is located below the lower ends of the plurality of pin fins. The semiconductor device further includes a refrigerant jacket fixed to the rib and the lower ends of the plurality of pin fins, and a refrigerant flow path is formed between the refrigerant jacket and the base plate. The refrigerant jacket includes a middle plate abutting against the lower end of the pin fin and a main body formed on the outer peripheral side of the middle plate and abutting against the lower end of the rib. The upper surface of the middle plate is located above the main body.

2. The semiconductor device according to claim 1, wherein The resin member is a molding resin that further encapsulates the semiconductor element.

3. The semiconductor device according to claim 1, wherein The resin component is a resin housing, The semiconductor device further includes a sealing resin that is filled in the resin case and seals the semiconductor element.

4. The semiconductor device according to claim 1, wherein A resin coating portion is formed on an inner peripheral surface of the rib portion and at a boundary between the base plate and the resin member.

5. The semiconductor device according to claim 1 or 4, wherein: A groove for accommodating an O-ring is formed at a lower end portion of the rib.

6. A method for manufacturing a semiconductor device, comprising manufacturing the semiconductor device according to claim 1, wherein the method for manufacturing a semiconductor device comprises the following steps: Step (a), mounting the semiconductor element on the upper surface of the heat sink; Step (b), after fitting a lower jig to the plurality of pin fins in a molding die, mounting the heat sink on the upper surface of the base plate via an insulating sheet to form an assembly; Step (c), molding the assembly; and Step (d) of removing the lower jig from the molded assembly.

7. The method for manufacturing a semiconductor device according to claim 6, wherein: The lower clamp is disposed on the molding die.

8. The method for manufacturing a semiconductor device according to claim 6, wherein: A protrusion is formed to protrude downward from the lower surface of the lower clamp.

9. The method for manufacturing a semiconductor device according to claim 7, wherein: A protrusion is formed to protrude downward from the lower surface of the lower clamp.

10. The method for manufacturing a semiconductor device according to any one of claims 6 to 9, wherein: In the step (c), a recessed portion is formed at a portion of the lower end portion of the rib portion that faces the lower clamp.

11. The method for manufacturing a semiconductor device according to any one of claims 6 to 9, wherein: The method further comprises a step (e) of performing mirror finishing on a portion of the rib portion that contacts the lower jig between the step (c) and the step (d).

12. The method for manufacturing a semiconductor device according to claim 10, wherein: The method further comprises a step (e) of performing mirror finishing on a portion of the rib portion that contacts the lower jig between the step (c) and the step (d).

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