Semiconductor device

Abstract

The present invention provides a semiconductor device which has good insulation properties and heat dissipation properties.　The semiconductor device 1 comprises: a semiconductor element 2; an electrically conductive lead frame 3 that is connected to the semiconductor element 2; a sealing resin 4 for sealing the semiconductor element 2 and the lead frame 3; and an insulating heat conduction part 5 that is composed of a ceramic molded body. A part of the heat conduction part 5 is sealed with the sealing resin 4, and the heat conduction part 5 is connected to the lead frame 3 inside the sealing resin 4. The other parts of the heat conduction part 5 are exposed from the sealing resin 4. Consequently, heat generated in the semiconductor element 2 can be released to the outside through the lead frame 3 and the heat conduction part 5.

Description

Semiconductor Devices

[0001] The present invention relates to a semiconductor device.

[0002] Examples of semiconductor devices in which a semiconductor element and a lead frame are sealed with a sealing resin include those disclosed in Japanese Patent Application Laid-Open Nos. 2003-222199, 2003-222223, and 2003-222235.

[0003] FIG. 1 of Patent Document 1 shows a structure in which a semiconductor chip (1) and a lead frame (5) are sealed in a resin-sealed package (4) with a mounting hole provided in the center.

[0004] 1 and paragraphs 0018, 0019, and 0026-0028 of Patent Document 2 describe a structure in which a first semiconductor element (101), a second semiconductor element (102), and a lead frame (108) including a die pad (121) are sealed with a molded resin (109), and an insulating sheet (110) is exposed to the outside of the molded resin (109). Furthermore, paragraph 0029 of Patent Document 2 describes that the insulating sheet (110) has a thermal conductivity higher than that of the molded resin (109), and that the insulating sheet (110) includes an insulating layer, the insulating layer including a matrix made of resin and a filler made of ceramics having high thermal conductivity, and the filler is dispersed in the matrix.

[0005] 1 and paragraphs 0011 to 0016 of Patent Document 3 describe a structure in which a semiconductor element (24), a main terminal (20), and a heat sink (12) mainly composed of Cu or Al are sealed with a resin (39), the underside of the heat sink (12) is exposed from the resin (39), and an insulating sheet (40) is attached to the underside of the heat sink (12). Paragraph 0015 of Patent Document 3 describes that the insulating sheet (40) includes a first film (42) and a second film (44), and that the insulating sheet 40 is made of a material that has both electrical insulation and heat dissipation properties, such as a ceramic material.

[0006] JP 2002-26245 A JP 2020-181917 A International Publication No. 2016 / 006054

[0007] However, in the case of the structure described in Patent Document 1, heat dissipation is performed via the resin-sealed package (4), which has the problem of not being very high in heat dissipation. Furthermore, if a highly thermally conductive resin containing a filler is used to enhance heat dissipation, there is a problem of reduced fluidity and filling during molding. Furthermore, if the resin-sealed package (4) on the side that comes into contact with other components during installation is made thin in order to enhance heat dissipation, there are problems with reduced filling during molding and dielectric strength.

[0008] In the case of the structure described in Patent Document 2, the insulating sheet (110) has a structure in which ceramic filler is dispersed in a resin matrix, which causes a problem of inferior thermal conductivity compared to a ceramic molded body. Furthermore, adding filler reduces fluidity and filling properties, which may cause voids to form, which may cause discharge in the voids at high voltages, resulting in a decrease in withstand voltage.

[0009] In the case of the structure described in Patent Document 3, the lower surface of the conductive heat sink (12) is exposed from the resin (39), which poses a problem that an insulating sheet (40) made of a ceramic material or the like must be attached to the lower surface of the heat sink (12).

[0010] The problem to be solved by the present invention is to provide a semiconductor device having high insulating properties and heat dissipation properties.

[0011] In order to solve the above-mentioned problems, the semiconductor device of the present invention comprises a semiconductor element, a conductive lead frame connected to the semiconductor element, a sealing resin that seals the semiconductor element and the lead frame, and an insulating heat-conducting part made of a ceramic molded body, and is characterized in that a part of the heat-conducting part is sealed with the sealing resin and connected to the lead frame inside the sealing resin, and another part is exposed from the sealing resin.

[0012] According to the present invention, a semiconductor device with high insulating properties and heat dissipation properties can be realized.

[0013] 11 is a top perspective view of a semiconductor device of Example 1. A back view of the semiconductor device of Example 1. A cross-sectional view taken along line A-A' in FIG. 1. A cross-sectional view showing the semiconductor device of Example 1 in an attached state. A top perspective view of a semiconductor device of Example 2. A cross-sectional view taken along line B-B' in FIG. 5. A top perspective view of a semiconductor device of Example 3. A back view of the semiconductor device of Example 3. A cross-sectional view taken along line CC' in FIG. 7. A cross-sectional view showing the semiconductor device of Example 3 in an attached state. A top perspective view of a semiconductor device of Example 4. A back view of the semiconductor device of Example 4. A cross-sectional view taken along line D-D' in FIG. 11. A cross-sectional view showing the semiconductor device of Example 4 in an attached state.

[0014] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each drawing and each embodiment, the same or similar components are designated by the same reference numerals, and redundant explanations will be omitted.

[0015] Fig. 1 is a top perspective view of the semiconductor device of Example 1. Fig. 2 is a rear view of the semiconductor device of Example 1. Fig. 3 is a cross-sectional view taken along line AA' in Fig. 1. Note that Fig. 1 shows the internal structure seen through the sealing resin 4.

[0016] The semiconductor device 1 of this embodiment has a semiconductor element 2, a conductive lead frame 3 connected to the semiconductor element 2, a sealing resin 4 that seals the semiconductor element 2 and the lead frame 3, and an insulating heat conductive part 5 made of a ceramic molded body.

[0017] The semiconductor elements 2 are, for example, diodes or semiconductor switching elements. Fig. 1 illustrates a case in which there are four semiconductor elements 2. The semiconductor elements 2 are connected to the lead frame 3 via a joining member such as solder (not shown).

[0018] The lead frame 3 is made of, for example, a conductive metal. In this embodiment, for example, part of the lead frame 3 and part of the electrical wiring structure such as the terminals of the semiconductor element 2 are not shown.

[0019] The sealing resin 4 is a molding resin such as an epoxy resin.

[0020] The thermal conductive part 5 is made of a ceramic molded body, which is a structure different from a structure in which ceramic filler is dispersed in a resin matrix. The thermal conductive part 5 of this embodiment is made entirely of ceramic, rather than a filler, so it can have higher thermal conductivity than a structure in which ceramic filler is dispersed in a resin matrix, and it can avoid problems caused by the addition of filler, such as poor fluidity and poor filling, and it can also suppress the occurrence of voids.

[0021] A part of the heat conductive portion 5 is sealed with the sealing resin 4 and connected to the lead frame 3 inside the sealing resin 4, and the other part is exposed from the sealing resin 4. This allows heat generated in the semiconductor element 2 to be dissipated to the outside via the lead frame 3 and the heat conductive portion 5.

[0022] The semiconductor device 1 of this embodiment has a through hole 6 that penetrates the sealing resin 4 and the heat conductive portion 5. The through hole 6 serves as an attachment hole. The heat conductive portion 5 is exposed from the sealing resin 4 inside the through hole 6.

[0023] 3, the heat conductive portion 5 has a cylindrical portion 5A, and the inner periphery of the cylindrical portion 5A is exposed from the sealing resin 4 inside the through hole 6. In addition, it is desirable that the lower surface of the cylindrical portion 5A is also exposed from the sealing resin 4.

[0024] Furthermore, the heat conducting portion 5 has a plate-shaped portion 5B connected to the outer periphery of the cylindrical portion 5A, and is connected to the lead frame 3 via the plate-shaped portion 5B.

[0025] FIG. 3 shows an example of a connection structure between the heat conductive portion 5 and the lead frame 3, in which the lead frame 3 has a hole, the plate-shaped portion 5B of the heat conductive portion 5 has a convex connection portion 5C, and the connection portion 5C is press-fitted into the hole in the lead frame 3. However, the connection structure is not limited to this. For example, the hole in the lead frame 3 may be through or non-through. Furthermore, instead of press-fitting, a screw structure may be provided on both, and connection may be made by screwing. Alternatively, a structure may be used in which a hole is provided in the heat conductive portion 5, and a convex connection portion is provided on the lead frame 3. Furthermore, connection may be made by sandwiching one of the lead frame 3 and the connection portion 5C, sandwiching the other. Furthermore, connection may be made by soldering or bonding with an adhesive. Furthermore, connection may be made by a combination of press-fitting, sandwiching, or screwing with soldering or bonding with an adhesive.

[0026] The semiconductor device 1 of this embodiment also has a conductive outer lead 7. The outer lead 7 is made of, for example, a conductive metal. A portion of the outer lead 7 is sealed with the sealing resin 4 and connected to the lead frame 3 inside the sealing resin 4, with the other portion exposed from the sealing resin 4. The outer lead 7 serves as an external connection terminal. The outer lead 7 may be formed integrally with the lead frame 3. According to the structure of this embodiment, the conductive lead frame 3 is not exposed from the sealing resin 4 except for the outer lead 7, so that insulation can be ensured and corrosion of the lead frame 3 can be prevented.

[0027] FIG. 4 is a cross-sectional view showing a state in which the semiconductor device of the first embodiment is attached.

[0028] The semiconductor device 1 of this embodiment can be attached to the heat dissipation member 10 by inserting screws 11 into the through holes 6. The heat dissipation member 10 is, for example, a heat sink or a housing. The heat dissipation member 10 has a threaded structure. The screws 11 are preferably made of a material with high thermal conductivity, such as metal. The inner circumferential side of the cylindrical portion 5A of the heat conduction member 5 preferably has a threaded structure. The threaded structure increases the contact area between the cylindrical portion 5A of the heat conduction member 5 and the screws 11 and improves adhesion, thereby increasing thermal conductivity. Grease, such as silicone grease, may be used to fill gaps at the interface between the heat conduction member 5 and the screws 11, the interface between the heat conduction member 5 and the heat dissipation member 10, and the interface between the sealing resin 4 and the heat dissipation member 10 to ensure thermal conductivity. Note that FIG. 4 illustrates an example in which the heat dissipation member 10 has a threaded structure. However, this is not limited thereto. If the heat dissipation member 10 does not have a threaded structure, it may be attached using a separate nut (not shown) located on the underside of the heat dissipation member 10.

[0029] According to this embodiment, heat generated in the semiconductor element 2 can be dissipated to the heat dissipation member 10 via the lead frame 3, the heat conduction portion 5, and the screws 11. Furthermore, if the lower surface of the cylindrical portion 5A of the heat conduction portion 5 is exposed from the sealing resin 4, the heat can also be dissipated to the heat dissipation member 10 via this portion.

[0030] As described above, according to this embodiment, a semiconductor device 1 having high insulating properties and heat dissipation properties can be realized.

[0031] Fig. 5 is a top perspective view of a semiconductor device according to Example 2. Fig. 6 is a cross-sectional view taken along line BB' in Fig. 5.

[0032] In this embodiment, the plate-like portion 5B of the heat conducting portion 5 in the first embodiment is omitted, and the heat conducting portion 5 is connected to the lead frame 3 on the outer periphery of the cylindrical portion 5A.

[0033] 6, a recess is provided on the outer periphery of the cylindrical portion 5A, and the lead frame 3 is sandwiched between the recess and the cylindrical portion 5A to connect the two, but this is not limited to this. As in the first embodiment, the heat conductive portion 5 and the lead frame 3 may be connected by any of press-fitting, sandwiching, screwing, soldering, and bonding with an adhesive, or by a combination of press-fitting, sandwiching, and screwing with soldering and bonding with an adhesive.

[0034] In this embodiment, the same effects as those in the first embodiment can be obtained.

[0035] Fig. 7 is a top perspective view of the semiconductor device of Example 3. Fig. 8 is a rear view of the semiconductor device of Example 3. Fig. 9 is a cross-sectional view taken along CC' in Fig. 7.

[0036] In this embodiment, the heat conductive portion 5 is connected to the lead frame 3 at a position overlapping the semiconductor element 2, and has a columnar portion 5D whose other portion is exposed from the sealing resin 4 at a position overlapping the semiconductor element.

[0037] According to this embodiment, the path for heat dissipation can be shortened, and therefore heat dissipation is high.

[0038] The columnar portion 5D can be a columnar member of various shapes, such as a cylinder, a rectangular cylinder, an elliptical cylinder, a cone, a truncated cone, a truncated sphere, a truncated pyramid, or a column with a waist, and the shape is not limited.

[0039] Similarly to Example 1, the heat conductive portion 5 and the lead frame 3 may be connected by any of press-fitting, clamping, screwing, soldering, and bonding with an adhesive, or by a combination of press-fitting, clamping, and screwing with soldering and bonding with an adhesive. The side surfaces and surfaces of the heat conductive portion 5 may be roughened to provide an anchor effect, thereby improving contact with the lead frame 3 and adhesion with the sealing resin 4.

[0040] FIG. 10 is a cross-sectional view showing a state in which the semiconductor device of the third embodiment is attached.

[0041] In this embodiment, unlike the first embodiment, the heat conductive portion 5 does not have a cylindrical portion 5A or a plate-like portion 5B. Therefore, the through hole 6 has a structure that penetrates the sealing resin 4. The inner periphery of the through hole 6 in the sealing resin 4 may or may not have a thread structure. If the inner periphery of the through hole 6 in the sealing resin 4 does not have a thread structure, the process of forming the thread structure can be eliminated.

[0042] The heat conductive portion 5 may also be configured to have a columnar portion 5D that is connected to the lead frame 3 and has the other portion exposed from the sealing resin 4 on the surface where the heat dissipation member 10 is attached. In this case, it is desirable that the heat conductive portion 5 is connected to the lead frame 3 at a position overlapping the semiconductor element 2, but the heat conductive portion 5 may also be connected to the lead frame 3 at a position that is not overlapping the semiconductor element 2 but is as close as possible to the semiconductor element 2. According to this embodiment, heat generated by the semiconductor element 2 can be conducted to the heat conductive portion 5 directly or via the lead frame 3 and dissipated to the heat dissipation member 10 over a short distance.

[0043] Fig. 11 is a top perspective view of the semiconductor device of Example 4. Fig. 12 is a rear view of the semiconductor device of Example 4. Fig. 13 is a cross-sectional view taken along the line DD' of Fig. 11. Fig. 14 is a cross-sectional view showing the semiconductor device of Example 4 in an attached state.

[0044] This embodiment is a combination of the first embodiment and the third embodiment. According to this embodiment, it is possible to obtain the effects of the first embodiment and the third embodiment. However, this is not limiting, and the second embodiment and the third embodiment may be combined.

[0045] Although the embodiments of the present invention have been described above, the present invention is not limited to the configurations described in the embodiments, and various modifications are possible within the scope of the technical concept of the present invention. In addition, some or all of the configurations described in each embodiment may be combined and applied.

[0046] 1: semiconductor device, 2: semiconductor element, 3: lead frame, 4: sealing resin, 5: heat conducting portion, 5A: cylindrical portion, 5B: plate-shaped portion, 5C: connecting portion, 5D: columnar portion, 6: through hole, 7: outer lead, 10: heat dissipation member, 11: screw

Claims

1. A semiconductor device comprising: a semiconductor element; a conductive lead frame connected to the semiconductor element; a sealing resin that seals the semiconductor element and the lead frame; and an insulating heat conductive part composed of a ceramic molded body, a part of the heat conductive part being sealed with the sealing resin and connected to the lead frame inside the sealing resin, and another part being exposed from the sealing resin.

2. A semiconductor device according to claim 1, further comprising a through hole penetrating the sealing resin and the heat conductive portion, the other portion of the heat conductive portion being exposed from the sealing resin inside the through hole.

3. A semiconductor device according to claim 2, wherein the heat conductive portion has a cylindrical portion, the inner circumference of the cylindrical portion being exposed from the sealing resin inside the through hole.

4. A semiconductor device according to claim 3, characterized in that the heat conductive portion has a plate-like portion connected to the outer periphery of the cylindrical portion and is connected to the lead frame via the plate-like portion.

5. A semiconductor device according to claim 3, wherein the heat conductive portion is connected to the lead frame on the outer periphery side of the cylindrical portion.

6. A semiconductor device according to claim 1, characterized in that the heat conductive portion has a columnar portion connected to the lead frame at a position overlapping the semiconductor element, and the other portion is exposed from the sealing resin at a position overlapping the semiconductor element.

7. A semiconductor device according to claim 2, characterized in that the heat conductive portion has a columnar portion connected to the lead frame at a position overlapping the semiconductor element, and the other portion is exposed from the sealing resin at a position overlapping the semiconductor element.

8. A semiconductor device according to claim 1, wherein the heat conductive portion has a columnar portion connected to the lead frame and exposed from the sealing resin on a surface where the other portion is attached to a heat dissipation member.

9. A semiconductor device according to claim 2, wherein the heat conductive portion has a columnar portion connected to the lead frame and exposed from the sealing resin on the surface where the other portion is attached to the heat dissipation member.

10. A semiconductor device according to claim 1, characterized in that the thermal conductive portion and the lead frame are connected by any of press-fitting, clamping, screwing, soldering, and bonding with an adhesive, or by a combination of press-fitting, clamping, and screwing together with soldering and bonding with an adhesive.

Images