Semiconductor module and method for manufacturing semiconductor module

Abstract

To provide a semiconductor module and a method for manufacturing the semiconductor module that can improve transportability when applying gels to encapsulant.SOLUTION: It has a laminate substrate 5 where a semiconductor element 1 is mounted, a case 7 for housing sealed components including the semiconductor element 1 and the laminate substrate 5, an encapsulant that fills the case 7 and seals the sealed components, and a mica sheet 20 on the top surface of the encapsulant, the encapsulant contains gel 11 on the mica sheet 20 side and the mica sheet 20 is provided on the gel 11.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a semiconductor module and a method for manufacturing the semiconductor module. [Background technology]

[0002] Conventionally, a power module including one or more power semiconductor chips, a case for accommodating the power semiconductor chips, and silicone gel filled in the case for sealing the power semiconductor chips has been known (see Patent Document 1 below). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-216558 A Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional semiconductor modules, when gel is used as a sealing material, the gel retains its adhesiveness even after hardening, which causes a problem of poor transportability.

[0005] The present disclosure aims to provide a semiconductor module and a method for manufacturing a semiconductor module that can improve transportability when applying a gel to a sealing material, in order to solve the problems associated with the conventional techniques described above. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object of the present disclosure, the semiconductor module according to this disclosure has the following features: The semiconductor module includes a laminated substrate on which a semiconductor element is mounted, a case for accommodating a sealed member including the semiconductor element and the laminated substrate, a sealant filled in the case for sealing the sealed member, and a mica sheet provided on an upper surface of the sealant. The sealant includes a gel on the mica sheet side, and the mica sheet is provided on the gel.

[0007] According to the disclosure above, since the mica sheet is non-adhesive and has excellent flame retardancy and insulation properties, it can be transported by sucking the upper surface with a suction nozzle, improving transportability. Therefore, there is no need to redesign transport equipment for semiconductor modules that use gel as a sealing material, and depreciation costs, etc. can be reduced. Effect of the Invention

[0008] The semiconductor module and the method for manufacturing the semiconductor module according to the present disclosure have the advantage that the transportability can be improved when applying a gel to the sealing material. [Brief description of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view showing a configuration of a semiconductor module according to an embodiment; [Diagram 2] 1 is a top view showing a configuration of a semiconductor module according to an embodiment; [Diagram 3] 1 is a cross-sectional view showing the transportation of a semiconductor module according to an embodiment; [Figure 4] 4 is a flowchart showing a method for manufacturing a semiconductor module according to an embodiment. [Diagram 5] 1 is a cross-sectional view showing the transportation of a conventional epoxy resin-encapsulated semiconductor module. [Figure 6] 1 is a cross-sectional view showing the transportation of a conventional gel-sealed semiconductor module. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] <Overview of the embodiment of the present disclosure> In order to solve the above-mentioned problems and achieve the object of the present disclosure, the semiconductor module according to this disclosure has the following features: The semiconductor module includes a laminated substrate on which a semiconductor element is mounted, a case for accommodating a sealed member including the semiconductor element and the laminated substrate, a sealant filled in the case for sealing the sealed member, and a mica sheet provided on an upper surface of the sealant. The sealant includes a gel on the mica sheet side, and the mica sheet is provided on the gel.

[0011] According to the disclosure above, since the mica sheet is non-adhesive and has excellent flame retardancy and insulation properties, it can be transported by sucking the upper surface with a suction nozzle, improving transportability. Therefore, there is no need to redesign transport equipment for semiconductor modules that use gel as a sealing material, and depreciation costs, etc. can be reduced.

[0012] In addition, the semiconductor module according to this disclosure is characterized in that, in the above disclosure, the sealing material seals the sealed member with the gel.

[0013] The semiconductor module according to this disclosure is characterized in that, in the above disclosure, the sealing material is a resin on the semiconductor element side, and a gel is provided on the resin.

[0014] According to the above disclosure, it is possible to prevent the layer that bonds the semiconductor element and the laminated substrate from moving due to stress.

[0015] In addition, the semiconductor module according to this disclosure is characterized in that, in the above disclosure, the mica sheet covers 10% or more of the area of ​​the upper surface of the gel.

[0016] In addition, the semiconductor module according to this disclosure is characterized in that, in the above disclosure, the mica sheet has a thickness of 0.2 mm or more and 0.5 mm or less.

[0017] According to the above disclosure, deformation of the gel can be suppressed and the ability of the gel to conform to the surface shape can be ensured.

[0018] In order to solve the above-mentioned problems and achieve the object of the present disclosure, the manufacturing method of a semiconductor module according to this disclosure has the following features: It includes a first step of bonding a semiconductor element to a laminated substrate, a second step of mounting the laminated substrate in a case, a third step of applying a gel to the inside of the case, a fourth step of curing the gel, and a fifth step of mounting a mica sheet on the upper surface of the gel.

[0019] In addition, the manufacturing method of a semiconductor module according to this disclosure is characterized in that, in the above disclosure, it includes a sixth step of injecting resin into the case after the second step and before the third step, and a seventh step of hardening the resin.

[0020] <Foundational knowledge of this disclosure> First, the problems of the conventional semiconductor module will be described. The conventional semiconductor module includes a semiconductor chip, a laminated substrate, a case, a heat dissipation base, and a metal wire. The semiconductor chip is a power semiconductor chip such as a MOSFET, an IGBT, or a diode, and is bonded to the laminated substrate with a bonding layer such as solder. A laminated substrate is a substrate in which a first conductive plate such as copper is provided on the front surface of an insulating substrate such as a ceramic substrate, and a second conductive plate such as copper is provided on the back surface. The laminated substrate is bonded to the heat dissipation base with a bonding layer such as solder. In the case of a MOSFET, a source electrode pad is formed on the front surface of the semiconductor chip as a power terminal electrode pad (current supply terminal). Then, a conductive connection member such as a lead frame or a metal wire is disposed as an output terminal from the power terminal electrode pad. A case is bonded to the semiconductor module, and a lid is attached with a metal terminal penetrating therethrough and protruding to the outside. The case is filled with a sealing material that insulates and protects the laminated substrate and the semiconductor chip on the substrate from the external environment.

[0021] Fig. 5 is a cross-sectional view showing the transportation of a conventional epoxy resin-sealed semiconductor module. Fig. 5 shows a semiconductor module using epoxy resin 108 as a sealing material, and illustrates semiconductor chip 101, laminated substrate 105 having insulating substrate 102 and first conductive plate 103, case 107, epoxy resin 108, metal wire 110, and bonding layer 125.

[0022] When the semiconductor module is transported in the manufacturing process, the module is transported by adsorbing the suction nozzle 121 to the surface of the epoxy resin 108. Since the resin surface of the epoxy resin 108 is solidified after curing, no problem occurs with adsorption.

[0023] However, when epoxy resin 108 is used in small-capacity module products, if a short circuit occurs due to a crack in the chip or circuit, the circuit is not broken because of the pressure caused by the epoxy resin curing and shrinking, and the application of an overcurrent due to the large current drive continues, which can eventually lead to a fire.

[0024] For this reason, a method has been proposed in which gel 111 is used as a sealant instead of epoxy resin 108 in order to cut off the conductive path at the time of initial ignition. Fig. 6 is a cross-sectional view showing the transportation of a conventional gel-sealed semiconductor module. When gel 111 is used as a sealant, the gel 111 remains sticky even after hardening, so it cannot be separated after adsorption, making adhesive transportation difficult and causing a problem of deterioration in transportability in the manufacturing facility.

[0025] Hereinafter, preferred embodiments of a semiconductor module and a method for manufacturing a semiconductor module according to the present disclosure will be described in detail with reference to the accompanying drawings. However, the present disclosure is not limited to the embodiments described below.

[0026] (Embodiment) A semiconductor module according to an embodiment for solving the above-mentioned problems will be described below. FIG. 1 is a cross-sectional view showing the configuration of the semiconductor module according to the embodiment. FIG. 2 is a top view showing the configuration of the semiconductor module according to the embodiment. FIG. 1 is a cross-sectional view taken along the line A-A' in FIG. 2. In the semiconductor module 50, a first conductive plate 3 made of copper is arranged on one surface, which is the front surface, of an insulating substrate 2, and a second conductive plate (not shown) made of copper or the like is arranged on the other surface, which is the back surface, to form a laminated substrate 5. A plurality of semiconductor chips 1 are mounted on the front surface of the first conductive plate 3 of the laminated substrate 5 via a bonding layer 25 made of solder or a sintered material. The first conductive plate 3 is formed in a predetermined circuit pattern on the front surface (first main surface) of the insulating substrate 2. The second conductive plate on the back surface of the laminated substrate 5 is bonded to the front surface of a heat dissipation base (not shown) with a bonding layer (not shown) made of solder or a sintered material or the like. The second conductive plate may be a metal foil formed on the entire back surface of the insulating substrate 2.

[0027] Metal terminals 9 for extracting signals to the outside are bonded to the inside of the case 7. Furthermore, a conductive connection member such as a pin-type terminal or a lead frame is attached to the front surface (e.g., a source electrode pad) of the semiconductor chip 1 via a metal wire 10 (bonding wire) such as an aluminum wire or a bonding layer (not shown). The semiconductor chip 1 and the metal terminals 9 are electrically connected by a metal wire 10 such as an aluminum wire. A lead frame may also be used. Furthermore, a gel 11 is filled inside the case 7 as a sealant.

[0028] Also, the sealing material may be a hybrid of gel 11 and sealing resin (not shown). In this case, the semiconductor chip 1 side from the line T in FIG. 1 is filled with sealing resin such as epoxy resin, and the sealing resin is filled with gel 11. The line T is about half the height of the case 7. It is preferable that the metal wire 10 is sealed with sealing resin. This is because, in the temperature range of -50°C to 150°C, if only gel 11 is used, the bonding layer 25 may move due to stress. In the embodiment, a mica sheet 20 is attached to the upper surface of the gel 11 to improve transportability. Note that the configuration of the semiconductor module 50 shown in the figure is an example, and the present disclosure is not limited to this configuration.

[0029] FIG. 3 is a cross-sectional view showing the transportation of a semiconductor module according to an embodiment. The semiconductor module 50 of the present disclosure is used for a small-capacity module product. The small-capacity module product is, for example, a product weighing 300 g or less, more specifically, a product weighing 50 g or more and 150 g or less. In the transportation of the manufacturing process of the small-capacity module product, the suction nozzle 21 is adsorbed on the upper surface of the semiconductor module and transported. As shown in FIG. 3, even on the upper surface of the gel 11 that is sticky, the mica sheet 20 is not sticky, so the upper surface can be adsorbed by the suction nozzle 21 and transported, improving transportability. Therefore, there is no need to redesign the transportation equipment for the semiconductor module 50 that uses the gel 11 as a sealing material, and depreciation costs and the like can be reduced.

[0030] (Semiconductor chip 1) The semiconductor chip 1 is a power chip such as a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), an IGBT (Insulated Gate Bipolar Transistor), or an SBD (Schottky Barrier Diode), and a device using Si, SiC, or GaN can be used as the semiconductor substrate. The number of semiconductor chips 1 mounted may be one or more.

[0031] (Laminated substrate 5) The laminated substrate 5 can be composed of an insulating substrate 2, a first conductive plate 3 formed in a predetermined shape on one of its main surfaces, and a second conductive plate formed on the other main surface. The insulating substrate 2 can be made of a material having excellent electrical insulation and thermal conductivity. Examples of the material for the insulating substrate 2 include Al. 2 O 3 , AlN, SiN, etc. In particular, for high voltage applications, a material that has both electrical insulation and thermal conductivity is preferable, and AlN and SiN can be used, but are not limited to these. As the first conductive plate 3 and the second conductive plate, Cu (copper) or a Cu alloy, which has excellent workability, can be used. Note that a Cu alloy is an alloy containing 80% or more of Cu. Among such conductive plates made of Cu or a Cu alloy, a conductive plate that is not in contact with the semiconductor chip 1 may be referred to as a back copper foil or a back conductive plate. Methods for disposing a conductive plate on the insulating substrate 2 include a direct bonding method (direct copper bonding method) and a brazing material bonding method (active metal brazing method). In addition, a Ni or Ni alloy layer may be formed by plating the surface of the conductive substrate with Ni (nickel) or the like.

[0032] (Joining layer 25) The bonding layer 25 can be formed using lead-free solder. For example, Sn-Sb, Sn-Cu, Sn-Ag, Sn-Sb-Ag, etc. can be used, but are not limited to these. The bonding layer 25 can also be formed using a connecting material containing fine metal particles, such as a sintered body of nano-silver particles.

[0033] (Case 7) The lower end of the case 7 made of resin or the like is bonded to the periphery of the heat dissipation base. The case 7 is in the shape of a substantially rectangular cylinder and surrounds the periphery of the front surface of the heat dissipation base. A box-shaped recess is formed with the front surface of the heat dissipation base as the bottom surface and the inner wall of the case 7 perpendicular to the front surface of the heat dissipation base as the side wall. The semiconductor chip 1, the laminated substrate 5, and wiring member parts wired with the wiring member of the metal wire 10 are stored inside this recess. The semiconductor chip 1 and the laminated substrate 5 can also be wired using a connector made of a Cu alloy. The material of the case 7 may be, for example, a thermoplastic resin such as polyphenylene sulfide (PPS) or polybutylene terephthalate (PBT) or a thermosetting resin such as a phenolic resin.

[0034] (Gel 11) The gel 11 has high viscosity, loses its fluidity, and becomes solid. The gel 11 is, for example, a silicone gel.

[0035] (Mica Sheet 20) The mica sheet 20 has excellent flame retardancy and insulation properties, making it an optimal material for use as a cover for the semiconductor module 50. The elastic modulus of the mica sheet 20 is about 74 GPa ± 10%, which is more appropriate than that of silicone rubber, which has an elastic modulus of 0.001 to 0.1 GPa, and therefore is less likely to deform excessively, making it easier to transport. Furthermore, since the elastic modulus is not too large, the mica sheet can conform to the surface shape of the gel 11 when attached, and has good adhesiveness.

[0036] The shape of the mica sheet 20 is preferably the same as that of the upper surface of the semiconductor module 50, and is preferably equal to or larger than the area of ​​the portion that the suction nozzle 21 is attached to. Since the portion that the suction nozzle 21 is attached to is a circle or ellipse with a diameter or major axis of 30 mm or more and 50 mm or less, the shape of the mica sheet 20 is preferably a rectangle with a minor axis of 30 mm or more and 50 mm or less. In addition, for example, the mica sheet 20 is preferably a size that covers 10% or more of the area of ​​the upper surface of the gel 11. Furthermore, a plurality of mica sheets 20 may be attached according to the shape of the suction nozzle 21 for conveyance. In addition, the thickness of the mica sheet 20 is preferably 0.2 mm or more and 0.5 mm or less in order to suppress deformation of the gel 11 and ensure conformability to the surface shape of the gel 11. In the embodiment, the mica sheet 20 is used, but other materials may be used as long as they are flame retardant, insulating, hard, and can conform to the surface shape of the gel 11.

[0037] (Method of manufacturing a semiconductor module according to an embodiment) Next, a method for manufacturing a semiconductor module according to an embodiment will be described. Fig. 4 is a flowchart showing a method for manufacturing a semiconductor module according to an embodiment. First, the semiconductor chip 1 is bonded to the heat dissipation base and the laminated substrate 5 by the bonding layer 25 (step S1: first step).

[0038] Thereafter, the case 7 is attached to the heat dissipation base, and then the laminated substrate 5 is mounted on the case 7 (step S2: second process). Next, the lead frame is joined, and wire bonding is performed with the metal wires 10 (step S3).

[0039] Next, a sealing resin such as epoxy resin is injected into the case 7 (step S4: sixth process). Next, the sealing resin is provisionally cured at 100 to 120°C for 10 to 120 minutes, and then fully cured at about 175 to 185°C for 1 to 2 hours (step S5: seventh process). Steps S4 and S5 are performed in the case of a hybrid structure of gel 11 and sealing resin, and are not necessary when filling only with gel 11 and no sealing resin is used.

[0040] Next, the gel 11 is applied inside the case 7 (Step S6: third process). Next, the gel 11 is cured (Step S7: fourth process). Next, the mica sheet 20 is mounted on the upper surface of the gel 11 (Step S8: fifth process). When mounting, the mica sheet 20 may be placed on the upper surface of the gel 11 and pressed in. The mica sheet 20 may be attached using the adhesiveness of the gel 11 itself, or may be attached using a separate adhesive. When the adhesiveness of the gel 11 is used, the mica sheet 20 can be attached simply by placing it on the upper surface of the gel 11, eliminating the need for an adhesive process, and reducing equipment costs and labor. In this manner, the semiconductor module 20 shown in FIG. 1 and FIG. 2 can be manufactured.

[0041] As described above, according to the semiconductor module and the manufacturing method of the semiconductor module of the embodiment, the mica sheet is non-adhesive and has excellent flame retardancy and insulation properties, so that the upper surface can be sucked with a suction nozzle for transportation, improving transportability. Therefore, there is no need to redesign the transport equipment for semiconductor modules that use gel as a sealing material, and depreciation costs, etc. can be reduced.

[0042] The present invention can be modified in various ways without departing from the spirit of the present invention, and in each of the above-mentioned embodiments, for example, the dimensions of each part and the impurity concentration are set in various ways according to the required specifications, etc. Also, in each of the above-mentioned embodiments, the semiconductor can be applied to wide band gap semiconductors such as silicon carbide (SiC) and gallium nitride (GaN) in addition to silicon. [Industrial Applicability]

[0043] INDUSTRIAL APPLICABILITY As described above, the semiconductor module and the method for manufacturing the semiconductor module according to the present invention are useful for power semiconductor modules used in power conversion devices such as inverters, power supply devices for various industrial machines, igniters for automobiles, and the like. [Explanation of symbols]

[0044] 1, 101 Semiconductor chip 2, 102 Insulating substrate 3, 103 First conductive plate 5, 105 Laminated board 7, 107 cases 9, 109 Metal terminal 10, 110 Metal Wire 11, 111 Gel 20 Mica Sheet 21, 121 Suction nozzle 25, 125 bonding layer 50 Semiconductor Module 108 Epoxy Resin

Claims

1. A laminated substrate having a semiconductor element mounted thereon; a case that accommodates a sealed member including the semiconductor element and the laminated substrate; a sealant filled in the case and configured to seal the member to be sealed; A mica sheet provided on an upper surface of the sealing material; Equipped with 13. A semiconductor module, comprising: the sealing material including a gel on the mica sheet side; and the mica sheet being disposed on the gel.

2. 2. The semiconductor module according to claim 1, wherein the sealing material seals the member to be sealed with the gel.

3. 2. The semiconductor module according to claim 1, wherein the sealing material is a resin on the semiconductor element side, and a gel is provided on the resin.

4. 2. The semiconductor module according to claim 1, wherein the mica sheet covers 10% or more of an area of ​​an upper surface of the gel.

5. 2. The semiconductor module according to claim 1, wherein the mica sheet has a thickness of 0.2 mm or more and 0.5 mm or less.

6. A first step of bonding a semiconductor element to a laminate substrate; a second step of mounting the laminated substrate in a case; A third step of applying gel to the inside of the case; A fourth step of hardening the gel; A fifth step of mounting a mica sheet on the upper surface of the gel; A method for manufacturing a semiconductor module comprising the steps of:

7. After the second step and before the third step, a sixth step of injecting resin into the case; A seventh step of curing the resin; 7. The method for manufacturing a semiconductor module according to claim 6, further comprising:

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