JP6847013B2 - Power semiconductor device - Google Patents

Description

The present invention relates to a power semiconductor device, and more particularly to a power semiconductor device for an in-vehicle power conversion device for an electric vehicle and a hybrid vehicle.

In an electric vehicle or a hybrid vehicle, a motor is mounted as a power source of the vehicle, and generally, a power conversion device is provided to control the electric power supplied to the motor.

The power conversion device includes a power semiconductor device having a built-in power semiconductor element such as an IGBT (Insulated Gate Bipolar Transistor), a drive circuit for driving the power semiconductor device, a control circuit for controlling them, and a capacitor for current smoothing. I have.

In particular, power semiconductor devices generate a large amount of heat due to the loss of power conversion, and various technological developments have been made for the cooling structure thereof.

Air cooling is generally used as the cooling technology for power semiconductor elements, but water cooling technology is also widely used for automobiles. Among them, the heat dissipation base is directly attached to the power semiconductor device and the heat dissipation base is inserted into the cooling flow path. The direct water cooling structure provides high cooling performance.

Double-sided cooling, which cools both the front and back sides of a power semiconductor element, is also a highly capable cooling method, and a double-sided direct water cooling structure that combines them has also been put into practical use.

For example, Patent Document 1 (Japanese Unexamined Patent Publication No. 2010-214212) discloses a structure in which heat dissipation bases provided on both sides of a power semiconductor device are inserted into a cooling flow path. In this structural proposal, the water on one side is sealed with an elastic body, so that the tolerance generated in the heat dissipation bases on the front and back of the power semiconductor device is absorbed by the deformation of the elastic body.

An O-ring or the like can be considered as a specific example of the elastic body, but in order to seal with the O-ring, the width of the O-ring groove and the O-ring groove in which the O-ring having a thickness corresponding to the amount of deformation to be absorbed can be accommodated around the O-ring. The required space is required on both sides of the ring groove, and the problem is that the unit becomes large.

Japanese Unexamined Patent Publication No. 2010-21241

An object of the present invention is to reduce the size of a power semiconductor device and improve its reliability.

The power semiconductor device according to the present invention includes a circuit body having a power semiconductor element and sealing the power semiconductor element with a resin member, a first heat radiation base and a second heat radiation base sandwiching the circuit body, and the circuit body. A first flow path forming body and a second flow path forming body that are sandwiched and face each other and form a flow path through which a refrigerant flows are provided, and the first flow path forming body is blocked by the first heat dissipation base. The first heat radiation base is formed, the second flow path forming body forms a second opening closed by the second heat radiation base, and each of the first heat radiation base and the second heat radiation base has a main surface. And a side surface, and a part of the side surface of the first heat dissipation base faces the inner side surface of the first flow path forming body forming the opening space of the first opening, and the second heat dissipation A part of the main surface of the base faces the outer surface of the second flow path forming body forming the periphery of the second opening, and a part of the side surface of the first heat dissipation base facing each other and the first. The inner side surface of the flow path forming body is joined, and a part of the main surface of the second heat dissipation base facing each other and the outer surface of the second flow path forming body are joined .

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to reduce the size of a power semiconductor device and improve its reliability.

It is a perspective view of the power semiconductor device 1 which concerns on this embodiment. It is sectional drawing of the power semiconductor device seen from the arrow direction of the plane A of FIG. It is a perspective view which shows the arrangement of the power module 1a to 1c in the assembly process of a power semiconductor device 1. It is a perspective view which shows the state which the flow path main body part 6a and 6b are assembled to the power module 1a to 1c in the assembly process of a power semiconductor device 1. It is a completed perspective view in the assembly process of a power semiconductor device 1. It is a perspective view of the flow path main body 6a which concerns on this embodiment. It is sectional drawing of the power module 1a which concerns on this embodiment. It is sectional drawing for demonstrating the manufacturing intersection of power module 1a. It is an enlarged sectional view around the opening 7a of the flow path main body 6a. It is sectional drawing of the power semiconductor device 1 which shows the state after a welding process. It is an enlarged sectional view around the opening 7a of the flow path main body 6a. It is an enlarged sectional view around the opening 7a of the flow path main body 6b.

Prior to explaining embodiments of the present invention, the background of the present invention will be described.

As a means for joining the power semiconductor device and the cooling flow path in a space-saving manner, for example, laser welding can be considered.

According to laser welding, since the bead is thin, it can be fixed in a very space-saving manner. Further, in laser welding, since the range affected by heat can be kept narrow, the influence on the resin member used in the power semiconductor device can be suppressed to be small.

However, since the bead is thin, that is, the tolerance (gap) that can be absorbed at the time of joining is narrow, it is necessary to assemble the joined portion in a state where it is accurately abutted in advance.

However, since a power semiconductor device is formed by joining a plurality of parts with solder or the like, the relative positions of the heat dissipation bases on the front and back sides have a certain tolerance. Specifically, the position of the heat dissipation base is not exactly on the front and back, and a tolerance in the surface direction that deviates in the direction parallel to the surface and a tolerance in the thickness direction in which the thickness of the power semiconductor device deviates from the design value occurs.

Therefore, when the structure of the opening of the cooling flow path on the front and back is the same, in order to insert the heat dissipation base into the opening, it is necessary to form a large opening by the tolerance and leave a gap between the heat dissipation base and the heat dissipation base. , There is a gap in the tolerance in the thickness direction as well.

Then, as described above, laser welding cannot fill a wide gap, which makes joining difficult.

An embodiment of the present invention based on the above background will be described.

FIG. 1 is a perspective view of the power semiconductor device 1 according to the present embodiment. FIG. 2 is a cross-sectional view of the power semiconductor device seen from the direction of the arrow in the plane A of FIG.

As shown in FIG. 1, a power semiconductor device includes a power module 1a that outputs a U-phase alternating current, a power module 1b that outputs a V-phase alternating current, and a power module 1c that outputs a W-phase alternating current. It has an inverter circuit that is configured. The power modules 1a to 1c are sandwiched between the cooling flow path forming body 2a and the cooling flow path forming body 2b.

As shown in FIG. 2, the cooling water flows in from the cooling water inlet pipe 3 and passes through the heat dissipation base under the power module 1c, the power module 1b, and the power module 1a while flowing through the cooling flow path forming body 2b. To cool.

After that, the cooling water flows into the cooling flow path forming body 2a through the intermediate pipe 5. Further, the cooling water flows through the cooling flow path forming body 2a, passes through the heat dissipation base on the upper side of the power module 1a, the power module 1b, and the power module 1c, cools, and flows out from the cooling water outlet pipe 4.

FIG. 3 is a perspective view showing the arrangement of the power modules 1a to 1c in the assembly process of the power semiconductor device 1. FIG. 4 is a perspective view showing a state in which the flow path main bodies 6a and 6b are assembled to the power modules 1a to 1c in the assembly process of the power semiconductor device 1. FIG. 5 is a completed perspective view in the assembly process of the power semiconductor device 1. FIG. 6 is a perspective view of the flow path main body 6a according to the present embodiment. The flow path main body 6b has a different length in the width direction from the flow path main body 6a, but other structures are basically the same.

As shown in FIG. 6, the flow path main body 6a forms an opening 7a into which the power module 1a is inserted, an opening 7b into which the power module 1b is inserted, and an opening 7c into which the power module 1c is inserted. To do.

As shown in FIG. 4, the power modules 1a to 1c are sandwiched between the flow path main body portions 6a and 6b. The heat dissipation bases of the power modules 1a to 1c are arranged in the openings 7a to 7c of the flow path forming bodies 6a and 6b, respectively.

Then, by welding (for example, laser welding) the edges of the flow path main bodies 6a and 6b forming the openings 7a to 7c to the heat dissipation bases of the power modules 1a to 1c, respectively, the power modules 1a to 1c and the flow path main body are formed. 6a and 6b are integrated.

Further, as shown in FIG. 5, each of the flow path lids 8a and 8b is covered with the flow path body portions 6a and 6b, respectively, and the edges of the flow path lids 8a and 8b are welded to the flow path body portions 6a and 6b. Will be done.

FIG. 7 is a cross-sectional view of the power module 1a according to the present embodiment. The power modules 1b and 1c also have the same configuration and functions as the power module 1a.

The power module 1a includes a plurality of power semiconductor elements 25, substrates 9a and 9b that sandwich the plurality of power semiconductor elements 25 and have a conductive function and an insulating function, and a heat dissipation base 10a that sandwiches the substrates 9a and 9b and has a heat dissipation function. And 10b, and the resin member 11. The resin member 11 seals a plurality of power semiconductor elements 25, substrates 9a and 9b, and a part of heat dissipation bases 10a and 10b.

FIG. 8 is a cross-sectional view for explaining the manufacturing intersection of the power module 1a.

Since the dimension A of the heat dissipation base 10a is molded by a mold, it can be manufactured with relatively high accuracy. Since this dimension A can be matched with the openings 7a to 7c of the flow path main body 6a with a relatively small tolerance, the side surface of the heat dissipation base 10a is assembled so as to be substantially abutted against the inner surface of the openings 7a to 7c. Can be done.

This state will be described with reference to FIGS. 9, 12 and 13. 9 and 11 are enlarged cross-sectional views around the opening 7a of the flow path main body 6a. FIG. 12 is an enlarged cross-sectional view of the periphery of the opening 7a of the flow path main body 6b.

As shown in FIGS. 9 and 11, the side surface 12 of the heat radiating base 10a can be in contact with the inner side surface forming the opening 7a.

At this time, the dimensions B and C shown in FIG. 8 have some tolerance as a result of joining a plurality of members such as the power semiconductor element 25 and the substrate 9a.

Therefore, the tolerance of dimension B is absorbed by providing a gap 13 between the main surface 26 of the heat dissipation base 10a shown in FIG. 9 and the outer surface 27 of the flow path main body 6a.

Further, the main surface of the heat dissipation base 10b and the outer surface of the flow path main body 6b have a contact structure like the contact portion 14. Instead, a tolerance of dimension C is absorbed by opening a gap 15 between the side surface of the heat dissipation base 10b and the opening 7a of the flow path main body 6b.

By welding this with the laser beams 16a and 16b, the power semiconductor device 1 integrated with the cooling flow path can be assembled.

As shown in the enlarged view of FIG. 12, the edge of the opening 7a of the flow path main body 6b is cut diagonally so as to be thinner in the direction closer to the heat dissipation base 10b, so that the laser beam 16b for welding is formed. Can be hit from directly below.

FIG. 10 is a cross-sectional view of the power semiconductor device 1 showing a state after the welding process. Since the welding beads 17a and 17b can be provided at the positions shown in FIG. 10, the bonding can be performed in a very space-saving manner, so that the power semiconductor device can be miniaturized.

Further, at this time, although the power module 1a is already molded by the resin member 11, the heat-affected zone can be kept narrow by joining by laser welding, so that the resin member 11 is damaged by welding. Can be prevented. The welding bead 17a takes a distance from the resin member 11 in the thickness direction of the heat dissipation base 10a, and the welding bead 17b can avoid the influence of heat by keeping a distance from the resin member 11 in the horizontal direction.

1 ... Power semiconductor device, 1a to 1c ... Power module, 2a and 2b ... Cooling flow path forming body, 3 ... Cooling water inlet pipe, 4 ... Cooling water outlet pipe, 5 ... Intermediate pipe, 6a and 6b ... Flow path main body , 7a to 7c ... openings, 8a and 8b ... flow path lids, 9a and 9b ... substrates, 10a and 10b ... heat dissipation bases, 11 ... resin members, 12 ... side surfaces of heat dissipation bases 10a, 13 ... gaps, 14 ... contacts , 15 ... Gap, 16a and 16b ... Laser beam, 17a and 17b ... Welded bead, 25 ... Power semiconductor element, 26 ... Main surface of heat dissipation base 10a, 27 ... Outer surface of flow path main body 6a

Claims (3)

A circuit body having a power semiconductor element and sealing the power semiconductor element with a resin member,
The first heat dissipation base and the second heat dissipation base that sandwich the circuit body,
A first flow path forming body and a second flow path forming body that face each other across the circuit body and form a flow path through which a refrigerant flows are provided.
The first flow path forming body forms a first opening to be closed by the first heat dissipation base.
The second flow path forming body forms a second opening to be closed by the second heat dissipation base.
Each of the first heat dissipation base and the second heat dissipation base is formed by a main surface and a side surface.
A part of the side surface of the first heat dissipation base faces the inner side surface of the first flow path forming body forming the opening space of the first opening.
A part of the main surface of the second heat dissipation base faces the outer surface of the second flow path forming body forming the periphery of the second opening.
A part of the side surface of the first heat dissipation base facing each other and the inner side surface of the first flow path forming body are joined to each other.
A power semiconductor device in which a part of the main surface of the second heat dissipation base facing each other and an outer surface of the second flow path forming body are joined. In the power semiconductor device according to claim 1,
A metal melting portion is formed at the joint portion between the first heat dissipation base and the first flow path forming body.
A power semiconductor device in which a metal melting portion is formed at a joint portion between the second heat dissipation base and the second flow path forming body. In the power semiconductor device according to claim 1 or 2.
The second flow path forming body is a power semiconductor device formed so that the edge of the second opening becomes thinner along the direction toward the second heat dissipation base.

Images