Electric power conversion device

Abstract

This electric power conversion device comprises: a plurality of semiconductor packages that each have a built-in semiconductor element and have a first surface and a second surface on opposite sides from each other; a wiring board that is bonded to the first surface with an electrically conductive bonding material interposed therebetween; and a heat dissipation member that is connected to the second surface with a heat conduction member interposed therebetween, wherein each semiconductor package has, around the portion where the bonding material is disposed on the first surface, a protrusion that protrudes in a direction away from the heat dissipation member and that keeps the distance between the first surface and the wiring substrate constant.

Description

Power Conversion Device

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

[0002] The following Patent Document 1 discloses a configuration in which, in a semiconductor device having a structure in which the heat dissipation surface is only one side, a protrusion is provided on the heat dissipation member side to prevent the semiconductor package mounted on the heat dissipation member from tilting.

[0003] JP 2011-134949 A

[0004] In the configuration described in Patent Document 1, the solder used to join the semiconductor package to the heat dissipation member needs to be formed to a certain thickness to improve reliability, but when trying to make the solder thinner to achieve miniaturization, thinning the solder thickness with protrusions creates issues with processing accuracy.

[0005] The power conversion device comprises a plurality of semiconductor packages each having a built-in semiconductor element and a first surface and a second surface facing each other, a wiring board joined to the first surface via a conductive bonding material, and a heat dissipation member connected to the second surface via a thermally conductive member, and the semiconductor packages have protrusions that protrude away from the heat dissipation member around the area where the bonding material is arranged on the first surface and maintain a constant distance between the first surface and the wiring board.

[0006] It is possible to provide a power conversion device that achieves improved heat dissipation, miniaturization, and high output.

[0007] 1 is a cross-sectional view showing the configuration of a plurality of semiconductor packages according to an embodiment of the present invention; 2 is a perspective view of a plurality of semiconductor packages on a wiring substrate according to an embodiment of the present invention; 3 is a cross-sectional view showing the configuration of a semiconductor package according to an embodiment of the present invention;

[0008] Hereinafter, an embodiment 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 some omissions and simplifications have been made as appropriate for clarity of explanation. The present invention can be implemented in various other forms. Unless otherwise specified, each component may be singular or plural.

[0009] In order to facilitate understanding of the invention, the position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc. Therefore, the present invention is not necessarily limited to the position, size, shape, range, etc. disclosed in the drawings.

[0010] (One embodiment and overall configuration) (FIGS. 1 to 3) A power conversion device 100 has a semiconductor package 1, a heat dissipation member 2, a fixing member 3, and a wiring board 4. Multiple semiconductor packages 1 are arranged adjacent to one another on the wiring board 4. The heat dissipation member 2 is a refrigerant flow path through which a refrigerant flows. The fixing member 3 is a member for fixing the semiconductor package 1, the heat dissipation member 2, and the wiring board 4 to one another. Fixing screws 5 pass through the heat dissipation member 2 and the wiring board 4 and are fastened to the fixing member 3. As a result, the heat dissipation member 2 and each semiconductor package 1 are pressed against the wiring board 4 and fixed in place.

[0011] The fixing member 3 may be made of, for example, a metal, a metal oxide, a resin, or a composite material made of a mixture of two or more materials. When fastening and fixing with the fixing screws 5, a method of directly fixing to the wiring board 4 without using the fixing member 3 may also be used.

[0012] 3 , the semiconductor package 1 includes a semiconductor element 10, a first conductor 11, a second conductor 12, an external terminal 12a, and a sealing resin 15. The first conductor 11, the second conductor 12, and the external terminal 12a are sealed by the sealing resin 15, with portions exposed and protruding from the sealing resin 15. The first conductor 11 and the second conductor 12 are electrically connected to the semiconductor element 10.

[0013] The semiconductor element 10 built into the semiconductor package 1 is a field effect transistor made of SiC, which is a wide band gap semiconductor, but other semiconductor elements such as an IGBT made of Si may also be used.

[0014] The semiconductor package 1 has a first surface 21 on the wiring substrate 4 side and a second surface 22 on the heat dissipation member 2 side. The first surface 21 and the second surface 22 are surfaces that face each other on the semiconductor package 1. On the first surface 21, a portion of the first conductor 11 is exposed from the sealing resin 15. On the second surface 22, a portion of the second conductor 12 is exposed from the sealing resin 15.

[0015] A conductive bonding material 6 such as solder is provided between the first surface 21 and the wiring board 4, and the first surface 21 and the wiring board 4 are electrically bonded to each other by the conductive bonding material 6. A thermally conductive insulating member 7 is provided between the second surface 22 and the heat dissipation member 2, and the insulating member 7 thermally connects the second surface 22 and the heat dissipation member 2.

[0016] The wiring board 4 has a copper pattern 14. The copper pattern 14 is formed in multiple layers on the wiring board 4, and the copper pattern 14 on the surface of the wiring board 4 facing the semiconductor package 1 is electrically connected to the external terminal 12 a and the first conductor 11 via the conductive bonding material 6.

[0017] The copper pattern 14 includes multiple wiring layers, such as positive wiring, negative wiring, and AC wiring for configuring an inverter circuit, gate wiring for controlling the driving of the semiconductor package, etc. Furthermore, thick copper wiring exceeding 100 μm can be used for these wiring layers in order to pass a large current.

[0018] A portion of the first conductor 11 is exposed from the sealing resin 15 on the first surface 21, and the first conductor 11 exposed from the first surface 21 and the wiring board 4 are electrically connected to each other via the conductive bonding material 6. As a result, electrodes electrically connected to the semiconductor element 10 are provided on the heat dissipation surface, that is, the first surface 21, so that the number of joints between the wiring board 4 and the semiconductor package 1 can be reduced, and the number of terminals that need to be formed from the semiconductor package 1 to the wiring board 4 can be reduced. In addition, the process of processing the terminal shape required for bonding to the wiring board 4 can be eliminated. Furthermore, the conductive bonding material 6 applied to the wiring board 4 can be unified, which simplifies the process and reduces the number of management items.

[0019] The conductive bonding material 6 is not limited to solder, and may be a metal, a metal oxide, a resin, or a composite material made by mixing two or more of these. The insulating member 7 may be a metal oxide, a resin, a metal that has been subjected to an insulating treatment, or a composite material made by mixing two or more of these.

[0020] The semiconductor package 1 has a protrusion 1b on the first surface 21 that protrudes away from the heat dissipation member 2 around the portion where the conductive bonding material 6 is disposed on the exposed surface of the first conductor 11. The protrusion 1b is part of the sealing resin 15 and is formed during the resin sealing process. The height of the protrusion 1b can be determined, for example, according to the thickness required to ensure the bonding reliability of the conductive bonding material 6. In addition, the number of protrusions 1b per semiconductor package is two or more, and the shape of the protrusions 1b is not limited to a columnar protrusion, and may be tapered, hemispherical, or other shapes.

[0021] Because the semiconductor package 1 has the protrusion 1b, the distance between the first conductor 11 and the wiring board 4 can be maintained constant, thereby suppressing variations in solder thickness that occur when multiple semiconductor packages 1 are joined on the same plane of the wiring board 4 with the conductive bonding material 6, and preventing variations in thermal resistance between each semiconductor package 1, thereby achieving high output.

[0022] Furthermore, by forming the protrusion 1b using a mold used in the sealing stage with the sealing resin 15 when manufacturing the semiconductor package 1, the height dimension to the second surface 22 can be controlled with high precision based on the surface of the wiring board 4, which is the installation surface of the protrusion 1b, and there is no need to absorb the thickness variations of the conductive bonding material 6 between multiple semiconductor packages 1 or the tilt of the semiconductor package 1 using the insulating member 7 on the second surface 22 side.

[0023] Furthermore, the thickness of the insulating member 7 provided on the second surface 22 of the semiconductor package 1, which is the surface opposite to the first surface 21 on which the protrusion 1b is provided, can be made uniform and thin. Furthermore, the thickness of the insulating member 7 can be made smaller than the height of the protrusion 1b, which contributes to miniaturization. Furthermore, the thinner the insulating member 7, the lower the thermal resistance to the heat dissipation member 2, thereby lowering the internal temperature of the semiconductor package 1 during operation. Furthermore, since there is a margin of error up to the maximum operating temperature of the components of the semiconductor package 1 compared to conventional configurations, it is possible to achieve higher output (higher voltage and larger current) while improving the heat dissipation performance of the semiconductor package 1.

[0024] (First Modification) (FIG. 4) In order to improve the insulating performance between the second surface 22 of the semiconductor package 1 and the heat dissipation member 2 in response to the increase in output of the power conversion device 100, an insulating plate 13 may be disposed. The insulating plate 13 has higher insulating performance than the thermally conductive insulating member 7 and allows for easier control of uniform thermal resistance. While the insulating plate 13 is illustrated as being sandwiched between the insulating members 7, the configuration is not limited to this and the insulating plate 13 may be disposed between the second surface 22 and the heat dissipation member 2. The insulating plate 13 may be, for example, an insulating ceramic plate, and may be made of a metal, a metal oxide, a resin, or a composite material made of a mixture of two or more materials.

[0025] This configuration improves the insulation performance more than when only the insulating member 7 is disposed between the heat dissipation member 2 and the semiconductor package 1, and enables the power conversion device 100 to operate at a higher voltage. Furthermore, since there is no need to thicken the insulating member 7 in response to an increase in voltage, voids and compositional imbalances do not occur inside the insulating member 7, and thermal resistance variations do not occur within the member.

[0026] (Second Modification) (FIG. 5) The wiring board 4 may have through holes 14a that penetrate the wiring board 4 in the thickness direction and have electrical and thermal conductivity. By joining the through holes 14a for heat transfer to the first conductors 11 with the conductive bonding material 6 in this way, the through holes 14a for heat transfer can also serve as electrical wiring, achieving both electrical conduction and heat dissipation and contributing to a reduction in the number of wires on the wiring board 4. The through holes 14a do not need to be hollow and may be configured as copper inlays or thermal vias. Furthermore, the heat dissipation member 2 may be disposed in contact with the wiring board 4 as long as insulation from the wiring board 4 can be ensured.

[0027] According to the embodiment of the present invention described above, the following advantageous effects are achieved.

[0028] (1) The power conversion device 100 includes a plurality of semiconductor packages 1 each having a first surface 21 and a second surface 22 facing each other, a wiring board 4 bonded to the first surface 21 via a conductive bonding material 6, and a heat dissipation member 2 connected to the second surface 22 via a thermally conductive member 7, and the semiconductor package 1 has a protrusion 1b that protrudes away from the heat dissipation member 2 around the portion of the first surface 21 where the bonding material 6 is arranged and maintains a constant distance between the first surface 21 and the wiring board 4. This ensures heat dissipation, making it possible to provide a power conversion device 100 that is compact and has high output.

[0029] (2) The semiconductor package 1 has a sealing resin 15, and the protrusion 1b is a part of the sealing resin 15. This allows the height precision of each semiconductor package 1 to be improved.

[0030] (3) The thermally conductive member 7 and the insulating plate 13 are disposed between the second surface 22 and the heat dissipation member 2. This improves the insulating performance for the heat dissipation member 2.

[0031] (4) The semiconductor package 1 has a conductor electrically connected to the semiconductor element 10, and the conductor is sealed with the sealing resin 15, and a portion of the conductor is exposed on the first surface 21. This configuration can reduce the number of steps required to process the terminals in the semiconductor package 1.

[0032] (5) The wiring board 4 and the conductor exposed from the first surface 21 are electrically connected to each other via the bonding material 6. This makes it possible to reduce the number of bonding points between the semiconductor package 1 and the wiring board 4 and to standardize the bonding material 6 applied to the wiring board 4.

[0033] (6) The wiring board 4 has through holes 14a that penetrate the wiring board 4 in the thickness direction and have electrical and thermal conductivity. This allows the number of wires on the wiring board 4 to be reduced.

[0034] The present invention is not limited to the above-described embodiments, and various modifications and combinations of other configurations are possible without departing from the spirit of the present invention. Furthermore, the present invention is not limited to those having all of the configurations described in the above-described embodiments, and includes those in which some of the configurations are omitted.

[0035] REFERENCE SIGNS LIST 1 semiconductor package 1b protrusion 2 heat dissipation member 3 fixing member 4 wiring board 5 fixing screw 6 conductive bonding material 7 insulating member 10 semiconductor element 11 first conductor 12 second conductor 13 insulating plate 14 copper pattern 14a through hole 15 sealing resin 21 first surface 22 second surface 100 power conversion device

Claims

1. A power conversion device comprising: a plurality of semiconductor packages each having a built-in semiconductor element and a first surface and a second surface facing each other; a wiring board joined to the first surface via a conductive bonding material; and a heat dissipation member connected to the second surface via a thermally conductive member, wherein the semiconductor packages have protrusions that protrude away from the heat dissipation member around the periphery of the portion of the bonding material on the first surface and maintain a constant distance between the first surface and the wiring board.

2. The power conversion device according to claim 1, wherein the semiconductor package has a sealing resin, and the protrusion is a part of the sealing resin.

3. The power conversion device according to claim 1, wherein the heat conduction member and an insulating plate are disposed between the second surface and the heat dissipation member.

4. The power conversion device according to claim 2, wherein the semiconductor package has a conductor electrically connected to the semiconductor element, the conductor being sealed with the sealing resin, and a portion of the conductor being exposed on the first surface.

5. The power conversion device according to claim 4, wherein the wiring board and the conductor exposed from the first surface are electrically connected to each other via the bonding material.

6. The power conversion device according to claim 5, wherein the wiring board has a through-hole that penetrates the wiring board in the thickness direction and has electrical and thermal conductivity.

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