Semiconductor Devices

Abstract

To provide a semiconductor device capable of reducing the number of components and reducing the cost.SOLUTION: A semiconductor device 1 comprises: a heat radiator 7a that is thermally contacted to a heat radiation surface of a plurality of power modules 100A to 100C arranged in serial; and a fixing member that fixes the heat radiator 7a so as to be pressed to the heat radiation surface. The heat radiator 7a includes: a main body part 70 that is pressed to the heat radiation surface of each of the power modules 100A to 100C; and a plurality of cantilever beam shaped fixing flanges 71a and 71b that is formed along a direction of an arrangement of the power modules 100A to 100C with the main body part 70, and of which a bent rigidity is smaller than that of the main body part 70. The fixing member fixes the heat radiator 7a so as to press the main body part 70 to the heat radiation surface of the power modules 100A to 100C by an elastic force of the fixing flanges 71a and 71b by elastically deforming the fixing flanges 71a and 71b.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] In recent years, hybrid and electric vehicles have become increasingly popular in order to reduce the burden on the environment. In hybrid and electric vehicles, miniaturization and cost reduction of components installed are important, and semiconductor devices in power conversion systems are no exception, and miniaturization and cost reduction are also required. In order to miniaturize semiconductor devices, which generate a large amount of heat among the electronic components that make up power conversion systems, it is necessary to improve their cooling performance. Therefore, such semiconductor devices generally include a cooling device, such as a radiator or cooler, for cooling a semiconductor module incorporating a power semiconductor element.

[0003] For example, Patent Document 1 discloses a structure in which a semiconductor module incorporating a power semiconductor element is sandwiched between a pair of cooling pipes, and the cooling pipes are pressed against the semiconductor module by a pressure plate. The pressure plate generates a compressive force on the contact surface between the heat dissipation surface of the semiconductor module and the cooling pipe, forcing the heat dissipation surface into tight contact with the cooling pipe. Furthermore, the pressure plate is configured to press against the semiconductor module with the biasing force of a spring member, thereby improving the tightness of contact. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-182312 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the technique of Patent Document 1 requires additional pressure plates and spring members to ensure close contact, which increases the number of parts and costs. [Means for solving the problem]

[0006] A semiconductor device according to an aspect of the present invention includes a plurality of semiconductor modules each having a heat dissipation surface and incorporating a power semiconductor element; a heat sink in thermal contact with the heat dissipation surface of the plurality of semiconductor modules arranged in a row; and a fixing member for fixing the heat sink so as to press it against the heat dissipation surface, wherein the heat sink includes a heat dissipation base portion pressed against the heat dissipation surface of the semiconductor module; and a fixing member for fixing the heat sink in such a way that the heat sink is integral with the heat dissipation base portion and the plurality of fixing members are formed along the direction of the arrangement, and the bending rigidity of the heat dissipation base is Department and a fixing flange portion having a cantilever shape smaller than the fixing member, and the fixing member fixes the heat sink so that the fixing flange portion elastically deforms and the elastic force of the fixing flange portion presses the heat dissipation base portion against the heat dissipation surface of the semiconductor module. [Effects of the Invention]

[0007] According to the present invention, it is possible to reduce the number of components in a semiconductor device and reduce costs. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a plan view showing an example of a semiconductor device. [Figure 2] FIG. 2 is a circuit diagram showing an example of a circuit configuration of a power module. [Figure 3] FIG. 3 is a plan view showing the external shape of the power module. [Figure 4] FIG. 4 is a cross-sectional view taken along the line BB in FIG. [Figure 5] FIG. 5 is a cross-sectional view taken along line AA in FIG. [Figure 6] FIG. 6 is a cross-sectional view taken along line CC in FIG. [Figure 7A] FIG. 7A is a diagram showing the shape of the fixing flange before being connected with the bolts and nuts. [Figure 7B] FIG. 7B is a diagram showing the shape of the fixing flange after connection. [Figure 8A]FIG. 8A is a plan view of a semiconductor device in which all the fixing flanges have the same width dimension. [Figure 8B] FIG. 8B is a diagram illustrating deformation of the heat sink. [Figure 9] FIG. 9 is a diagram showing the first modification. [Figure 10] FIG. 10 is a diagram showing a second modification. [Figure 11A] FIG. 11A is a plan view of a heat sink according to the third modification. [Figure 11B] FIG. 11B is a side view of the heat sink in the third modification. [Figure 12A] FIG. 12A is a diagram showing another structure of the third modification. [Figure 12B] FIG. 12B is a diagram showing another structure of the third modification. [Figure 13A] FIG. 13A is a plan view showing the fourth modification. [Figure 13B] FIG. 13B is a side view of the semiconductor device in the fourth modification. [Figure 14] FIG. 14 is a diagram showing a fifth modification. [Figure 15] FIG. 15 is a diagram showing a sixth modification. [Figure 16] FIG. 16 is a diagram showing a seventh modification. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment 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 appropriate omissions and simplifications have been made for clarity of explanation. Furthermore, in the following description, identical or similar elements and processes are given the same reference numerals, and duplicate explanations may be omitted. Note that the content described below merely shows an example of an embodiment of the present invention, and the present invention is not limited to the following embodiment, and can be implemented in various other forms.

[0010] FIG. 1 is a plan view showing an example of a semiconductor device 1 according to the present embodiment. In the following description, coordinate axes are set such that the longitudinal direction of the semiconductor device 1 is the X direction, the lateral direction of the semiconductor device 1 is the Y direction, and the height direction of the semiconductor device 1 is the Z direction. The semiconductor device 1 according to the present embodiment is provided in, for example, an inverter circuit of a power conversion device mounted on an electric vehicle, a hybrid vehicle, or the like. The power conversion device performs power conversion between a DC power source and a motor generator (e.g., a three-phase AC rotating electric machine) for vehicle operation. The power conversion device includes a smoothing capacitor and an inverter circuit serving as a power converter. The inverter circuit converts input DC power into three-phase AC power of a predetermined frequency and outputs the power to the motor generator. The semiconductor device 1 of FIG. 1 is provided in the inverter circuit and includes three-phase power modules 100A, 100B, and 100C.

[0011] FIG. 2 is a circuit diagram showing an example of the circuit configuration of the power module 100A. The power modules 100A to 100C have the same configuration. The circuit of the power module 100A is configured with an upper arm 100U and a lower arm 100L connected in series. The upper arm 100U includes a power semiconductor element 121U and a diode 122U. The lower arm 100L includes a power semiconductor element 121L and a diode 122L. The power semiconductor elements 121U and 121L are configured with, for example, an insulated gate bipolar transistor (IGBT) or a MOSFET. The power semiconductor element 121U of the upper arm 100U is on / off controlled by a control signal input to an upper arm control terminal 114. Similarly, the power semiconductor element 121L of the lower arm 100L is on / off controlled by a control signal input to a lower arm control terminal 115.

[0012] An external connection P terminal 111 of the upper arm 100U is connected to a high-potential power line of a DC power supply, and an external connection N terminal 112 of the lower arm 100L is connected to a low-potential power line of the DC power supply. An external connection AC terminal 113 is provided at the connection point between the upper arm 100U and the lower arm 100L, and AC current is output from the external connection AC terminal 113 to an external device (e.g., a motor). A capacitor or the like is connected to the DC power supply line in parallel with the upper and lower arms 100U and 100L.

[0013] Fig. 3 is a plan view showing the external shape of the power module 100A. Fig. 4 is a cross-sectional view taken along line BB of Fig. 3. The power semiconductor elements 121U, 121L and diodes 122U, 122L of the power module 100A are sealed with sealing resin 10 made of an electrically insulating material. The external connection P terminal 111, the external connection N terminal 112, the external connection AC terminal 113, the upper arm control terminal 114, and the lower arm control terminal 115 are exposed from the sealing resin 10. Insulating layers 4 are arranged on both the front and back surfaces of the power module 100A so as to be exposed from the sealing resin 10.

[0014] As shown in the B-B cross-sectional view of FIG. 4, the front electrode of the power semiconductor element 121U is joined to the conductor 3a by the bonding material 2. The back electrode of the power semiconductor element 121U is connected to the conductor 3b by the bonding material 2. Similarly, the front electrode of the diode 122L is joined to the conductor 3c by the bonding material 2. The back electrode of the diode 122L is joined to the conductor 3d by the bonding material 2. The conductors 3a to 3d are formed of, for example, copper, copper alloy, aluminum, aluminum alloy, or the like. The bonding material 2 is formed of a solder material, a sintered material, or the like. Although not shown in the figure, the front and back electrodes of the diode 122U are joined to the conductors 3a and 3b in the same way as the power semiconductor element 121U. The front and back electrodes of the power semiconductor element 121L are joined to the conductors 3c and 3d in the same way as the diode 122L.

[0015] The conductors 3a to 3d each have an element bonding surface and a heat dissipation surface 300 on the opposite side. A thermally conductive insulating layer 4 is provided on the heat dissipation surface 300 of the conductors 3a and 3c. Similarly, an insulating layer 4 is also provided on the heat dissipation surface 300 of the conductors 3b and 3d. The insulating layer 4 conducts heat generated from the semiconductor elements (121U, 122U, 121L, 122U) to heat dissipation members (heat dissipators 7a and 7b, described below) arranged on both the front and back sides of the power module 100A, and is made of a material with high thermal conductivity and high dielectric strength. For example, ceramics such as aluminum oxide (alumina), aluminum nitride, and silicon nitride, or insulating sheets or adhesives containing fine powders of these materials can be used.

[0016] 1, the three power modules 100A, 100B, and 100C are arranged in a row in the longitudinal direction (X direction) of the semiconductor device 1. The power modules 100A to 100C are arranged such that the terminals 111 to 115 protrude laterally in the Y direction of the semiconductor device 1.

[0017] Fig. 5 is a cross-sectional view taken along line AA in Fig. 1. Fig. 6 is a cross-sectional view taken along line CC in Fig. 1. As shown in Fig. 5, the power modules 100A to 100C are sealed with a sealing resin 10 so that the insulating layer 4 covering the heat dissipation surfaces 300 of the conductors 3a to 3d is exposed to the surface (see Fig. 4). A thermally conductive layer 5 is provided on the surface of the insulating layer 4 that is exposed from the sealing resin 10. A highly thermally conductive material such as grease or a thermal interface material (TIM) is used for the thermally conductive layer 5.

[0018] The heat sinks 7a and 7b are provided so as to sandwich the power modules 100A, 100B, and 100C provided with the thermal conduction layer 5. In this embodiment, coolers having flow paths 700 through which a coolant flows in a main body 70 are used as the heat sinks 7a and 7b. As shown in Fig. 6, a plurality of flow paths 700 extending in the longitudinal direction (X direction) are formed in the main body 70 of the heat sinks 7a and 7b.

[0019] As shown in FIG. 1, a plurality of fixing flanges 71a, 71b are formed on the y-direction side surface of the main body 70 of the heat sink 7a, and are arranged at predetermined intervals along the longitudinal direction of the heat sink 7a. The fixing flanges 71a, 71b are cantilever-shaped flanges that protrude laterally (in the Y direction) from the main body 70. Although not visible in FIG. 1, the heat sink 7b is provided on the rear surface side of the power modules 100A to 100C. The heat sink 7b also has similar fixing flanges 71a, 71b formed at positions facing the fixing flanges 71a, 71b of the heat sink 7a (see FIG. 6). The thicknesses of the fixing flanges 71a, 71b are the same. However, with regard to the width, the width dimension W2 of the fixing flanges 71b arranged at both longitudinal ends is set smaller than the width dimension W1 of the other fixing flanges 71a arranged longitudinally inward from the both ends.

[0020] Each of the fixing flanges 71a, 71b has a through hole 711 formed therein, through which a bolt 11 is inserted. As shown in Fig. 6, the fixing flanges 71a, 71b of the heat sink 7a are connected and fixed to the opposing fixing flanges 71a, 71b of the heat sink 7b using bolts 11 and nuts 12, thereby fixing the heat sinks 7a, 7b to both the front and back surfaces of the power modules 100A to 100C arranged in a row.

[0021] The heat sinks 7a and 7b are formed from a thermally conductive material, such as a composite material of Cu, a Cu alloy, Cu-C, or Cu-CuO, or a composite material of Al, an Al alloy, AlSiC, or Al-C. Heat generated in the power modules 100A to 100C is conducted to the main body 70 of the heat sinks 7a and 7b through the insulating layer 4 and the thermally conductive layer 5, and is then dissipated into the coolant flowing through the flow path 700.

[0022] Fig. 7A is a diagram showing the shape of fixing flange 71b before being connected with bolts 11 and nuts 12. Fig. 7B is a diagram showing the shape of fixing flange 71b after being connected. Although not visible in Figs. 7A and 7B, fixing flange 71a also has the same shape as fixing flange 71b shown in Figs. 7A and 7B.

[0023] In radiators 7a and 7b, the thickness dimensions of the fixing flanges 71a and 71b are all set to t1. And the thickness dimension t1 of the fixing flanges 71a and 71b is set to be smaller than the thickness dimension t2 of the main body portion 70 in which the flow path 700 is formed. Therefore, when a pair of opposing fixing flanges 71b are connected by bolts 11 and nuts 12 and the tightening torque of the bolts 11 is increased, the fixing flanges 71a and 71b having relatively low bending rigidity compared to the main body portion 70 elastically deform toward the power module 100C side so as to approach each other as indicated by the arrows (see FIG. 7B). Here, bending rigidity is used as an index of ease of deformation, but the second moment of area, section modulus, etc. may also be used as indices.

[0024] The main body portion 70 of the radiators 7a and 7b is pressed against the power modules 100A to 100C by the elastic force due to the elastic deformation of the fixing flanges 71a and 71b. Thus, by applying surface pressure between the radiators 7a and 7b and the power modules 100A to 100C, the heat conduction efficiency from the power modules 100A to 100C to the radiators 7a and 7b is improved.

[0025] In the fixed state shown in FIG. 7B, the surface-to-surface distance d2 between the fixing flanges 71b at the bolt-fixed portion is smaller than the surface-to-surface distance d1 of the main body portion 70 in which the flow path 700 of the radiators 7a and 7b is formed (d2 < d1). The same applies to the fixing flange 71a. That is, in the fixed state shown in FIG. 7B, a deformed bent portion 712 (the portion surrounded by the broken line) occurs between the root region 713 on the main body portion 70 side and the bolt-fixed region 714 of the fixing flange 71b. Therefore, the deformation of the main body portion 70 in which the flow path 700 of the radiators 7a and 7b is formed is suppressed, and the uniformity of the surface pressure with respect to the power module 100C is obtained.

[0026] 1, of the multiple fixing flanges 71a, 71b arranged in the longitudinal direction of the heat sinks 7a, 7b, the width dimension W2 of the fixing flanges 71b arranged at both longitudinal ends is set smaller than the width dimension W1 of the fixing flange 71a arranged on the inner side in the longitudinal direction. In other words, the bending rigidity of the fixing flanges 71b is set smaller than the bending rigidity of the fixing flanges 71a, so that, in the fixed state, bending in the longitudinal direction of the main body 70 of the heat sinks 7a, 7b can be prevented.

[0027] For example, consider a case where the width dimensions of multiple fixing flanges 171a, 171b arranged along the longitudinal direction are all set to the same value W2, as in heat sinks 17a, 17b shown in Figures 8A and 8B. That is, all of fixing flanges 171a, 171b are set to a thickness dimension t1 and a width dimension W2. In this case, when a pair of fixing flanges 171a, 171b facing each other in the Z direction are connected and fixed to each other, if the amounts of deformation of fixing flanges 171a, 171b are the same, the elastic force F1 of fixing flange 171a and the elastic force F2 of fixing flange 171b acting on heat sink 17a will be equal, i.e., F1 = F2.

[0028] In this way, when the elastic force F2 acting near both ends of the heat sink 17a is equal to the elastic force F1 acting at the inner position, the heat sink 17a deforms to be curved convexly upward as shown in Fig. 8B. The same applies to the lower heat sink 17b, which is curved convexly downward. Therefore, the surface pressure applied from the heat sinks 17a and 17b to each of the power modules 100A to 100C is large at both ends in the heat sink's longitudinal direction and decreases toward the center, resulting in uneven heat dissipation performance in the longitudinal direction and raising concerns about deterioration of the heat dissipation performance of the power modules near the center.

[0029] 1, by setting the width W2 of the fixing flanges 71b at both ends smaller than the width W1 of the fixing flanges 71a, that is, by making the bending rigidity of the fixing flanges 71a greater than the bending rigidity of the fixing flanges 71b, it is possible to make the elastic force F2 of the fixing flanges 71b smaller than the elastic force F1 of the fixing flanges 71a (F1>F2) even if the deformation amounts of the fixing flanges 71a, 71b in the connected and fixed state are the same. As a result, it is possible to suppress bending deformation in the longitudinal direction of the main body 70 of the heat sinks 7a, 7b, and to uniformize the surface pressure on the multiple power modules 100A to 100C arranged in the longitudinal direction.

[0030] Of course, even in a configuration such as W1 = W2 as shown in Figure 8A, it is theoretically possible to suppress longitudinal bending deformation of the main body 70 by not setting the deformation amounts when connecting and fixing each fixing flange 71a, 71b to be the same and by controlling the tightening torque of each bolt 11 so that the elastic forces F1, F2 due to deformation satisfy F1 > F2. However, assembling while controlling the tightening torque of each bolt 11 becomes cumbersome and reduces workability. On the other hand, setting W1 > W2 as shown in Figure 1 and controlling the dimensions so that the distance between all fixing flanges 71a, 71b after connecting and fixing is d2 (see Figure 7B) is superior in assembly workability and easier to control.

[0031] As described above, in this embodiment, the fixing flanges 71a, 71b are integrally formed with the main body 70 of the heat sinks 7a, 7b, and the fixing flanges 71a, 71b are elastically deformed to fix the heat sinks 7a, 7b. This makes it possible to press the heat sinks 7a, 7b against the power modules 100A-100C to generate compressive surface pressure without the need for additional pressing members such as leaf springs as in the conventional case. This also reduces the number of components in the semiconductor device 1 and reduces costs.

[0032] Furthermore, in the present embodiment, the width dimensions W1 and W2 are set such that W1 > W2 so that the bending rigidity of the fixing flange 71b is smaller than that of the fixing flange 71a. As a result, the surface pressure on the plurality of power modules 100A to 100C arranged side by side in the longitudinal direction of the radiator can be made uniform, and the heat dissipation performance can be improved.

[0033] (Modification Example 1) FIG. 9 is a diagram showing Modification Example 1 of the above-described embodiment. As shown in FIG. 7B, the interval between the opposing fixing flanges 71a and 71b in the connected and fixed state is set to d2 for all. Therefore, in Modification Example 1, a spacer 13 as shown in FIG. 9 is provided at the bolt fixing portion so that the interval d2 can be easily managed. The shape of the spacer 13 is a columnar body with an annular cross-sectional shape and a length of d2. The spacer 13 is disposed between the fixing flanges 71a and 71b of the radiator 7a and the fixing flanges 71a and 71b of the radiator 7b, and the bolt 11 is inserted through the through hole 130 of the spacer 13 and the nut 12 is tightened. Then, the upper and lower fixing flanges 71a and 71b are deformed so as to approach each other, and the nut 12 is tightened until the spacer 13 is sandwiched between them, thereby completing the connection and fixing. By using such a spacer 13, the interval between the upper and lower fixing flanges 71a and 71b can be easily set to an accurate value d2.

[0034] (Modification Example 2) FIG. 10 is a diagram showing Modification Example 2. In Modification Example 2, the fixing flanges 71a and 71b are formed in a tapered shape in which the width dimensions at the root portions are W1 and W2 and the width dimension becomes smaller as it approaches the tip. In Modification Example 2, by forming the fixing flanges 71a and 71b in a tapered shape with width dimensions of W1 and W2 (<W1) at the root portions, the elastic force of the fixing flange 71b can be made smaller than the elastic force of the fixing flange 71a, and the bending deformation of the main body portions 70 of the radiators 7a and 7b as shown in FIG. 8B can be suppressed.

[0035] In Modification 2, the fixing flanges 71a, 71b are tapered so that the width decreases from the base to the tip, thereby reducing the weight of the heat sinks 7a, 7b. Furthermore, tapering the fixing flanges 71a, 71b makes it possible to increase the space for drawing the terminals 111-115 out to the side of the semiconductor device 1, facilitating the terminal connection work.

[0036] (Variation 3) 11A and 11B are diagrams showing a heat sink 7a in Modification 3. FIG. 11A is a plan view of the heat sink 7a. FIG. 11B is a side view of the heat sink 7a. Although not shown, the heat sink 7b also has a shape similar to that of the heat sink 7a, and the configuration of the semiconductor device 1 other than the heat sinks 7a and 7b is the same as that of the above-described embodiment. In the above-described embodiment and Modification 2, the width dimensions of the fixing flanges 71a and 71b are made different so that the elastic force caused by deformation of the fixing flanges 71b at both ends is smaller than the elastic force caused by deformation of the inner fixing flange 71a.

[0037] In Modification 3, as shown in Fig. 11A, fixing flanges 71a and 71b are set to have the same width (W2), and by making their thicknesses different as shown in Fig. 11B, the bending rigidity of fixing flanges 71b at both ends is made smaller than the bending rigidity of fixing flange 71a. As shown in Fig. 11B, thickness t1 of fixing flange 71b is smaller than thickness t3 of fixing flange 71a, and for the same amount of deformation, the elastic force of fixing flange 71b is smaller than the elastic force of fixing flange 71a.

[0038] 11A and 11B, fixing flange 71b has a uniform thickness t1 from the base to the tip of the flange, but it may have a cross-sectional shape as shown in Figures 12A and 12B. Figures 12A and 12B are cross-sectional views of a portion of heat sink 7a where fixing flange 71b is provided.

[0039] The fixing flange 71b shown in Fig. 12A is formed by processing, such as pressing, a part of the root region of the flange portion formed in the same shape as the fixing flange 71a (thickness dimension t3) except for other parts to a thickness dimension t1. A step 715 is formed in the fixing flange 71b by processing, such as pressing. When the fixing flange 71b is connected and fixed to the opposing fixing flange 71b, the thin portion 716 with the thickness dimension t1 is deformed. Therefore, during deformation, an elastic force similar to that of the fixing flange 71b shown in Fig. 11B is generated.

[0040] The fixing flange 71b shown in Fig. 12B is formed by processing, such as pressing, the middle portion in the length direction of the flange portion formed in the same shape as the fixing flange 71a (thickness dimension t3) to a thickness dimension t1. A recess 717 with a thickness dimension t1 is formed in the fixing flange 71b by processing, such as pressing. When the fixing flange 71b is connected and fixed to the opposing fixing flange 71b, the recess 717 is deformed, generating an elastic force similar to that of the fixing flange 71b shown in Fig. 11B.

[0041] (Modified Example 4) Figs. 13A and 13B are diagrams showing Modified Example 4. Fig. 13A is a plan view of the semiconductor device 1. Fig. 13B is a view of the semiconductor device 1 seen from the side, with the heat sink 7a shown in cross-section. The illustration of the terminals 111 to 115 of the power modules 100A to 100C is omitted. In the case of Modified Example 4 as well, similar to the case of Modified Example 3 (see Fig. 11B), the width dimensions of the fixing flanges 71a and 71b are all set to the same value W2, the thickness dimension of the fixing flange 71a is set to t3, and the thickness dimension of the fixing flange 71b is set to t1 (<t3).

[0042] As shown in Figs. 13A and 13B, on the surfaces of the heat sinks 7a and 7b facing the power modules 100A to 100C, convex portions 718 extending in the Y direction (the short side direction of the heat sinks 7a and 7b) are formed. The height of the convex portion 718 is h, and the width dimension is the same as that of the fixing flanges 71a and 71b, which is W2. The power modules 100A to 100C are arranged between adjacent convex portions 718.

[0043] 13A and 13B, the positions of the fixing flanges 71a and 71b in the radiator longitudinal direction (X direction) are set to the same position as the protrusion 718, and the surfaces of the fixing flanges 71a and 71b and the protrusion 718 facing the power module are on the same plane. In other words, the fixing flanges 71a and 71b are formed so as to be continuous with the protrusion 718. Of course, the protrusion 718 may be formed on the main body 70 of the radiators 7a and 7b of the above-described embodiment and modifications 1 to 3.

[0044] By forming the protrusions 718 extending in the Y direction on the main body 70 of the heat sinks 7a, 7b, it is possible to increase the bending rigidity of the main body 70 against deformation along the short side direction (Y direction) of the main body 70, and to suppress deformation of the main body 70 due to the elastic force of the fixing flanges 71a, 71b. Furthermore, the power modules 100A to 100C can be positioned in the X direction using the protrusions 718, thereby improving the ease of assembly.

[0045] The longitudinal position of the protrusion 718 does not have to be the same as the position of the fixing flanges 71 a, 71 b. Also, instead of forming the protrusion 718 integrally with the main body 70 of the heat sinks 7 a, 7 b, the protrusion 718 may be formed by joining a separate member to the main body 70.

[0046] (Variation 5) Fig. 14 is a diagram showing Modification 5. In the above-described embodiment and modifications, the width and thickness dimensions of fixing flanges 71a and 71b are made different so that the bending rigidity of fixing flange 71b is smaller than the bending rigidity of fixing flange 71a. In Modification 5, as shown in Fig. 14, the length dimension L2 of fixing flange 71b is set larger than the length dimension L1 of fixing flange 71a, so that the bending rigidity of fixing flange 71b is smaller than the bending rigidity of fixing flange 71a.

[0047] (Variation 6) FIG. 15 is a diagram showing a sixth modification. In the above-described embodiment and modifications, the main body 70 of the heat sinks 7a and 7b is provided with a plurality of flow paths 700 through which the coolant flows. On the other hand, in the sixth modification, as shown in FIG. 15, the heat sinks 7a and 7b are configured to have heat dissipation fins 720 on the front surface side of the main body 70 (the surface opposite to the surface facing the power module). The other configurations are the same as those of the heat sinks 7a and 7b shown in FIG. 6 of the above-described embodiment. In the example shown in FIG. 15, the heat dissipation fins 720 are configured as pin fins, but they may also be straight fins or corrugated fins.

[0048] The heat sinks 7a and 7b are made of materials with good thermal conductivity, such as composites of Cu, Cu alloy, Cu-C, Cu-CuO, etc., or composites of Al, Al alloy, AlSiC, Al-C, etc. In the case of the heat sinks 7a and 7b having such heat sink fins 720, the thickness t1 of the fixing flanges 71a and 71b is set to be larger than the plate thickness t2 of the main body 70 so that the bending rigidity of the main body 70 facing the power modules 100A to 100C is larger than the bending rigidity of the fixing flanges 71a and 71b.

[0049] (Variation 7) 16 is a diagram showing Modification 7. In the above-described embodiments and modifications, the power modules 100A to 100C are provided with heat dissipation surfaces 300 on both the front and back sides, and heat dissipators 7a, 7b are provided on both the front and back sides of the power modules 100A to 100C. On the other hand, the semiconductor device 1 of Modification 7 is a semiconductor device with a single-sided cooling structure in which a heat dissipator is provided on only one side of the power module.

[0050] In a power module 200 provided in the semiconductor device 1 shown in FIG. 16, a back surface electrode of a power semiconductor element 210 is joined to a conductor 3 by a bonding material 2. A thermally conductive insulating layer 4 is provided on a heat dissipation surface 300 of the conductor 3. The back surface side of the insulating layer 4 is exposed from the sealing resin 10, and a thermally conductive layer 5 is provided on the exposed surface. A heat sink 7 is provided on the back surface side of the power module 200 via the thermally conductive layer 5. Fixing flanges 71a and 71b of the heat sink 7 are fixed to a plate 230 provided on the front surface side of the power module 200 by bolts 11 and nuts 12.

[0051] In the case of the seventh modification, as in the above-described embodiment and modifications, the bending rigidity of fixing flanges 71b provided at both longitudinal ends of heat sink 7 is set to be smaller than the bending rigidity of fixing flange 71a provided on the inner side in the longitudinal direction. That is, the elastic force of fixing flange 71b in the fixed state is smaller than the elastic force of fixing flange 71a, so that deformation of heat sink 7 as shown in FIG. 8B can be prevented.

[0052] In the above-described embodiments and variants, examples have been shown in which the sealing resin 10 includes the insulating layer 4 and all but the surface of the insulating layer 4 is sealed, but the structure may also be such that the conductors 3a to 3c and the conductor 3 are sealed in the sealing resin 10, and the insulating layer 4 covers the heat dissipation surface 300 exposed from the sealing resin 10.

[0053] Furthermore, in the above-described embodiment and modified example, an example has been described in which a plurality of power semiconductor elements are provided in the power module, but the present invention can also be similarly applied to a semiconductor device including a power module having only one power semiconductor element.

[0054] According to the embodiment and the modified example of the present invention described above, the following advantageous effects can be achieved.

[0055] (C1) As shown in FIGS. 1, 6, etc., the semiconductor device 1 includes a plurality of power modules 100A to 100C each having a heat dissipation surface 300 and each incorporating a power semiconductor element 121L and a diode 122L, heat dissipators 7a and 7b in thermal contact with the heat dissipation surfaces 300 of the plurality of power modules 100A to 100C arranged in a row, and bolts 11 and nuts 12 as fixing members for fixing the heat dissipators 7a and 7b so as to press them against the heat dissipation surfaces 300. The heat dissipators 7a and 7b are fixed to the power modules 100A to 100C. and a plurality of cantilever-shaped fixing flanges 71a, 71b formed integrally with the main body 70 along the direction of arrangement of the plurality of power modules 100A to 100C and having a bending rigidity smaller than that of the main body 70. The bolts 11 and nuts 12 fix the radiators 7a, 7b so that the fixing flanges 71a, 71b elastically deform, causing the elastic force of the fixing flanges 71a, 71b to press the main body 70 against the heat dissipation surfaces 300 of the power modules 100A to 100C.

[0056] Fixing flanges 71a, 71b are formed on the main body 70 of the heat sinks 7a, 7b, and the main body 70 is pressed against the heat dissipation surface 300 of the power modules 100A to 100C by the elastic force generated when the fixing flanges 71a, 71b are elastically deformed. This makes it possible to press the main body 70 of the heat sinks 7a, 7b against the power module without the need for a separate biasing member such as a spring plate, as in the conventional case. As a result, the number of parts of the semiconductor device and the cost can be reduced.

[0057] (C2) In (C1) above, as shown in Figure 7A, etc., the thickness dimension t1 of the fixing flanges 71a, 71b is set smaller than the thickness dimension t2 of the main body portion 70, thereby setting the bending rigidity of the fixing flanges 71a, 71b smaller than the bending rigidity of the main body portion 70.

[0058] (C3) In (C1) above, as shown in Fig. 10 etc., the widths W1, W2 of the fixing flanges 71a, 71b are set to be smaller as they approach the tip of the cantilever beam shape. As a result, it is possible to increase the space for drawing out the terminals 111-115 provided on the power modules 100A-100C to the side of the semiconductor device 1, making it easier to connect the terminals.

[0059] (C4) In (C1) above, as shown in Fig. 7B etc., fixing flanges 71a, 71b of heat sinks 7a, 7b fixed by bolts 11 and nuts 12, which are fixing members, have bent portions 712 due to elastic deformation between root regions 713 of the cantilever shape and fixed regions 714 by bolts 11. Since the bending rigidity of fixing flanges 71a, 71b is smaller than the bending rigidity of main body 70, when fixed by the bolts, fixing flanges 71a, 71b elastically deform, generating bent portions 712. The elastic force of bent portions 712 presses main body 70 toward the power module.

[0060] (C5) In (C4) above, as shown in Figures 6, 7A, 7B, etc., the heat dissipation surface 300 is provided on both the front and back sides of the power modules 100A to 100C in the thickness direction, and includes a first heat sink 7a pressed against the heat dissipation surface 300 on the front side and a second heat sink 7b pressed against the heat dissipation surface 300 on the back side, and the inter-surface distance d2 between the fixing region 714 of the fixing flanges 71a, 71b provided on the first heat sink 7a and the fixing region 714 of the fixing flanges 71a, 71b provided on the second heat sink 7b is set to be smaller than the inter-surface distance d1 between the first heat sink 7a and the second heat sink 7b. Therefore, in the fixed state, the elastic force of the deformed fixing flanges 71a, 71b presses the heat sinks 7a, 7b toward the heat dissipation surface 300 of the power modules 100A to 100C.

[0061] (C6) In (C4) above, as shown in Fig. 16 etc., a plate 230 is further provided which is provided so as to abut against one surface of the power module 200 in the thickness direction, and to which the fixing flanges 71a, 71b are connected and fixed by bolts 11 and nuts 12, a heat dissipation surface 300 against which the heat dissipator 7 is pressed is provided on the other surface of the power module 200 in the thickness direction, and a surface-to-surface distance d12 between the fixing regions 714 of the fixing flanges 71a, 71b provided on the heat dissipator 7 and the plate 230 is set to be smaller than a surface-to-surface distance d11 between the main body 70 of the heat dissipator 7 and the plate 230. Therefore, in the fixed state, the heat dissipator 7 is pressed in the direction of the heat dissipation surface 300 of the power module 200 by the elastic force of the deformed fixing flanges 71a, 71b.

[0062] (C7) In (C1) above, as shown in Fig. 1 etc., among the multiple fixing flanges 71a, 71b provided along the arrangement direction (X direction) of the power modules 100A to 100C, the fixing flanges 71b arranged at both ends in the X direction have a bending rigidity set smaller than the bending rigidity of the other fixing flanges 71a arranged on the inside. Therefore, in the fixed state, it is possible to prevent bending of the main body 70 of the heat sinks 7a, 7b in the longitudinal direction.

[0063] (C8) In (C7) above, as shown in Fig. 1 etc., the thickness dimensions of the multiple fixing flanges 71a, 71b are equal, and the width dimension W2 of the fixing flanges 71b arranged at both ends in the arrangement direction of the power modules 100A to 100C is set smaller than the width dimension W1 of the other fixing flanges 71a arranged on the inside. With this configuration, the bending rigidity of the fixing flanges 71b is set smaller than the bending rigidity of the fixing flanges 71a.

[0064] 11A, 11B, etc., the width dimension W2 of each of the fixing flanges 71a, 71b is equal, and the thickness dimension t1 of the fixing flanges 71b arranged at both ends in the arrangement direction of the power modules 100A to 100C is set smaller than the thickness dimension t3 of the other fixing flanges 71a arranged on the inside. With this configuration, the bending rigidity of the fixing flanges 71b is set smaller than the bending rigidity of the fixing flanges 71a.

[0065] (C10) In (C7) above, as shown in Fig. 14 etc., the width dimension W2 of each of the fixing flanges 71a, 71b is equal, and the length dimension L2 of the fixing flanges 71b arranged at both ends in the arrangement direction of the power modules 100A to 100C is set to be larger than the length dimension L1 of the other fixing flanges 71a arranged on the inside. With this configuration, the bending rigidity of the fixing flanges 71b is set to be smaller than the bending rigidity of the fixing flanges 71a.

[0066] (C11) In (C7) above, as shown in Figures 12A, 12B, etc., fixing flanges 71b arranged at both ends in the arrangement direction of power modules 100A to 100C have thin-walled portions 716 and recessed portions 717 whose thickness dimension is smaller than that of root region 713 between cantilever-shaped root region 713 and fixed region 714 by bolt 11 and nut 12. Therefore, fixing flange 71b bends at these thin-walled portions 716 and recessed portions 717, and has a lower bending rigidity than fixing flange 71a with thickness dimension t3.

[0067] (C12) In (C9) above, as shown in FIGS. 13A, 13B, etc., the main body 70 has a protrusion 718 extending in a direction (Y direction) perpendicular to the arrangement direction (X direction) on the surface on the power modules 100A-100C side in an area where the power modules 100A-100C do not face, and the fixing flanges 71a, 71b are formed so as to be continuous with the protrusion 718. By providing the main body 70 with the protrusion 718 extending in the Y direction, the bending rigidity of the main body 70 along the Y direction is improved. Furthermore, the protrusion 718 can be used as a positioning portion when arranging the power modules 100A, 100C, thereby improving the ease of assembly.

[0068] (C13) In (C1) above, as shown in Fig. 9 etc., a spacer 13 is further provided that restricts the amount of deformation of the fixing flanges 71a, 71b by the bolts 11 and nuts 12 to a predetermined value d2. By using the spacer 13, the distance between the upper and lower fixing flanges 71a, 71b can be easily set to the accurate value d2, thereby improving workability.

[0069] The above-described embodiments and various modifications are merely examples, and the present invention is not limited to these, and the above-described embodiments and modifications may be combined as long as the features of the invention are not impaired. Furthermore, although various embodiments and modifications have been described above, the present invention is not limited to these. Other aspects conceivable within the scope of the technical idea of ​​the present invention are also included within the scope of the present invention. [Explanation of symbols]

[0070] 1...semiconductor device, 3, 3a to 3d...conductor, 7, 7a, 7b, 17a, 17b...heat sink, 10...sealing resin, 11...bolt, 12...nut, 13...spacer, 70...main body, 71a, 71b, 171a, 171b...fixing flange, 100, 100A to 100C, 200...power module, 121U, 121L, 210...power semiconductor element, 122U, 122L...diode, 230...plate, 300...heat dissipation surface, 712...bent portion, 713...root region, 714...fixing region, 715...step, 716...thin portion, 717...recess, 718...protrusion, 720...heat dissipation fin

Claims

1. a plurality of semiconductor modules each having a heat dissipation surface and each incorporating a power semiconductor element; a heat sink in thermal contact with the heat dissipation surfaces of the semiconductor modules arranged in a row; a fixing member that fixes the heat sink so as to press it against the heat sink surface, The heat sink is a heat dissipation base portion that is pressed against the heat dissipation surface of the semiconductor module; a plurality of cantilever-shaped fixing flange portions formed integrally with the heat dissipating base portions along the direction of arrangement, the fixing flange portions having a bending rigidity smaller than that of the heat dissipating base portions; The fixing member fixes the heat sink so that the fixing flange portion is elastically deformed and the elastic force of the fixing flange portion presses the heat dissipation base portion against the heat dissipation surface of the semiconductor module.

2. 2. The semiconductor device according to claim 1, The thickness of the fixing flange portion is set smaller than the thickness of the heat dissipation base portion.

3. 2. The semiconductor device according to claim 1, The width dimension of the fixing flange portion is set to a smaller value as it approaches the tip of the cantilever beam shape.

4. 2. The semiconductor device according to claim 1, The fixing flange portion of the heat sink fixed by the fixing member has a bent portion due to elastic deformation between a base region of the cantilever shape and a region fixed by the fixing member.

5. 5. The semiconductor device according to claim 4, the heat dissipation surfaces are provided on both the front and back surfaces of the semiconductor module in the thickness direction, a first heat sink pressed against the heat sink surface on the front side, and a second heat sink pressed against the heat sink surface on the back side; a surface-to-surface distance between the fixing area of ​​the fixing flange portion provided on the first heat sink and the fixing area of ​​the fixing flange portion provided on the second heat sink is set to be smaller than a surface-to-surface distance between the heat dissipation base portion of the first heat sink and the heat dissipation base portion of the second heat sink.

6. 5. The semiconductor device according to claim 4, a plate provided in contact with one surface of the semiconductor module in a thickness direction, the plate being connected and fixed to the fixing flange portion by the fixing member; the heat dissipation surface against which the heat sink is pressed is provided on the other surface in the thickness direction of the semiconductor module, a surface-to-surface distance between the fixing region of the fixing flange portion provided on the heat sink and the plate is set smaller than a surface-to-surface distance between the heat sink base portion of the heat sink and the plate.

7. 2. The semiconductor device according to claim 1, A semiconductor device, wherein, of the plurality of fixing flange portions arranged along the direction of arrangement, the bending rigidity of the fixing flange portions arranged at both ends in the direction of arrangement is set to be smaller than the bending rigidity of the other fixing flange portions.

8. 8. The semiconductor device according to claim 7, A semiconductor device in which the thickness dimensions of each of the multiple fixing flange portions are equal, and the width dimensions of the fixing flange portions arranged at both ends in the arrangement direction are set smaller than the width dimensions of the other fixing flange portions.

9. 8. The semiconductor device according to claim 7, A semiconductor device in which the width dimensions of each of the multiple fixing flange portions are equal, and the thickness dimensions of the fixing flange portions arranged at both ends in the arrangement direction are set smaller than the thickness dimensions of the other fixing flange portions.

10. 8. The semiconductor device according to claim 7, A semiconductor device in which the width dimensions of each of the multiple fixing flange portions are equal, and the length dimensions of the fixing flange portions arranged at both ends in the arrangement direction are set larger than the length dimensions of the other fixing flange portions.

11. 8. The semiconductor device according to claim 7, The fixing flange portions arranged at both ends in the arrangement direction have a thin-walled portion between the cantilever-shaped root region and the fixing region by the fixing member, the thickness dimension of which is smaller than that of the root region.

12. 10. The semiconductor device according to claim 9, the heat dissipation base portion has a plurality of protrusions extending in a direction perpendicular to the arrangement direction in an area of ​​the surface on the semiconductor module side that does not face the semiconductor modules, The fixing flange portion is formed so as to be continuous with the protrusion portion.

13. 2. The semiconductor device according to claim 1, The semiconductor device further includes a restricting portion that restricts the amount of deformation of the fixing flange portion caused by the fixing member to a predetermined value.

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