JP7016375B2 - Power semiconductor module - Google Patents

Description

The present application relates to a power semiconductor module.

An electric vehicle such as an electric vehicle or a hybrid vehicle in which a motor is used as a drive source is equipped with a plurality of electric power conversion devices. Power converters include chargers that convert commercial AC power to DC power to charge high-voltage batteries, and DC / DC converters that convert the DC power of high-pressure batteries to the voltage of batteries for auxiliary equipment (eg 12V). Examples thereof include an inverter device that controls a motor by converting DC power from a battery into AC power to a motor.

The inverter device includes a power semiconductor module equipped with a power semiconductor element, and the inverter circuit is formed by the power semiconductor module. DC power and AC power are mutually converted by the switching operation of the inverter circuit. These electric powers are used to perform power running operation and regenerative operation of the motor.

In recent years, with the miniaturization and high output of power semiconductor modules, the demand for heat dissipation performance has increased. In order to satisfy the requirements for heat dissipation performance, in addition to copper or a copper alloy generally used as a heat diffusion member, graphite having an anisotropic thermal conductivity has been proposed. For example, there is disclosed a heat diffusion member in which a plurality of graphites in which plate-shaped graphene sheets are laminated in the plate thickness direction are laminated in a direction perpendicular to the direction of low thermal conductivity (see, for example, Patent Document 1). The graphene sheet has better thermal conductivity than copper or a copper alloy in the longitudinal direction and the width direction as compared with the plate thickness direction. On the other hand, the thermal conductivity in the plate thickness direction is lower than that of copper or a copper alloy. By arranging a plurality of graphites so that the laminated direction having low thermal conductivity is orthogonal to the direction connecting the semiconductor element which is a heating element and the cooler, the heat diffusion member generates heat generated in the semiconductor element. Is efficiently transmitted to the cooler.

Japanese Unexamined Patent Publication No. 2011-258755

In Patent Document 1, the efficiency of heat diffusion of graphite in the direction connecting the semiconductor element and the cooler can be enhanced by laminating a plurality of graphites with the directions of low thermal conductivity orthogonal to each other. However, a material having an anisotropic thermal conductivity, such as graphite, generally has an anisotropic linear expansion coefficient. For example, in graphite on which graphene sheets are laminated, the linear expansion coefficient in the longitudinal direction and the width direction of the graphene sheet is smaller than the linear expansion coefficient in the laminated direction. In the case of a heat diffusion member in which graphite, which is an anisotropic linear expansion member, is laminated in a direction orthogonal to each other in which the linear expansion coefficient is large, the heat diffusion member will be curved in a saddle shape due to the difference in the linear expansion coefficient. And. Therefore, a large thermal stress is generated in the bonding material provided between the heat diffusion member and another member bonded to the heat diffusion member. Since thermal stress causes fatigue fracture in the bonding material, it becomes difficult to maintain a thermal connection between the heat diffusion member and other members via the bonding material, and the heat transfer performance of the power semiconductor module is significantly reduced. There was a problem.

Therefore, an object of the present application is to obtain a power semiconductor module capable of suppressing deterioration of heat transfer performance by suppressing bending of the heat diffusion member.

The power semiconductor module disclosed in the present application includes a laminated N-layer (N is an odd number of 3 or more) plate-shaped heat conduction anisotropic member and an outer plate of the first layer heat conduction anisotropic member. In the heat conduction anisotropic member of the odd-th layer, which is provided with a power semiconductor element bonded to the surface, the heat conductivity in the direction of the plate thickness and the heat conductivity in the first direction parallel to the plate surface are orthogonal to the first direction. In the heat conduction anisotropic member of the even-th layer, which is higher than the heat conductivity in the second direction parallel to the plate surface, the heat conductivity in the plate thickness direction and the second direction is the heat conductivity in the first direction. The thickness of the heat conduction anisotropic member of the first layer is the same as the thickness of the heat conduction anisotropic member of the Nth layer, which is higher than that of the heat conduction anisotropic member of the oddth layer. The sum of the thicknesses is the same as the sum of the thicknesses of the heat conduction anisotropic members of the even-th layer, and the thickness of the heat conduction anisotropic members of the even-th layer is the heat of the odd-th layer. It is larger than the thickness of the conduction anisotropic member .

According to the power semiconductor module disclosed in the present application, the thermal conductivity in the plate thickness direction is high in both the heat conduction anisotropic member of the odd-th layer and the heat conduction anisotropic member of the even-th layer. The laminated N-layer (N is an odd number of 3 or more) plate-shaped heat conduction anisotropic member can efficiently transfer the heat generated by the power semiconductor element in the direction of the plate thickness. Further, the thermal conductivity in the first direction parallel to the plate surface of the heat conduction anisotropic member of the odd-th layer is higher than the thermal conductivity in the second direction orthogonal to the first direction and parallel to the plate surface, and is even. Since the thermal conductivity of the heat conduction anisotropic member of the second layer in the second direction is higher than the thermal conductivity of the first direction, the heat conduction anisotropic member of the odd-th layer and the heat conduction of the even-th layer By laminating the anisotropic member, the laminated plate-shaped thermal conductivity anisotropic member of the N layer (N is an odd number of 3 or more) efficiently transfers the heat generated by the power semiconductor element in the first direction. And can also be transmitted in the second direction. Furthermore, the thickness of the heat transfer anisotropic member of the first layer is the same as the thickness of the heat transfer anisotropic member of the Nth layer, and by making these thicknesses the same, the thickness of the first layer can be increased. The force to bend between the heat transfer anisotropic member and the heat transfer anisotropic member of the second layer, which is the even-th layer, and the heat transfer anisotropic member and the even-th layer of the Nth layer. Since it is possible to cancel the bending force generated with the heat transfer anisotropic member of the N-1st layer, which is, the plate-like heat transfer difference of the laminated N layers (N is an odd number of 3 or more). The bending of the square member is suppressed, and the deterioration of the heat transfer performance of the power semiconductor module can be suppressed.

It is a perspective view schematically showing the appearance of the power semiconductor module which concerns on Embodiment 1. FIG. It is a figure explaining the heat conduction anisotropic member of the power semiconductor module which concerns on Embodiment 1. FIG. It is a perspective view schematically showing the appearance of the power semiconductor module which concerns on Embodiment 2. FIG. It is a perspective view schematically showing the appearance of the power semiconductor module which concerns on Embodiment 3. FIG. It is a perspective view schematically showing the appearance of the power semiconductor module which concerns on Embodiment 4. FIG. It is a top view schematically showing the appearance of the power semiconductor module which concerns on Embodiment 5.

Hereinafter, the power conversion device according to the embodiment of the present application will be described with reference to the drawings. In each figure, the same or corresponding members and parts will be described with the same reference numerals.

Embodiment 1.
FIG. 1 is a perspective view schematically showing the appearance of the power semiconductor module 100 according to the first embodiment, and FIG. 2 is a diagram illustrating a heat conduction anisotropic member 3 of the power semiconductor module 100. The power semiconductor module 100 is a module on which a power semiconductor element 1 is mounted, and constitutes an inverter circuit in, for example, an inverter device.

The power semiconductor module 100 is formed on the outer side of the laminated N-layer (N is an odd number of 3 or more) plate-shaped heat conduction anisotropic member 3 and the first heat conduction anisotropic member 3a of the first layer. A power semiconductor element 1 bonded to an element bonding surface 2a, which is a plate surface, is provided. As shown in FIG. 1, in the first embodiment, the power semiconductor module 100 including the three-layer heat conduction anisotropic member 3 when N is 3 will be described. The heat diffusion member 2 is formed of three layers of heat conduction anisotropic members 3. The power semiconductor module 100 is cooled by being joined to the cooler joint surface 2b, which is the outer plate surface of the third heat conduction anisotropic member 3c of the third layer, via an insulating heat dissipation member (not shown). A vessel 20 is provided. The cooler joint surface 2b is a plate surface on the opposite side of the heat diffusion member 2 parallel to the element joint surface 2a. The heat generated in the power semiconductor element 1 is diffused toward the cooler 20 via the heat diffusion member 2, and the power semiconductor element 1 is cooled.

<Power semiconductor element 1>
As the power semiconductor element 1, a power control semiconductor element such as a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), an IGBT (Insulated Gate Bipolar Transistor), a freewheeling diode, or the like is used. Further, as the power semiconductor element 1, a semiconductor made of a material such as silicon carbide, silicon, or gallium nitride is used. The power semiconductor device 1 is thermally and electrically connected to the device bonding surface 2a by using a sintered material (not shown) containing silver as a main component. The bonding of the power semiconductor element 1 may be solder bonding, diffusion bonding, or the like.

<Heat conduction anisotropic member 3>
As shown in FIG. 2, the heat conduction anisotropic member 3 is graphite 4 on which a plurality of rectangular graphene sheets 5 are laminated. The graphene sheet 5 is a thin plate in which carbon atoms are bonded in a sheet shape so as to form a hexagonal network. Graphite 4 has anisotropic thermal conductivity. It has a high thermal conductivity (for example, about 1700 W / mK) in the direction parallel to the surface of the graphene sheet 5, and shows a low thermal conductivity (for example, about 7 W / mK) in the direction perpendicular to the surface of the graphene sheet 5. ..

<Heat diffusion member 2>
As shown in FIG. 1, the heat diffusion member 2 includes a first heat conduction anisotropic member 3a in the first layer, a second heat conduction anisotropic member 3b in the second layer, and a third layer. The third heat conduction anisotropic member 3c is provided. The heat conduction anisotropic members 3 are joined by brazing with a brazing material (not shown). The first heat conduction anisotropic member 3a and the third heat conduction anisotropic member 3c of the odd-th layer and the second heat conduction anisotropic member 3b of the even-th layer have high thermal conductivity. The direction is different. In the first heat conduction anisotropic member 3a and the third heat conduction anisotropic member 3c of the odd-th layer, the thermal conductivity in the direction of the plate thickness and in the first direction parallel to the plate surface is the first direction. It is higher than the thermal conductivity in the second direction orthogonal to and parallel to the plate surface. The first heat conduction anisotropic member 3a and the third heat conduction anisotropic member 3c of the odd-th layer have a rectangular shape in which the long side is parallel to the first direction and the short side is parallel to the plate thickness direction. It is formed by laminating a plurality of graphene sheets 5 in the second direction. In the second heat conduction anisotropic member 3b of the even-th layer, the heat conductivity in the plate thickness direction and the second direction is higher than the heat conductivity in the first direction. The second heat conduction anisotropic member 3b of the even-th layer has a plurality of rectangular graphene sheets 5 having long sides parallel to the second direction and short sides parallel to the plate thickness direction in the first direction. It is formed by stacking.

The power semiconductor element in any of the first heat conduction anisotropic member 3a and the third heat conduction anisotropic member 3c of the odd-th layer and the second heat conduction anisotropic member 3b of the even-th layer. The thermal conductivity in the direction of the plate thickness connecting 1 and the cooler 20 is high. According to this configuration, since the thermal conductivity of the heat diffusion member 2 in the plate thickness direction connecting the power semiconductor element 1 and the cooler 20 is high, the heat diffusion member 2 efficiently dissipates the heat generated by the power semiconductor element 1. Can be transmitted to the cooler 20.

The first heat conduction anisotropic member 3a and the third heat conduction anisotropic member 3c in the odd-th layer and the second heat conduction anisotropic member 3b in the even-th layer are the power semiconductor element 1. The direction of high thermal conductivity of each plate surface is orthogonal to the direction orthogonal to the direction of the plate thickness connecting the cooler 20. The heat diffusion member 2 connects the power semiconductor element 1 and the cooler 20 by laminating the respective heat conduction anisotropic members 3 so that the first direction and the second direction, which are the directions having high thermal conductivity, are orthogonal to each other. The thermal conductivity in the direction orthogonal to the plate thickness direction is also high. According to this configuration, the thermal conductivity of the heat diffusion member 2 in the direction orthogonal to the plate thickness direction connecting the power semiconductor element 1 and the cooler 20 can also be increased, so that the heat diffusion member 2 is the power semiconductor element 1. The heat generated in the above can be transferred to the cooler 20 more efficiently.

<Thickness of heat conduction anisotropic member 3>
The structure of the thickness of the heat conduction anisotropic member 3 which is the main part of the present application will be described. A member having an anisotropic thermal conductivity generally also has anisotropy in the linear expansion coefficient. For example, in graphite 4 shown in FIG. 2, the linear expansion coefficient in the direction parallel to the plane of the graphene sheet 5 is smaller than the linear expansion coefficient in the direction perpendicular to the plane of the graphene sheet 5. When two graphites 4 are laminated so that the directions in which the linear expansion coefficients are large are orthogonal to each other, the two laminated graphites 4 tend to bend in a saddle shape due to the difference in the linear expansion coefficients. Due to this bending force, a large thermal stress is generated in the bonding material provided between the graphite 4 and the other member bonded to the graphite 4. When fatigue fracture occurs in the bonding material due to thermal stress, the thermal connection between graphite 4 and other members via the bonding material is not maintained, so that the heat transfer performance of the power semiconductor module 100 is significantly reduced.

As shown in FIG. 1, the thickness of the first heat conduction anisotropic member 3a of the first layer is the same as the thickness of the third heat conduction anisotropic member 3c of the third layer. By making these thicknesses the same, the bending force generated in the first heat conduction anisotropic member 3a and the second heat conduction anisotropic member 3b and the second heat conduction anisotropic member 3b The bending forces generated in the 3b and the third heat conduction anisotropic member 3c act in opposite directions, and the forces are balanced, so that the forces can be canceled out. Therefore, it is possible to prevent the heat diffusion member 2 from bending into a saddle shape.

According to this configuration, it is possible to suppress the heat diffusion member 2 from bending into a saddle shape, and it is possible to suppress fatigue failure of the insulating bonding member which is a bonding material provided between the heat diffusion member 2 and the cooler 20. The thermal connection between the heat diffusion member 2 and the cooler 20 via the insulating bonding member is maintained, and deterioration of the heat transfer performance in the power semiconductor module 100 can be suppressed.

Further, the sum of the thicknesses of the first heat conduction anisotropic member 3a and the third heat conduction anisotropic member 3c of the odd-th layer is the sum of the thicknesses of the second heat conduction anisotropic member 3c of the even-th layer. It is the same as the thickness of 3b. The sum of the thicknesses of the first heat conduction anisotropic member 3a and the third heat conduction anisotropic member 3c of the odd-th layer and the second heat conduction anisotropic member 3b of the even-th layer. By making the thickness the same, the effective linear expansion coefficients in the first direction and the second direction when the heat diffusion member 2 is viewed as a whole can be made equal. Since the effective linear expansion coefficients in the first direction and the second direction are the same, it is possible to prevent the heat diffusion member 2 from bending into a saddle shape.

According to this configuration, fatigue fracture of the insulating joining member that joins the heat diffusion member 2 and the cooler 20 is further suppressed, so that deterioration of the heat transfer performance in the power semiconductor module 100 can be further suppressed.

<Cooler 20>
The cooler 20 is made of a metal having high thermal conductivity such as aluminum. The cooler 20 has, for example, a thickness in the height direction, has a cooling surface 20a on the outside, and forms a flow path through which the refrigerant flows and cooling fins on the inside. The refrigerant is a fluid, and the refrigerant flows in and out from two pipes (not shown) provided on the side surface of the cooler 20. As the refrigerant, for example, water or an ethylene glycol liquid is used. The cooling surface 20a is cooled by the refrigerant. The cooler 20 forms a part of a cooling circuit that circulates a refrigerant together with a tank, a pump, a radiator, and the like. The insulating heat-dissipating member that joins the cooler 20 and the cooler joint surface 2b is, for example, a silicone grease, an insulating sheet containing a heat-dissipating filler, or an insulating adhesive containing a heat-dissipating filler. The cooler 20 and the heat diffusion member 2 are thermally connected and not electrically connected.

It is desirable that the power semiconductor device 1 includes a MOSFET made of a silicon carbide semiconductor. Silicon carbide semiconductors are more expensive than silicon semiconductors. Further, the graphite 4 constituting the heat diffusion member 2 is more expensive than copper, which is another heat diffusion member. Therefore, by improving the heat transfer property of the heat diffusion member 2, the silicon carbide semiconductor can be made into a smaller element size, so that the power semiconductor module 100 can be manufactured at a lower cost.

As described above, in the power semiconductor module 100 according to the first embodiment, in the first heat conduction anisotropic member 3a and the third heat conduction anisotropic member 3c of the odd-th layer, the direction of the plate thickness and the plate In the second heat conduction anisotropic member 3b of the even-th layer, the heat conductivity in the first direction parallel to the surface is higher than the heat conductivity in the second direction orthogonal to the first direction and parallel to the plate surface. , The heat conductivity in the thickness direction and the second direction is higher than the heat conductivity in the first direction, and the first heat conduction anisotropic member 3a and the third heat conduction anisotropic member of the odd-th layer are Since the heat conductivity in the direction of the plate thickness is high in both the 3c and the second heat conduction anisotropic member 3b of the even-th layer, the laminated three-layer plate-shaped heat conduction anisotropic member 3 is used. The heat generated by the power semiconductor element 1 can be efficiently transferred in the direction of the plate thickness. Further, the first heat conduction anisotropic member 3a and the third heat conduction anisotropic member 3c of the odd-th layer and the second heat conduction anisotropic member 3b of the even-th layer are laminated. The three-layered plate-shaped heat conduction anisotropic member 3 can efficiently transfer the heat generated by the power semiconductor element 1 to the first direction and the second direction. Further, since the thickness of the first heat transfer anisotropic member 3a of the first layer is the same as the thickness of the third heat transfer anisotropic member 3c of the third layer, these thicknesses are made the same. As a result, the force to bend generated in the first heat conduction anisotropic member 3a and the second heat conduction anisotropic member 3b, and the second heat conduction anisotropic member 3b and the third heat conduction It is possible to cancel the bending force generated in the anisotropic member 3c, the curvature of the three-layered plate-shaped heat transfer anisotropic member 3 is suppressed, and the heat diffusion member 2 and the cooler 20 Since the fatigue failure of the insulating joining member, which is the joining material provided between the two, is suppressed, it is possible to suppress the deterioration of the heat transfer performance of the power semiconductor module.

Further, in the first heat conduction anisotropic member 3a and the third heat conduction anisotropic member 3c of the odd-th layer, the long side is parallel to the first direction and the short side is parallel to the plate thickness direction. The second heat conduction anisotropic member 3b of the even-th layer, which is formed by laminating a plurality of graphene sheets 5 in the second direction, has a long side parallel to the second direction and a short side having a plate thickness. Since a plurality of rectangular graphene sheets 5 parallel to the direction are laminated in the first direction, the plate is orthogonal to the first direction parallel to the plate surface or the first direction in addition to the plate thickness direction. The thermal conductivity in the second direction parallel to the plane can be increased. In addition, the heat conduction anisotropic member 3 can be easily manufactured. Further, the sum of the thicknesses of the first heat transfer anisotropic member 3a and the third heat transfer anisotropic member 3c of the odd-th layer is the sum of the thicknesses of the second heat transfer anisotropic member 3a of the even-th layer. When the thickness is the same as that of 3b, the fatigue failure of the insulating joining member that joins the heat diffusion member 2 and the cooler 20 is further suppressed, so that the deterioration of the heat transfer performance in the power semiconductor module 100 can be further suppressed. can. Further, when the power semiconductor element 1 includes a MOSFET made of a silicon carbide semiconductor, the power semiconductor module 100 can be manufactured at a lower cost. Further, when the cooler 20 bonded via the insulating heat radiating member is provided on the outer plate surface of the third heat conduction anisotropic member 3c of the third layer which is the lowest layer, the power semiconductor element 1 is provided. It can be cooled efficiently.

Embodiment 2.
The power semiconductor module 100 according to the second embodiment will be described. FIG. 3 is a perspective view schematically showing the appearance of the power semiconductor module 100 according to the second embodiment. The power semiconductor module 100 according to the second embodiment has a configuration including a five-layer heat conduction anisotropic member 3 when N is 5.

<Heat diffusion member 2>
The heat diffusion member 2 is a first heat conduction anisotropic member 3a of the first layer, a second heat conduction anisotropic member 3b of the second layer, and a third heat conduction anisotropic member of the third layer. It includes a sex member 3c, a fourth heat conduction anisotropic member 3d in the fourth layer, and a fifth heat conduction anisotropic member 3e in the fifth layer. The heat conduction anisotropic members 3 are joined by brazing with a brazing material (not shown). The first heat conduction anisotropic member 3a, the third heat conduction anisotropic member 3c and the fifth heat conduction anisotropic member 3e of the odd-th layer and the second heat conduction anisotropic member of the even-th layer The direction of high thermal conductivity is different between the sex member 3b and the fourth heat conduction anisotropic member 3d. In the first heat conduction anisotropic member 3a, the third heat conduction anisotropic member 3c, and the fifth heat conduction anisotropic member 3e of the odd-th layer, the first heat conduction anisotropic member 3a is parallel to the plate thickness direction and the plate surface. The thermal conductivity in one direction is higher than the thermal conductivity in the second direction, which is orthogonal to the first direction and parallel to the plate surface. In the second heat conduction anisotropic member 3b and the fourth heat conduction anisotropic member 3d of the even-th layer, the thermal conductivity in the plate thickness direction and the second direction is higher than the thermal conductivity in the first direction. Is also expensive.

<Thickness of heat conduction anisotropic member 3>
The thickness of the first heat conduction anisotropic member 3a of the first layer is the same as the thickness of the fifth heat conduction anisotropic member 3e of the fifth layer, and the thickness of the second heat conduction anisotropic member 3e of the second layer is the same. The thickness of the anisotropic member 3b is the same as the thickness of the fourth heat conduction anisotropic member 3d of the fourth layer. By making these thicknesses the same, the thickness of the heat conduction anisotropic member 3 is provided so as to be symmetrical in the direction of the plate thickness. Since the thickness of the heat conduction anisotropy member 3 is symmetrical in the direction of the plate thickness, the first heat conduction anisotropy member 3a, the second heat conduction anisotropy member 3b, and the third heat conduction anisotropy member 3b. The bending force generated in the member 3c and the bending force generated in the third heat conduction anisotropic member 3c, the fourth heat conduction anisotropic member 3d, and the fifth heat conduction anisotropic member 3e. The forces that do work in the opposite direction, and the forces are balanced, so they can be counteracted. Therefore, it is possible to prevent the heat diffusion member 2 from bending into a saddle shape.

According to this configuration, it is possible to suppress the heat diffusion member 2 from bending into a saddle shape, and it is possible to suppress fatigue failure of the insulating bonding member which is a bonding material provided between the heat diffusion member 2 and the cooler 20. The thermal connection between the heat diffusion member 2 and the cooler 20 via the insulating bonding member is maintained, and deterioration of the heat transfer performance in the power semiconductor module 100 can be suppressed.

Further, the sum of the thicknesses of the first heat conduction anisotropic member 3a, the third heat conduction anisotropic member 3c, and the fifth heat conduction anisotropic member 3e of the odd-th layer is an even number. It is the same as the thickness of the second heat conduction anisotropic member 3b and the fourth heat conduction anisotropic member 3d of the layer. The sum of the thicknesses of the first heat conduction anisotropic member 3a, the third heat conduction anisotropic member 3c, and the fifth heat conduction anisotropic member 3e of the odd-th layer, and the thickness of the even-th layer. By making the thickness of the second heat conduction anisotropic member 3b and the fourth heat conduction anisotropic member 3d the same, the heat diffusion member 2 as a whole is viewed in the first direction and the second direction. The effective linear expansion coefficients can be equalized. Since the effective linear expansion coefficients in the first direction and the second direction are the same, it is possible to prevent the heat diffusion member 2 from bending into a saddle shape.

According to this configuration, fatigue fracture of the insulating joining member that joins the heat diffusion member 2 and the cooler 20 is further suppressed, so that deterioration of the heat transfer performance in the power semiconductor module 100 can be further suppressed.

If the thickness of the first heat conduction anisotropic member 3a of the first layer, which is the odd-th layer, and the thickness of the fifth heat conduction anisotropic member 3e of the fifth layer are the same, the third layer. Even if the thickness of the third heat conduction anisotropic member 3c of the layer is not the same as the thickness of the other odd-th layer, the thickness of the heat conduction anisotropic member 3 is symmetrical in the direction of the plate thickness. Can be provided. However, the thicknesses of the first heat conduction anisotropic member 3a, the third heat conduction anisotropic member 3c, and the fifth heat conduction anisotropic member 3e of the odd-numbered layer are the same. Is desirable. When the thicknesses of the first heat conduction anisotropic member 3a, the third heat conduction anisotropic member 3c, and the fifth heat conduction anisotropic member 3e of the odd-th layer are the same, the first The force to bend generated in the heat conduction anisotropic member 3a, the second heat conduction anisotropic member 3b, and the third heat conduction anisotropic member 3c, and the third heat conduction anisotropic member 3c. Since the bending forces generated in the fourth heat conduction anisotropic member 3d and the fifth heat conduction anisotropic member 3e are easily balanced, the heat diffusion member 2 is curved in a saddle shape. It can be further suppressed. Further, when the thicknesses of the first heat conduction anisotropic member 3a, the third heat conduction anisotropic member 3c, and the fifth heat conduction anisotropic member 3e of the odd-th layer are the same, the thickness is odd. Since the first heat conduction anisotropic member 3a, the third heat conduction anisotropic member 3c, and the fifth heat conduction anisotropic member 3e of the second layer are all members having the same dimensions, an easy manufacturing process. The heat diffusion member 2 can be manufactured with.

Although the configuration of the power semiconductor module 100 including the five-layer heat conduction anisotropic member 3 when N is 5, the N may be an odd number of 5 or more. When N is an odd number of 5 or more, it is desirable that the thicknesses of the heat conduction anisotropic members 3 of the odd-numbered layers are the same. When N is an odd number of 5 or more, the thickness of the heat conduction anisotropic member 3 of the first layer is the same as the thickness of the heat conduction anisotropic member 3 of the Nth layer, and the heat of the second layer is the same. If the thickness of the conduction anisotropic member 3 is the same as the thickness of the heat conduction anisotropic member 3 of the N-1st layer, the two layers of the heat conduction anisotropic member 3 on one side of the heat diffusion member 2 And the thickness of the two layers of the heat conduction anisotropic member 3 on the other side are symmetrical in the plate thickness direction. Further, if the thicknesses of the heat transfer anisotropic members 3 of the odd-numbered layers are the same, the symmetry of the heat diffusion member 2 in the plate thickness direction is improved, so that the heat diffusion member 2 and the cooler 20 are joined. Fatigue failure of the insulating joint member is further suppressed, and deterioration of heat transfer performance in the power semiconductor module 100 can be suppressed.

As described above, in the power semiconductor module 100 according to the second embodiment, the thickness of the first heat transfer anisotropic member 3a of the first layer is that of the fifth heat transfer anisotropic member 3e of the fifth layer. Since it is the same as the thickness and the thickness of the second heat transfer anisotropic member 3b of the second layer is the same as the thickness of the fourth heat transfer anisotropic member 3d of the fourth layer, the heat diffusion member Fatigue failure of the insulating joining member that joins 2 and the cooler 20 can be suppressed, and deterioration of the heat transfer performance in the power semiconductor module 100 can be suppressed. Further, the sum of the thicknesses of the first heat transfer anisotropic member 3a, the third heat transfer anisotropic member 3c, and the fifth heat transfer anisotropic member 3e of the odd-th layer is an even number. When the thickness of the second heat transfer anisotropic member 3b and the fourth heat transfer anisotropic member 3d of the layer is the same, the fatigue failure of the insulating joining member that joins the heat diffusion member 2 and the cooler 20 is caused. Since it is further suppressed, it is possible to further suppress the deterioration of the heat transfer performance in the power semiconductor module 100. Further, when the thicknesses of the first heat conduction anisotropic member 3a, the third heat conduction anisotropic member 3c, and the fifth heat conduction anisotropic member 3e of the odd-th layer are the same, heat is obtained. It is possible to further suppress the diffusion member 2 from being curved in a saddle shape.

Embodiment 3.
The power semiconductor module 100 according to the third embodiment will be described. FIG. 4 is a perspective view schematically showing the appearance of the power semiconductor module 100 according to the third embodiment. The power semiconductor module 100 according to the third embodiment has a configuration including a four-layer heat conduction anisotropic member 3 when N is 4.

<Heat diffusion member 2>
The heat diffusion member 2 is a first heat conduction anisotropic member 3a of the first layer, a second heat conduction anisotropic member 3b of the second layer, and a third heat conduction anisotropic member of the third layer. The sex member 3c and the fourth heat conduction anisotropic member 3d of the fourth layer are provided. The heat conduction anisotropic members 3 are joined by brazing with a brazing material (not shown). The first heat conduction anisotropic member 3a and the third heat conduction anisotropic member 3c of the odd-th layer, the second heat conduction anisotropic member 3b and the fourth heat conduction heterogeneity of the even-th layer. The direction of high thermal conductivity is different from that of the sex member 3d. In the first heat conduction anisotropic member 3a and the third heat conduction anisotropic member 3c of the odd-th layer, the thermal conductivity in the direction of the plate thickness and in the first direction parallel to the plate surface is the first direction. It is higher than the thermal conductivity in the second direction orthogonal to and parallel to the plate surface. In the second heat conduction anisotropic member 3b and the fourth heat conduction anisotropic member 3d of the even-th layer, the thermal conductivity in the plate thickness direction and the second direction is higher than the thermal conductivity in the first direction. Is also expensive.

<Thickness of heat conduction anisotropic member 3>
The thickness of the first heat conduction anisotropic member 3a of the first layer is the same as the thickness of the third heat conduction anisotropic member 3c of the third layer, and the thickness of the second heat conduction anisotropic member 3c of the second layer is the same. The thickness of the anisotropic member 3b is the same as the thickness of the fourth heat conduction anisotropic member 3d of the fourth layer. By making these thicknesses the same, the thickness of the heat conduction anisotropic member 3 is provided so as to be symmetrical in the direction of the plate thickness. Since the thickness of the heat conduction anisotropic member 3 becomes symmetrical in the direction of the plate thickness, the force that tends to bend between the first heat conduction anisotropic member 3a and the second heat conduction anisotropic member 3b , The bending forces generated in the third heat conduction anisotropic member 3c and the fourth heat conduction anisotropic member 3d act in opposite directions, and the forces are balanced. You can counteract the power. Therefore, it is possible to prevent the heat diffusion member 2 from bending into a saddle shape.

According to this configuration, it is possible to suppress the heat diffusion member 2 from bending into a saddle shape, and the fatigue failure of the insulation joining member that joins the heat diffusion member 2 and the cooler 20 is suppressed. The thermal connection between the heat diffusion member 2 and the cooler 20 is maintained, and deterioration of the heat transfer performance in the power semiconductor module 100 can be suppressed.

Further, the sum of the thicknesses of the first heat conduction anisotropic member 3a and the third heat conduction anisotropic member 3c of the odd-th layer is the sum of the thicknesses of the second heat conduction anisotropic member 3c of the even-th layer. It is the same as the thickness of 3b and the fourth heat conduction anisotropic member 3d. The sum of the thicknesses of the first heat conduction anisotropic member 3a and the third heat conduction anisotropic member 3c in the odd-th layer, and the second heat conduction anisotropic member 3b and the second heat conduction anisotropic member 3b in the even-th layer. By making the thickness of the fourth heat conduction anisotropic member 3d the same, the effective linear expansion coefficients in the first direction and the second direction when the heat diffusion member 2 is viewed as a whole can be made equal. can. Since the effective linear expansion coefficients in the first direction and the second direction are the same, it is possible to prevent the heat diffusion member 2 from bending into a saddle shape.

According to this configuration, fatigue fracture of the insulating joining member that joins the heat diffusion member 2 and the cooler 20 is further suppressed, so that deterioration of the heat transfer performance in the power semiconductor module 100 can be further suppressed.

Although the configuration of the power semiconductor module 100 including the four-layer heat conduction anisotropic member 3 when N is 4, the N may be an even number of 4 or more. When N is an even number of 4 or more, it is desirable that the thicknesses of the heat conduction anisotropic members 3 of the odd-numbered layers are the same. When N is an even number of 4 or more, the thickness of the heat conduction anisotropic member 3 of the first layer is the same as the thickness of the heat conduction anisotropic member 3 of the N-1st layer, and the thickness of the second layer is the same. If the thickness of the heat conduction anisotropic member 3 of the above is the same as the thickness of the heat conduction anisotropic member 3 of the Nth layer, the two layers of the heat conduction anisotropic member 3 on one side of the heat diffusion member 2 And the thickness of the two layers of the heat conduction anisotropic member 3 on the other side are symmetrical in the plate thickness direction. Further, if the thicknesses of the heat transfer anisotropic members 3 of the odd-numbered layers are the same, the symmetry of the heat diffusion member 2 in the plate thickness direction is improved, so that the heat diffusion member 2 and the cooler 20 are joined. Fatigue failure of the insulating joint member is further suppressed, and deterioration of heat transfer performance in the power semiconductor module 100 can be suppressed.

As described above, in the power semiconductor module 100 according to the third embodiment, the thickness of the first heat transfer anisotropic member 3a of the first layer is that of the third heat transfer anisotropic member 3c of the third layer. It is the same as the thickness, and the thickness of the second heat transfer anisotropic member 3b of the second layer is the same as the thickness of the fourth heat transfer anisotropic member 3d of the fourth layer, and is the oddth layer. The sum of the thicknesses of the first heat conduction anisotropic member 3a and the third heat transfer anisotropic member 3c is the second heat transfer anisotropic member 3b and the fourth heat of the even-th layer. Since the thickness is the same as that of the conduction anisotropic member 3d, fatigue failure of the insulating joining member that joins the heat diffusion member 2 and the cooler 20 is suppressed, and deterioration of the heat transfer performance in the power semiconductor module 100 is suppressed. Can be done. Further, when N is an even number of 4 or more and the thickness of each of the heat transfer anisotropic members 3 of the odd-numbered layers is the same, fatigue failure of the insulating joining member that joins the heat diffusion member 2 and the cooler 20 Is further suppressed, and deterioration of heat transfer performance in the power semiconductor module 100 can be suppressed.

Embodiment 4.
The power semiconductor module 100 according to the fourth embodiment will be described. FIG. 5 is a perspective view schematically showing the appearance of the power semiconductor module 100 according to the fourth embodiment. The power semiconductor module 100 according to the fourth embodiment has a configuration including two power semiconductor elements 1a and 1b.

The power semiconductor module 100 includes two power semiconductor elements 1a and 1b. The two power semiconductor devices 1a and 1b are arranged in the second direction on the element junction surface 2a which is the outer plate surface of the first heat conduction anisotropic member 3a of the first layer which is an odd-numbered layer. , Are joined. In the first heat conduction anisotropic member 3a, the thermal conductivity in the second direction parallel to the element junction surface 2a is higher than the thermal conductivity in the first direction orthogonal to the second direction and parallel to the element junction surface 2a. Low.

According to this arrangement, the heat generated in the power semiconductor element 1a is not in the second direction in which the power semiconductor element 1b is arranged in the first heat conduction anisotropic member 3a, but in the power semiconductor element 1b. Not mainly diffused in the first direction. Further, the heat generated by the power semiconductor element 1b is not in the second direction in which the power semiconductor element 1a is arranged in the first heat conduction anisotropic member 3a, but in the first direction in which the power semiconductor element 1a is not arranged. Mainly spread to. Even if the two power semiconductor elements 1a and 1b are arranged side by side, the heat diffusion between the two power semiconductor elements 1a and 1b that are generating heat is suppressed, so that the heat diffusion efficiency of the heat diffusion member 2 is suppressed. Can be enhanced. Further, it is possible to suppress thermal interference between the power semiconductor elements 1, and it is possible to reduce the size of the power semiconductor module 100 and improve the heat transfer performance.

When a MOSFET is used for the power semiconductor element 1, by arranging a plurality of power semiconductor elements 1 side by side and densely arranging them, the input waveform of the gate signal input to each power semiconductor element 1 is disturbed and flows between the drain and the source. Current variation can be suppressed. Therefore, a power semiconductor module 100 having good electrical characteristics can be obtained.

Although the configuration including the two power semiconductor elements 1a and 1b is shown here, a plurality of power semiconductor elements 1 may be provided side by side in the second direction. When a plurality of power semiconductor elements 1 are provided, if at least two power semiconductor elements 1 are provided side by side in the second direction, the efficiency of heat diffusion of the heat diffusion member 2 can be improved.

As described above, in the power semiconductor module 100 according to the fourth embodiment, the two power semiconductor elements 1a and 1b are on the outer element bonding surface 2a of the first heat conduction anisotropic member 3a of the first layer. Since they are arranged and joined in two directions, the efficiency of heat diffusion of the heat diffusion member 2 can be improved. Further, it is possible to suppress thermal interference between the two power semiconductor elements 1a and 1b, and it is possible to reduce the size of the power semiconductor module 100 and improve the heat transfer performance. Further, when a MOSFET is used for the power semiconductor element 1, a power semiconductor module 100 having good electrical characteristics can be obtained.

Embodiment 5.
The power semiconductor module 100 according to the fifth embodiment will be described. FIG. 6 is a plan view schematically showing the appearance of the power semiconductor module 100 according to the fifth embodiment. The power semiconductor module 100 according to the fifth embodiment is configured to include an external connection electrode.

A member having anisotropy thermal conductivity generally also has anisotropy in electrical conductivity. For example, in graphite 4 shown in FIG. 2, the electric conductivity in the direction parallel to the plane of the graphene sheet 5 is larger than the electric conductivity in the direction perpendicular to the plane of the graphene sheet 5. That is, in graphite 4, the electric resistance of the graphene sheet 5 in the stacking direction is large.

A case where MOSFETs are used for power semiconductor devices 1a and 1b will be described. The power semiconductor module 100 includes a drain terminal 6 which is an external connection electrode. The drain terminal 6 is provided on the element junction surface 2a, which is the outer plate surface of the first heat conduction anisotropic member 3a of the first layer bonded to the electrode on the junction surface side of the power semiconductor elements 1a and 1b. It is electrically connected. The element junction surface 2a to which the drain terminal 6 is connected is the drain potential of the MOSFET. The drain terminal 6 is arranged on one side of the power semiconductor elements 1a and 1b in the first direction. The source terminal 7 is electrically connected to the electrodes on the surface side of the power semiconductor elements 1a and 1b. Further, each of the power semiconductor elements 1a and 1b is provided with a gate pad 10 on the surface side thereof. The gate pad 10 is electrically connected to the external gate terminal 8 by a bonded wire 9. The main current flowing through the power semiconductor module 100 flows from the drain terminal 6 to the source terminal 7.

In the first heat conduction anisotropic member 3a, the electric resistance in the first direction parallel to the element joining surface 2a is smaller than the electric resistance in the second direction orthogonal to the first direction and parallel to the element joining surface 2a. Since the drain terminal 6 is arranged on one side of the power semiconductor elements 1a and 1b in the first direction, the electric resistance between the drain terminal 6 and the electrodes on the junction surface side of the power semiconductor elements 1a and 1b is reduced. Can be configured. Since the electric resistance from the drain terminal 6 to the source terminal 7 can be reduced, the loss of the power semiconductor module 100 can be improved.

Although the case where MOSFETs are used for the power semiconductor elements 1a and 1b has been described, the power semiconductor element 1 is not limited to the MOSFET, and may be another power control semiconductor element, a freewheeling diode, or the like. By arranging the external connection electrode on one side in the first direction of the power semiconductor element 1, the electric resistance between the external connection electrode and the electrode on the joint surface side of the power semiconductor element 1 can be reduced.

As described above, in the power semiconductor module 100 according to the fifth embodiment, since the drain terminal 6 is arranged on one side of the power semiconductor elements 1a and 1b in the first direction, the drain terminal 6 and the power semiconductor element 1a, The electric resistance between the electrode and the electrode on the joint surface side of 1b can be made small, and the loss of the power semiconductor module 100 can be improved.

In the above, the heat conduction anisotropic member 3 is graphite 4 on which a plurality of rectangular graphene sheets 5 are laminated, but the configuration of the heat conduction anisotropic member 3 is not limited to this. For example, the heat conduction anisotropic member 3 composed of a layer made of a fibrous metal may be used.

The present application also describes various exemplary embodiments and examples, although the various features, embodiments, and functions described in one or more embodiments are those of a particular embodiment. It is not limited to application, but can be applied to embodiments alone or in various combinations.
Therefore, innumerable variations not illustrated are envisioned within the scope of the techniques disclosed herein. For example, it is assumed that at least one component is modified, added or omitted, and further, at least one component is extracted and combined with the components of other embodiments.

1 power semiconductor element, 1a power semiconductor element, 1b power semiconductor element, 2 heat diffusion member, 2a element joint surface, 2b cooler joint surface, 3 heat conduction anisotropic member, 3a first heat conduction anisotropic member, 3b 2nd heat conduction anisotropic member, 3c 3rd heat conduction anisotropic member, 3d 4th heat conduction anisotropic member, 3e 5th heat conduction anisotropic member, 4 graphite, 5 graphene sheet , 6 drain terminal, 7 source terminal, 8 gate terminal, 9 wire, 10 gate pad, 20 cooler, 20a cooling surface, 100 power semiconductor module

Claims (9)

Laminated N-layer (N is an odd number of 3 or more) plate-shaped heat conduction anisotropic member,
A power semiconductor device bonded to the outer plate surface of the heat conduction anisotropic member of the first layer is provided.
In the heat conduction anisotropic member of the odd-th layer, the thermal conductivity in the direction of the plate thickness and the heat conductivity in the first direction parallel to the plate surface is orthogonal to the first direction and parallel to the plate surface in the second direction. Higher than thermal conductivity,
In the heat conduction anisotropic member of the even-th layer, the heat conductivity in the plate thickness direction and the second direction is higher than the heat conductivity in the first direction.
The thickness of the heat conduction anisotropic member in the first layer is the same as the thickness of the heat conduction anisotropic member in the Nth layer.
The sum of the thicknesses of the heat conduction anisotropic members of the even-numbered layer is the same as the sum of the thicknesses of the heat conduction anisotropic members of the even-numbered layer, and the heat of the even-numbered layer is the same. A power semiconductor module in which the thickness of the conduction anisotropic member is larger than the thickness of the heat conduction anisotropic member of the even-numbered layer. It is provided with the three-layered plate-shaped heat conduction anisotropy member.
In the heat conduction anisotropic member of the first layer and the third layer, the heat conductivity in the plate thickness direction and the first direction is higher than the heat conductivity in the second direction.
In the heat conduction anisotropic member of the second layer, the heat conductivity in the plate thickness direction and the second direction is higher than the heat conductivity in the first direction.
The thickness of the heat conduction anisotropic member of the first layer is the same as the thickness of the heat conduction anisotropic member of the third layer.
The first aspect of the present invention, wherein the sum of the thicknesses of the heat conduction anisotropic members of the first layer and the third layer is the same as the thickness of the heat conduction anisotropic members of the second layer. Power semiconductor module. The power semiconductor module according to claim 1, wherein the thickness of the heat conduction anisotropic member of the second layer is the same as the thickness of the heat conduction anisotropic member of the N-1st layer. The power semiconductor module according to claim 1, wherein the thicknesses of the heat conduction anisotropic members of the odd-numbered layers are the same. In the heat conduction anisotropic member of the odd-th layer, a plurality of rectangular graphene sheets whose long sides are parallel to the first direction and whose short sides are parallel to the plate thickness direction are laminated in the second direction. Formed by
In the heat conduction anisotropic member of the even-th layer, a plurality of rectangular graphene sheets whose long sides are parallel to the second direction and whose short sides are parallel to the plate thickness direction are laminated in the first direction. The power semiconductor module according to any one of claims 1 to 4 , which is formed in the above-mentioned. Equipped with a plurality of the power semiconductor elements,
From claim 1, the at least two power semiconductor devices are arranged and joined in the second direction on the outer plate surface of the heat conduction anisotropic member of the first layer, which is an odd-numbered layer. 5. The power semiconductor module according to any one of 5. The power semiconductor module according to any one of claims 1 to 6 , wherein the power semiconductor element includes a MOSFET made of a silicon carbide semiconductor. An external connection electrode electrically connected to the outer plate surface of the heat conduction anisotropic member of the first layer bonded to the electrode on the bonding surface side of the power semiconductor device is provided.
The power semiconductor module according to any one of claims 1 to 7 , wherein the external connection electrode is arranged on one side of the first direction of the power semiconductor element. The power semiconductor module according to any one of claims 1 to 8 , further comprising a cooler bonded to the outer plate surface of the heat conduction anisotropic member of the Nth layer via an insulating heat dissipation member.

Images