JP6710163B2 - Power semiconductor device - Google Patents

Description

The present invention relates to a power semiconductor device, and more particularly to a power semiconductor device used in a power conversion device that controls a motor for driving a vehicle.

In recent years, in order to reduce the load on the environment, the spread of hybrid vehicles and electric vehicles is urgent. In hybrid vehicles and electric vehicles, miniaturization and cost reduction of parts to be mounted are important, and power converters are no exception, and miniaturization and cost reduction are required.

Since the heat generation density increases with the downsizing of the power conversion device, it is necessary to improve the cooling performance in the power semiconductor device that generates a large amount of heat among the electronic components forming the power conversion device. As shown, a double-sided direct cooling type power semiconductor device is disclosed.

In the power semiconductor device described in Patent Document 1, a front surface and a back surface of a power semiconductor chip are soldered to conductive plates, and a sealing body is sealed with resin in a state where the conductive plates are exposed. It is housed in a metal case of the mold. The inside of the metal case (heat dissipation member) and the conductor plate are bonded by a heat conductive insulating adhesive (insulating member), so that the heat generated by the power semiconductor chip can be absorbed by the conductor plates on both sides and the heat conductive insulating bond. Heat is radiated to the outside through the agent (insulating member) and the heat radiating member.

In order to favorably transfer heat from the chip heat generating portion to the heat radiating member, it is preferable that the heat radiating member inside the metal case and the thermally conductive insulating resin be in close contact with each other without being separated. Therefore, pressure is applied from the outside of the metal case, and the metal case is crushed to bond the inside of the metal case (heat dissipation member) to the thermally conductive insulating resin and the sealing body.

Japanese Patent Laid-Open No. 2013-212942

However, if the size of the opening (flange) of the metal case is reduced to reduce the size of the power semiconductor device, the rigidity of the flange decreases. As a result, an increase in springback of the case near the opening has become apparent in the process of crushing the case. An increase in springback leads to an increase in the peeling force between the inner heat dissipation member of the metal case and the thermally conductive insulating resin, so that peeling easily occurs at the interface, and there is concern that the heat dissipation performance of the power semiconductor device may deteriorate.

Therefore, an object of the present invention is to provide a highly reliable power semiconductor device which prevents the insulating resin from peeling off in the deformation process of the metal case and prevents the heat dissipation performance from deteriorating.

A power semiconductor device according to the present invention includes a circuit body having a power semiconductor element, and a case that houses the circuit body, the case including a first base portion and a second base portion that sandwich the circuit body, A frame part forming an opening connected to the storage space of the case, a frame part connected to the first base or the second base, and a connection formed to be thinner than the first base and the second base. And a connection part, the connection part has a first connection part on a side closer to the opening of the frame part, and a second connection part on a side far from the opening of the frame part, The first connecting portion is formed to have a lower rigidity than the second connecting portion.

According to the present invention, the amount of springback of the metal case near the opening can be reduced, and the insulating member can be prevented from peeling from the inside of the case (heat dissipation member). Therefore, deterioration of the heat dissipation performance of the circuit body can be prevented and reliability can be improved. It is possible to realize a highly reliable power semiconductor device.

It is an appearance perspective view as one embodiment of a power converter device 200 of the present invention. FIG. 2 is an exploded perspective view of the power conversion device 200 shown in FIG. 1. It is an appearance top view as one embodiment of a power module 100 of the present invention. FIG. 4 is a vertical sectional view taken along the line AA′ of the power module 100 illustrated in FIG. 3. It is sectional drawing of the metal case of the power module 100 which concerns on this embodiment. It is sectional drawing of the circuit body 30 of the power module 100 which concerns on this embodiment. It is a conceptual sectional view which shows a part of manufacturing process of the power module 100 which is a comparative example, the upper figure is a state before the metal case 40 is deformed, and the central figure shows that the metal case 40 is loaded with a load. The state shown in the figure below is a state in which the load is removed from the metal case 40. It is a conceptual sectional view of power module 100 in this embodiment. It is a graph which shows the effect of this embodiment. It is a top view of the power module 101 which shows 2nd Embodiment.

<<Embodiment 1>>
[Power converter]
An embodiment of a power conversion device according to the present invention will be described below with reference to the drawings.

FIG. 1 is an external perspective view of an embodiment of a power conversion device 200 of the present invention. FIG. 2 is an exploded perspective view of the power conversion device 200 shown in FIG.

The power conversion device 200 is used as a power supply device for electric vehicles and hybrid vehicles. Although not shown, the power conversion device 200 includes an inverter circuit connected to the motor generator, a booster circuit connected to an external battery, and a control circuit for controlling the whole.

The power conversion device 200 has a housing body 201 formed of an aluminum-based metal such as aluminum or an aluminum alloy, and a bottom lid 202 fastened to the housing body 201 by a fastening member (not shown). The housing main body 201 and the bottom cover 202 can also be formed by integral molding.

An upper lid (not shown) is fastened to the upper part of the housing body 201 by a fastening member to form a sealed container.

A peripheral wall 211 for forming a cooling flow path is formed inside the housing body 201, and a cooling chamber 210 is formed by the peripheral wall 211 and the bottom lid 202.

A support member 220 having a plurality of (four in FIG. 2) side walls 221 and a plurality of (three in FIG. 2) power modules 100 arranged between the side walls 221 are housed in the cooling chamber 210. Details of the power module 100 will be described later.

A pair of through holes is provided in one side portion of the housing body 201, an inlet pipe 203a is provided in one of the through holes, and an outlet pipe 203b is provided in the other of the through holes. ..

A cooling medium such as cooling water flows into the cooling chamber 210 through the inlet pipe 203a, flows through the cooling passage between the side wall 221 of the support member 220 and each power module 100, and flows out through the outlet pipe 203b. ..

The cooling medium flowing out from the outlet pipe 203b is cooled by a cooling device such as a radiator (not shown), and circulates so as to flow into the cooling chamber 210 from the inlet pipe 203a again.

The cooling chamber 210 is sealed by a cover member 240 with a seal member 231 interposed. The cover member 240 forms an opening 241 into which the terminal of the power module 100 is inserted. The peripheral portion of the cover member 240 is fixed to the upper part of the peripheral wall 211 forming the cooling chamber 210 by a fastening member (not shown).

A capacitor module 250 including a plurality of capacitor elements 251 for smoothing DC power supplied to the inverter circuit is housed in an area outside the cooling chamber 210 of the housing body 201.

The DC side bus bar assembly 261 is disposed on the capacitor module 250 and the power module 100. The DC side bus bar assembly 261 transmits DC power between the capacitor module 250 and the power module 100.

A control circuit board assembly 262 including a driver circuit unit that controls the inverter circuit is disposed above the DC side bus bar assembly 261 and the cover member 240.

The AC side bus bar assembly 263 is connected to the power module 100 and transmits AC power. Further, the AC side bus bar assembly 263 has a current sensor.

[Power module 100]
The power module 100 will be described with reference to FIGS. 3 to 6.

FIG. 3 is an external plan view showing one embodiment of the power module 100 of the present invention. FIG. 4 is a vertical cross-sectional view of the power module 100 shown in FIG. 3, taken along the line AA′. FIG. 5 is a cross-sectional view of the metal case of the power module 100 according to this embodiment. FIG. 6 is a cross-sectional view of the circuit body 30 of the power module 100 according to this embodiment.

As shown in FIGS. 3 and 4, the power module 100 has a metal case 40, and the circuit body 30 shown in FIG. 6 is housed in the metal case 40 shown in FIG.

As illustrated in FIG. 4, a heat conductive insulating layer 51 is interposed between the circuit body 30 and the pair of heat dissipation members 41. The insulating layer 51 conducts heat generated from the circuit body 30 to the heat dissipation member 41, and is formed of a material having high thermal conductivity and high withstand voltage. For example, a thin film of aluminum oxide (alumina), aluminum nitride, or the like, or an insulating sheet or adhesive containing fine powder of these can be used.

As shown in FIG. 6, conductor plates 33 and 34 to which the power semiconductor element 31 is joined by, for example, soldering are exposed on both front and back surfaces of the circuit body 30, and the insulating layer 51 is composed of the conductor plates 33 and 34. 34 and the heat dissipation member 41 are coupled so as to be able to conduct heat.

Further, the gap between the metal case 40 and the insulating layer 51 and the circuit body 30 is filled with the second sealing resin 49.

As shown in FIG. 5, the metal case 40 is composed of a pair of heat dissipation members 41 having a plurality of heat dissipation fins 42 and a frame body 43. The metal case 40 is, for example, a cooler having a flat tubular shape having the insertion port 17 on one surface and the bottom portion on the other surface.

The metal case 40 is formed of a member having electrical conductivity, for example, a composite material such as Cu, Cu alloy, Cu-C, Cu-CuO, or a composite material such as Al, Al alloy, AlSiC, Al-C. ing. The power module 100 shown in FIGS. 3 to 5 has a structure in which no opening is provided other than the insertion port 17, and the insertion port 17 is surrounded by the seal portion 11 on the outer periphery thereof.

The pair of heat dissipation members 41 are joined to the frame body 43. As the joining, for example, FSW (friction stir welding), laser welding, brazing or the like can be applied. By using the metal case 40 having such a shape, it is possible to prevent the cooling medium from entering the inside of the power module 100 even when the power module 100 is inserted into the flow path in which the refrigerant such as water, oil, or organic matter flows. It can be prevented with a simple configuration.

In the present embodiment, the case where the heat dissipation member 41 and the frame body 43 are different members is shown, but the heat dissipation member 41 and the frame body 43 may be the same member or may be integrated.

The heat dissipation member 41 and the frame body 43 are connected to each other via the connection portion 44 and the connection portion 45. The connection portion 44 and the connection portion 45 are thinner than the heat dissipation member 41 and the frame body 43.

The frame body 43 on the side close to the insertion port 17 shown in FIG. 3 and the heat dissipation member 41 are connected via a connection portion 44. Further, the frame body 43 other than the insertion port 17 and the heat dissipation member 41 are connected via the connection portion 45.

As described above, in the power module 100, the circuit body 30 is inserted into the metal case 40, and the inner wall 41a of the heat dissipation member 41 and the front and back surfaces of the circuit body 30 are connected via the insulating layer 51. Therefore, the total thickness of the circuit body 30 and the insulating layer 51 is smaller than the distance 41b between the inner walls 41a of the heat dissipation member 41 of the power module 100.

After inserting the circuit body 30 and the insulating layer 51 into the metal case 40, a load is applied from the outside to the metal case 40 to plastically deform the connection portion 44 and the connection portion 45, and the inner wall 41a of the heat dissipation member 41. Both the front and back sides of the circuit body 30 are connected.

The length 44a of the connection portion 44 that connects the frame body 43 on the side closer to the insertion port 17 and the heat radiation member 41 is the length of the connection portion 45 that connects the frame body 43 other than the insertion port 17 and the heat radiation member 41. It is longer than 45a and is formed to have the same plate thickness.

2 to 4, the structure having the flange as the seal portion 11 on the insertion port 17 side of the metal case 40 is shown, but the flange may be omitted. Although the insertion opening 17 formed in the metal case 40 functions as an opening for inserting the circuit body 30, it may be an opening other than the insertion of the circuit body 30.

[Circuit body 30]
As shown in FIG. 6, each electrode of the power semiconductor element 31 is sandwiched by a conductor plate 33 and a conductor plate 34 which are arranged so as to face the respective electrode surfaces. The semiconductor element and the conductor plate 33 and the conductor plate 34 are joined by the joining material 32.

The circuit body 30 is obtained by sealing these with the first sealing resin 6. On the front surface side of the circuit body 30, the first sealing resin 6 exposes the upper surface 33a of the conductor plate 33 and the upper surface 34a of the conductor plate 34, and covers the entire periphery of the conductor plates 33 and 34. The surface of the first sealing resin 6 is flush with the upper surface 33a of the conductor plate 33 and the upper surface 34a of the conductor plate 34. The conductor plate 33 and the conductor plate 34 are formed of, for example, copper, copper alloy, aluminum, aluminum alloy, or the like.

[Effects of this embodiment]
In the power module 100 according to the present embodiment, the length 44a of the connecting portion 44 that connects the frame 34a on the side closer to the insertion opening 17 of the metal case 40 and the heat dissipation member 41 is the frame 43b other than the insertion opening 17. Is longer than the length 45a of the connection portion 45 that connects the heat radiation member 41 with the heat radiation member 41, and the plate thickness is the same.

FIG. 7 is a conceptual diagram showing a part of the manufacturing process of the power module 100 in the present embodiment, the upper diagram is a state before the metal case 40 is deformed, and the center diagram shows a load on the metal case 40. It is in a loaded state, and the figure below shows a state in which the load is removed from the metal case 40. In FIG. 7, the insulating layer 51 is omitted.

As shown in the upper diagram of FIG. 7, a deformation process of the metal case 40 for connecting the circuit body 30 and the inner wall 41a of the heat dissipation member 41 of the metal case 40 is shown. Before the metal case 40 shown in FIG. 7 is deformed, there is a gap between the inner wall 41 a and the circuit body 30.

In the load applying step shown in the central view of FIG. 7, the connecting portion 44 and the connecting portion 45 are plastically deformed by applying a load to the metal case 40 from the outside.

Then, when a load is applied as shown in the lower diagram of FIG. 7, the springback amount on the insertion port 17 side of the heat dissipation member 41 becomes larger than that on the side far from the insertion port 17. As a result, a gap is created between the circuit body 30 and the heat dissipation member 41, and there is concern that the heat dissipation performance may deteriorate.

The spring back of the insertion opening 17 has a smaller rigidity than the bottom surface or side surface of the metal case 40 other than the insertion opening 17, and the insertion opening 17 side receives a load in the load applying step of the central view of FIG. 7. This is because it is elastically deformed in the direction. As a result, the springback amount in the vicinity of the insertion opening 17 increases, and a gap is created between the inner wall 41a of the heat dissipation member 41 and the surface of the circuit body 30.

In the power module 100 of the present embodiment, the length 44a of the connecting portion 44 that connects the heat dissipation member 41 to the frame 43 on the side closer to the insertion port 17 of the metal case 40 is the same as the frame 43b other than the opening 100a. It is formed to be longer than the length 45a of the connecting portion 45 connecting to the heat dissipation member 41 and have the same plate thickness.

In this way, the rigidity of the connecting portion 44 on the side of the insertion opening 17 is made smaller than the rigidity of the connecting portion 45 on the bottom surface and the side surface other than the insertion opening 17, so that the opening portion at the time of load load shown in the central view of FIG. It is possible to suppress elastic deformation in the load direction. Therefore, as shown in FIG. 8, it is possible to suppress the amount of springback after the load is unloaded, and it is possible to suppress the formation of a gap between the inner wall 41a of the heat dissipation member 41 and the surface of the circuit body 30.

FIG. 9 is a graph showing the effect of this embodiment. It is the result of evaluating the springback amount after unloading by performing an analysis simulating the crushing process of the metal case shown in FIG. 7 by finite element analysis.

The ratio of the length of the connecting portion 44 on the insertion port 17 side to the length of the connecting portion 45 on the side far from the opening (the length of the connecting portion 44/the length of the connecting portion 45) is used as a parameter, and the spring of the heat dissipation member 41 is used. The change in the back amount is shown.

The vertical axis represents the ratio to the springback amount when the lengths of the connecting portion 44 and the connecting portion 45 are the same. The springback amount decreases as the ratio of the length of the connecting portion 44/the length of the connecting portion 45 increases, and when the ratio of the length of the connecting portion 44/the length of the connecting portion 45 is 1.1 or more, the spring is reduced. It turns out that the back is suppressed.

In this way, by making the length of the connecting portion 44 on the insertion opening 17 side longer than the length of the connecting portion 45 on the side far from the insertion opening 17, the amount of springback of the heat radiation member 41 can be suppressed, and the heat radiation member. A gap can be suppressed between the inner wall 41a of 41 and the surface of the circuit body 30.

As a result, although omitted in FIGS. 7 and 8, peeling of the insulating layer 51 interposed at the interface between the inner wall 41a of the heat dissipation member 41 and the circuit body 30 can be suppressed, deterioration of heat dissipation can be prevented, and reliability is improved. A highly efficient power converter can be realized.

In this embodiment, the bending rigidity is reduced by making the length of the connecting portion 44 longer than the length of the connecting portion 45. However, the rigidity of the connecting portion 44 is lower than that of the connecting portion 45. Similar effects can be obtained by reducing

That is, the thickness of the connecting portion 44 may be smaller than the thickness of the connecting portion 45. Alternatively, the connecting portion 44 and the connecting portion 45 may be made of different materials, and the Young's modulus of the material of the connecting portion 44 may be smaller than the Young's modulus of the material of the connecting portion 45.

Alternatively, the connecting portion 44 and the connecting portion 45 may be made of different materials, and the yield stress of the material of the connecting portion 44 may be smaller than the yield stress of the material of the connecting portion 45. Thereby, the same effect can be obtained.

<<Embodiment 2>>
In the above-described embodiment, the example of the power module 100 in which the opening corresponding to the insertion opening 17 is only one direction is shown, but the present invention is also applied to the two-direction power module 100 in which the openings face each other as shown in FIG. It is possible to

In the power module 101 in the second embodiment shown in FIG. 10, the openings 101a of the metal case are provided in two opposite directions, and the conductor plate 33 and the conductor plate 34 of the circuit body 30 are made of metal from both sides. The structure is outside the case.

In the power module 101, the length 44a of the connecting portion 44 on the side closer to the opening 101a of the metal case 40 is longer than the length 45a of the connecting portion 45 other than the opening. The plate thickness is the same. As a result, the same effect as that of the first embodiment can be obtained.

In the above-described embodiment, the shape of the heat dissipation fin 42 of the heat dissipation member 41 is a pin fin, but other shapes such as a straight fin or a corrugated fin may be used.

Further, in the above-described embodiment, the in-vehicle power conversion device mounted in an electric vehicle or a hybrid vehicle has been described as an example, but if the power conversion device has a cooling structure in which the power module is immersed in a cooling medium, The invention can be similarly applied. In addition, the present invention is not limited to the above-described embodiment, and various modifications can be applied within the scope of the gist of the present invention.

6... 1st sealing resin, 11... Seal part, 17... Insertion port, 30... Circuit body, 30a... Thickness, 31... Power semiconductor element, 32... Bonding material, 33... Conductor plate, 33a... Top surface, 34... Conductor plate, 34a... Top surface, 40... Metal case, 41... Radiating member, 41a... Inner wall, 41b... Distance, 42... Radiating fin, 43... Frame body, 44... Connection portion, 44a... Length, 45... Connection portion , 45a... Length, 49... Second sealing resin, 51... Insulating layer, 100... Power module, 101... Power module, 101a... Opening part, 200... Power conversion device, 201... Housing body, 202... Bottom lid , 203a... Inlet pipe, 203b... Outlet pipe, 210... Cooling chamber, 211... Peripheral wall, 221... Side wall, 220... Support member, 231... Seal member, 240... Cover member, 241... Opening part, 250... Capacitor Module, 251... Capacitor element, 261,... DC side bus bar assembly, 262... Control circuit board assembly, 263... AC side bus bar assembly

Claims (6)

A circuit body having a power semiconductor element,
A case for accommodating the circuit body,
The case includes a first base portion and a second base portion that sandwich the circuit body, a frame portion that forms an opening that connects to a storage space of the case, and the frame portion and the first base or the second base. And a connecting portion formed to be thinner than the first base and the second base,
The connection part includes a first connection part on a side closer to the opening of the frame part, and a second connection part on a side far from the opening of the frame part,
The power semiconductor device, wherein the first connecting portion is formed so as to have a rigidity smaller than that of the second connecting portion. The power semiconductor device according to claim 1, wherein
The power semiconductor device, wherein the length of the first connecting portion is larger than the length of the second connecting portion. The power semiconductor device according to claim 1, wherein
The power semiconductor device, wherein the length of the first connecting portion is 1.1 times or more the length of the second connecting portion. The power semiconductor device according to claim 1, wherein
A power semiconductor device in which the thickness of the first connecting portion is smaller than the thickness of the second connecting portion. The power semiconductor device according to claim 1, wherein
A power semiconductor device in which the materials of the first connecting portion and the second connecting portion are different, and the Young's modulus of the material of the first connecting portion is smaller than the Young's modulus of the material of the second connecting portion. The power semiconductor device according to claim 1, wherein
A power semiconductor device in which the materials of the first connecting portion and the second connecting portion are different, and the yield stress of the material of the first connecting portion is smaller than the yield stress of the material of the second connecting portion.

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