JP6724707B2 - Semiconductor cooling device - Google Patents

Description

The present specification discloses a semiconductor cooling device that cools a semiconductor element.

Patent Document 1 discloses a semiconductor cooling device that includes a sealing body that seals a semiconductor element and a cooler that faces the sealing body.

The heat dissipation plate is exposed on the surface of the sealing body of Patent Document 1. A heat dissipation material and an insulating plate are sandwiched between the sealing body and the cooler. The insulating plate insulates between the radiator plate and the cooler. The heat dissipation material is sandwiched between the heat dissipation plate and the insulating plate. When viewed from the direction in which the sealing body, the heat dissipation material, the insulating plate, and the cooler are stacked, the existence range of the heat dissipation material is smaller than the existence range of the heat dissipation plate and the insulation plate. The sealing body and the cooler are compressed in the stacking direction such that the heat dissipation material is in close contact with the insulating plate and also in the heat dissipation plate.

JP 2001-267475 A

When the sealing body and the cooler are compressed, a reaction force is applied to the insulating plate from the heat dissipation material. Generally, the shape of the heat dissipation material is a flat rectangular parallelepiped. That is, it is provided with an insulating plate contact surface that adheres to the insulating plate, a heat dissipation plate contact surface that adheres to the heat dissipation plate, and a side surface that extends between the insulating plate contact surface and the heat dissipation plate contact surface. The heat dissipation material forms a rectangle when observed from the stacking direction. That is, the contour of the insulating plate contact surface is rectangular and has four apex angles. At each apex angle, the side faces form an edge. In addition, the boundary between the contact surface of the insulating plate and the side surface also forms an edge. In the portion forming the edge, a larger reaction force acts on the insulating plate from the heat dissipation material than in the portion other than the edge. That is, there is a possibility that a larger force acts on the place where the edge of the insulating plate is in contact with the edge than the other place, and the insulating plate is damaged. The present specification discloses a technique for preventing a large force from acting on the insulating plate.

A semiconductor cooling device disclosed in the present specification includes a sealing body in which a semiconductor element is sealed and a heat dissipation plate is exposed, and a cooler facing the sealing body. A heat sink and an insulating plate are sandwiched between the heat sink and the cooler. The heat dissipation material is sandwiched between the heat dissipation plate and the insulating plate. When viewed from the stacking direction, the existence range of the heat dissipation material is smaller than both the existence range of the heat dissipation plate and the existence range of the insulating plate. The heat dissipation material includes an insulating plate contact surface that adheres to the insulating plate, a heat dissipation plate contact surface that adheres to the heat dissipation plate, and a side surface that extends between the insulation plate contact surface and the heat dissipation plate contact surface. The contour of the insulating plate contact surface may be polygonal. The apex angle of the polygon and at least one of the boundaries between the insulating plate adhering surface and the side surface are chamfered. Chamfering here means that a sharp edge is made obtuse or curved by connecting a plane or a curved surface between two surfaces forming the edge. Chamfering the apex angle of the polygon forming the contour of the insulating plate contact surface means chamfering in the shape viewed from the stacking direction, and chamfering the boundary between the insulating plate contact surface and the side surface is It refers to chamfering in the shape seen along the sides of the polygon.

In either case, it is possible to prevent the edge formed on the heat dissipation material from coming into contact with the insulating plate. When the edge formed on the heat dissipation material contacts the insulating plate, a reaction force concentration phenomenon occurs. According to the technique of the present specification, the edge formed on the heat dissipation material can be prevented from coming into contact with the insulating plate, so that the reaction force concentration phenomenon does not occur. Details of the technology disclosed in the present specification and further improvements will be described in the following “Description of Embodiments”.

It is a perspective view of the semiconductor cooling device of an Example. It is sectional drawing of the semiconductor cooling device of 1st Example. It is a top view of the semiconductor cooling device of a 1st Example. It is a top view of the semiconductor cooling device of a 2nd example. It is sectional drawing of the semiconductor cooling device of 3rd Example. It is an enlarged view in the area|region VI of FIG. It is a graph which shows the reaction force in a comparative example. It is a graph which shows the reaction force in a 3rd Example. It is an enlarged view in a 4th example. It is a perspective view of a heat dissipation material.

(First embodiment)
A semiconductor cooling device 10 according to a first embodiment will be described with reference to the drawings. FIG. 1 is a perspective view of the semiconductor cooling device 10. The semiconductor cooling device 10 includes a laminated body 40 in which a plurality of power cards and a plurality of coolers are alternately laminated, a housing 41 in which the laminated body 40 is housed, and a leaf spring 42. .. Each power card is a sealed body in which a semiconductor element is sealed with resin. In FIG. 1, the casing 41 is drawn by an imaginary line so that the entire laminated body 40 can be seen. It should be noted that XYZ coordinates are shown in the drawing, and the configuration of the semiconductor cooling device 10 will be described below by appropriately using XYZ coordinates.

In FIG. 1, only one of the plurality of power cards is given the reference numeral 2, and the other power cards are not given the reference numeral. Further, among the plurality of coolers, the adjacent two coolers are denoted by reference numerals 3a and 3c, and the other coolers are omitted from the reference numeral. The power card 2 is sandwiched between the adjacent coolers 3a and 3c. That is, the power card 2 faces the cooler 3 a on one side (X-axis positive direction) of the stacking direction (X-axis direction) of the stacked body 40 and on the other side (X-axis negative direction) of the cooler. Faced with 3c. In FIG. 1, the power card 2 is drawn from between the coolers 3a and 3c so that the entire power card 2 can be seen.

The power card 2 seals four semiconductor elements 22a, 22b, 23a, 23b. The semiconductor elements 22a and 22b are IGBTs (abbreviation of Insulated Gate Bipolar Transistor). The semiconductor elements 23a and 23b are diodes. A part of the inverter circuit is configured by the four semiconductor elements. Since the inverter circuit is well known, detailed description will be omitted. In the modification, the semiconductor elements 22a and 22b may be other transistors, for example, MOSFET (abbreviation of Metal Oxide Semiconductor Field Effect Transistor).

As shown in FIG. 1, the plurality of power cards are of a flat plate type and are stacked so that the flat surfaces having the largest areas among the plurality of side surfaces face each other. Metallic heat sinks are exposed on both flat surfaces 2a, 2c of the power card 2 in the stacking direction (that is, the X-axis direction). Two heat dissipation plates 21a and 21b are exposed on the flat surface 2a in the X-axis positive direction. Although one heat sink (see heat sink 21c in FIG. 2) is exposed on the flat surface 2c in the negative direction of the X-axis, it is not visible in FIG. The two semiconductor elements 22a and 23a face the heat sink 21a, and the two semiconductor elements 22b and 23b face the heat sink 21b. Further, three output terminals 12 are projected on the side surface in the Z axis positive direction of the power card 2, and a plurality of gate terminals 13 are projected on the side surface in the Z axis negative direction. Each output terminal is connected to the emitter electrode or collector electrode of the IGBT, and each gate terminal is connected to the gate electrode of the IGBT.

In addition, an insulating plate is sandwiched between the power card and the cooler, which are adjacent to each other, of the plurality of power cards and the plurality of coolers. In particular, an insulating plate 4a is sandwiched between the power card 2 and the cooler 3a, and an insulating plate 4b is sandwiched between the power card 2 and the cooler 3c. The insulating plates 4a and 4b are insulating plates made of, for example, ceramic. Further, as will be described later, between the power card 2 and the insulating plate 4a and between the power card 2 and the insulating plate 4b, a heat radiating material (see 5a, 5b, 5c in FIG. 2) and grease (see FIG. 2). 6a and 6c) are sandwiched. In FIG. 1, the illustration of the heat dissipation material and the grease is omitted.

The plurality of coolers are flat-plate type like the plurality of power cards, and are stacked so that the flat surface having the largest area among the plurality of side surfaces faces each other. Coolers are located at both ends of the stack 40 in the stacking direction (that is, the X-axis direction). The leaf spring 42 is inserted between the cooler arranged at one of both ends of the stacked body 40 (that is, the end on the negative side in the X-axis direction) and the side wall of the housing 41. The cooler arranged at the other of the both ends of the stacked body 40 (that is, the end on the X-axis positive direction side) is in contact with the side wall of the housing 41. The leaf spring 42 applies a load to the stacked body 40 from both sides in the stacking direction. Due to the load, the heat dissipation material between the power card and the insulating plate is compressed and adheres to both the power card and the insulating plate. This improves the heat transfer efficiency between the power card and the insulating plate, that is, between the power card and the cooler.

Connection pipes 31 and 32 connect between the coolers. The connecting pipe 31 is arranged on one end side in the longitudinal direction (that is, the Y-axis direction) of the cooler, and the connecting pipe 32 is arranged on the other end side. The connecting pipes 31 and 32 communicate with the space inside the cooler. Further, a refrigerant supply pipe 33 and a refrigerant discharge pipe 34 are connected to the cooler arranged at the end of the stacked body 40 on the positive side in the X-axis direction. The refrigerant supply pipe 33 is arranged on one end side in the longitudinal direction of the cooler, and is arranged on the other end side of the refrigerant discharge pipe 34. The coolant supplied through the coolant supply pipe 33 is distributed to all of the plurality of coolers through the connection pipe 31. The refrigerant absorbs heat from the power card adjacent to each cooler while passing through each cooler. The refrigerant passing through each cooler passes through the connecting pipe 32 and is discharged from the refrigerant discharge pipe 34.

The structure of the power card and the structure between the power card and the cooler will be described with reference to FIG. FIG. 2 is a cross-sectional view of the power card 2 and the coolers 3a and 3c in the laminated body 40. This cross-sectional view is taken along the XY plane that passes through the semiconductor elements 22a and 22b. In FIG. 2, illustration of power cards other than the power card 2 and coolers other than the coolers 3a and 3c is omitted.

The side surface of the semiconductor element 22a in the positive direction of the X-axis is connected to the heat sink 21a via a block 24a made of metal, and the side surface on the negative side of the X-axis is directly connected to the heat sink 21c. The semiconductor element 22a and the block 24a and the block 24a and the heat sink 21a are connected by solder (reference numeral omitted). Similarly, the side surface of the semiconductor element 22b in the positive direction of the X-axis is connected to the heat sink 21b via the block 24b made of metal, and the side surface on the negative side of the X-axis is directly connected to the heat sink 21c. ing.

Between the flat surface 2a of the power card 2 and the insulating plate 4a, two heat radiating materials 5a and 5b and grease 6a are sandwiched. The heat dissipation member 5a is sandwiched between the heat dissipation plate 21a exposed on the flat surface 2a and the insulating plate 4a, and the heat dissipation member 5b is sandwiched between the heat dissipation plate 21b and the insulating plate 4a adjacent to the heat dissipation plate 21a. Has been. The grease 6a is filled in the space between the flat surface 2a and the insulating plate 4a, in which the heat dissipation members 5a and 5b are not arranged. The heat dissipation members 5a and 5b are in close contact with both the insulating plate 4a and the heat dissipation plates 21a and 21b by the compressive force of the leaf spring 42. The space in which the heat dissipation members 5a and 5b are not arranged is filled with a sufficient amount of grease 6a to fill the space in the thickness of the heat dissipation members 5a and 5b after compression. Similarly, the heat radiating material 5c and the grease 6c are also sandwiched between the insulating plate 4b and the flat surface 2b opposite to the flat surface 2a. The heat radiating material 5c is sandwiched between the heat radiating plate 21c exposed on the flat surface 2b and the insulating plate 4c, and the grease 6c has the heat radiating material 5c arranged between the flat surface 2b and the insulating plate 4c. The space that is not filled is filled.

For example, in another mode in which the entire space between the flat surface 2a and the insulating plate 4a is filled with grease, the grease sandwiched between the heat dissipation plate 21a and the insulating plate 4a flows out, and the semiconductor element 22a and the cooler 3a are separated from each other. Aged deterioration of heat transfer efficiency may occur. Since the solid heat dissipation material 5a does not flow out between the heat dissipation plate 21a and the insulating plate 4a, it is possible to prevent deterioration of heat transfer efficiency between the semiconductor element and the cooler over time. Further, by filling the space between the flat surface 2a and the insulating plate 4a in which the heat radiating material 5a is not arranged with the grease 6a, it is insulated from the area of the flat surface 2a where the heat radiating plate 21a is not exposed. The heat transfer efficiency with the plate 4a can also be improved. The flat surface 2a may be provided with a structure (for example, a ridge) for preventing the grease 6a from flowing out between the flat surface 2a and the insulating plate 4a.

Further, grease 6b is sandwiched between the insulating plate 4a and the cooler 3a. The grease 6b is thinly stretched by the compressive force of the leaf spring 42, and is filled between the insulating plate 4a and the cooler 3a. Similarly, the grease 6d is also sandwiched between the insulating plate 4b and the cooler 3c.

The shape of the heat dissipation material will be described with reference to FIGS. 2 and 3. The heat dissipation members 5a to 5c are sheet-shaped and have the same shape. Below, it demonstrates focusing on the heat-radiating material 5a. FIG. 3 is a plan view of the surface of the power card 2 on which the heat dissipation plates 21a and 21b are arranged. In FIG. 3, the cooler is not shown, and the insulating plate 4a is drawn by a virtual line.

The flat heat dissipation material 5a includes an insulation plate contact surface Sa1 that adheres to the insulation plate 4a, a heat dissipation plate contact surface Sa2 that adheres to the heat dissipation plate 21a, and a side surface Sa3 that extends between the insulation plate adhesion surface Sa1 and the heat dissipation plate contact surface Sa2. And As shown in FIG. 3, the apex angle C1 of the rectangle forming the contour of the insulating plate contact surface Sa1 is chamfered. In other words, the edges between the side surfaces Sa3 and Sa3 are obtuse by connecting the side surfaces Sa3 and Sa3 with a plane. Furthermore, in other words, in the shape of the heat dissipation material 5a viewed from the stacking direction of the stacked body 40, a rectangular apex angle C1 is chamfered.

The chamfered shape of the heat dissipation material 5a is formed, for example, by the following steps. First, a mold having a shape in which the apex angle of the rectangular parallelepiped is chamfered (that is, the outer shape of the heat dissipation material 5a) is prepared. Next, this mold is placed on the heat dissipation plate 21a. Next, the material which becomes the heat dissipation material 5a is poured into the mold in a liquid state. Next, the material in the mold is heated to cure the material in the mold. Then, after the material in the mold is hardened, the mold is removed from the heat dissipation plate 21a. As a result, the heat dissipation member 5a in which the apex angle of the rectangular parallelepiped is chamfered is formed. In a modification, a sheet-shaped heat dissipation material formed in the shape of the embodiment may be attached on the heat dissipation plate 21a.

Further, as shown in FIG. 3, the existence range of the heat dissipation member 5a is smaller than both the existence range of the heat dissipation plate 21a and the existence range of the insulating plate 4a. Therefore, when the laminated body 40 is compressed, the entire heat dissipation member 5a is sandwiched between the insulating plate 4a and the heat dissipation plate 21a. Then, a reaction force acts on the insulating plate 4a from the heat radiating material 5a over the entire area where the heat radiating material 5a exists.

For example, assume a case where the apex angle C1 forms an edge without being chamfered. The reaction force is generated over the entire range of the existence of the heat dissipation member 5a, and at the apex angle C1, a larger reaction force acts on the insulating plate 4a from the heat dissipation member 5a than in the portion other than the apex angle C1. That is, the edge formed on the heat dissipation material contacts the insulating plate 4a, so that the reaction force concentrates on the portion in contact with the edge. This phenomenon may damage the insulating plate 4a.

On the other hand, according to the configuration of the present embodiment, since the apex angle C1 is chamfered, it is possible to prevent the edge between the side surface Sa3 and the side surface Sa3 from contacting the insulating plate 4a. The reaction force acting on the insulating plate 4a from the heat dissipation material 5a can be prevented from being concentrated at the edge.

(Second embodiment)
The semiconductor cooling device 10 according to the second embodiment will be described with reference to FIG. The semiconductor cooling device 10 of the second embodiment is the same as that of the first embodiment except that the shape of the heat dissipation material is different from that of the first embodiment. The shape of the heat dissipation material will be described below. The heat dissipating members having different shapes from those of the first embodiment are designated by the reference numerals 15a and 15b, and the other members having the same shape are designated by the same reference numerals. The semiconductor cooling device 10 of the third to fourth embodiments described later is also the same as the first embodiment except that the shape of the heat dissipation material is different from that of the first embodiment.

FIG. 4 is a plan view of the power card 2 similar to FIG. The heat dissipation member 15a is sandwiched between the insulating plate 4a and the heat dissipation plate 21a, like the heat dissipation member 5a of the first embodiment. The rectangular apex C2 forming the contour of the insulating plate contact surface Sa1 of the heat radiating material 15a is chamfered with a curved surface unlike the first embodiment. In other words, the edges between the side surfaces Sa3 and Sa3 are curved by connecting the side surfaces Sa3 and Sa3 with a curved surface. Even with such a configuration, the edge between the side surface Sa3 and the side surface Sa3 can be prevented from coming into contact with the insulating plate 4a, and the same effect as that of the first embodiment can be obtained.

(Third embodiment)
A semiconductor cooling device 10 according to a third embodiment will be described with reference to FIGS. The heat dissipating members having different shapes from those in the first embodiment are designated by the reference numerals 25a, 25b, 25c, and the other members having the same shape are designated by the same reference numerals.

FIG. 5 is a sectional view of the power card 2 and the coolers 3a and 3c similar to FIG. Like the heat dissipation member 25a and the heat dissipation member 5a of the first embodiment, it is sandwiched between the insulating plate 4a and the heat dissipation plate 21a. FIG. 6 is an enlarged view of the area VI indicated by the alternate long and short dash line in FIG. As shown in FIG. 6, the boundary C3 between the insulating plate contact surface Sa1 and the side surface Sa3 of the heat dissipation material 25a is chamfered. In other words, by connecting the insulating plate contact surface Sa1 and the side surface Sa3 with a plane, the right-angled boundary is obtuse. Further, in other words, in the shape of the heat dissipation material 5a viewed from the direction along the side of the insulating plate contact surface Sa1 (that is, the Z-axis direction), the insulating plate contact surface Sa1 side out of the four vertex angles of the rectangle. The two apexes located at are chamfered.

FIG. 7 shows a comparative example in which a right-angled boundary is not chamfered. In FIG. 7, the illustration of the insulating plate 4a, the grease 6a, and the cooler 3a is omitted. The boundary C13 between the insulating plate contact surface Sa1 and the side surface Sa3 of the heat dissipation member 105a of the comparative example is not chamfered and forms a right-angled edge. In the graph of FIG. 7, the horizontal axis represents the position between one boundary and the other boundary of the heat dissipation material 105a, and the vertical axis represents the magnitude of the reaction force acting from the heat dissipation material 105a to the insulating plate 4a. As shown in the graph of FIG. 7, the reaction force at the boundary C13 is larger than the reaction force between the boundaries. That is, the reaction force concentrates on the portion in contact with the boundary C13 (that is, the edge).

On the other hand, the graph of FIG. 8 shows the magnitude of the reaction force in the heat dissipation material 25a of this embodiment. As shown in the graph of FIG. 8, the reaction force at the chamfered boundary C3 is smaller than the reaction force between the boundaries. That is, it is possible to prevent the reaction force acting on the insulating plate 4a from the heat radiating material 25a from concentrating at the edge.

(Fourth embodiment)
The semiconductor cooling device 10 of the fourth embodiment will be described with reference to FIG. The heat dissipating material having a shape different from that of the first embodiment is denoted by the reference numeral 35a, and the other members having the same shape are denoted by the same reference numeral.

FIG. 9 is an enlarged view similar to FIG. The heat dissipation material 35a is sandwiched between the insulating plate 4a and the heat dissipation plate 21a. As shown in FIG. 9, the boundary C4 between the insulating plate contact surface Sa1 and the side surface Sa3 is chamfered with a curved surface unlike the third embodiment. In other words, by connecting the insulating plate contact surface Sa1 and the side surface Sa3 with a curved surface, the right-angled boundary is curved.

FIG. 10 is a perspective view of the heat dissipation member 35a. In the heat dissipation material 35a, the boundary C4 between the insulating plate contact surface Sa1 and the side surface Sa3 is chamfered, but the edge E1 between the side surface Sa3 and the side surface Sa3 and the boundary between the heat dissipation plate contact surface Sa2 and the side surface Sa3 (that is, Both the edge) E2 are not chamfered. The edges E1 and E2 contact the heat dissipation plate 21a but do not contact the insulating plate 4a. Since the edge is prevented from coming into contact with the insulating plate 4a, the same effect as that of the third embodiment can be obtained. On the other hand, the heat radiating plate 21a is made of metal and has a higher proof strength against reaction force (that is, strength against shearing force) than the insulating plate 4a. Even if the edges E1 and E2 contact the heat sink 21a, the heat sink 21a is not damaged. In addition, in a modification, the edge E1 may be chamfered.

Hereinafter, points to be noted regarding the technique shown in the embodiment will be described. The semiconductor cooling device 10 may not include the grease 6a between the insulating plate 4a and the power card 2 and the grease 6c between the insulating plate 4b and the power card 2.

The contour of the insulating plate contact surface Sa1 may be a polygon other than a rectangle. For example, a triangle or a pentagon may be used. Further, the shape of the heat dissipation material 5a may be circular when viewed from the stacking direction. The circle is included in the shape in which the apex angle of the polygon forming the contour of the insulating plate contact surface Sa1 is chamfered.

Specific examples of the present invention have been described above in detail, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in the present specification or the drawings exert technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Further, the technique illustrated in the present specification or the drawings can simultaneously achieve a plurality of purposes, and achieving the one purpose among them has technical utility.

2: Power card (sealed body)
3a, 3c: Coolers 4a, 4b, 4c: Insulation plates 5a, 5b, 5c, 15a, 15b, 15c, 25a, 25b, 25c, 35a: Heat dissipation material 10: Semiconductor cooling devices 21a, 21b, 21c: Heat dissipation plate 22a , 22b, 23a, 23b: semiconductor element 40: laminated body 41: housing 42: leaf spring Sa1: insulating plate contact surface Sa2: heat dissipation plate contact surface Sa3: side surfaces C1, C2: apex angles C3, C4: boundary

Claims (1)

A sealing body in which the semiconductor element is sealed and the heat sink is exposed,
A cooler facing the sealing body,
It is provided with a heat dissipation material and an insulating plate sandwiched between the sealing body and the cooler,
The sealing body and the cooler are compressed in their stacking direction,
The heat dissipation material is sandwiched between the heat dissipation plate and the insulating plate,
When viewed from the stacking direction, the existence range of the heat dissipation material is smaller than both the existence range of the heat dissipation plate and the existence range of the insulating plate,
The heat dissipation material includes an insulating plate contact surface that adheres to the insulating plate, a heat dissipation plate contact surface that adheres to the heat dissipation plate, and a side surface that extends between the insulating plate contact surface and the heat dissipation plate contact surface. The semiconductor cooling device according to claim 1, wherein at least one of the apex angle of a polygon forming the contour of the insulating plate contact surface and the boundary between the insulating plate contact surface and the side surface is chamfered.

Images