Semiconductor device

Abstract

The semiconductor device includes: a plurality of semiconductor modules having built-in power semiconductor elements and having a heat dissipation surface; a heat sink in thermal contact with the heat dissipation surfaces of the plurality of semiconductor modules arranged in a row; and a fixing member that fixes the heat sink so as to press the heat sink against the heat dissipation surface. The heat sink has a heat dissipation base portion pressed against the heat dissipation surface of the semiconductor module, and a plurality of cantilever beam-shaped fixing flange portions formed integrally with the heat dissipation base portion in the arrangement direction and having a bending rigidity smaller than that of the heat dissipation base portion, and the fixing member fixes the heat sink. The heat dissipation base portion is pressed against the heat dissipation surface of the semiconductor module by means of the elastic force of the fixing flange portion so that the fixing flange portion is elastically deformed and the heat dissipation base portion is pressed against the heat dissipation surface of the semiconductor module by means of the elastic force of the fixing flange portion.

Description

Technical Field

[0001] The present invention relates to semiconductor devices. Background Art

[0002] In recent years, hybrid vehicles and electric vehicles are being promoted to reduce the load on the environment. In hybrid vehicles and electric vehicles, the miniaturization and low cost of the components carried are emphasized, and the semiconductor devices in the power conversion device are no exception, requiring miniaturization and low cost. In order to miniaturize the semiconductor devices with high heat generation among the electronic components constituting the power conversion device, it is necessary to improve the cooling performance. Therefore, in such semiconductor devices, cooling devices such as radiators and coolers are generally provided for cooling semiconductor modules with built-in power semiconductor elements.

[0003] For example, Patent Document 1 discloses a structure in which a semiconductor module having a built-in power semiconductor element is clamped by a pair of cooling tubes, and the cooling tubes are pressed against the semiconductor module by a pressing plate. By providing the pressing plate, a compressive force is generated at the contact surface between the heat dissipation surface of the semiconductor module and the cooling tube, so that the heat dissipation surface and the cooling tube are in close contact. Furthermore, by making it so that the pressing plate is pressed against the semiconductor module by the force of a spring member, the close contact is improved. Prior art literature Patent Literature

[0004] Patent Document 1: Japanese Patent Application Publication No. 2009-182312 Summary of the invention Technical problem to be solved by the invention

[0005] However, the technology of Patent Document 1 requires a pressing plate and a spring member in order to ensure close contact, which leads to problems of an increase in the number of components and an increase in cost. Technical means for solving technical problems

[0006] The semiconductor device of the present invention comprises: a plurality of semiconductor modules, each of which has a built-in power semiconductor element and a heat dissipation surface; a heat sink, which is in thermal contact with the heat dissipation surfaces of the plurality of semiconductor modules arranged in a row; and a fixing member, which fixes the heat sink in a manner of pressing the heat sink against the heat dissipation surface, the heat sink comprising a heat dissipation base portion pressed against the heat dissipation surface of the semiconductor module, and a plurality of cantilever beam-shaped fixing flange portions which are integrally formed with the heat dissipation base portion along the direction of the arrangement and have a bending rigidity smaller than that of the heat dissipation base, the fixing member fixing the heat sink so that the fixing flange portion is elastically deformed, and the heat dissipation base portion can be pressed against the heat dissipation surface of the semiconductor module by utilizing the elastic force of the fixing flange portion. Effects of the Invention

[0007] According to the present invention, it is possible to reduce the number of components of a semiconductor device and reduce the cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a plan view showing an example of a semiconductor device. Figure 2 is a circuit diagram showing an example of a circuit configuration of a power module. Figure 3 It is a plan view showing the appearance of the power module. Figure 4 yes Figure 3 BB cross-sectional view. Figure 5 yes Figure 1 AA section view. Figure 6 yes Figure 1 CC cross-sectional view. Fig. 7A It is a figure which shows the shape of the fixing flange before being fastened with bolts and nuts. Figure 7B It is a figure which shows the shape of the fixing flange after connection. Fig. 8A This is a top view of a semiconductor device when the width dimensions of all the fixing flanges are the same. Figure 8B It is a figure explaining deformation|transformation of a heat sink. Fig. 9 It is a diagram showing modification example 1. Fig.10 It is a diagram showing modification example 2. Fig.11A 3 is a top view of a heat sink in Modification 3. Fig. 11B It is a side view of the heat sink in Modification 3. Fig. 12A This is a diagram showing another structure of Modification Example 3. Fig. 12B This is a diagram showing another structure of Modification Example 3. Fig.13A It is a top view showing modification example 4. Fig. 13B This is a diagram of a semiconductor device according to Modification 4 as viewed from the side. Fig.14 It is a diagram showing modification example 5. Fig.15 It is a diagram showing modification example 6. Fig.16 It is a diagram showing modification example 7. DETAILED DESCRIPTION

[0009] Hereinafter, with reference to the accompanying drawings, the mode for implementing the present invention will be described. The following description and the accompanying drawings are examples for illustrating the present invention, and for the clarity of the description, they are appropriately omitted and simplified. In addition, in the following description, the same or similar elements and processes are marked with the same symbols, and repeated descriptions are sometimes omitted. The content of the following description always represents an example of an embodiment of the present invention, and the present invention is not limited to the following embodiments, and various other modes may also be implemented.

[0010] Figure 1 1 is a top view showing an example of a semiconductor device 1 according to the present embodiment. In the following, the coordinate axes are set such that the long side direction of the semiconductor device 1 is set as the X direction, the short side direction of the semiconductor device 1 is set as the Y direction, and the height direction of the semiconductor device 1 is set as the Z direction. The semiconductor device 1 according to the present embodiment is provided in an inverter circuit of a power conversion device mounted on an electric vehicle or a hybrid vehicle, for example. The power conversion device performs power conversion between a DC power supply and an electric generator for driving the vehicle (for example, a rotating motor of a three-phase AC type). The power conversion device includes a smoothing capacitor and an inverter circuit as a power converter. The inverter circuit converts the input DC power into a three-phase AC of a specified frequency and outputs it to the electric generator. Figure 1 The semiconductor device 1 is provided in an inverter circuit and includes three-phase power modules 100A, 100B, and 100C.

[0011] Figure 2 1 is a circuit diagram showing an example of a circuit structure of a power module 100A. Power modules 100A to 100C have the same structure. The circuit of the power module 100A is composed of 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 composed of, for example, insulated gate bipolar transistors (IGBTs), MOSFETs, etc. The power semiconductor element 121U of the upper arm 100U is controlled to be on and off by a control signal input to the upper arm control terminal 114. Similarly, the power semiconductor element 121L of the lower arm 100L is controlled to be on and off by a control signal input to the lower arm control terminal 115.

[0012] The external connection P terminal 111 of the upper arm 100U is connected to the high potential power line of the DC power supply, and the external connection N terminal 112 of the lower arm 100L is connected to the 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 an AC current is output from the external connection AC terminal 113 to an external device (such as a motor). On the DC power line, a capacitor or the like is connected in parallel to the upper and lower arms 100U and 100L.

[0013] Figure 3 1 is a top view showing the appearance of the power module 100A. Figure 4 yes Figure 3 BB cross-sectional view. The power semiconductor elements 121U, 121L and the diodes 122U, 122L of the power module 100A are sealed with a sealing resin 10 formed of an electrical 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. On both the front and back surfaces of the power module 100A, an insulating layer 4 is arranged in a manner exposed from the sealing resin 10.

[0014] like Figure 4 As shown in the BB cross-sectional view, the surface electrode of the power semiconductor element 121U is bonded to the conductor 3a through the bonding material 2. The back electrode of the power semiconductor element 121U is connected to the conductor 3b through the bonding material 2. Similarly, the surface electrode of the diode 122L is bonded to the conductor 3c through the bonding material 2. The back electrode of the diode 122L is bonded to the conductor 3d through the bonding material 2. The conductors 3a to 3d are formed, for example, of copper, copper alloy or aluminum, aluminum alloy, etc. The bonding material 2 is formed of solder, sintered material, etc. Although omitted from the figure, the electrodes on the front and back sides of the diode 122U are bonded to the conductors 3a and 3b in the same way as the power semiconductor element 121U. In addition, the electrodes on the front and back sides of the power semiconductor element 121L are bonded to the conductors 3c and 3d in the same way as the diode 122L.

[0015] The conductors 3a to 3d have an element bonding surface and a heat dissipation surface 300 on the opposite side of the surface. A heat 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 is a layer that conducts heat generated from the semiconductor element (121U, 122U, 121L, 122U) to the heat dissipation members (heat sinks 7a and 7b described later) arranged on the front and back sides of the power module 100A, and is formed of a material with high thermal conductivity and high insulation withstand voltage. For example, ceramics such as aluminum oxide (alumina), aluminum nitride, silicon nitride, or an insulating sheet or adhesive containing fine powders of these can be used.

[0016] return Figure 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] Figure 5 yes Figure 1 AA section view. Figure 6 yes Figure 1 CC section view of Figure 5 As shown, the power modules 100A to 100C are sealed by the sealing resin 10 so that the insulating layer 4 covering the heat dissipation surface 300 of the conductors 3a to 3d is exposed on the surface (see Figure 4 A heat conducting layer 5 is provided on the surface of the insulating layer 4 exposed from the sealing resin 10. For the heat conducting layer 5, a good heat conducting member such as grease or thermal interface material (TIM) is used.

[0018] The heat sinks 7a and 7b are provided so as to sandwich the power modules 100A, 100B, and 100C provided with the heat conducting layer 5. In the present embodiment, a cooler having a flow path 700 for the flow of a coolant in a main body 70 is used as the heat sink 7a and 7b. Figure 6 As shown, a plurality of flow paths 700 extending along the longitudinal direction (X direction) are formed in the main body 70 of the heat sink 7a, 7b.

[0019] like Figure 1 As shown in FIG. 1 , a plurality of fixing flanges 71a and 71b are formed on the side surface of the main body 70 of the heat sink 7a in the Y direction and are arranged at predetermined intervals in the long side direction of the heat sink 7a. The fixing flanges 71a and 71b are cantilever-shaped flanges and are formed so as to protrude from the main body 70 to the side (Y direction). Figure 1 Although not visible in the figure, the heat sink 7b is provided on the back side of the power modules 100A to 100C. The heat sink 7b also has similar fixing flanges 71a and 71b formed at positions opposite to the fixing flanges 71a and 71b of the heat sink 7a (see FIG. Figure 6 ). The thickness dimensions of the plurality of fixing flanges 71a and 71b are the same. However, regarding the width dimension, the width dimension W2 of the fixing flanges 71b disposed at both ends in the longitudinal direction is set to be smaller than the width dimension W1 of the other fixing flanges 71a disposed further inward in the longitudinal direction than the two ends.

[0020] Through holes 711 for inserting bolts 11 are formed in each of the fixing flanges 71a and 71b. Figure 6As shown, the fixing flanges 71a and 71b of the heat sink 7a are connected and fixed to the fixing flanges 71a and 71b of the heat sink 7b by using bolts 11 and nuts 12, thereby fixing the heat sinks 7a and 7b on both sides of the power modules 100A to 100C arranged in a row.

[0021] The heat sinks 7a and 7b are formed of a member having thermal conductivity, for example, a composite material such as Cu, Cu alloy, Cu-C, Cu-CuO, or a composite material such as Al, Al alloy, AlSiC, Al-C, etc. The heat generated in the power modules 100A to 100C is thermally conducted to the main body 70 of the heat sinks 7a and 7b via the insulating layer 4 and the heat conducting layer 5, and is dissipated to the coolant flowing through the flow path 700.

[0022] Fig. 7A It is a figure which shows the shape of the fixing flange 71b before being fastened with the bolt 11 and the nut 12. Figure 7B 71b is a diagram showing the shape of the fixing flange 71b after connection. Fig. 7A , 7B Although not visible in the figure, the shape of the fixing flange 71a is also similar to Fig. 7A , 7B The fixing flange 71b shown is the same. In the heat sinks 7a and 7b, the thickness dimensions of the fixing flanges 71a and 71b are all set to t1. Moreover, 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 70 in which the flow path 700 is formed. Therefore, the pair of fixing flanges 71b facing each other are connected to each other by the bolts 11 and the nuts 12. If the tightening torque of the bolts 11 is increased, the fixing flanges 71a and 71b, which have relatively low bending rigidity compared to the main body 70, are elastically deformed toward the power module 100C side in a manner close to each other as shown by the arrows (refer to FIG. 1 ). Figure 7B ). Here, bending rigidity is used as an indicator of the ease of deformation, but the secondary moment of area, section modulus, etc. may also be used as an indicator.

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

[0025] exist Figure 7BIn the fixed state shown, the distance d2 between the faces of the fixing flanges 71b in the bolt-fixed part is smaller than the distance d1 between the faces of the main body part 70 forming the flow paths 700 of the radiators 7a and 7b (d2 < d1). The same applies to the fixing flange 71a. That is, in Figure 7B In the fixed state shown, a deformed bent part 712 (the part surrounded by the dashed line) is generated between the root region 713 on the main body part 70 side and the bolt fixing region 714 of the fixing flange 71b. Therefore, deformation of the main body part 70 forming the flow paths 700 of the radiators 7a and 7b can be suppressed, and uniformity of the surface pressure with respect to the power module 100C can be obtained.

[0026] In addition, as Figure 1 shown, among the plurality of fixing flanges 71a and 71b arranged in the longitudinal direction of the radiators 7a and 7b, the width dimension W2 of the fixing flanges 71b arranged at both ends in the longitudinal direction is set to be smaller than the width dimension W1 of the fixing flanges 71a arranged inside them in the longitudinal direction. That is, since the bending rigidity of the fixing flange 71b is set to be smaller than the bending rigidity of the fixing flange 71a, in the fixed state, bending of the main body part 70 of the radiators 7a and 7b in the longitudinal direction can be prevented.

[0027] For example, consider the case where, as Fig. 8A 、 8B shown, the width dimensions of the plurality of fixing flanges 171a and 171b arranged along the longitudinal direction of the radiators 17a and 17b are all set to the same value W2. That is, the thickness dimension of all the fixing flanges 171a and 171b is set to t1, and the width dimension is set to W2. In this case, when connecting and fixing a pair of fixing flanges 171a and 171b facing each other in the Z direction, if the deformation amounts of the fixing flanges 171a and 171b are the same, the elastic forces F1 applied to the fixing flange 171a of the radiator 17a and the elastic force F2 of the fixing flange 171b are equal as F1 = F2.

[0028] As a result, when the elastic force F2 acting near both ends of the radiator 17a is equal to the elastic force F1 acting on the inner position, as Figure 8B shown, the radiator 17a deforms in an upwardly convex bending manner. The same applies to the lower radiator 17b, which bends downward in a convex manner. Therefore, the surface pressure applied from the radiators 17a and 17b to each of the power modules 100A to 100C is larger at both ends in the longitudinal direction of the radiator and smaller as it approaches the center, and the heat dissipation performance in the longitudinal direction becomes non-uniform, and there is a concern that the heat dissipation performance deteriorates in the power module near the center.

[0029] On the other hand, as Figure 1As shown, by setting the width dimension W2 of the fixing flanges 71b at both ends smaller than the width dimension W1 of the fixing flange 71a, that is, by making the bending rigidity of the fixing flange 71a larger than the bending rigidity of the fixing flange 71b, even if the deformation amounts of the fixing flanges 71a and 71b in the connected and fixed state are the same, the elastic force F2 of the fixing flange 71b can be made smaller than the elastic force F1 of the fixing flange 71a (F1>F2). As a result, the bending deformation of the main body 70 of the heat sink 7a and 7b in the long side direction can be suppressed, and the surface pressure on the plurality of power modules 100A to 100C arranged in the long side direction can be made uniform.

[0030] Of course, if Fig. 8A As shown, even if the structure is such that W1=W2, the deformation amount when connecting and fixing the fixing flanges 71a and 71b is not set to be the same, and the tightening torque of each bolt 11 is managed so that the elastic forces F1 and F2 generated by the deformation become F1>F2, which can theoretically suppress the bending deformation in the long side direction of the main body 70. However, it becomes complicated to perform the assembly work while managing the tightening torque of each bolt 11, which will lead to a decrease in workability. On the other hand, Figure 1 As shown in FIG. 1 , W1>W2 is set, and the dimensions of all fixing flanges 71a and 71b are managed so that the interval after connection and fixing is d2 (see FIG. 1 ). Figure 7B ), excellent assembly workability and easy management.

[0031] As described above, in this embodiment, the fixing flanges 71a and 71b are integrally formed on the main body 70 of the heat sink 7a and 7b, and the fixing flanges 71a and 71b are elastically deformed to fix the heat sink 7a and 7b. As a result, it is not necessary to additionally provide a pressing member such as a leaf spring as in the past, and the heat sink 7a and 7b can be pressed against the power module 100A to 100C to generate a compressive surface pressure. In addition, the number of components of the semiconductor device 1 can be reduced and the cost can be reduced.

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

[0033] (Variant 1) Fig. 9 FIG. 1 is a diagram showing a first modification of the above-mentioned embodiment. Figure 7B As shown in FIG. 1 , the intervals between the fixing flanges 71a and 71b facing each other in the connected and fixed state are all set to d2. Therefore, in the first modification, in order to facilitate the management of the interval d2, Fig. 9 The spacer 13 shown is provided on the bolt fixing portion. The shape of the spacer 13 is a columnar body having a circular ring cross-sectional shape and a length d2. The spacer 13 is arranged between the fixing flanges 71a, 71b of the heat sink 7a and the fixing flanges 71a, 71b of the heat sink 7b, and the bolt 11 is inserted into the through hole 130 of the spacer 13 and the nut 12 is tightened. Moreover, the upper and lower fixing flanges 71a, 71b are deformed in a manner close to each other, and the connection and fixing are completed by tightening the nut 12 until the spacer 13 is clamped therebetween. By using such a spacer 13, the interval between the upper and lower fixing flanges 71a, 71b can be easily set to an accurate value d2.

[0034] (Variant 2) Fig.10 : is a diagram showing a second modification. In the second modification, the fixing flanges 71a and 71b are formed into a tapered shape with the width dimensions W1 and W2 at the root portion and the width dimension becoming smaller as it approaches the tip. In the second modification, by forming the fixing flanges 71a and 71b into a tapered shape with the width dimensions W1 and W2 (<W1) at the root portion, the elastic force of the fixing flange 71b can be made smaller than the elastic force of the fixing flange 71a, and the elastic force of the fixing flange 71b can be suppressed. Figure 8B The main body 70 of the heat sink 7a, 7b is shown to be bent.

[0035] Furthermore, in Modification 2, by forming the fixing flanges 71a and 71b into a tapered shape with a decreasing width from the root portion to the tip portion, the heat sinks 7a and 7b can be made lighter. In addition, by forming the fixing flanges 71a and 71b into a tapered shape, the space for leading the terminals 111 to 115 to the side of the semiconductor device 1 can be further increased, making the terminal connection operation easier.

[0036] (Variant 3) Fig.11A , 11B It is a diagram showing a heat sink 7a in a third modification. Fig.11A It is a top view of the heat sink 7a. Fig. 11B 7a. Although not shown in the figure, the heat sink 7b also has the same shape as the heat sink 7a, and the structure of the semiconductor device 1 other than the heat sinks 7a and 7b is the same as that of the above-mentioned embodiment. In the above-mentioned embodiment and modification 2, by making the width dimensions of the fixing flanges 71a and 71b different, the elastic force generated by the deformation of the fixing flanges 71b at both ends is smaller than the elastic force generated by the deformation of the fixing flange 71a on the inside.

[0037] In variation 3, if Fig.11A As shown in FIG. 1 , the width dimensions of the fixing flanges 71a and 71b are set to be the same (W2). Fig. 11B As shown in FIG. 1 , by making the thickness dimensions different, the bending rigidity of the fixing flanges 71b at both ends is made smaller than the bending rigidity of the fixing flanges 71a. Fig. 11B As shown, the thickness dimension t1 of the fixing flange 71b is smaller than the thickness dimension t3 of the fixing flange 71a. Under the condition of the same deformation amount, the elastic force of the fixing flange 71b is smaller than the elastic force of the fixing flange 71a.

[0038] exist Fig.11A , 11B In the example shown, the thickness of the fixing flange 71b is set to be the same thickness dimension t1 from the flange root portion to the front end portion. Alternatively, Fig. 12A , 12B The cross-sectional shape shown. Fig. 12A , 12B It is a cross-sectional view of a portion of the heat sink 7a where the fixing flange 71b is provided.

[0039] Fig. 12A The fixing flange 71b shown is formed into a flange portion having the same shape as the fixing flange 71a (thickness dimension t3) by stamping, etc., except for a portion of the root region, and processed to have a thickness dimension t1. The fixing flange 71b is formed with a step 715 by stamping, etc. When the fixing flange 71b is connected and fixed to the opposite fixing flange 71b, the thin-walled portion 716 of the thickness dimension t1 is deformed. Therefore, when deformed, a step 715 is formed. Fig. 11B The same elastic force is applied to the fixing flange 71b shown. Fig. 12B The fixing flange 71b shown in the figure is formed by pressing a flange portion having the same shape as the fixing flange 71a (thickness dimension t3) and a middle portion in the longitudinal direction thereof being processed to have a thickness dimension t1. A recessed portion 717 having a thickness dimension t1 is formed on the fixing flange 71b by pressing a recessed portion 717 having a thickness dimension t1. When the fixing flange 71b is connected and fixed to the opposite fixing flange 71b, the recessed portion 717 is deformed to produce a shape similar to that of the fixing flange 71a. Fig. 11B The same elastic force is applied to the fixing flange 71b shown.

[0041] (Variant 4) Fig.13A , 13B It is a diagram showing modification example 4. Fig.13A It is a top view of the semiconductor device 1 . Fig. 13B The semiconductor device 1 is viewed from the side, and the heat sink 7a is a cross-sectional view. The terminals 111 to 115 of the power modules 100A to 100C are omitted. 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] like Fig.13A , 13B As shown, a convex portion 718 extending in the Y direction (the short side direction of the heat sink 7a, 7b) is formed on the surface of the heat sink 7a, 7b on the side opposite to the power modules 100A to 100C. The height of the convex portion 718 is h, and the width dimension is the same as that of the fixing flanges 71a, 71b, both of which are W2. The power modules 100A to 100C are arranged between the convex portion 718 and the adjacent convex portion 718.

[0043] exist Fig.13A , 13B In the case of the heat sinks 7a and 7b shown in the figure, the positions of the fixing flanges 71a and 71b in the long side direction (X direction) of the heat sink are set at the same position as the convex portion 718, and the surfaces of the fixing flanges 71a and 71b and the convex portion 718 on the power module side are on the same plane. That is, the fixing flanges 71a and 71b are formed to be continuous with the convex portion 718. Of course, the convex portion 718 may be formed on the main body 70 of the heat sinks 7a and 7b of the above-mentioned embodiment and modified examples 1 to 3.

[0044] By forming the convex portion 718 extending in the Y direction on the main body 70 of the heat sink 7a, 7b, the bending rigidity against deformation of the main body 70 in the short-side direction (Y direction) can be improved, and deformation of the main body 70 caused by the elastic force of the fixing flanges 71a, 71b can be suppressed. In addition, since the power modules 100A to 100C can be positioned in the X direction using the convex portion 718, the assembly workability can be improved.

[0045] The position of the convex portion 718 in the longitudinal direction may not be the same as the position of the fixing flanges 71a and 71b. In addition, instead of forming the convex portion 718 integrally with the main body 70 of the heat sink 7a and 7b, the convex portion 718 may be formed by joining another member to the main body 70.

[0046] (Variant 5) Fig.14 2 is a diagram showing a fifth modification. In the above-mentioned embodiment and modification, the width and thickness of the fixing flanges 71a and 71b are different, and the bending rigidity of the fixing flange 71b is smaller than that of the fixing flange 71a. Fig.14As shown, by setting the length dimension L2 of the fixing flange 71b to be larger than the length dimension L1 of the fixing flange 71a, the bending rigidity of the fixing flange 71b is made smaller than the bending rigidity of the fixing flange 71a. (Variant 6) Fig.15 2 is a diagram showing a sixth modification. In the above-mentioned embodiment and modification, a plurality of flow paths 700 for the flow of the coolant are provided on the main body 70 of the radiator 7a, 7b. On the other hand, in the sixth modification, Fig.15 As shown in the figure, the heat sink 7a, 7b is configured to have a heat sink 720 on the surface side of the main body 70 (the surface opposite to the surface facing the power module). Figure 6 The heat sinks 7a, 7b shown are identical. Fig.15 In the example shown, the heat sink 720 is formed by pin-shaped fins, but 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 Cu, Cu alloy, Cu-C, Cu-CuO and other composite materials, or Al, Al alloy, AlSiC, Al-C and other composite materials. In the case of the heat sinks 7a and 7b having such heat sinks 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] (Variant 7) Fig.16 1 is a diagram showing a modification example 7. In the above-mentioned embodiments and modifications, the power modules 100A to 100C are provided with heat dissipation surfaces 300 on both sides, and heat sinks 7a and 7b are provided on both sides. On the other hand, the semiconductor device 1 of the modification example 7 is a semiconductor device with a single-sided cooling structure having a heat sink only on one side of the power module.

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

[0051] In the case of the modification 7, as in the case of the above-mentioned embodiment or the modification, the bending rigidity of the fixing flanges 71b provided at both ends in the long-side direction of the heat sink 7 is set to be smaller than the bending rigidity of the fixing flanges 71a provided on the inner side in the long-side direction. That is, since the elastic force of the fixing flanges 71b in the fixed state is smaller than the elastic force of the fixing flanges 71a, it is possible to prevent the fixing flanges 71a from being bent. Figure 8B A variation of the heat sink 7 is shown.

[0052] In the above-mentioned embodiments and modifications, an example is shown in which the sealing resin 10 contains the insulating layer 4 and the surface of the insulating layer 4 is sealed, but it can also be a structure in which the structure up to the conductors 3a~3c or the conductor 3 is sealed by 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 examples, a case where a plurality of power semiconductor elements are provided in a power module is described as an example, 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 effects are achieved.

[0055] (C1) Figure 1 , 6 As shown in the figures, the semiconductor device 1 includes: a plurality of power modules 100A to 100C having a built-in power semiconductor element 121L and a diode 122L and having a heat dissipation surface 300; heat sinks 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; bolts 11 and nuts 12 as fixing members for fixing the heat sinks 7a and 7b by pressing them against the heat dissipation surfaces 300, and the heat sinks 7a and 7b have a heat dissipation surface 300 pressed against the power modules 100A to 100C. A main body 70 is formed on the heat dissipation surface 300 of the power modules 100A to 100C, and a plurality of cantilever beam-shaped fixing flanges 71a and 71b are formed integrally with the main body 70 along the arrangement direction of the plurality of power modules 100A to 100C and have a lower bending rigidity than the main body 70. Bolts 11 and nuts 12 fix the heat sinks 7a and 7b so that the fixing flanges 71a and 71b are elastically deformed, and the main body 70 is pressed against the heat dissipation surface 300 of the power modules 100A to 100C by the elastic force of the fixing flanges 71a and 71b.

[0056] Since the fixing flanges 71a and 71b are formed on the main body 70 of the heat sink 7a and 7b, the main body 70 is pressed against the heat dissipation surface 300 of the power module 100A to 100C by the elastic force when the fixing flanges 71a and 71b are elastically deformed, and therefore, it is not necessary to separately provide a biasing member such as a spring plate as in the past, and the main body 70 of the heat sink 7a and 7b can be pressed against the power module. As a result, the number of components of the semiconductor device can be reduced and the cost can be reduced.

[0057] (C2) In the above (C1), if Fig. 7A As shown in FIG. 1 and FIG. 2 , by setting the thickness dimension t1 of the fixing flanges 71 a and 71 b to be smaller than the thickness dimension t2 of the main body 70 , the bending rigidity of the fixing flanges 71 a and 71 b is set to be smaller than the bending rigidity of the main body 70 .

[0058] (C3) In the above (C1), if Fig.10 As shown in FIG. 1 , the width dimensions W1 and W2 of the fixing flanges 71a and 71b are set to be smaller as they approach the tip of the cantilever beam shape. As a result, the space for leading the terminals 111 to 115 provided on the power modules 100A to 100C to the side of the semiconductor device 1 can be further increased, making it easier to perform terminal connection work.

[0059] (C4) In the above (C1), if Figure 7B As shown in FIG. 1 and FIG. 2 , the fixing flanges 71a and 71b of the heat sinks 7a and 7b fixed by the bolts 11 and nuts 12 as fixing members have a bent portion 712 caused by elastic deformation between the root region 713 of the cantilever beam shape and the fixing region 714 formed by the bolts 11. Since the bending rigidity of the fixing flanges 71a and 71b is lower than the bending rigidity of the main body 70, when the bolts are fixed, the fixing flanges 71a and 71b are elastically deformed to form the bent portion 712. The elastic force of the bent portion 712 presses the main body 70 toward the power module.

[0060] (C5) In (C4) above, if Figure 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 on the heat dissipation surface 300 on the front side, and a second heat sink 7b pressed on the heat dissipation surface 300 on the back side, and the surface distance d2 between the fixing area 714 of the fixing flanges 71a and 71b provided on the first heat sink 7a and the fixing area 714 of the fixing flanges 71a and 71b provided on the second heat sink 7b is set to be smaller than the surface distance d1 between the first heat sink 7a and the second heat sink 7b. Therefore, in the fixed state, the heat sinks 7a and 7b are pressed toward the heat dissipation surface 300 of the power modules 100A to 100C by the elastic force of the deformed fixing flanges 71a and 71b.

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

[0062] (C7) In the above (C1), if Figure 1 As shown in FIG. 1 and FIG. 2 , among the plurality of fixing flanges 71a and 71b provided along the direction (X direction) in which the power modules 100A to 100C are arranged, the bending rigidity of the fixing flanges 71b arranged at both ends in the X direction is set to be smaller than the bending rigidity of the fixing flanges 71a arranged on the other inner sides. Therefore, in the fixed state, the main body 70 of the heat sink 7a and 7b can be prevented from bending in the long side direction.

[0063] (C8) In (C7) above, if Figure 1 As shown in the figure, the thickness dimensions of the plurality of fixing flanges 71a and 71b are equal, and the width dimension W2 of the fixing flanges 71b arranged at both ends of the arrangement direction of the power modules 100A to 100C is set smaller than the width dimension W1 of the fixing flanges 71a arranged on the other inner sides. By adopting such a structure, the bending rigidity of the fixing flange 71b is set smaller than the bending rigidity of the fixing flange 71a.

[0064] (C9) In (C7) above, if Fig.11A ,11B As shown in the figure, the width dimensions W2 of each of the plurality of fixing flanges 71a and 71b are 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 to be smaller than the thickness dimension t3 of the fixing flanges 71a arranged on the other inner sides. By adopting such a structure, the bending rigidity of the fixing flange 71b is set to be smaller than the bending rigidity of the fixing flange 71a.

[0065] (C10) In the above (C7), if Fig.14 As shown in the figure, the width dimensions W2 of each of the plurality of fixing flanges 71a and 71b are equal, and the length dimension L2 of the fixing flanges 71b arranged at both ends of the arrangement direction of the power modules 100A to 100C is set to be larger than the length dimension L1 of the fixing flanges 71a arranged on the other inner sides. By adopting such a structure, the bending rigidity of the fixing flange 71b is set to be smaller than the bending rigidity of the fixing flange 71a.

[0066] (C11) In the above (C7), if Fig. 12A , 12B As shown in FIG. 1 and FIG. 2 , the fixing flanges 71b disposed at both ends of the power modules 100A to 100C in the arrangement direction have thin-walled portions 716 and recessed portions 717 having a smaller thickness dimension than the root region 713 between the root region 713 of the cantilever beam shape and the fixing region 714 formed by the bolts 11 and the nuts 12. Therefore, the fixing flanges 71b are bent at the thin-walled portions 716 and the recessed portions 717, and the bending rigidity is smaller than that of the fixing flanges 71a having a thickness dimension t3.

[0067] (C12) In the above (C9), if Fig.13A , 13B As shown in the figures, the main body 70 has a convex portion 718 extending in a direction (Y direction) orthogonal to the arrangement direction (X direction) in an area on the surface of the power modules 100A to 100C side where the power modules 100A to 100C are not opposite, and the fixing flanges 71a and 71b are formed to be continuous with the convex portion 718. By providing the convex portion 718 extending in the Y direction on the main body 70, the bending rigidity of the main body 70 along the Y direction is improved. In addition, the convex portion 718 can be used as a positioning portion when arranging the power modules 100A and 100C, and the assembly workability can be improved. (C13) In the above (C1), if Fig. 9As shown in the figures, the spacer 13 is further included, which limits the deformation of the fixing flanges 71a and 71b caused by the bolts 11 and the nuts 12 to a predetermined value d2. By using the spacer 13, the interval between the upper and lower fixing flanges 71a and 71b can be easily set to an accurate value d2, which can improve the workability.

[0069] Each embodiment and various modifications described above are only examples. As long as the features of the invention are not impaired, the present invention is not limited to these contents, and the above-mentioned embodiments and modifications may also be combined. In addition, although various embodiments and modifications are described above, the present invention is not limited to these contents. Other modes that can be considered within the scope of the technical concept of the present invention are also included in the scope of the present invention. Description of symbols 1…semiconductor device, 3, 3a to 3d…conductors, 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…flat plate, 300…heat dissipation surface, 712…bend portion, 713…root region, 714…fixing region, 715…step, 716…thin wall portion, 717…recessed portion, 718…convex portion, 720…heat sink.

Claims

1. A semiconductor device, characterized in that: include: A plurality of semiconductor modules, each of which has a built-in power semiconductor element and a heat dissipation surface; a heat sink in thermal contact with the heat dissipation surfaces of the plurality of semiconductor modules arranged in a row; as well as a fixing member that fixes the heat sink by pressing the heat sink against the heat dissipation surface, The radiator has: a heat dissipation base portion pressed against the heat dissipation surface of the semiconductor module; as well as A plurality of cantilever beam-shaped fixing flange portions are formed integrally with the heat dissipation base portion along the arrangement direction and have a bending rigidity smaller than that of the heat dissipation base. The fixing member fixes the heat sink so that the fixing flange portion is elastically deformed and the heat dissipation base portion is pressed against the heat dissipation surface of the semiconductor module by the elastic force of the fixing flange portion.

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

3. The semiconductor device according to claim 1, wherein: The width dimension of the fixing flange portion is set to a value that becomes smaller as it approaches the front end of the cantilever beam shape.

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

5. The semiconductor device according to claim 4, wherein: The heat dissipation surface is arranged on both the front and back sides of the semiconductor module in the thickness direction. The heat dissipation device includes a first heat sink pressed against the heat dissipation surface on the front side and a second heat sink pressed against the heat dissipation surface on the back side. The inter-surface distance between the fixing region of the fixing flange portion provided on the first heat sink and the fixing region of the fixing flange portion provided on the second heat sink is set to be smaller than the inter-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. The semiconductor device according to claim 4, wherein: It also includes a flat plate, which is arranged to abut against one surface of the semiconductor module in the thickness direction, and is connected and fixed to the fixing flange portion by the fixing member. The heat dissipation surface of the heat sink is pressed to be arranged on the other surface in the thickness direction of the semiconductor module, The inter-plane distance between the fixing region of the fixing flange portion provided on the heat sink and the flat plate is set to be smaller than the inter-plane distance between the heat dissipation base portion of the heat sink and the flat plate.

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

8. The semiconductor device according to claim 7, wherein: The plurality of fixing flanges have the same thickness dimension, and the fixing flanges disposed at both ends in the arrangement direction have width dimensions that are smaller than the width dimensions of the other fixing flanges.

9. The semiconductor device according to claim 7, wherein: The plurality of fixing flanges have the same width dimensions, and the fixing flanges disposed at both ends in the arrangement direction have thickness dimensions that are smaller than the thickness dimensions of the other fixing flanges.

10. The semiconductor device according to claim 7, wherein: The plurality of fixing flanges have the same width dimensions, and the fixing flanges disposed at both ends in the arrangement direction have length dimensions greater than those of the other fixing flanges.

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

12. The semiconductor device according to claim 9, wherein The heat dissipation base has a plurality of protrusions extending in a direction perpendicular to the arrangement direction in a region of a surface of the semiconductor module side that does not face the semiconductor module. The fixing flange portion is formed to be continuous with the convex portion.

13. The semiconductor device according to claim 1, wherein: The invention 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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