JP6528730B2 - Semiconductor device - Google Patents

Description

  The present invention relates to a semiconductor device in which a power card containing semiconductor elements and a cooler are stacked with an insulating member interposed therebetween and pressurized in the stacking direction.

  There is known a semiconductor device in which a power card containing a semiconductor element and a cooler are stacked with an insulating member interposed therebetween (for example, Patent Document 1). In the semiconductor device of Patent Document 1, a conductive heat dissipating member for releasing heat generated in the semiconductor element is exposed on the surface of the power card. An insulating member is interposed between the conductive heat dissipating member and the cooler in order to insulate the cooler. In order to enhance the efficiency of heat conduction from the heat radiating member to the cooler via the insulating member, the laminate of the power card, the cooler and the insulating member is pressurized in the stacking direction thereof.

Unexamined-Japanese-Patent No. 2007-165620

  In the above semiconductor device, if the contact surface between the insulating member and the cooler or the contact surface between the insulating member and the heat sink is ideally flat, the entire contact surface of the insulating member is uniformly pressurized. However, if a projection is present on the surface of any of the members, the insulating member is pressurized unevenly, and there is a risk that the insulating member may be broken to lower the insulation. When an insulating member made of a soft material is adopted to absorb irregularities on the surface of the member, the power card, the insulating member and the cooler are stacked according to the variation in pressure applied in the stacking direction of the power card, the insulating member and the cooler. The thickness of the body (semiconductor device) changes. The present specification relates to a semiconductor device in which a power card and a cooler are stacked with an insulating member interposed therebetween, and provides a technique for achieving both insulation securing and thickness maintenance of the semiconductor device.

  In the semiconductor device disclosed in the present specification, a power card containing a semiconductor element and a cooler are stacked with the first insulating member interposed therebetween and pressurized in the stacking direction. On the surface of the power card, a conductive heat dissipating member for releasing heat generated in the semiconductor element is exposed. On the surface of the power card, insulation at the position where the conductive heat dissipating member is exposed is important. A hole is formed in the first insulating member at a position facing the heat releasing member, and the hole is filled with a second insulating member softer than the first insulating member. According to the configuration, even if the protrusion is present on the surface of the first insulating member and the first insulating member is broken, the second insulating member is soft and is not affected by the first crack. It is possible to maintain insulation. On the other hand, since the thickness does not change even if the first member is broken, the thickness of the semiconductor device (laminated body of the cooler, the insulating member and the power card) is maintained. In the semiconductor device disclosed in the present specification, compatibility between securing the insulation between the power card and the cooler and maintaining the thickness of the semiconductor device can be achieved.

  The details and further improvement of the technology disclosed in the present specification will be described in the following "Forms for Carrying Out the Invention".

It is a perspective view of the semiconductor device of an example. It is sectional drawing of the semiconductor device cut by XY plane in the coordinate system of FIG. It is a top view of an insulating board.

(Example)
The semiconductor device 2 of the embodiment will be described with reference to the drawings. FIG. 1 is a perspective view of the semiconductor device 2 of the first embodiment. The semiconductor device 2 is a device in which a plurality of power cards 10 and a plurality of coolers 3 are stacked. More specifically, in the semiconductor device 2, the power card 10 housing the semiconductor elements (Ta, Tb, Da, Db) and the cooler 3 are stacked with the insulating plates 6 a and 6 b interposed therebetween and pressure is applied in the stacking direction Devices that are In addition, in FIG. 1, the code | symbol 10 is attached | subjected to one power card, and the code | symbol is abbreviate | omitted to the other power card. Similarly, in FIG. 1, only one cooler is denoted by 3 and the other coolers are omitted. Further, a case 31 for housing the semiconductor device 2 is drawn by a virtual line so that the whole of the semiconductor device 2 can be seen. One power card 10 is sandwiched between two coolers 3. Insulating plates 6a and 6b are interposed between the power card 10 and one cooler 3 and between the power card 10 and the other cooler 3, respectively. Further, in FIG. 1, for the sake of easy understanding, one power card 10 and two insulating plates 6 a and 6 b sandwiching the power card 10 are drawn out from the semiconductor device 2.

  One power card 10 accommodates four semiconductor elements. Specifically, the four semiconductor elements are two transistors Ta and Tb and two diodes Da and Db. The semiconductor element is cooled by the refrigerant passing through the cooler 3. The refrigerant is a liquid, typically water.

  The power card 10 and the cooler 3 are both flat type, and are stacked such that the flat surface of the largest area of the plurality of side surfaces is opposed to each other. The power cards 10 and the coolers 3 are alternately stacked, and coolers are located at both ends of the semiconductor device 2 in the stacking direction. The plurality of coolers 3 are connected by connection pipes 5a and 5b. A refrigerant supply pipe 4 a and a refrigerant discharge pipe 4 b are connected to the cooler 3 located at one end of the semiconductor device 2 in the stacking direction. The refrigerant supplied through the refrigerant supply pipe 4a is distributed to all the coolers 3 through the connection pipe 5a. The refrigerant absorbs heat from the adjacent power cards 10 while passing through each cooler 3. The refrigerant having passed through each cooler 3 passes through the connection pipe 5b and is discharged from the refrigerant discharge pipe 4b.

  When the semiconductor device 2 is accommodated in the case 31, the leaf spring 32 is inserted to the other end side in the stacking direction. The plate spring 32 applies pressure to the semiconductor device 2 in which the power card 10, the insulating plates 6a and 6b, and the cooler 3 are stacked from both sides in the stacking direction. By the pressurization in the stacking direction, the power card 10, the insulating plates 6a and 6b, and the cooler 3 are in close contact, and the cooling efficiency is enhanced. The power card 10 is directly deprived of heat by the insulating plates 6a and 6b.

  The power card 10 will be described. In the power card 10, the heat radiation plates 16a and 16b are exposed on one flat surface 10a facing the insulating plate 6a. Another heat sink 17 (not shown in FIG. 1) is exposed on the flat surface 10b opposite to the flat surface 10a. The insulating plate 6b is in contact with the flat surface 10b with grease interposed therebetween. Three electrode terminals 7a, 7b and 7c extend from the upper surface (the surface facing the positive direction of the Z axis in the figure) of the power card 10, and from the lower surface (the surface facing the negative direction in the Z axis direction in the drawing) The control terminal 29 is extended.

  The insulating plates 6a and 6b sandwiched between the power card 10 and the cooler 3 will be described with reference to FIGS. 2 and 3. FIG. 2 is a cross-sectional view of the power card 10 of FIG. 1 cut along a plane parallel to the XY plane of the coordinate system in the drawing and across the transistors Ta and Tb.

  First, the internal structure of the power card 10 will be described. Four semiconductor elements (transistors Ta and Tb, diodes Da and Db) are accommodated in a resin package 13. The package 13 is formed by injection molding and seals the semiconductor element. In the following, the flat surfaces 10 a and 10 b of the power card 10 may be referred to as flat surfaces 10 a and 10 b of the package 13.

  Both semiconductor devices are flat chips. The collector electrode is exposed on one flat surface of the chip of the transistor Ta (Tb), and the emitter electrode is exposed on the other flat surface. The electrode on one flat surface of the transistor Ta is joined to the back surface of the heat sink 16 a by the solder 15. The surface of the heat sink 16 a is exposed to the flat surface 10 a of the package 13. The electrode on the other flat surface of the transistor Ta is joined to the back surface of the heat sink 17 by the solder 15 through the conductive spacer 14. The surface of the heat sink 17 is exposed to the flat surface 10 b of the package 13. The gate electrode of the transistor Ta (Tb) is provided at one end of the flat surface of the chip. Further, each electrode of the transistor Tb is also joined to the heat sink 16 b and the heat sink 17 by using the solder 15 and the spacer 14 in the same manner as the transistor Ta. The heat sinks 16a, 16b, 17 (electrode terminals 7a, 7b, 7c) and the spacer 14 are made of copper excellent in conductivity and heat conductivity.

  The heat sink 16a is a part of the electrode terminal 7a. In the electrode terminal 7a for connecting the electrode of the transistor Ta to another external device, a portion exposed to the flat surface 10a of the package 13 corresponds to the heat sink 16a.

  The heat sinks 16b and 17 are also parts of the electrode terminals 7b and 7c, respectively, similarly to the heat sink 16a. The diodes Da and Db are also flat chips, similarly to the transistors Ta and Tb. The electrodes exposed on the flat surfaces of the diodes Da and Db are connected to the heat sinks 16a, 16b and 17 as in the transistors Ta and Tb.

  The insulating plates 6a and 6b are made of ceramic which is thin and has high insulation and good heat conductivity. It should be noted that in the drawings, the thickness of the insulating plates 6a and 6b is emphasized in order to facilitate understanding. The insulating plate 6a will be described with reference to FIG. Holes are formed in the insulating plate 6a at positions facing the heat sinks 16a and 16b. The hole also faces the region of the package 13 between the heat sink 16a and the heat sink 16b. The holes are filled with the insulating member 8a. The insulating member 8a is formed of an insulating material (for example, boron nitride (BN), an epoxy material, or the like) softer than the insulating plates 6a and 6b. In the present specification, the hardness of a substance means a value determined by any scale representing the hardness of a substance (for example, Brinell hardness, Vickers hardness, Rockwell hardness, etc.). The insulating plate 6b has the same shape as the insulating plate 6a. Holes are formed in the insulating plate 6 b at positions facing the heat sink 17. The holes are filled with the insulating member 8b. The insulating member 8b is formed of the same material as the insulating member 8a.

  The electrode terminal 7a is in contact with the electrode of the transistor Ta, the electrode terminal 7b is in contact with the electrode of the transistor Tb, and the electrode terminal 7c is in contact with the electrodes of the transistors Ta and Tb. Therefore, the electrode terminals 7a to 7c easily transmit the heat inside the transistor. On the other hand, since the cooler 3 is made of aluminum (conductive metal), it is necessary to insulate the heat sinks 16 a, 16 b and 17. Therefore, the insulating member 8a is sandwiched between the cooler 3 and the heat sinks 16a and 16b, and the insulating member 8b is sandwiched between the cooler 3 and the heat sink 17.

  The effects of this embodiment will be described. Conventionally, an insulating plate made of a hard uniform material has been employed. In that case, if projections are present on the surface of any member of the insulating plate, the power card, and the cooler, the insulating plate may be unevenly pressed, which may cause the insulating plate to be broken and the insulation performance to be deteriorated. The When an insulating member made of a soft material is adopted to absorb irregularities on the surface of the member, the power card, the insulating member and the cooler are stacked according to the variation in pressure applied in the stacking direction of the power card, the insulating plate and the cooler. The thickness of the body (semiconductor device) changes. In the semiconductor device 2 of the embodiment, the insulating plate 6a in which a hole is formed at a position facing the heat sinks 16a and 16b, and the insulating member 8a softer than the insulating plate 6a filled in the hole are employed. If only the soft insulating member 8 is used, the thickness of the insulating member 8a changes in accordance with the change in pressure in the stacking direction. That is, the thickness of the semiconductor device 2 (the thickness in the stacking direction of the cooler 3 and the power card 10) changes. On the other hand, in the semiconductor device 2 of the embodiment, since the insulating plate 6a is hard, the thickness can be maintained even if the pressure in the stacking direction changes. The insulating plate 6 a holds the thickness of the semiconductor device 2. On the other hand, the hard insulating plate 6a may be broken by pressure. If the insulating plate is broken, the insulation performance may be reduced. However, in the semiconductor device 2 of the embodiment, the insulating plate 6a faces the insulating package 13, but does not face the conductive heat sinks 16a and 16b. Holes are provided in regions of the insulating plate 6a facing the conductive heat radiation plates 16a and 16b, and the holes are filled with the insulating member 8a softer than the insulating plate 6a. In the semiconductor device 2 of the embodiment, the insulating member 8a filled in the holes of the insulating plate 6a is softer than the insulating plate 6a, and is not affected by the damage of the insulating plate 6a between the heat sinks 16a and 16b and the cooler 3. Can maintain the insulation properties of In the semiconductor device 2 of the embodiment, compatibility between securing of the insulation between the power card 10 and the cooler 3 and maintenance of the thickness of the semiconductor device 2 can be achieved. The same applies to the insulating plate 6b and the insulating member 8b disposed on the opposite side of the power card 10 to the insulating plate 6a.

  Since the insulating plate 6b is opposed to the position where the conductive heat sink 17 is exposed (ie, the position where the need for insulation is high), like the insulating plate 6a, the position where the need for insulation is high is high. The insulation of the semiconductor device can be maintained.

  Points to note regarding the technology described in the embodiment will be described. In the present embodiment, one hole is lightly formed in the insulating plate 6a at a position facing the heat sinks 16a and 16b. In the modification, one hole may be formed in the insulating plate 6a at a position facing the heat sink 16a, and another hole may be formed at a position facing the heat sink 16b. Then, the insulating member 8a may be filled in each of the two holes.

  As mentioned above, although the specific example of this invention was described in detail, these are only an illustration and do not limit a claim. The art set forth in the claims includes various variations and modifications of the specific examples illustrated above. The technical elements described in the present specification or the drawings exhibit technical usefulness singly or in various combinations, and are not limited to the combinations described in the claims at the time of application. In addition, the techniques exemplified in the present specification or the drawings can simultaneously achieve a plurality of purposes, and achieving one of the purposes itself has technical utility.

2: Semiconductor device 3: Cooling device 6a, 6b: Insulating plate 8a, 8b: Insulating member 10: Power card 16a, 16b, 17: Heat dissipation plate

Claims (1)

A semiconductor device in which a power card containing a semiconductor element and a cooler are stacked with a first insulating member interposed therebetween and pressed in the stacking direction,
On the surface of the power card, a conductive heat dissipating member for releasing heat generated in the semiconductor element is exposed,
A hole is formed in the first insulating member at a position facing the heat dissipating member,
The semiconductor device, wherein the hole is filled with a second insulating member softer than the first insulating member.

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