Power semiconductor device

Abstract

To provide a power semiconductor device with high reliability, in which a stress reduction, an improvement of an insulation pressure, and an improvement heat dissipation are realized.SOLUTION: A power semiconductor device has: a heat dissipation member 7 in which a heat dissipation surface 10a of a semiconductor element 1 is exposed from a sealing resin 10, and that is arranged so as to be opposite to the heat dissipation surface 10a; and an insulation plate 4. The insulation plate 4 is partially arranged at least on the outside of the sealing resin 10 in a plan surface direction. The heat dissipation member 7 comprises: a convex part 7c that is projected toward the heat dissipation surface 10a, and provided with a projection surface 7d to be opposite to the heat dissipation surface 10a; and a concave part 7e that is provided around the convex part 7c in the plan surface direction, and is formed away from the insulation plate 4 as compared with the projection surface 7d in a lamination direction. The projection surface 7d is formed larger in the plan surface direction than that of the heat dissipation surface 10a to be arranged oppositely. The concave part 7e is formed at a position where an end part X3 of the sealing resin 10 and the insulation plate 4 are overlapped in view of a plan surface.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] For reducing the environmental load, the spread of hybrid vehicles and electric vehicles has been promoted. For example, in a power semiconductor device in a power conversion device, which is one of the components mounted on these vehicles, miniaturization and cost reduction are emphasized. In order to miniaturize a power semiconductor device with a large amount of heat generation, it is necessary to improve the cooling performance. For example, Patent Document 1 discloses a configuration of a power semiconductor device in which a power module is provided with a cooler via a heat conduction member and an insulating member, and the power module, the heat conduction member, and the cooler are connected to ensure cooling performance.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the technique described in Patent Document 1, when the power module is made compatible with high voltage, an insulating member is provided to ensure insulation between the heat dissipation member and the external terminals of the semiconductor module. This insulating member reduces the thermal resistance by pressurizing the heat dissipation member to ensure the cooling performance and improves the long-term reliability. However, an insulating member with high dielectric breakdown voltage such as a ceramic plate may crack when pressurized, resulting in a problem of reduced reliability. In view of this, an object of the present invention is to provide a highly reliable power semiconductor device that realizes stress reduction, improvement of dielectric breakdown voltage, and improvement of heat dissipation.

Means for Solving the Problems

[0005] The power semiconductor device includes a semiconductor element, a conductor portion thermally and electrically connected to the semiconductor element, and a sealing member that mold-seals the semiconductor element and the conductor portion. A semiconductor package has a heat dissipation surface, which is a surface opposite to the surface connecting to the semiconductor element in the conductor portion, exposed from the sealing member. The power semiconductor device further includes a heat dissipation member disposed opposite to the heat dissipation surface, and an insulating plate provided between the semiconductor package and the heat dissipation member. A part of the insulating plate is disposed at least outside the sealing member in the planar direction. The heat dissipation member has a convex portion that protrudes toward the heat dissipation surface and has a protruding surface facing the heat dissipation surface, and a concave portion provided around the convex portion in the planar direction and formed at a position away from the insulating plate compared to the protruding surface in the stacking direction. The protruding surface is formed larger in the planar direction than the heat dissipation surface disposed opposite thereto. The concave portion is formed at a position where the end of the sealing member and the insulating plate overlap when viewed in plan.

Advantages of the Invention

[0006] It is possible to provide a highly reliable power semiconductor device that realizes stress reduction, improvement of dielectric breakdown voltage, and improvement of heat dissipation performance.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0008] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following description and drawings are examples for explaining the present invention, and for the sake of clarity of explanation, appropriate omissions and simplifications have been made. The present invention can be implemented in various other forms. Unless otherwise specified, each component may be singular or plural.

[0009] In the drawings, the positions, sizes, shapes, ranges, etc. of the respective components shown may not represent the actual positions, sizes, shapes, ranges, etc. in order to facilitate understanding of the invention. For this reason, the present invention is not necessarily limited to the positions, sizes, shapes, ranges, etc. disclosed in the drawings.

[0010] (First Embodiment and Overall Configuration of the Present Invention) (Fig. 1) A semiconductor package 100 having the role of a semiconductor module in a power semiconductor device includes a semiconductor element 1, a first conductor portion 3a, a second conductor portion 3b, and an external terminal 3c. The first conductor portion 3a and the second conductor portion 3b are thermally and electrically connected to the semiconductor element 1, and their materials are, for example, copper, copper alloy, or aluminum, aluminum alloy, etc. The electrode provided on one surface of the semiconductor element 1 is joined to the first conductor portion 3a by a joining material 2. The electrode provided on the other surface of the semiconductor element 1 is joined to the second conductor portion 3b by a joining material 2. The material of the joining material 2 is, for example, a solder material, a sintered material, etc.

[0011] The first conductor portion 3a and the second conductor portion 3b are molded and sealed such that the heat dissipation surfaces 10a, which are the surfaces opposite to the surfaces connected to the semiconductor element 1 respectively, are exposed from a sealing resin 10 which is a sealing member. Thereby, the semiconductor package 100 can dissipate the heat generated in the semiconductor package 100 to a heat dissipation member 7 described later through the heat dissipation surfaces 10a exposed on both of its surfaces. A part of the external terminal 3c protrudes externally from the sealing member 10, whereby the semiconductor package 100 can be electrically connected to an external wiring (not shown).

[0012] (Fig. 2) The first conductor portion 3a is connected to an insulating plate 4, which is an insulating layer having electrical insulation properties, via a heat conduction layer 5a formed of a heat conductive material on the heat dissipation surface 10a. This insulating plate 4 is connected to a heat conduction layer 5b formed of a heat conductive material on the surface opposite to the surface to which the first conductor portion 3a is connected, and is connected to the heat dissipation member 7 via the heat conduction layer 5b. In this way, of the heat dissipation members 7 provided on both surfaces of the semiconductor package 100, one heat dissipation member 7 faces the heat dissipation surface 10a of the first conductor portion 3a.

[0013] Also, the second conductor portion 3b is connected to the insulating plate 4 via the heat conduction layer 5a on the heat dissipation surface 10a. This insulating plate 4 is connected to the heat conduction layer 5b on the surface opposite to the surface to which the second conductor portion 3b is connected, and is connected to the heat dissipation member 7. In this way, of the heat dissipation members 7 provided on both surfaces of the semiconductor package 100, the other heat dissipation member 7 faces the heat dissipation surface 10a of the second conductor portion 3b.

[0014] The insulating plate 4 and the heat conduction layers 5a and 5b sandwiching this insulating plate 4 are provided between the semiconductor package 100 and the heat dissipation member 7 and are in close contact with each other. As a result, a refrigerant flows inside the heat dissipation member 7, and the semiconductor package 100 ensures coolability by thermally conducting the heat generated from the semiconductor element 1 to the heat dissipation member 7 through the heat conduction layers 5a, 5b and the insulating plate 4, and also electrically insulates the semiconductor package 100 and the heat dissipation member 7.

[0015] The insulating plate 4 is an insulating sheet formed of a material having high thermal conductivity and high dielectric breakdown voltage, and the material thereof contains, for example, ceramics such as aluminum oxide (alumina), aluminum nitride, silicon nitride, or fine powders thereof.

[0016] Members having heat conductivity such as heat conduction grease, TIM (Thermal Interface Material), or a heat dissipation sheet are used for the heat conduction layers 5a and 5b.

[0017] The heat radiating member 7 is made of a member having thermal conductivity. Such members include, for example, composites such as Cu, Cu alloys, Cu-C, Cu-CuO, or composites such as Al, Al alloys, AlSiC, Al-C, etc.

[0018] The heat radiating member 7 has a convex portion 7c that protrudes toward the heat radiating surface 10a of the first conductor portion 3a and the heat radiating surface 10a of the second conductor portion 3b, and is provided with a protruding surface 7d that faces each heat radiating surface 10a. Further, the heat radiating member 7 has a concave portion 7e that is provided around the convex portion 7c in the planar direction and is formed so as to be farther from the insulating plate 4 than the protruding surface 7d in the stacking direction. The protruding surface 7d is formed larger in the planar direction than the opposing heat radiating surface 10a, so that the heat released from the heat radiating surface 10a can be reliably absorbed by the heat radiating member 7, and the heat radiating performance is not deteriorated. The heat radiating member 7 is being pressed toward the semiconductor package 100 in accordance with the arrow of the pressing portion 11.

[0019] Let the end portion in the planar direction of the first conductor portion 3a and the second conductor portion 3b be X1, the end portion in the planar direction of the convex portion 7c of the heat radiating member 7 be X2, the end portion in the planar direction of the sealing resin 10 be X3, and the end portion in the planar direction of the insulating plate 4 be X4.

[0020] The end portion X2 is provided at a position outside the end portion X1 in the planar direction, and is provided so as to be inside the end portion X3 of the sealing member 10 in the planar direction. The concave portion 7e of the heat radiating member 7 is formed at a position where the end portion X3 of the sealing member 10 and the insulating plate 4 overlap when viewed in plan.

[0021] The end portion X4 of the insulating plate 4 is disposed outside the end portion X3 of the sealing resin 10, and at least a part of the insulating plate 4 is provided outside the sealing resin 10 in the planar direction. The insulating plate 4 is a ceramic white plate provided with no wiring layer forming conductors on both sides, and by being sandwiched between the heat conduction layers 5a and 5b on both sides, it contributes to suppressing cracks in the insulating plate 4.

[0022] (Fig. 3) FIG. 3(a) is a plan view of semiconductor package 100 including heat dissipation member 7 of FIG. 2 with the upper heat dissipation member 7, first conductor portion 3a, and semiconductor element 1 removed. FIG. 3(b) is a plan view of heat dissipation member 7 of FIG. 3(a), and FIG. 3(c) is a cross-sectional view of heat dissipation member 7 of FIG. 3(b).

[0023] As shown in FIG. 3, heat dissipation member 7 has bolt holes 9 at its four corners respectively. When bolts (not shown) are inserted into bolt holes 9, pressure in the direction of the arrow of pressure application portion 11 (FIG. 2) is generated, and heat dissipation member 7 is pressed toward semiconductor package 100. Note that as long as the structure is such that heat dissipation member 7 is pressed toward semiconductor package 100, not only bolts but also clips, leaf springs, etc. may be used. Further, pressure application portion 11 of semiconductor package 100 may be formed at the position of convex portion 7c of the heat dissipation member in the stacking direction.

[0024] Semiconductor package 100 has external terminals 3c protruding to the outside from sealing member 10. However, insulating plate 4 overlaps at least a part of external terminals 3c when viewed in plan. By doing so, the creepage distance between external terminals 3c and heat dissipation member 7 formed on both surfaces of semiconductor package 100 is increased, the dielectric withstand voltage is improved, and breakdown can be prevented even when semiconductor package 100 is used at high voltage. Note that insulating plate 4 for securing the creepage distance may not be configured to be disposed entirely in the planar direction as shown in FIG. 3, and may be formed only in the portion where external terminals 3c protrude from sealing member 10 to the outside.

[0025] Since heat conduction layer 5b is provided between insulating plate 4 and convex portion 7c, convex portion 7c does not directly contact heat dissipation member 7, so it acts as a stress relaxation layer. Here, when a load is applied to pressure application portion 11 of heat dissipation member 7, heat dissipation member 7 undergoes bending deformation with the end X2 of convex portion 7c as a fulcrum. Heat conduction layer 5b on recessed portion 7e affected by the stress due to this deformation is provided thicker in the stacking direction by the step difference between convex portion 7c and recessed portion 7e. Thereby, even when pressure is applied to pressure application portion 11, it becomes difficult for stress to be applied to insulating plate 4, so cracks in insulating plate 4 are suppressed.

[0026] Note that the heat radiating member 7 may be composed not only of a single member but also of a plurality of members. Further, the heat radiating member 7 may be provided with a water passage through which a refrigerant flows, pin fins, corrugated fins, etc., and may be in other cooling forms such as air cooling.

[0027] (Second Embodiment) (Figs. 4 and 5) Fig. 5(a) is a plan view of the semiconductor package 100 including the heat radiating member 7 of Fig. 4 with the upper heat radiating member 7, the first conductor portion 3a, and the semiconductor element 1 removed in the stacking direction, Fig. 3(b) is a plan view of the heat radiating member 7 of Fig. 3(a), and Fig. 3(c) is a cross-sectional view of the heat radiating member 7 of Fig. 3(b).

[0028] As shown in Fig. 5(a), the recess 7e is formed so that the range of the recess 7e does not extend to the position of the bolt hole 9 of the heat radiating member 7 when viewed in plan. Note that the end X5 of the recess 7e in the planar direction is provided on the outer side of the end X4. By doing so, it is possible to prevent the wall thickness of the heat radiating member 7 from becoming thin around the bolt hole 9 which is a load bearing portion for pressing the heat radiating member 7 toward the semiconductor package 100 side, and thus it is possible to pressurize efficiently.

[0029] According to the embodiments of the present invention described above, the following operational effects are obtained.

[0030] (1) A semiconductor package 100 having a semiconductor element 1, conductors 3a and 3b thermally and electrically connected to the semiconductor element 1, and a sealing member 10 that mold-seals the semiconductor element 1 and the conductors 3a and 3b, wherein a heat dissipation surface 10a, which is a surface on the opposite side of the conductors 3a and 3b from the surface connected to the semiconductor element 1, is exposed from the sealing member 10; a heat dissipation member 7 disposed opposite to the heat dissipation surface 10a; and an insulating plate 4 provided between the semiconductor package 100 and the heat dissipation member 7. The insulating plate 4 has a part thereof disposed at least outside the sealing member 10 in the planar direction. The heat dissipation member 7 has a convex portion 7c that protrudes toward the heat dissipation surface 10a and is provided with a protruding surface 7d facing the heat dissipation surface 10a, and a concave portion 7e provided around the convex portion 7c in the planar direction and formed at a position away from the insulating plate 4 compared to the protruding surface 7d in the stacking direction. The protruding surface 7d is formed larger in the planar direction than the heat dissipation surface 10a disposed opposite thereto, and the concave portion 7e is formed at a position where the end portion X3 of the sealing member 10 and the insulating plate 4 overlap when viewed in plan. By doing so, a highly reliable power semiconductor device can be provided that realizes stress reduction, improvement of dielectric breakdown voltage, and improvement of heat dissipation performance.

[0031] (2) The insulating plate 4 is a ceramic white plate provided without a wiring layer formed of a conductor. By using such a member, stress reduction and improvement of dielectric breakdown voltage can be realized.

[0032] (3) The semiconductor package 100 has a terminal portion 3c protruding from the sealing member 10 to the outside, and at least a part of the insulating plate 4 overlaps the terminal portion 3c when viewed in plan. By doing so, the creepage distance between the heat dissipation member 7 and the terminal portion 3c is ensured, and the dielectric breakdown voltage is improved.

[0033] (4) A thermally conductive material is provided between the insulating plate 4 and the heat dissipation member 7. By doing so, heat generated from the semiconductor package 100 can be transferred to the heat dissipation member 7 while electrically insulating between the semiconductor package 100 and the heat dissipation member 7.

[0034] A heat conductive material is provided between the insulating board 4 and the semiconductor package 100, or between the insulating board 4 and the heat dissipation member 7. By doing so, heat generated from the semiconductor package 100 can be transferred to the heat dissipation member 7 while electrically insulating between the semiconductor package 100 and the heat dissipation member 7.

[0035] Note that the present invention is not limited to the above-described embodiments, and various modifications and other configurations can be combined without departing from the gist thereof. Further, the present invention is not limited to those having all the configurations described in the above embodiments, and those in which a part of the configuration is deleted are also included.

Explanation of Signs

[0036] 1 Semiconductor element 2 Bonding material 3a First conductor part 3b Second conductor part 3c External terminal 4 Insulating board 5a, 5b Heat conduction layer 7 Heat dissipation member 7c Protrusion of heat dissipation member 7d Protruding surface 7e Recess of heat dissipation member 9 Bolt hole 10 Encapsulating resin 10a Heat dissipation surface 11 Pressing part X1 End of conductor part X2 End of protrusion of heat dissipation member X3 End of encapsulating resin X4 End of insulating board X5 End of recess of heat dissipation member 100 Semiconductor package

Claims

1. A semiconductor package having a semiconductor element, a conductor portion thermally and electrically connected to the semiconductor element, and a sealing member that mold-seals the semiconductor element and the conductor portion, wherein a heat dissipation surface, which is a surface on the conductor portion opposite to the surface connected to the semiconductor element, is exposed from the sealing member, a heat dissipation member disposed to face the heat dissipation surface, and an insulating plate provided between the semiconductor package and the heat dissipation member, wherein a part of the insulating plate is disposed at least outside the sealing member in a planar direction, the heat dissipation member has a convex portion that protrudes toward the heat dissipation surface and has a protruding surface facing the heat dissipation surface, and a concave portion provided around the convex portion in a planar direction and formed to be separated from the insulating plate compared to the protruding surface in a stacking direction, the protruding surface is formed larger in a planar direction than the heat dissipation surface disposed opposite thereto, and the concave portion is formed at a position where an end portion of the sealing member and the insulating plate overlap when viewed in a plane. A power semiconductor device.

2. The power semiconductor device according to claim 1, wherein the insulating plate is a ceramic white plate provided without a wiring layer formed of a conductor. A power semiconductor device.

3. The power semiconductor device according to claim 1, wherein the semiconductor package has a terminal portion protruding outward from the sealing member, and the insulating plate overlaps at least a part of the terminal portion when viewed in a plane. A power semiconductor device.

4. The power semiconductor device according to claim 1, wherein a thermally conductive material is provided between the insulating plate and the heat dissipation member. A power semiconductor device.

5. The power semiconductor device according to claim 1, wherein a thermally conductive material is provided between the insulating plate and the semiconductor package or between the insulating plate and the heat dissipation member. A power semiconductor device.

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