Power semiconductor device

Abstract

To provide a highly reliable power semiconductor device that can be pressed efficiently in a lamination direction by achieving size reduction, decreasing in the number of components and improvement in heat dissipation.SOLUTION: A power semiconductor device comprises an elastically deformable energizing member pressing a heat dissipation member against power modules, wherein the energizing member has a pair of pressing part which abut on the heat dissipation member, a plurality of loaded parts provided outside the pair of pressing parts and receiving a load by a fixation member, and an intermediate part provided between the pair of pressing parts and generating bending stress corresponding to the load, the plurality of power modules are arranged along the extending direction of the pair of pressing parts, and the intermediate part elastically deforms away from the heat dissipation member with the bending stress when the energizing member presses the heat dissipation member.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a power semiconductor device.

Background Art

[0002] In recent years, in order to reduce the environmental load, the spread of hybrid vehicles and electric vehicles has been promoted. Regarding the components mounted in hybrid vehicles and electric vehicles, miniaturization and cost reduction are emphasized. Among them, the power semiconductor device of the power conversion device is required to be miniaturized and cost-reduced, and in order to miniaturize the power semiconductor device, which generates a large amount of heat among the electronic components constituting the power conversion device, it is necessary to improve the cooling performance at the same time.

[0003] For example, in Patent Document 1, a cooler is provided for a power module via a heat conduction member, a leaf spring is provided on the outside thereof, and by pressurizing the power module, the heat conduction member, and the cooler, a power semiconductor device that realizes miniaturization and improves the mounting property of components is disclosed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the case of the leaf spring structure of the power semiconductor device described in Patent Document 1, when a load is applied to the load application portion formed outside the power module, the pressurization point is displaced in the horizontal direction, resulting in a problem that efficient pressurization in the stacking direction cannot be achieved. That is, in the conventional structure, in order to improve the cooling performance, it is necessary to efficiently pressurize the entire wider heat dissipation surface. In view of this, an object of the present invention is to provide a highly reliable power semiconductor device that realizes miniaturization, reduction in the number of components, and improvement in heat dissipation, and can be efficiently pressurized in the stacking direction. [Means for solving the problem]

[0006] In order to achieve the above objective, A power semiconductor device according to one embodiment of the present invention comprises a plurality of power modules formed by molding and sealing semiconductor elements and conductive plates joined to the semiconductor elements, a heat dissipation member that contacts at least one surface of the power modules via a heat conductive member, and an elastically deformable biasing member that presses the heat dissipation member toward the power modules. picture, The biasing member has a pair of pressurizing portions that contact the heat dissipation member, a plurality of load-bearing portions provided outside the pair of pressurizing portions and receiving load by a fixing member, and an intermediate portion provided between the pair of pressurizing portions and generating bending stress corresponding to the load, the plurality of power modules are arranged along the extending direction of the pair of pressurizing portions, the intermediate portion has a flat plate shape and is parallel to the heat dissipation member while in contact with the heat dissipation member in the state before the biasing member receives the load and is pressed against the heat dissipation member, and as the intermediate portion elastically deforms away from the heat dissipation member due to the bending stress when the biasing member presses against the heat dissipation member, the pair of pressurizing portions press the heat dissipation member toward the power module The biasing member has, in a cross section perpendicular to the extending direction, a pair of inclined portions formed extending away from the heat dissipation member with respect to the pair of pressurized portions, and a plurality of flange portions formed extending outward from both ends of the pair of inclined portions, each of the plurality of flange portions having a plurality of protrusions formed in a direction away from the power modules at positions between the arrangement of the plurality of power modules when viewed from the direction to which the fixing member is fixed and the biasing member presses the heat dissipation member, and a connecting portion formed between the inclined portions and the protrusions and formed along the extending direction, and the load-bearing portion is formed on the tip side of the plurality of protrusions It is characterized by the following: Furthermore, in order to achieve the above objective, a power semiconductor device according to another embodiment of the present invention comprises a plurality of power modules formed by molding and sealing a semiconductor element and a conductive plate joined to the semiconductor element, a heat dissipation member that contacts at least one surface of the power module via a heat conductive member, and an elastically deformable biasing member that presses the heat dissipation member toward the power module, wherein the biasing member comprises a pair of pressurizing parts that abut the heat dissipation member, a plurality of load-bearing parts provided on the outside of the pair of pressurizing parts and receiving load by a fixing member, and an intermediate part provided between the pair of pressurizing parts and generating bending stress corresponding to the load. The power module comprises a portion and a plurality of power modules arranged along the extending direction of the pair of pressurizing portions, the intermediate portion having a flat plate shape and being parallel to the heat dissipating member while in contact with the heat dissipating member in the state before the biasing member is pressed against the heat dissipating member by the load, the intermediate portion elastically deforms in a direction away from the heat dissipating member from the state in contact with the heat dissipating member due to the bending stress when the biasing member presses against the heat dissipating member, the pair of pressurizing portions press the heat dissipating member toward the power module, and the intermediate portion has a plurality of convex ribs on the surface opposite to the surface in contact with the heat dissipating member. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a highly reliable power semiconductor device that achieves miniaturization, a reduction in the number of components, and improved heat dissipation, and can efficiently apply pressure in the stacking direction. [Brief explanation of the drawing]

[0008] [Figure 1] Cross-sectional view showing a semiconductor module of a power semiconductor device. [Figure 2] Overall perspective view of a power semiconductor device according to the first embodiment of the present invention [Figure 3] Cross-sectional view of a power semiconductor device in Figure 2. [Figure 4] Explanatory drawing showing problems of the structure of a conventional power semiconductor device [Figure 5] Explanatory drawing showing the structure of a power semiconductor device to which the present invention is applied [Figure 6] Plan view of a power semiconductor device showing a first embodiment of the present invention [Figure 7] Cross-sectional view taken along line A-A of FIG. 6 [Figure 8] Cross-sectional view taken along line B-B of FIG. 6 [Figure 9] Plan explanatory drawing of a biasing member according to a first embodiment of the present invention [Figure 10] Cross-sectional view of a power semiconductor device as viewed from the power module array direction [Figure 11] Plan explanatory drawing of a loaded portion of a biasing member according to a first embodiment of the present invention [Figure 12] Cross-sectional view of a power semiconductor device according to a second embodiment of the present invention [Figure 13] Cross-sectional view of a power semiconductor device according to a third embodiment of the present invention [Figure 14] Cross-sectional view of a power semiconductor device according to a fourth embodiment of the present invention [Figure 15] Plan view of a biasing member according to a fifth embodiment of the present invention [Figure 16] Cross-sectional view taken along line C-C of FIG. 15 [Figure 17] Cross-sectional view of a biasing member according to a sixth embodiment of the present invention [Figure 18] Cross-sectional view of a biasing member according to a seventh embodiment of the present invention [Figure 19] Plan view of a biasing member according to an eighth embodiment of the present invention [Figure 20] Cross-sectional view of a power semiconductor device according to a ninth embodiment of the present invention

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following description and drawings are examples for explaining the present invention, and for the sake of clarity of explanation, appropriate omissions and simplifications have been made. The present invention can be implemented in various other forms. Unless otherwise limited, each component may be in a single or plural number.

[0010] The positions, sizes, shapes, ranges, etc. of the respective components shown in the drawings may not represent the actual positions, sizes, shapes, ranges, etc. in order to facilitate understanding of the invention. Therefore, the present invention is not necessarily limited to the positions, sizes, shapes, ranges, etc. disclosed in the drawings.

[0011] (First Embodiment of the Present Invention and Overall Configuration) (Fig. 1) The plurality of semiconductor modules 100 (power modules 100) included in the power semiconductor device according to the embodiment of the present invention include a power semiconductor element 1, a first conductor 3 and a second conductor 3b which are conductor plates joined to the power semiconductor element 1. The power semiconductor element 1, the first conductor 3 and the second conductor 3b are joined to each other by a joining material 2. The surface electrode of the power semiconductor element 1 is connected to the second conductor 3b by the joining material 2. The first conductor 3 and the second conductor 3b are, for example, copper, a copper alloy, or aluminum, an aluminum alloy, etc. The joining material 2 is, for example, a solder material, a sintered material, etc.

[0012] The first conductor 3 is connected to an insulating layer 4 which is a heat-conductive member on the surface opposite to the surface connected to the power semiconductor element 1. Similarly, the second conductor 3b is connected to an insulating layer 4 which is a heat-conductive member on the surface opposite to the surface connected to the power semiconductor element 1. The insulating layer 4 conducts heat generated from the power semiconductor element 1 to the heat radiating members 7, 7b described later, and is formed of a material having a high thermal conductivity and a large insulation breakdown voltage. The insulating layer 4 is, for example, ceramics such as aluminum oxide (alumina), aluminum nitride, silicon nitride, or an insulating sheet or adhesive containing fine powders of these.

[0013] The semiconductor module 100 is formed by molding and sealing with a sealing resin 10 such that the insulating layer 4 is exposed on the surface. The surface of the insulating layer 4 exposed from the sealing resin 10 is the heat dissipation surface of the semiconductor module 100. The semiconductor module 100 has external terminals 3c for electrically connecting the power semiconductor element 1 to external wiring, etc. The external terminals 3c protrude to the outside from the sealing resin 10.

[0014] (Figure 2) The semiconductor module 100 has a heat dissipation member 7 (7b) that contacts the semiconductor module 100 via the aforementioned insulating layer 4 on at least one side. Figure 2 illustrates how the first heat dissipation member 7 and the second heat dissipation member 7b contact the semiconductor module 100, sandwiching it from both sides. The semiconductor module 100 faces the fixed flange 8 with the first heat dissipation member 7 in between. The semiconductor module 100 also faces the spring plate member 9 with the second heat dissipation member 7b in between. The spring plate member 9 is an elastically deformable biasing member that presses the heat dissipation member 7b toward the semiconductor module 100. Note that this is not limited to the double-sided cooled semiconductor module 100 shown, but can also be applied to a single-sided cooled semiconductor module 100.

[0015] The spring plate member 9 has a pair of pressurizing portions 9a and 9b that contact the heat dissipation member 7b. The pressurizing portions 9a and 9b are generated when the spring plate member 9 presses against the heat dissipation member 7b. First fixing members 13 are inserted into holes formed at multiple ends of the spring plate member 9. The fixing flange 8 is connected to each second fixing member 12, thereby becoming a supporting member when the spring plate member 9 is fixed. The first fixing member 13 is connected to the fixing flange 8 by being inserted into the second fixing member 12 corresponding to each hole in the spring plate member 9. As a result, the spring plate member 9 receives a load at each position where the fixing member 13 is inserted, and consequently, the spring plate member 9 presses against the heat dissipation member 7b.

[0016] (Figure 3) The insulating layer 4 is in contact with the thermal conductive layer 5 on the side opposite to the side that contacts the first conductor 3 and the second conductor 2. The thermal conductive layer 5 is in contact with the heat dissipation members 7 and 7b on the side opposite to the side that contacts the insulating layer 4. The thermal conductive layer 5 is a thermal conductive material such as thermal conductive grease, TIM (Thermal Interface Material), or a heat dissipation sheet. The first heat dissipation member 7 and the second heat dissipation member 7b are thermally conductive materials, such as composite materials such as Cu, Cu alloy, Cu-C, Cu-CuO, or composite materials such as Al, Al alloy, AlSiC, Al-C.

[0017] Preferably, the positions of the pair of pressurizing portions 9a and 9b are located between the center of the heat conduction layer 5 and both ends of the heat conduction layer 5 in the cross-section shown in Figure 3. This allows the spring plate member 9 to generate uniform and overall surface pressure on the heat conduction layer 5 when it presses against the heat dissipation member 7b, enabling a reliable power semiconductor device with high heat dissipation performance without the semiconductor module 100 and the heat dissipation member 7b separating.

[0018] The spring plate member 9 has an intermediate portion 9c between a pair of pressurizing portions 9a and 9b. The spring plate member 9 also has a plurality of load-bearing portions 11 provided on the outside of the pair of pressurizing portions 9a and 9b and receiving load by the fixing member 13.

[0019] The pair of pressurizing portions 9a and 9b are formed in a position that overlaps with the arrangement area of ​​the power semiconductor element 1 in cross-section. The positions of the pair of pressurizing portions 9a and 9b do not necessarily have to overlap with the arrangement area of ​​the power semiconductor element 1, but by forming them in a position that overlaps with the arrangement area of ​​the power semiconductor element 1, the pressing force of the heat dissipation member 7b against the semiconductor module 100 becomes higher than in other areas, making it possible to improve the heat dissipation performance of the arrangement area of ​​the power semiconductor element 1 where heat dissipation is most needed, and thus realizing a power semiconductor device with high overall heat dissipation performance.

[0020] (Comparison of conventional structure and the structure of the present invention) (Figures 4 and 5) Figure 4(a) shows the state before the conventional spring plate member 50 presses against the heat dissipation member 7b, and Figure 4(b) shows the state after the conventional spring plate member 50 has pressed against the heat dissipation member 7b. Furthermore, Figure 5(a) shows the state before the spring plate member 9 of the present invention presses against the heat dissipation member 7b, and Figure 5(b) shows the state after the spring plate member 9 of the present invention has pressed against the heat dissipation member 7b.

[0021] In the conventional structure shown in Figure 4(a), before the conventional spring plate member 50 presses against the heat dissipation member 7b, a pair of conventional pressurizing parts 50a and 50b are in line contact (point contact on the cross-section) with the heat dissipation member 7b toward the back of the cross-section. The conventional pressurizing parts 50a and 50b have a predetermined space between them and the heat dissipation member 7b, and an acute angle θ1 is formed from each of the conventional pressurizing parts 50a and 50b toward the center line 50c.

[0022] In such a conventional structure, when a downward force 60 is applied to the conventional load-bearing parts 51a and 51b, which are formed further outward in the left-right cross-sectional direction than the conventional pressurizing parts 50a and 50b, the positions of the conventional pressurizing parts 50a and 50b will be shifted laterally in the horizontal direction of the arrow toward the center line 50c, as shown in Figure 4(b). Therefore, the conventional spring plate member 50 will have difficulty efficiently pressing the heat dissipation member 7b. In addition, because the conventional pressurizing parts 50a and 50b are in line contact with the heat dissipation member 7b, the area over which the compressive stress applied to the inside of the heat dissipation member 7b is distributed will be narrowed.

[0023] In view of this, the present invention forms an intermediate portion 9c between a pair of pressurizing portions 9a and 9b, as shown in Figure 5. The intermediate portion 9c has a flat plate shape that makes surface contact with the heat dissipation member 7b. As shown in Figure 5(a), when the spring plate member 9 is in contact with the heat dissipation member 7b before it is pressed against the heat dissipation member 7b by a load, it is parallel to the heat dissipation member 7b.

[0024] In this way, when the load-bearing portion 11 protruding from the outer cross-section of the spring plate member 9 is subjected to a load, even if a horizontal force acts between the pressurizing portions 9a and 9b, the intermediate portion 9c suppresses lateral displacement of the pressurizing portions 9a and 9b, thereby preventing damage to the heat dissipation member 7b and improving vibration resistance. Furthermore, by spreading the load on the spring plate member 9 to the surface contact portion of the intermediate portion 9c and distributing the load, the range over which compressive stress is distributed within the heat dissipation member 7b can be widened, and compressive stress can be generated throughout the entire heat dissipation member 7b.

[0025] The intermediate section 9c between the pair of pressurizing sections 9a and 9b has greater bending rigidity than the conventional structure. In other words, when the load-bearing section 11, which is located outside the pressurizing sections 9a and 9b, is subjected to a load, a bending stress corresponding to the load from the fixing member 13 is generated in the intermediate section 9c. As shown in Figure 5(b), the intermediate section 9c attempts to elastically deform away from the surface of the heat dissipation member 7b due to this bending stress. Consequently, a reaction force (restoring force) is generated in the intermediate section 9c in the opposite direction to the elastic deformation force acting away from the surface of the heat dissipation member 7b, and a force acts to bring the intermediate section 9c into surface contact as much as possible. As a result, the spring plate member 9 can efficiently press against the heat dissipation member 7 and the semiconductor module 100, enabling the realization of a power semiconductor device with high heat dissipation performance and high reliability.

[0026] Furthermore, in order to realize the effects of the present invention, it is preferable that the angle θ2 formed between the intermediate portion 9c and the pair of inclined portions 11d, which are formed at both ends of the intermediate portion 9c on the side opposite to the heat dissipation member 7b in the spring plate member 9 and are formed between the intermediate portion 9c and the load-bearing portion 11, be obtuse. Also, although the pair of pressurizing portions 9a, 9b, the pair of inclined portions 11d and the pair of load-bearing portions 11 in the spring plate member 9 have been illustrated above, the paired portions are not limited to having the same shape as long as the resulting effects are similar.

[0027] (Figure 6) Multiple semiconductor modules 100 are arranged along the extending direction of a pair of pressurizing portions 9a and 9b. Furthermore, the pair of pressurizing portions 9a and 9b are formed in a position that overlaps with the region where the semiconductor element 1 is arranged, when viewed from the direction in which the spring plate member 9 presses against the heat dissipation member 7b (viewed in a plan view).

[0028] The spring plate member 9 has a pair of pressurizing sections 9a and 9b formed so as to span the three-phase semiconductor module 100. A pair of load-bearing sections 11 are provided on both the upper and lower outer sides of the pair of pressurizing sections 9a and 9b in the plan view. The load-bearing sections 11 are formed to protrude outward on the plane at a position away from the installation position of the semiconductor module 100. Of the multiple load-bearing sections 11, those provided at the four corners are designated as load-bearing sections 11a, and those provided at other locations are designated as load-bearing sections 11b.

[0029] (Figures 7 and 8) As shown in the cross-sectional views of the heat dissipation members 7(7b) in Figure 7, which is a cross-sectional view of AA in Figure 6, and in Figure 8, which is a cross-sectional view of BB in Figure 6, the heat dissipation members 7 and 7b have hollow refrigerant flow paths with heat dissipation fins 7e arranged inside. The heat dissipation members 7 and 7b have a region where fins 7e are formed and a hollow region 7f where fins 7e are not formed. Although refrigerant flows through the hollow region 7f where fins 7e are not formed, the hollow flow paths of the heat dissipation members 7 and 7b may be air-cooling flow paths through which air flows, provided that a similar effect can be obtained.

[0030] If the pressurizing sections 9a and 9b are provided in the hollow region 7f as shown in Figure 8, the cover of the second heat dissipation member 7b will dent when pressurized by the spring plate member 9, making it impossible to efficiently generate compressive stress in the heat conduction layer 5. Therefore, as shown in Figure 6, it is preferable that the pair of pressurizing sections 9a and 9b be provided within the range of the fin-forming region 7d, which is the region where the heat dissipation fins 7e are arranged, when viewed from the direction in which the spring plate member 9 presses against the heat dissipation member 7b (viewed in a plan view). This makes it possible to efficiently generate compressive stress throughout the entire heat conduction layer 5.

[0031] (Figure 9) The pair of inclined portions 11d are formed in a cross-section perpendicular to the extending direction of the pressurized portions 9a and 9b (see Figure 5), extending away from the heat dissipation member 7b with respect to the pair of pressurized portions 9a and 9b. In the spring plate member 9, a plurality of flange portions 11f are provided on the upper and lower outer sides in the planar direction of the intermediate portion 9c and the pressurized portions 9a and 9b, respectively, extending outward from both ends of the pair of inclined portions 11d.

[0032] The flange portion 11f has a plurality of protrusions 11g that project outward from the intermediate portion 11c. The plurality of protrusions 11g are formed in a direction away from the semiconductor modules 100, at positions between the arrangement of the plurality of semiconductor modules 100, when viewed from the direction in which the spring plate member 9 presses the heat dissipation member 11b (viewed in a plan view). The flange portion 11f also has a pair of connecting portions 11e formed between the inclined portion 11d and the protrusions 11g, and formed along the extending direction of the pressurizing portions 9a and 9b.

[0033] Each of the multiple protrusions 11g has a hole 11c into which the fixing member 13 is fixed. In other words, the load-bearing portions 11a and 11b are formed on the tip side of the multiple protrusions 11g and have holes 11c into which the fixing member 13 is inserted.

[0034] (Figure 10) The semiconductor modules 100 are arranged in a three-phase configuration on the power semiconductor device, but each phase may be sealed with a sealing resin 10. Heat dissipation of the semiconductor modules 100 is achieved by pressing and fixing three phases of semiconductor modules 100, each sealed with a sealing resin 10, together from the top and bottom of the cross-section between the first heat dissipation member 7 and the second heat dissipation member 7b. Note that the number of semiconductor modules 100 arranged is just an example and is not limited to three phases.

[0035] (Figure 11) Figure 11 shows a simplified spring plate member 9. The load-bearing portions 11a and 11b are formed to correspond to the four corners of the arrangement area 100b of one phase of the semiconductor module 100. As a result, the load-bearing portions 11a and 11b can generate compressive stress throughout the thermal conductive layer 5 of the semiconductor module 100.

[0036] Furthermore, among the multiple load-bearing portions 11a and 11b, the first spring constant of the load-bearing portion 11a formed at the four corners of the spring plate member 9 is smaller than the second spring constant of the load-bearing portion 11b formed at positions other than the four corners, and the second spring constant is less than or equal to twice the first spring constant. In other words, the load on the load-bearing portion 11b formed at positions other than the four corners is greater than the load on the load-bearing portion 11a formed at the four corners of the spring plate member 9. By doing so, the variation in compressive stress generated in each semiconductor module 100 when the spring plate member 9 presses against the heat dissipation member 7b can be reduced. It is preferable that the bending stiffness of the load-bearing portions 11a and 11b be close to each other.

[0037] (Second embodiment) (Figure 12) The intermediate portion 9c is shown in the case where it is in direct surface contact with the heat dissipation member 7b that is being pressed, but an intermediate layer 15 may be provided between the spring plate member 9 and the heat dissipation member 7b. By using a material for the intermediate layer 15 that has a lower Young's modulus (longitudinal modulus) than the material of the heat dissipation member 7b or the spring plate member 9, even if there are minute irregularities on the surface of the intermediate portion 9c between the heat dissipation member 7b and the spring plate member 9, the gap can be filled, and the spring plate member 9 can apply even pressure to the heat dissipation member 7b. Furthermore, if the material for the intermediate layer 15 is a material with a higher Young's modulus than the material of the heat dissipation member 7b, it is possible to obtain the advantage of preventing the heat dissipation member 7b from being slightly deformed by the pressurized portions 9a and 9b.

[0038] Furthermore, although the above describes the case where the entire surface of the contact surface of the intermediate portion 9c of the spring plate member 9 with the heat dissipation member 7b is in contact with the heat dissipation member 7b before the spring plate member 9 is pressed against the heat dissipation member 7b, even if a part of the plane of the intermediate portion 9c is separated from the heat dissipation member 7b after a load is applied to the spring plate member 9 (see Figure 5), the same effect as in the first embodiment can be obtained because the intermediate layer 15 material is arranged therein.

[0039] (Third embodiment) (Figure 13) The semiconductor module 100 may not be a single molded encapsulation, but rather composed of multiple small molded encapsulations 101, and the same effect can be obtained even in this case.

[0040] (Fourth embodiment) (Figure 14) Even if there is a recess 70 in a part of the heat dissipation member 7b that is in contact with the spring plate member 9, the same effect as in the above-described embodiment can be obtained as long as the surface on the heat dissipation member 7b side of the intermediate portion 9c between the pressurizing portions 9a and 9b and the surface on the spring plate member 9 side, which is the upper surface of the heat dissipation member 7b, are parallel.

[0041] (Fifth embodiment) (Figures 15 and 16) The intermediate portion 9c connecting the pressurizing portions 9a and 9b in the spring plate member 9 may have a plurality of convex ribs 9d on the surface opposite to the surface that contacts the heat dissipation member 7b. As shown in Figure 15, the ribs 9d are formed perpendicular to the formation direction (extension direction) of the pressurizing portions 9a and 9b when viewed in a plan view. This makes it possible to increase the bending rigidity of the intermediate portion 9c compared to the above embodiment, and when the spring plate member 9 is pressed, it is possible to prevent the central part of the intermediate portion 9c from separating from the heat dissipation member 7b (see Figure 5), and to press a wider area of ​​the heat dissipation member 7b.

[0042] (Sixth embodiment) (Figure 17) In the above-described intermediate portion 9c, the case was shown where the plate thickness of the intermediate portion 9c is uniform with the plate thickness of the load-bearing portion 11 and other areas. However, the intermediate portion 9c may also have a configuration in which the plate thickness T2 is formed to be thicker than the plate thickness T1 of the load-bearing portion 11 and other areas. By doing so, the bending rigidity of the intermediate portion 9c can be increased compared to the first embodiment described above, and when the spring plate member 9 presses against the heat dissipation member 7b, the central part of the intermediate portion 9c can be prevented from separating from the heat dissipation member 7b, making it possible to apply the load over a wider area.

[0043] (Seventh Embodiment) (Figure 18) The seventh embodiment aims to achieve similar effects and advantages as the sixth embodiment, but differs from the sixth embodiment in the manufacturing method of the thicker intermediate portion 9c, in which the intermediate portion 9c is formed thicker on the side opposite to the heat dissipation member 7b. The illustration shows that the thickness T4 of the intermediate portion 9c, which is thicker so as to be laminated on the side opposite to the side in contact with the heat dissipation member 7b, is thicker than the thickness T3 of the load-bearing portion 11 and other areas. In this way, the same effects and advantages as the sixth embodiment described above can be obtained. The thickened portion of the intermediate portion 9c may be made of the same material as the spring plate member 9, or it may be a structure in which different materials are laminated and connected to the spring plate member 9.

[0044] (Eighth embodiment) (Figure 19) In the embodiment described above, the flange portion 11f was shown to be rectangular in shape, with the base and tip portions of the flange having approximately the same width. However, the flange shape may also be tapered.

[0045] The tapered load-bearing portion 11 has a width W1 at the base of the flange portion 11f that is greater than the width W2 at the tip of the flange portion 11f. This not only provides the same effect as the previously described embodiment, but also allows for a smaller area of ​​the spring plate member 9 without reducing the surface pressure applied to the heat dissipation member 7b and the semiconductor module 100, thus achieving weight reduction. Furthermore, the tapered shape of the flange portion 11f is formed such that the extension of the diagonal lines overlaps near the center of the semiconductor module 100, making it possible to apply surface pressure to the center of the semiconductor module 100.

[0046] (Ninth embodiment) (Figure 20) The heat dissipation member 7b has a protrusion 70b on the surface that contacts the spring plate member 9. Accordingly, a bent portion 9e is provided in a part of the center of the intermediate portion 9c of the spring plate member 9 to match the shape of the protrusion 70b. The cross-sectional widths W5 and W6 of the intermediate portion 9c, excluding the bent portion 9e, are each larger than the cross-sectional width W4 of the protrusion 9e. As a result, the same effect as in the first embodiment can be obtained.

[0047] In the embodiments described above, the sealing resin 10 was shown to seal the semiconductor module 100 including the insulating layer 4, except for the heat dissipation surface. However, the semiconductor module 100 may also be constructed by sealing only the first conductor 3 and the second conductor 3b without sealing the insulating layers 4 and 4b. Furthermore, the present invention is not limited to the embodiments described above, and can be applied in various modified forms within the scope of the spirit of the present invention.

[0048] According to the embodiments of the present invention described above, the following effects and advantages are achieved.

[0049] (1) A power semiconductor device comprising: a plurality of semiconductor modules 100 formed by molding and sealing a semiconductor element 1 and conductive plates 3, 3b joined to the semiconductor element 1; heat dissipation members 7, 7b that contact at least one surface of the semiconductor module 100 via a heat conductive member 5; and an elastically deformable biasing member 9 that presses the heat dissipation members 7, 7b toward the semiconductor module 100, wherein the biasing member 9 has a pair of pressurizing parts 9a, 9b that abut against the heat dissipation member 7b; a plurality of load-bearing parts 11a, 11b provided on the outside of the pair of pressurizing parts 9a, 9b and receiving load by a fixing member 13; and an intermediate part 9c provided between the pair of pressurizing parts 9a, 9b and generating bending stress corresponding to the load. The plurality of semiconductor modules 100 are arranged along the extending direction of the pair of pressurizing parts 9a, 9b. The intermediate part 9c elastically deforms toward the heat dissipation member 7b due to the bending stress when the biasing member 9 presses against the heat dissipation member 7b. This approach enables miniaturization, a reduction in the number of components, and improved heat dissipation, resulting in a highly reliable power semiconductor device that can efficiently apply pressure in the stacking direction.

[0050] (2) The pair of pressurizing portions 9a and 9b are formed in a position that overlaps with the region where the semiconductor element 1 is located, when viewed from the direction in which the biasing member 9 presses against the heat dissipation member 7b. This makes it possible to further improve the heat dissipation performance of the power semiconductor device.

[0051] (3) The pair of pressurizing portions 9a and 9b are in contact with the heat dissipation member 7b at positions between the center of the heat conductive member 5 and both ends of the heat conductive member 5 in a cross section perpendicular to the extending direction. This allows for uniform and overall surface pressure to be generated on the heat conductive layer 5, enabling the realization of a reliable power semiconductor device with high heat dissipation performance.

[0052] (4) The heat dissipation member 7b has a hollow refrigerant channel with heat dissipation fins 7e arranged inside, and the pair of pressurizing parts 9a and 9b are formed within the region where the heat dissipation fins 7e are arranged when viewed from the direction in which the biasing member 9 presses against the heat dissipation member 7b. In this way, compressive stress can be efficiently generated throughout the heat conduction layer 5.

[0053] (5) The biasing member 9 has a pair of inclined portions 11d formed in a cross section perpendicular to the extending direction, extending away from the heat dissipation member 7b with respect to a pair of pressurizing portions 9a, 9b, and a plurality of flange portions 11f formed extending outward from both ends of the pair of inclined portions 11d. Each of the plurality of flange portions 11f has a fixing member 13 to which it is fixed, and a plurality of protrusions 11g formed in a direction away from the semiconductor modules 100 at positions between the arrangement of the plurality of semiconductor modules 100 when viewed from the direction in which the biasing member 9 presses the heat dissipation member 7b, and a connecting portion 11e formed between the inclined portions 11d and the protrusions 11g and formed along the extending direction. The load-bearing portions 11a, 11b are formed on the tip side of the plurality of protrusions 11g. This configuration allows for elastic deformation of the biasing member 9 in response to the load, achieving miniaturization, reduction of the number of parts, improvement of heat dissipation, and efficient pressurization in the stacking direction.

[0054] (6) The intermediate portion 9c has a flat plate shape and is parallel to the heat dissipation member 7b when it is in contact with the heat dissipation member 7b before the biasing member 9 is pressed against the heat dissipation member 7b by the load. This prevents damage to the heat dissipation member 7b and improves vibration resistance. In addition, compressive stress can be generated throughout the heat dissipation member 7b.

[0055] (7) The intermediate portion 9c has a plurality of convex ribs 9d on the surface opposite to the surface that contacts the heat dissipation member 7b. This increases the bending rigidity of the intermediate portion 9c, allowing it to press against a wider area of ​​the heat dissipation member 7b.

[0056] (8) The rib 9d is formed perpendicular to the extension direction of the pressurized sections 9a and 9b. This increases the bending rigidity of the intermediate section 9c.

[0057] (9) In the biasing member 9, the thickness T2 (T4) of the intermediate portion 9c is formed to be thicker than the thickness T1 (T3) of the other portions. This increases the bending rigidity of the intermediate portion 9c, making it possible to apply the load to a wider area of ​​the heat dissipation member 7b.

[0058] (10) In the biasing member 9, the angle θ2 formed by the intermediate portion 9c and the inclined portion 111d on the surface opposite to the surface in contact with the heat dissipation member 7b is obtuse. This allows for efficient pressing against the heat dissipation member 7 and the semiconductor module 100, enabling the realization of a power semiconductor device with high heat dissipation performance and high reliability.

[0059] (11) Of the multiple load-bearing parts 11a and 11b, the first spring constant of the load-bearing part 11a formed at the four corners of the biasing member 9 is smaller than the second spring constant of the load-bearing part 11b formed at positions other than the four corners, and the second spring constant is less than or equal to twice the first spring constant. This reduces the variation in compressive stress generated in each semiconductor module 100 when the spring plate member 9 presses against the heat dissipation member 7b.

[0060] (12) The flange portion 11f has a tapered shape. This makes it possible to reduce weight.

[0061] (13) Of the multiple load-bearing parts 11a, 11b, the load applied to the load-bearing parts 11a formed at the four corners of the biasing member is greater than the load applied to the load-bearing parts 11b formed at positions other than the four corners. This reduces the variation in compressive stress generated in each semiconductor module 100 when the spring plate member 9 presses against the heat dissipation member 7b.

[0062] It should be noted that the present invention is not limited to the embodiments described above, and various modifications and combinations of other configurations can be made without departing from the spirit of the invention. Furthermore, the present invention is not limited to having all the configurations described in the embodiments described above, and may also include configurations in which some of those configurations are omitted. [Explanation of symbols]

[0063] 1 Power semiconductor element 2 Bonding material 3. First conductor 3b Second conductor 3c external terminal 4. Insulating layer 5. Thermal conductive layer 7. First heat dissipation member 7b Second heat dissipation member 7d Fin formation region 7e Finn 7f Hollow region 8 Fixed flange 9. Spring plate member 9a, 9b pressurized sections 9c middle part 9d rib 9e Intermediate protrusion 10 Sealing resin 11 Loaded part 11a Loaded parts at the four corners 11b Loaded parts other than the four corners 11c Hole for passing the first fixing member 11d Slope 11e Connecting part 11f flange section 11g protrusion 12 Second fixing member 13 First fixing member 15 Middle Class 50 Conventional spring plate members 50a, 50b Conventional pressurized section 50c center line 51a, 51b Conventional load-bearing section 60 Load direction 70 recess 70b protrusion 100 semiconductor modules 100b Semiconductor module placement area 101 Small piece molded sealant

Claims

1. Multiple power modules formed by molding and sealing semiconductor elements and conductive plates joined to the semiconductor elements, A heat dissipation member that contacts at least one surface of the power module via a heat conductive member, A power semiconductor device comprising an elastically deformable biasing member that presses the heat dissipation member toward the power module, The biasing member has a pair of pressurizing parts that contact the heat dissipating member, a plurality of load-bearing parts provided on the outside of the pair of pressurizing parts and receiving load by a fixing member, and an intermediate part provided between the pair of pressurizing parts and generating bending stress corresponding to the load, The plurality of power modules are arranged along the extending direction of the pair of pressurizing sections, The intermediate portion has a flat plate shape and, in the state before the biasing member is pressed against the heat dissipation member by the load, is in contact with the heat dissipation member and is parallel to the heat dissipation member. As the intermediate portion elastically deforms from a state of contact with the heat dissipation member to a state of separation from the heat dissipation member due to the bending stress when the biasing member presses the heat dissipation member, the pair of pressurizing portions press the heat dissipation member toward the power module. The biasing member has, in a cross section perpendicular to the extending direction, a pair of inclined portions formed extending away from the heat dissipation member with respect to the pair of pressurized portions, and a plurality of flange portions formed extending outward from both ends of the pair of inclined portions. Each of the plurality of flange portions has a plurality of protrusions formed in a direction away from the power module at a position between the arrangement of the plurality of power modules, as viewed from the direction in which the fixing member is fixed and the biasing member presses the heat dissipation member, and a connecting portion formed between the inclined portion and the protrusions and formed along the extending direction, The load-bearing portion is formed on the tip side of the plurality of protrusions. Power semiconductor device.

2. A plurality of power modules formed by molding and sealing a semiconductor element and a conductive plate joined to the semiconductor element, A heat dissipation member that contacts at least one surface of the power module via a heat conductive member, A power semiconductor device comprising an elastically deformable biasing member that presses the heat dissipation member toward the power module, The biasing member has a pair of pressurizing parts that contact the heat dissipating member, a plurality of load-bearing parts provided on the outside of the pair of pressurizing parts and receiving load by a fixing member, and an intermediate part provided between the pair of pressurizing parts and generating bending stress corresponding to the load, The plurality of power modules are arranged along the extending direction of the pair of pressurizing sections, The intermediate portion has a flat plate shape and, in the state before the biasing member is pressed against the heat dissipation member by the load, is in contact with the heat dissipation member and is parallel to the heat dissipation member. As the intermediate portion elastically deforms from a state of contact with the heat dissipation member to a state of separation from the heat dissipation member due to the bending stress when the biasing member presses the heat dissipation member, the pair of pressurizing portions press the heat dissipation member toward the power module. The aforementioned intermediate portion has a plurality of convex ribs on the surface opposite to the surface that contacts the heat dissipation member. Power semiconductor device.

3. A power conversion device according to claim 1 or 2, The pair of pressurizing portions are formed in a position that overlaps with the region where the semiconductor element is located, when viewed from the direction in which the biasing member presses against the heat dissipation member. Power semiconductor device.

4. A power conversion device according to claim 1 or 2, The pair of pressurizing portions are in contact with the heat dissipating member at positions between the center of the heat conducting member and both ends of the heat conducting member, in a cross-section perpendicular to the extending direction. Power semiconductor device.

5. A power semiconductor device according to claim 1 or 2, The heat dissipation member has a hollow refrigerant flow path with heat dissipation fins arranged inside, The pair of pressurizing portions are formed within the region where the heat dissipation fins are located, when viewed from the direction in which the biasing member presses against the heat dissipation member. Power semiconductor device.

6. A power semiconductor device according to claim 2, The ribs are formed perpendicular to the extending direction of the pressurized portion. Power semiconductor device.

7. A power semiconductor device according to claim 1 or 2, In the biasing member, the thickness of the intermediate portion is formed to be thicker than the thickness of the other portions. Power semiconductor device.

8. A power semiconductor device according to claim 1, In the biasing member, the angle formed by the intermediate portion and the inclined portion on the surface opposite to the surface in contact with the heat dissipation member is an obtuse angle. Power semiconductor device.

9. A power semiconductor device according to claim 1 or 2, Of the multiple load-bearing parts, the first spring constant of the load-bearing part formed at the four corners of the biasing member is smaller than the second spring constant of the load-bearing part formed at positions other than the four corners. The second spring constant is no more than twice the first spring constant. Power semiconductor device.

10. A power semiconductor device according to claim 1, The flange portion has a tapered shape. Power semiconductor device.

11. A power semiconductor device according to claim 1 or 2, Of the multiple load-bearing parts, the load applied to the load-bearing parts formed at the four corners of the biasing member is greater than the load applied to the load-bearing parts formed at locations other than the four corners. Power semiconductor device.

Images