Method of manufacturing a semiconductor device

Abstract

To provide a technique capable of improving moisture absorption resistance of a semiconductor device.SOLUTION: A semiconductor device includes: a resin insulation sheet 1; a heat spreader 2 provided on the resin insulation sheet 1; a semiconductor element 3 mounted on the heat spreader 2; a lead frame 5 whose one end is connected to the semiconductor element 3; a first resin body 8 for sealing the resin insulation sheet 1, the heat spreader 2, the semiconductor element 3, and the one end of the lead frame 5 in a state where the rear face of the resin insulation sheet 1 is exposed; and a second resin body 9 for sealing the first resin body 8 in a state where the rear face of the resin insulation sheet 1 is exposed.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a semiconductor device and a method for manufacturing a semiconductor device.

Background Art

[0002] In order to improve the reliability of semiconductor devices, semiconductor devices having a plurality of resin layers have been proposed. For example, Patent Document 1 discloses a configuration of a semiconductor device that performs double encapsulation with a plurality of resin layers and a method for manufacturing a semiconductor device.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the technology described in Patent Document 1, the first resin layer constitutes the upper surface of the semiconductor device. That is, the upper side of the semiconductor element is sealed only by the first resin layer. Thus, since the upper side of the semiconductor element is not double-sealed, moisture in the air may enter the inside of the first resin layer.

[0005] Therefore, an object of the present disclosure is to provide a technology capable of improving the moisture absorption resistance of a semiconductor device.

Means for Solving the Problems

[0006] The semiconductor device according to the present disclosure Manufacturing methodIt includes an insulating sheet, a heat spreader provided on the insulating sheet, a semiconductor element mounted on the heat spreader, a lead frame having one end connected to the semiconductor element, and a first resin body that seals the insulating sheet, the heat spreader, the semiconductor element, and the one end of the lead frame with the back surface of the insulating sheet exposed, and a second resin body that seals the first resin body with the back surface of the insulating sheet exposed. and , a method of manufacturing a semiconductor device, comprising: a step (a) of forming a module by sealing the insulating sheet, the heat spreader, the semiconductor element, and the one end portion of the lead frame with the back surface of the insulating sheet exposed by the first resin body; a step (b) of cutting an excess portion on the other end side of the lead frame in the module, bending the other end side of the lead frame, and removing the excess portion of the first resin body; and a step (c) of sealing the module with the back surface of the insulating sheet exposed by the second resin body is what it is.

Advantages of the Invention

[0007] According to the present disclosure, since the semiconductor element is sealed by the first resin body and the first resin body is sealed by the second resin body, the first resin body can be hermetically sealed. As a result, the moisture absorption resistance of the semiconductor device can be improved.

Brief Description of the Drawings

[0008]

Fig. 1

Fig. 2

Fig. 3

Fig. 4

Fig. 5

Modes for Carrying Out the Invention

[0009] <Embodiment 1> <Configuration of the Semiconductor Device> Embodiment 1 will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a semiconductor device according to Embodiment 1.

[0010] As shown in FIG. 1, it includes a resin insulating sheet 1, a heat spreader 2, a semiconductor element 3, a plurality of lead frames 5, a first resin body 8, and a second resin body 9.

[0011] The resin insulating sheet 1 is a resin insulating sheet with a metal foil (for example, a copper foil) formed on the insulating sheet. The insulating sheet is composed mainly of, for example, an epoxy resin containing a BN filler. Note that the resin insulating sheet 1 may be a resin insulating sheet with thick copper.

[0012] The heat spreader 2 is composed mainly of, for example, copper and is provided on the resin insulating sheet 1. The semiconductor element 3 is, for example, a power semiconductor element such as an IGBT (Insulated Gate Bipolar Transistor) or a diode. The semiconductor element 3 is mounted on the heat spreader 2 via a solder 4. Note that the number of semiconductor elements 3 is not limited to one and may be plural.

[0013] Each lead frame 5 is composed mainly of, for example, copper and has one end connected to the surface electrode (not shown) of the semiconductor element 3 by a bonding wire 7. The bonding wire 7 is, for example, an aluminum wire or a copper wire. Note that the bonding wire 7 may be a ball bonding wire such as a gold wire or a silver wire.

[0014] The first resin body 8 is composed mainly of a thermosetting resin such as an epoxy resin. The first resin body 8 is formed, for example, in a rectangular parallelepiped shape and seals one end of the resin insulating sheet 1, the heat spreader 2, the semiconductor element 3, and the plurality of lead frames 5 with the back surface of the resin insulating sheet 1 exposed.

[0015] The second resin body 9 is composed mainly of a thermoplastic resin such as PPS (Poly Phenylene Sulfide), PBT (Poly Butylene Terephthalate), ABS (Acrylonitrile Butadiene Styrene), or PC (Polycarbonate). The second resin body 9 includes a main body portion 9a and a flange portion 9b that protrudes outward from the entire outer peripheral portion of the main body portion 9a. The main body portion 9a is formed, for example, in a rectangular parallelepiped shape and seals the first resin body 8 with the back surface of the resin insulating sheet 1 exposed. Since the first resin body 8 is sealed by the second resin body 9, it is possible to suppress the intrusion of moisture from the outside into the first resin body 8. Thereby, the moisture absorption resistance of the semiconductor device can be improved.

[0016] A plurality of lead frames 5 are integrally provided in the main body portion 9a by insert molding. One end portion of the plurality of lead frames 5 extends inside the first resin body 8, and the other end portions of the plurality of lead frames 5 are exposed to the outside from the upper end surface (front surface) of the main body portion 9a. A screw hole 5a through which a screw (not shown) for fixing to an external device (not shown) is inserted is provided at the other end portion of each lead frame 5. At a location in the second resin body 9 that faces the screw hole 5a, a nut box 9c that houses a nut 10 for fixing the screw inserted through the screw hole 5a is provided.

[0017] The flange portion 9b is provided with a plurality (for example, two) of mounting holes 9d that house a bush 11 to which a heat sink (not shown) can be attached.

[0018] Note that the other end portion of each lead frame 5 may be connected to an external device by soldering. In that case, the screw hole 5a is not provided in each lead frame 5, and the connection to the external device can be made without providing the nut 10 and the nut box 9c in the second resin body 9.

[0019] Further, it is desirable that the first resin body 8 is composed mainly of a resin material harder than the second resin body 9. The first resin body 8 in contact with the semiconductor element 3 being hard can be expected to improve reliability such as the power cycle tolerance in the semiconductor device. Also, since the second resin body 9 being softer can relieve the stress applied to the second resin body 9 when fastening to the heat sink via the bush 11, it can be expected to suppress cracks generated in the second resin body 9.

[0020] Moreover, it is desirable that the linear expansion coefficients of the first resin body 8, the second resin body 9, the resin insulating sheet 1, the heat spreader 2, the plurality of lead frames 5, and the bonding wires 7 are approximated. Thereby, improvement in reliability such as the power cycle tolerance in the semiconductor device can be expected. In particular, when the linear expansion coefficients of the first resin body 8 and the bonding wire 7 are approximated, the thermal stress on the bonding wire 7 due to heat generation and cooling during the driving of the semiconductor element 3 can be relieved, and improvement in the power cycle tolerance can be expected.

[0021] <Manufacturing method of semiconductor device> Next, the manufacturing method of the semiconductor device will be described. FIG. 2 is an explanatory diagram for explaining the manufacturing method of the semiconductor device according to the first embodiment. FIG. 3 is a cross-sectional view of the module 12 which is a configuration during the manufacturing of the semiconductor device according to the first embodiment.

[0022] As shown in FIG. 2, after fixing the heat spreader 2 on the resin insulating sheet 1, in the reflow apparatus 20, paste-like solder is applied on the heat spreader 2, and the semiconductor element 3 is mounted thereon and heated to perform soldering. Next, in the wire bonder 22, the bonding wire 7 is connected between each lead frame 5 and the semiconductor element 3. Note that the DLB apparatus 21 is used when connecting the lead frame 5 and the semiconductor element 3 by the direct lead bonding method as in the second embodiment described later.

[0023] Next, in the molding device 23, with the back surface of the resin insulating sheet 1 exposed by the first resin body 8, a primary molding is performed to form the module 12 shown in FIG. 3 by sealing the resin insulating sheet 1, the heat spreader 2, the semiconductor element 3, and one end portions of the plurality of lead frames 5.

[0024] Next, in the press 24, after cutting the surplus portions on the other end sides of the plurality of lead frames 5 and bending the other end sides of the plurality of lead frames 5, the surplus portion of the first resin body 8 is removed.

[0025] Next, in the molding device 25, a secondary molding is performed to seal the module 12 with the second resin body 9 with the back surface of the resin insulating sheet 1 exposed, whereby the semiconductor device shown in FIG. 1 is completed. Note that, in the molding device 23, a manufacturing method of simultaneously forming a plurality of modules 12 may also be used.

[0026] <Effect> The semiconductor device according to Embodiment 1 includes a resin insulating sheet 1, a heat spreader 2 provided on the resin insulating sheet 1, a semiconductor element 3 mounted on the heat spreader 2, a plurality of lead frames 5 having one end portions connected to the semiconductor element 3, a first resin body 8 that seals the resin insulating sheet 1, the heat spreader 2, the semiconductor element 3, and one end portions of the plurality of lead frames 5 with the back surface of the resin insulating sheet 1 exposed, and a second resin body 9 that seals the first resin body 8 with the back surface of the resin insulating sheet 1 exposed.

[0027] Since the semiconductor element 3 is sealed by the first resin body 8 and the first resin body 8 is sealed by the second resin body 9, the first resin body 8 can be hermetically sealed. Thereby, the moisture absorption resistance of the semiconductor device can be improved.

[0028] Further, the other end portions of the respective lead frames 5 are exposed from the surface of the second resin body 9, screw holes 5a are provided in the other end portions of the respective lead frames 5, and a nut box 9c for accommodating a nut 10 for fixing a screw inserted through the screw hole 5a is provided at a position in the second resin body 9 facing the screw hole 5a.

[0029] Therefore, the connection between the semiconductor device and the external device can be fastened by screws, and since these can be firmly connected, an improvement in the reliability of the semiconductor device can be expected.

[0030] Also, the first resin body 8 contains a resin material harder than the second resin body 9. It is expected that the first resin body 8 in contact with the semiconductor element 3 being hard will improve the reliability such as improving the power cycle tolerance in the semiconductor device. Further, since the second resin body 9 being softer can relieve the stress applied to the second resin body 9 when fastening to the heat sink via the bush 11, it is expected to suppress cracks generated in the second resin body 9.

[0031] Also, the semiconductor device further includes a bonding wire 7 that connects the semiconductor element 3 and one end portion of the lead frame 5. Since at least two of the bonding wire 7, the first resin body 8, the second resin body 9, the resin insulating sheet 1, the heat spreader 2, and the lead frame 5 have approximate linear expansion coefficients, an improvement in the power cycle tolerance in the semiconductor device can be expected. In particular, when the linear expansion coefficients of the first resin body 8 and the bonding wire 7 are approximate, the thermal stress on the bonding wire 7 associated with heat generation and cooling during driving of the semiconductor element 3 can be relieved, and an improvement in the power cycle tolerance can be expected.

[0032] Further, the method for manufacturing a semiconductor device according to Embodiment 1 includes a step (a) of forming a module 12 by encapsulating the resin insulating sheet 1, the heat spreader 2, the semiconductor element 3, and one end portions of a plurality of lead frames 5 with a first resin body 8 in a state where the back surface of the resin insulating sheet 1 is exposed, a step (b) of cutting surplus portions on the other end side of the plurality of lead frames 5 in the module 12, bending the other end sides of the plurality of lead frames 5, and removing the surplus portion of the first resin body 8, and a step (c) of encapsulating the module 12 with a second resin body 9 in a state where the back surface of the resin insulating sheet 1 is exposed.

[0033] Therefore, by performing lead cutting, lead venting, and surplus resin removal in a different mold from the primary mold before the secondary molding, the manufacturing efficiency of the semiconductor device is improved compared to performing these separately outside the mold.

[0034] Also, in step (a), since a plurality of modules 12 are formed, the manufacturing efficiency of the semiconductor device is improved compared to forming the modules 12 one by one.

[0035] <Embodiment 2> Next, a semiconductor device according to Embodiment 2 will be described. FIG. 4 is a cross-sectional view of the semiconductor device 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.

[0036] In Embodiment 1, one end portions of a plurality of lead frames 5 were connected to the semiconductor element 3 by bonding wires 7. However, in Embodiment 2, as shown in FIG. 4, one end portion of the lead frame 5 is connected to the surface electrode of the semiconductor element 3 by a direct lead bonding method. Specifically, in FIG. 4, one end portion of the right lead frame 5 and the surface electrode of the semiconductor element 3 are connected by soldering, brazing, welding, or a conductive adhesive. Note that not only the right lead frame 5 in FIG. 4 but also one end portion of the left lead frame 5 may be connected by the direct lead bonding method.

[0037] As a result, it is possible to expect an improvement in the reliability of the semiconductor device as compared with the case of the first embodiment.

[0038] <Embodiment 3> Next, a semiconductor device according to Embodiment 3 will be described. FIGS. 5(a) to 5(c) are top views showing connection change examples of the semiconductor device according to Embodiment 3. FIG. 5(a) is a connection change example when one 2-in-1 type is combined into one, and FIG. 5(b) is a connection change example when one 6-in-1 type is combined into one. FIG. 5(c) is a connection change example when the 2-in-1 type is made into three. In Embodiment 3, the same components as those described in Embodiments 1 and 2 are denoted by the same reference numerals and the description thereof is omitted.

[0039] As shown in FIGS. 5(a), 5(b), and 5(c), a plurality of modules 12 primary-molded by the first resin body 8 are arranged, and each module 12 is connected by a lead frame 5. Although not shown, thereafter, secondary molding is performed by a second resin body 9 mainly composed of a thermoplastic resin. The lead frame 5 may be connected to the semiconductor element 3 by bonding wires 7 as in the first embodiment, or may be connected to the semiconductor element 3 by a direct lead bonding method as in the second embodiment.

[0040] Since the second resin body 9 contains a thermoplastic resin, it is possible to diversify the shape of the semiconductor device, and an improvement in the manufacturing efficiency of the semiconductor device can be expected.

[0041] It should be noted that the respective embodiments can be freely combined, or the respective embodiments can be appropriately modified or omitted.

[0042] Hereinafter, aspects of the present disclosure will be collectively described as appendices.

[0043] (Appendix 1) An insulating sheet, a heat spreader provided on the insulating sheet, A semiconductor element mounted on the heat spreader, A lead frame having one end connected to the semiconductor element, A first resin body that seals the insulating sheet, the heat spreader, the semiconductor element, and the one end of the lead frame with the back surface of the insulating sheet exposed, A second resin body that seals the first resin body with the back surface of the insulating sheet exposed, A semiconductor device comprising:

[0044] (Supplementary Note 2) The other end of the lead frame is exposed from the surface of the second resin body, A screw hole is provided in the other end of the lead frame, The semiconductor device according to Supplementary Note 1, wherein a nut box for accommodating a nut for fixing a screw inserted through the screw hole is provided at a position of the second resin body facing the screw hole.

[0045] (Supplementary Note 3) The semiconductor device according to Supplementary Note 1, wherein the first resin body contains a resin material harder than the second resin body.

[0046] (Supplementary Note 4) The semiconductor device further comprises a bonding wire connecting the semiconductor element and the one end of the lead frame, The semiconductor device according to Supplementary Note 1, wherein at least two of the bonding wire, the first resin body, the second resin body, the insulating sheet, the heat spreader, and the lead frame have approximate linear expansion coefficients.

[0047] (Supplementary Note 5) The semiconductor device according to Supplementary Note 4, wherein the linear expansion coefficients of the bonding wire and the first resin body are approximate.

[0048] (Supplementary Note 6) The semiconductor device according to Supplementary Note 1, wherein the one end of the lead frame is connected to the surface electrode of the semiconductor element by a direct lead bonding method.

[0049] (Appendix 7) The semiconductor device according to Appendix 1, wherein the second resin body contains a thermoplastic resin.

[0050] (Appendix 8) A method for manufacturing the semiconductor device according to Appendix 1, (a) A step of forming a module by sealing the insulating sheet, the heat spreader, the semiconductor element, and one end portion of the lead frame with the first resin body in a state where the back surface of the insulating sheet is exposed; (b) A step of cutting an excess portion on the other end side of the lead frame in the module, bending the other end side of the lead frame, and removing the excess portion of the first resin body; (c) A step of sealing the module with the second resin body in a state where the back surface of the insulating sheet is exposed; A method for manufacturing a semiconductor device, comprising the above steps.

[0051] (Appendix 9) The method for manufacturing a semiconductor device according to Appendix 8, wherein in step (a), a plurality of the modules are formed.

Explanation of Reference Numerals

[0052] 1 Resin insulating sheet, 2 Heat spreader, 3 Semiconductor element, 5 Lead frame, 5a Screw hole, 8 First resin body, 9 Second resin body, 9c Nut box, 10 Nut, 12 Module.

Claims

1. An insulating sheet, a heat spreader provided on the insulating sheet, a semiconductor element mounted on the heat spreader, a lead frame having one end connected to the semiconductor element, a first resin body that seals the insulating sheet, the heat spreader, the semiconductor element, and the one end of the lead frame with the back surface of the insulating sheet exposed, a second resin body that seals the first resin body with the back surface of the insulating sheet exposed, A method for manufacturing a semiconductor device, comprising: (a) forming a module by sealing the insulating sheet, the heat spreader, the semiconductor element, and the one end of the lead frame with the back surface of the insulating sheet exposed by the first resin body; (b) cutting an excess portion on the other end side of the lead frame in the module, bending the other end side of the lead frame, and removing the excess portion of the first resin body; (c) sealing the module with the second resin body with the back surface of the insulating sheet exposed; A method for manufacturing a semiconductor device, comprising the steps of:

2. The method for manufacturing a semiconductor device according to claim 1, wherein in step (a), a plurality of the modules are formed.

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