Semiconductor module, power conversion device, and method for manufacturing semiconductor module

Abstract

The present disclosure provides a semiconductor module which uses a warped base plate having a plurality of fins formed thereon, and in which a degradation in heat dissipating performance can be suppressed. A semiconductor module 100 according to the present disclosure comprises: a semiconductor element S1; an insulating substrate 10 on which the semiconductor element S1 is mounted; and a heat sink H1. The heat sink H1 has a plurality of fins 71 and a base plate 70. The insulating substrate 10 is joined to a main surface 7s of the base plate 70. The base plate 70 is warped on the basis of a difference in expansion coefficient from the insulating substrate 10. The plurality of fins 71 are formed on a rear surface 7r of the warped base plate 70. Distal ends of the plurality of fins 71 are arranged on the same plane.

Description

[Technical field]

[0001] The present disclosure relates to a semiconductor module that uses a heat sink having a base plate on which a plurality of fins are formed, a power conversion device, and a method for manufacturing the semiconductor module. [Background technology]

[0002] Power modules are becoming more and more popular as modules mounted on products such as industrial equipment, home appliances, and information terminals, and high productivity is required for these products. For example, modules mounted on electric vehicles are required to have high heat dissipation properties. For example, a water-cooled heat sink is used for the modules. The water-cooled heat sink includes a base plate for heat dissipation.

[0003] The base plate is formed with a plurality of fins. The fins are elongated in shape. The fins are, for example, pin fins. The water-cooled heat sink is configured so that a water-cooled jacket can be attached to the base plate.

[0004] The water-cooled jacket has an internal space for accommodating a plurality of fins. The water-cooled jacket also has an internal bottom surface facing the internal space. The internal bottom surface is flat. The internal space of the water-cooled jacket is filled with cooling water.

[0005] Patent Documents 1 and 2 disclose a configuration using a water-cooled heat sink having a base plate on which a plurality of fins are formed.

[0006] A water-cooled jacket is attached to the base plate of the water-cooled heat sink. Hereinafter, the state in which the water-cooled jacket is attached to the base plate of the water-cooled heat sink is also referred to as the "attached state." In the attached state, a plurality of fins formed on the base plate are housed in the internal space. Also, in the attached state, the tips of the plurality of fins face the internal bottom surface. Also, in the attached state, a gap exists between the tips of the fins and the internal bottom surface. Also, in the attached state, the internal space is filled with cooling water. Also, in the attached state, the cooling water flows in the internal space filled with the cooling water.

[0007] Hereinafter, the configuration disclosed in Patent Document 1 will also be referred to as "related configuration A." Also, below, the configuration disclosed in Patent Document 2 will also be referred to as "related configuration B." [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2004-273479 A [Patent Document 2] JP 2012-248576 A Summary of the Invention [Problem to be solved by the invention]

[0009] In products such as industrial equipment, for example, a semiconductor module having a configuration in which an insulating substrate is bonded to a base plate of a water-cooled heat sink is used. In such semiconductor modules, warping may occur in the base plate on which a number of fins are formed. This warping occurs when the insulating substrate is bonded to the base plate in a situation in which there is a large difference between the linear expansion coefficients of the insulating substrate and the base plate.

[0010] In a mounting state in which a water-cooled jacket is mounted on a base plate of related configurations A and B, if the base plate is warped, the positions of the tips of the multiple fins will vary in the longitudinal direction of the fins. In this case, in the mounting state, there is variation in the size of the gaps between the tips of the fins and the inner bottom surface over the entire inner bottom surface of the water-cooled jacket. If such variation exists, the flow of cooling water will be disturbed in the water-cooled jacket in the mounting state. In this case, there is a problem that the heat dissipation performance of the semiconductor module will be reduced.

[0011] The present disclosure has been made to solve such problems, and aims to provide a semiconductor module etc. that uses a warped base plate having multiple fins formed thereon and that is capable of suppressing a decrease in the heat dissipation performance of the semiconductor module. [Means for solving the problem]

[0012] In order to achieve the above-mentioned object, a semiconductor module according to one embodiment of the present disclosure comprises a semiconductor element, an insulating substrate on which the semiconductor element is mounted, and a heat sink, the heat sink having a plurality of fins and a base plate, the base plate having a main surface and a back surface, the back surface of the base plate being the surface of the base plate opposite the main surface, the insulating substrate being bonded to the main surface of the base plate, the base plate being warped based on the difference in expansion coefficient with the insulating substrate, a plurality of fins being formed on the back surface of the warped base plate, and the tips of the plurality of fins being aligned on the same plane. Effect of the Invention

[0013] According to the present disclosure, an insulating substrate is bonded to a main surface of a base plate of a heat sink. The base plate is warped based on a difference in coefficient of expansion between the insulating substrate and the base plate. A plurality of fins are formed on the rear surface of the warped base plate. Tips of the plurality of fins are aligned on the same plane.

[0014] Here, assume that a water-cooled jacket having a flat inner bottom surface is attached to a warped base plate. As described above, the tips of the fins are aligned on the same plane. Therefore, in the water-cooled jacket attached to the warped base plate, there is no variation in the size of the gaps between the tips of the fins and the inner bottom surface of the water-cooled jacket over the entire inner bottom surface.

[0015] Therefore, it is possible to prevent the flow of cooling water from being disturbed in the water-cooled jacket when it is installed, and thus it is possible to prevent a decrease in the heat dissipation performance of a semiconductor module that uses a warped base plate on which a plurality of fins are formed.

[0016] The objects, features, aspects, and advantages of the present disclosure will become more apparent from the following detailed description and the accompanying drawings. [Brief description of the drawings]

[0017] [Figure 1] 1 is a diagram for explaining a configuration of a semiconductor module according to a first embodiment. [Diagram 2] 2 is a flowchart of a manufacturing method according to the first embodiment. [Diagram 3] 5A to 5C are cross-sectional views illustrating a manufacturing method of the semiconductor module according to the first embodiment. [Figure 4] 5A to 5C are cross-sectional views illustrating a manufacturing method of the semiconductor module according to the first embodiment. [Diagram 5] 11 is a cross-sectional view of a semiconductor module having a configuration of a first modified example. [Figure 6] 13A to 13C are diagrams for explaining a method for manufacturing a semiconductor module according to Modification 2. [Figure 7] FIG. 11 is a cross-sectional view of a semiconductor module according to a second embodiment. [Figure 8] 10A to 10C are cross-sectional views for illustrating a manufacturing method of a semiconductor module according to a second embodiment. [Figure 9] FIG. 11 is a cross-sectional view of a semiconductor module having a configuration of a third modified example. [Figure 10] FIG. 11 is a cross-sectional view of a semiconductor module according to a third embodiment. [Figure 11] FIG. 11 is a plan view of a semiconductor module according to a third embodiment. [Figure 12] FIG. 2 is a cross-sectional view showing a heat sink having a base plate in an unbonded state. [Figure 13] FIG. 11 is a block diagram showing a configuration of a power conversion system to which a power conversion device according to a fourth embodiment is applied. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, an embodiment will be described with reference to the drawings. In the following drawings, the same components are given the same reference numerals. The components given the same reference numerals have the same names and functions. Therefore, detailed descriptions of some of the components given the same reference numerals may be omitted.

[0019] The dimensions, materials, shapes, and relative positions of the components illustrated in the embodiments may be changed as appropriate depending on the configuration of the device, various conditions, etc. Furthermore, the dimensions of the components in the drawings may differ from the actual dimensions.

[0020] <Embodiment 1> (composition) 1 is a diagram for explaining the configuration of a semiconductor module 100 according to the first embodiment. The semiconductor module 100 is, for example, a power semiconductor module that operates at a high voltage. Note that the semiconductor module 100 is not limited to a power semiconductor module, and may be, for example, a semiconductor module that operates at a low voltage.

[0021] Fig. 1(a) is a cross-sectional view of a semiconductor module 100 according to embodiment 1. In Fig. 1(a), a water-cooling jacket 80 that is not included in the semiconductor module 100 is shown.

[0022] In FIG. 1(a), the X direction, the Y direction, and the Z direction are mutually orthogonal. The X direction, the Y direction, and the Z direction shown in the following figures are also mutually orthogonal. In the following, the direction including the X direction and the opposite direction of the X direction (-X direction) is also referred to as the "X-axis direction". In the following, the direction including the Y direction and the opposite direction of the Y direction (-Y direction) is also referred to as the "Y-axis direction". In the following, the direction including the Z direction and the opposite direction of the Z direction (-Z direction) is also referred to as the "Z-axis direction".

[0023] In the following, the plane including the X-axis direction and the Y-axis direction is also referred to as the "XY plane." In the following, the plane including the X-axis direction and the Z-axis direction is also referred to as the "XZ plane." In the following, the plane including the Y-axis direction and the Z-axis direction is also referred to as the "YZ plane."

[0024] Fig. 1(b) is a plan view of the semiconductor module 100 according to the embodiment 1. In order to make the configuration of the semiconductor module 100 easier to understand, a resin 8 serving as a sealing resin (described below) is not shown in Fig. 1(b).

[0025] As shown in FIGS. 1(a) and 1(b), the semiconductor module 100 includes a case 5, electrodes 6a and 6b, a heat sink H1, an insulating substrate 10, a plurality of semiconductor elements S1, wires W1 and W2, and a resin 8.

[0026] The case 5 has a cylindrical shape, for example. The case 5 has a closed loop shape in plan view. The case 5 is made of, for example, PPS (Poly Phenylene Sulfide) resin. The case 5 has a thickness of, for example, 6 mm. The outline of the case 5 has a rectangular shape in plan view. The size of the rectangle that is the shape of the case 5 is, for example, a size that can be expressed as "60 mm x 45 mm".

[0027] Electrodes 6a and 6b are provided in the case 5 by insert molding. The electrode 6a is an external electrode. The electrode 6b is a signal electrode. Hereinafter, each of the electrodes 6a and 6b will also be referred to as "electrode 6." The electrode 6 is made of, for example, copper. The electrode 6 has an elongated shape. The electrode 6 is bent.

[0028] The heat sink H1 is a water-cooled heat sink. The heat sink H1 has heat dissipation fins. The heat sink H1 has a plurality of fins 71 and a base plate 70.

[0029] The base plate 70 has a plate-like shape. The shape of the base plate 70 in a plan view is, for example, rectangular. The base plate 70 has a main surface 7s and a back surface 7r. The back surface 7r of the base plate 70 is the surface of the base plate 70 opposite to the main surface 7s.

[0030] The base plate 70 is made of, for example, an aluminum alloy. The thickness of the base plate 70 is, for example, 3 mm. The shape of the base plate 70 in plan view is rectangular. The size of the rectangle that is the shape of the base plate 70 is, for example, a size expressed as "60 mm x 45 mm". A main surface 7s of the base plate 70 is, for example, nickel-plated. Note that the main surface 7s of the base plate 70 does not have to be nickel-plated.

[0031] The base plate 70 of the present embodiment has the same thickness throughout the entire base plate 70. The linear expansion coefficient of the base plate 70 is, for example, 23 ppm / K.

[0032] The insulating substrate 10 is bonded to the main surface 7s of the base plate 70 via a bonding material b2. That is, the insulating substrate 10 is bonded to the main surface 7s of the base plate 70. The bonding material b2 is, for example, solder. The melting point of the solder that is the bonding material b2 is, for example, 217°C. The solder is made of tin, silver, and copper. The composition ratio of the solder that is the bonding material b2 is expressed as "96.5% tin, 3% silver, and 0.5% copper."

[0033] Hereinafter, the state of the base plate 70 in which the insulating substrate 10 is bonded to the main surface 7s of the base plate 70 will also be referred to as a “bonded state.” Figure 1(a) shows the base plate 70 in the bonded state.

[0034] The insulating substrate 10 is a substrate having insulating properties. The insulating substrate 10 is, for example, a ceramic substrate. The linear expansion coefficient of the insulating substrate 10 is smaller than the linear expansion coefficient of the base plate 70. The linear expansion coefficient of the insulating substrate 10 corresponds to the linear expansion coefficient of a base material 11, which is included in the insulating substrate 10 and will be described later. The linear expansion coefficient of the insulating substrate 10 is, for example, a value included in the range of 5 ppm / K to 8 ppm / K. Hereinafter, the difference between the linear expansion coefficient of the insulating substrate 10 and the linear expansion coefficient of the base plate 70 is also referred to as the "expansion coefficient difference."

[0035] In the manufacturing process of the semiconductor module 100, when the insulating substrate 10 is bonded to the main surface 7s of the base plate 70, a warp A occurs in the base plate 70 due to a difference in expansion coefficient. The warp A is a warp that expresses an upward convexity. As described above, FIG. 1(a) shows the base plate 70 in a bonded state. The base plate 70 in the bonded state is warped. In other words, the base plate 70 in the bonded state is curved. Hereinafter, the warped state of the base plate 70 will also be referred to as a "warped state." FIG. 1(a) shows the base plate 70 in a warped state.

[0036] The insulating substrate 10 includes a base material 11, a plurality of conductor layers 12, and a conductor layer 13. The base material 11 has a plate shape. The base material 11 has a thickness of, for example, 0.64 mm. The base material 11 is made of, for example, aluminum nitride.

[0037] A plurality of conductor layers 12 are formed on the upper surface of the base material 11 by brazing. Each conductor layer 12 is made of, for example, copper. The thickness of each conductor layer 12 is, for example, 0.8 mm. A conductor layer 13 is formed on the lower surface of the base material 11 by brazing. The conductor layer 13 is made of, for example, copper. The thickness of the conductor layer 13 is, for example, 0.8 mm.

[0038] A semiconductor element S1 is mounted on the insulating substrate 10. Specifically, a plurality of semiconductor elements S1 are mounted on each conductor layer 12 of the insulating substrate 10 by a bonding material b1. The configuration of the bonding material b1 is the same as the configuration of the bonding material b2. The bonding material b1 is, for example, solder. The material constituting the bonding material b1 is the same as the material constituting the bonding material b2.

[0039] Each of the semiconductor elements S1 is, for example, a semiconductor chip. Each of the semiconductor elements S1 has a plate shape. Each of the semiconductor elements S1 is, for example, a power semiconductor element that operates at a high voltage. Note that each of the semiconductor elements S1 is not limited to a power semiconductor element, and may be, for example, a semiconductor element that operates at a low voltage.

[0040] In this embodiment, the multiple semiconductor elements S1 mounted on the insulating substrate 10 include two adjacent semiconductor elements S1. Hereinafter, the two adjacent semiconductor elements S1 are also referred to as semiconductor elements S1a and S1b, respectively. The semiconductor element S1a is, for example, a diode. The semiconductor element S1b is, for example, an IGBT (Insulated Gate Bipolar Transistor).

[0041] The material constituting the semiconductor element S1a is, for example, silicon. The thickness of the semiconductor element S1a is, for example, 0.2 mm. The shape of the semiconductor element S1a in a plan view is rectangular. The size of the rectangle that is the shape of the semiconductor element S1a is, for example, a size expressed as "13 mm x 10 mm".

[0042] The material constituting the semiconductor element S1b is, for example, silicon. The thickness of the semiconductor element S1b is, for example, 0.2 mm. The shape of the semiconductor element S1b in a plan view is rectangular. The size of the rectangle that is the shape of the semiconductor element S1b is, for example, a size expressed as "13 mm x 13 mm".

[0043] Hereinafter, the state of the insulating substrate 10 in which a semiconductor element S1 is mounted on the insulating substrate 10 will also be referred to as an “element-mounted state.” Fig. 1(a) shows the insulating substrate 10 in an element-mounted state.

[0044] Furthermore, the main terminals of the semiconductor element S1a and the semiconductor element S1b are connected by wires W1 to electrodes 6a provided on the case 5. The wires W1 are made of, for example, aluminum. The cross-sectional diameter of the wires W1 is, for example, 0.4 mm.

[0045] As shown in FIG. 1(b), a gate electrode g1 is provided on the semiconductor element S1b. The gate electrode g1 of the semiconductor element S1b is connected to an electrode 6b provided on the case 5 by a wire W2. Specifically, the gate electrode g1 of the semiconductor element S1b is connected to the electrode 6b by wire bonding using the wire W2. This forms a circuit using the semiconductor element S1b. The wire W2 is made of, for example, aluminum. The cross-sectional diameter of the wire W2 is, for example, 0.15 mm.

[0046] The wire W1 shown in Fig. 1(a) is a wire represented by overlapping two types of wires W1 in Fig. 1(b). One of the two types of wires W1 in Fig. 1(b) is a wire W1 connected to the electrode 6a, the semiconductor element S1a, and the semiconductor element S1b. The other of the two types of wires W1 in Fig. 1(b) is a wire W1 connected to the semiconductor element S1a, the semiconductor element S1b, and the conductor layer 12.

[0047] The case 5 is bonded to the main surface 7s of the base plate 70 via a bonding material b3. The case 5 surrounds the insulating substrate 10, the semiconductor elements S1, the wires W1 and W2, etc. The bonding material b3 is, for example, an adhesive. The bonding material b3 is, for example, made of silicone.

[0048] Resin 8 is provided inside case 5. Resin 8 is a sealing resin for sealing components. For example, resin 8 is an epoxy resin in which silica filler is dispersed. Resin 8 is a thermosetting resin. Resin 8 mainly seals insulating substrate 10, multiple semiconductor elements S1, wires W1 and W2, etc.

[0049] In addition, a plurality of fins 71 are formed on the rear surface 7r of the base plate 70. In a plan view, the plurality of fins 71 are arranged, for example, in a matrix. As described above, the base plate 70 in the joined state shown in FIG. 1(a) is warped.

[0050] Each fin 71 is a pin fin. Each fin 71 has an elongated shape. Each fin 71 has, for example, a cylindrical shape. Each fin 71 has a cross-sectional diameter of, for example, 1.5 mm. Each fin 71 has a height that is, for example, within a range from 4.5 mm to 5 mm. The height of a fin 71 is the length of the fin 71 in the longitudinal direction of the fin 71.

[0051] The heat sink H1 is configured so that the water-cooling jacket 80 can be attached to the rear surface 7r of the base plate 70. For example, an O-ring is used to attach the water-cooling jacket 80. Hereinafter, the state of the heat sink H1 in which the water-cooling jacket 80 is attached to the base plate 70 of the heat sink H1 is also referred to as the "attached state."

[0052] 1(a) shows the heat sink H1 in an attached state. In the following, the state in which the water-cooling jacket 80 is attached to the base plate 70 of the heat sink H1 will also be referred to as the "attached state."

[0053] In the attached state, the water-cooled jacket 80 is attached to the rear surface 7r of the base plate 70 of the heat sink H1. Specifically, in the attached state, the water-cooled jacket 80 is attached to the peripheral portion of the rear surface 7r of the base plate 70 by an O-ring (not shown).

[0054] The water-cooling jacket 80 has a function of dissipating heat using cooling water. The water-cooling jacket 80 is made of, for example, an aluminum alloy.

[0055] The water-cooling jacket 80 has an internal space R8. The internal space R8 is a space for accommodating a plurality of fins 71 of the heat sink H1. The water-cooling jacket 80 also has an internal bottom surface 8s that faces the internal space R8. The internal bottom surface 8s is a flat surface. In other words, the internal bottom surface 8s is a plane.

[0056] In the attached state, the multiple fins 71 formed on the back surface 7r of the base plate 70 are accommodated in the internal space R8. In addition, in the attached state, the tips of the multiple fins 71 face the internal bottom surface 8s. In addition, in the attached state, a gap exists between the tip of each fin 71 and the internal bottom surface 8s. In addition, in the attached state, the internal space R8 is filled with cooling water. In addition, in the attached state, the cooling water flows in the internal space R8 filled with the cooling water.

[0057] The semiconductor module 100, in which the water-cooling jacket 80 is attached to the heat sink H1 of the semiconductor module 100, has a predetermined heat dissipation performance.

[0058] The warped base plate 70 shown in Fig. 1(a) has a warp. That is, the back surface 7r of the warped base plate 70 has a warp. In the following, the area of ​​the back surface 7r of the warped base plate 70 where the warp exists is also referred to as a "warped area." In the following, the area of ​​the back surface 7r of the warped base plate 70 where the warp does not exist is also referred to as a "non-warped area."

[0059] Hereinafter, the difference between the position of the warped region in the thickness direction of the base plate 70 and the position of the non-warped region in the thickness direction of the base plate 70 is also referred to as the "region height difference." The region height difference is, for example, a value in the range of 0.1 mm to 0.5 mm.

[0060] Hereinafter, the largest value among the different values ​​of the regional height difference is also referred to as the “maximum height difference.” In addition, below, the region having the maximum height difference on the rear surface 7r of the warped base plate 70 is also referred to as the “maximum height difference region.”

[0061] In the present embodiment, as an example, the maximum height difference region is the center of the rear surface 7r of the base plate 70 in Fig. 1(a). The maximum height difference of the maximum height difference region of the rear surface 7r of the base plate 70 is, for example, 0.5 mm.

[0062] The tips of the fins 71 of the heat sink H1 are aligned on the same plane. The expression "the tips of the fins 71 are aligned on the same plane" also means that the tips of the fins 71 are aligned on approximately the same plane.

[0063] Hereinafter, the longitudinal direction of the fin 71 is also referred to as the "fin longitudinal direction." Also, below, the length of the fin 71 in the longitudinal direction of the fin 71 is also referred to as the "fin length." The fin length is expressed, for example, as "L1," "L2," etc. The fin length in a situation where the fin 71 extends in the vertical direction is the height of the fin 71. For example, the fin length of the fin 71 shown in FIG. 1(a) is the length of the fin 71 in the Z-axis direction.

[0064] Hereinafter, a region of the rear surface 7r of the base plate 70 that overlaps with the insulating substrate 10 in a plan view is also referred to as a "region R1." The region R1 of the rear surface 7r is a region that overlaps with the insulating substrate 10 in a plan view. In FIG. 1(a), the region R1 of the rear surface 7r is, for example, a central portion of the rear surface 7r.

[0065] In addition, hereinafter, a region of the rear surface 7r of the base plate 70 that does not overlap with the insulating substrate 10 in a plan view is also referred to as a "region R2." The region R2 of the rear surface 7r is a region that does not overlap with the insulating substrate 10 in a plan view. In FIG. 1(a), the region R2 of the rear surface 7r is, for example, a peripheral portion of the rear surface 7r.

[0066] The rear surface 7r of the base plate 70 has a region R1 and a region R2.

[0067] The fins 71 of the heat sink H1 are configured to have different lengths in stages. For example, the fins 71 are configured such that the fin length of the fin 71 is longer as the fin 71 is closer to the maximum height difference region of the rear surface 7r.

[0068] Hereinafter, among the fins 71 included in the heat sink H1, the fin 71 having the longest fin length is also referred to as the "fin 71H." The fin length of the fin 71H is represented by "L2."

[0069] In the following description, the fin 71 having the shortest fin length among the multiple fins 71 of the heat sink H1 is also referred to as the "fin 71L." The fin length of the fin 71L is represented by "L1." The multiple fins 71 of the heat sink H1 include a fin 71H and a fin 71L.

[0070] The fin 71H is formed on the rear surface 7r of the base plate 70 in the center of the region R1.

[0071] The fins 71L are formed, for example, in the region R2 and the peripheral portion of the region R1 of the rear surface 7r of the base plate 70. In Fig. 1(a), as an example, the fins 71L formed in the region R2 of the rear surface 7r of the base plate 70 are shown.

[0072] The fins 71L may be formed in one of the region R2 and the peripheral portion of the region R1 of the rear surface 7r of the base plate 70. For example, the fins 71L may not be formed in the region R2 of the rear surface 7r of the base plate 70, but may be formed in the peripheral portion of the region R1.

[0073] The fin length L2 of the fin 71H formed in the center of the region R1 of the rear surface 7r of the base plate 70 is longer than the fin length L1 of the fin 71L.

[0074] The fin 71H formed in the center of the region R1 of the rear surface 7r of the base plate 70 has a fin length L2 of, for example, 5 mm. As described above, the maximum height difference of the maximum height difference region of the rear surface 7r of the base plate 70 is, for example, 0.5 mm. Therefore, the fin length L1 of the fin 71L is 4.5 mm.

[0075] Therefore, as described above, the tips of the fins 71 of the heat sink H1 are arranged on approximately the same plane. "Almost the same plane" means the same plane with a tolerance. The tolerance is, for example, a value in the range from -0.2 mm to 0.2 mm.

[0076] Due to the above-mentioned configuration of the multiple fins 71, in the installed state, the tips of the multiple fins 71 are aligned on the same plane parallel to the inner bottom surface 8s of the water-cooled jacket 80. Also, in the installed state, the gap between the tip of each fin 71 and the inner bottom surface 8s over the entire inner bottom surface 8s of the water-cooled jacket 80 is 0.2 mm or less.

[0077] (Manufacturing method) Next, an example of a manufacturing method for the semiconductor module 100 will be described with reference to Figures 2, 3, and 4. Hereinafter, the manufacturing method for the semiconductor module 100 will also be referred to as "manufacturing method Pr." Figure 2 is a flowchart of the manufacturing method Pr according to the first embodiment. Figure 2 shows only main steps included in the multiple steps of the manufacturing method Pr. Figures 3 and 4 are cross-sectional views for explaining the manufacturing method Pr for the semiconductor module 100 according to the first embodiment.

[0078] In the manufacturing method Pr, first, an element mounting process is performed (step S110). In the element mounting process, as shown in Fig. 3(a), the semiconductor elements S1a and S1b are bonded onto the conductor layer 12 of the insulating substrate 10 using a bonding material b1. That is, the semiconductor elements S1a and S1b are mounted onto the insulating substrate 10. This brings the insulating substrate 10 into an element-mounted state.

[0079] Next, a substrate bonding process is performed using the bonding material b2 (step S120). The bonding material b2 exists in a softened state and a hardened state. The bonding material b2 in the softened state has fluidity. The bonding material b2 in the hardened state has no fluidity. The bonding material b2 in the hardened state has a sheet-like shape. The thickness of the bonding material b2 in the hardened state is, for example, 0.4 mm. The bonding material b2 in the hardened state is the bonding material b2 present between the insulating substrate 10 and the base plate 70 in FIG. 3(a).

[0080] In the substrate bonding step, the insulating substrate 10 with elements mounted thereon is positioned. Specifically, the hardened bonding material b2 is placed on the main surface 7s of the base plate 70. Next, the insulating substrate 10 with elements mounted thereon is placed on the hardened bonding material b2.

[0081] Next, the hardened bonding material b2 is subjected to a heat treatment A. In the heat treatment A, the bonding material b2 is heated, and then the bonding material b2 is heated so as to harden the bonding material b2. The bonding material b2 is heated, for example, using a reflow furnace. As a result, as shown in FIG. 3(b), the insulating substrate 10 with the element mounted thereon is bonded to the main surface 7s of the base plate 70 by the bonding material b2. During the period in which the insulating substrate 10 with the element mounted thereon is bonded to the base plate 70, the above-mentioned warp A occurs in the base plate 70 due to the above-mentioned difference in expansion coefficient. The warp A is a warp based on the difference in expansion coefficient. The difference in expansion coefficient is the difference between the linear expansion coefficient of the insulating substrate 10 and the linear expansion coefficient of the base plate 70.

[0082] Next, a case bonding process is performed (step S130). In the case bonding process, as shown in FIG. 4(a), the case 5 is bonded to the peripheral portion of the main surface 7s of the base plate 70 via a bonding material b3. Specifically, in the case bonding process, the bonding material b3 is applied to the peripheral portion of the main surface 7s of the base plate 70. Then, the case 5 is placed on the bonding material b3, thereby bonding the case 5.

[0083] Next, an electrode connecting step is performed (step S140). In the electrode connecting step, the electrodes 6 are connected to the semiconductor element S1 by wires W1, W2, etc., as shown in FIG.

[0084] Specifically, in the electrode connection step, the semiconductor element S1a and the semiconductor element S1b are connected to the electrode 6a, which is an external electrode, by the wire W1. Also, the gate electrode g1 (not shown) of the semiconductor element S1b is connected to the electrode 6b, which is a signal electrode, by the wire W2. That is, the gate electrode g1 (not shown) of the semiconductor element S1b is connected to the electrode 6b by wire bonding using the wire W2.

[0085] Next, a sealing step is performed using resin 8 (step S150). Resin 8 is in a softened state and a hardened state. Resin 8 in the softened state has fluidity. Resin 8 in the hardened state has no fluidity.

[0086] In the sealing process, first, softened resin 8 is injected into the case 5 as shown in FIG. 4(b). Next, a heat treatment B is performed on the softened resin 8. In the heat treatment B, the softened resin 8 is heated so as to harden. The resin 8 is heated, for example, using an oven. As a result, the resin 8 becomes hardened. The resin 8 mainly seals the insulating substrate 10, the semiconductor elements S1, the wires W1 and W2, etc.

[0087] In this manner, the semiconductor module 100 shown in FIG. 4(b) is manufactured.

[0088] (summary) As described above, in summary, according to the present embodiment, the insulating substrate 10 is joined to the main surface 7s of the base plate 70 of the heat sink H1. The base plate 70 is warped. A plurality of fins 71 are formed on the rear surface 7r of the warped base plate 70. Tips of the plurality of fins 71 are aligned on the same plane.

[0089] Here, assume that the water-cooled jacket 80 having a flat inner bottom surface 8s is attached to the warped base plate 70. As described above, the tips of the multiple fins 71 are aligned on the same plane. Therefore, in the installation situation in which the water-cooled jacket 80 is attached to the warped base plate 70, there is no variation in the size of the gaps between the tips of the fins 71 and the inner bottom surface 8s of the water-cooled jacket 80 over the entire inner bottom surface 8s of the water-cooled jacket 80.

[0090] Therefore, it is possible to suppress turbulence of the flow of cooling water in the installed water-cooled jacket 80. This makes it possible to suppress deterioration of the heat dissipation performance of the semiconductor module 100 that uses the warped base plate 70 on which the multiple fins 71 are formed.

[0091] Specifically, according to the present embodiment, by bonding the insulating substrate 10 to the base plate 70, warping occurs in the base plate 70 based on the above-mentioned difference in expansion coefficient. That is, by bonding the insulating substrate 10 to the base plate 70, the base plate 70 is deformed. The tips of the multiple fins 71 of the warped base plate 70 of the heat sink H1 are aligned on the same plane. That is, the positions of the tips of the multiple fins 71 of the warped base plate 70 are aligned in the fin longitudinal direction.

[0092] Therefore, in a state where the water-cooled jacket 80 is attached to the base plate 70 of the heat sink H1, there is no variation in the size of the gap between the tip of each fin 71 and the inner bottom surface 8s over the entire inner bottom surface 8s of the water-cooled jacket 80. Therefore, even in a state where the base plate 70 is warped, it is possible to suppress the flow of cooling water from being disturbed in the water-cooled jacket 80. That is, in the water-cooled jacket 80 in the attached state, the water flow can be appropriately controlled. This provides the effect of suppressing the deterioration of the heat dissipation performance of the semiconductor module 100 in the attached state. Therefore, the reliability of the semiconductor module 100 can be improved.

[0093] Furthermore, even when the base plate 70 is warped, the positions of the tips of the fins 71 are aligned in the fin longitudinal direction. Therefore, it is possible to prevent an excessively large gap from being generated between the tips of the fins 71 and the inner bottom surface 8s during installation. The excessively large gap is, for example, a gap that exists when the positions of the tips of the fins 71 vary in the fin longitudinal direction.

[0094] According to this embodiment, the fin length L2 of the fin 71H formed in the center of the region R1 of the back surface 7r of the base plate 70 is longer than the fin length L1 of the fin 71L. Therefore, even if the warp A exists in the base plate 70, it is possible to prevent an excessively large gap from being generated between the tips of the multiple fins 71 and the inner bottom surface 8s in the mounting state. The warp A is a warp that expresses an upward convexity.

[0095] Meanwhile, with increasing awareness of environmental issues, power modules are becoming more widespread in situations where electrical energy is used for power generation, power transmission, regeneration, etc. In power modules, large currents, high voltages, etc. are used. For this reason, in power modules, for example, ceramic substrates having high insulation properties and high heat dissipation properties are used as insulating substrates.

[0096] The linear expansion coefficient of the material constituting the base material of the insulating substrate is much smaller than the linear expansion coefficient of the material constituting the heat sink such as the heat dissipation fin. The material constituting the base material of the insulating substrate is, for example, aluminum nitride, silicon nitride, etc. The material constituting the heat sink such as the heat dissipation fin is, for example, copper, aluminum, etc. The heat sink such as the heat dissipation fin is composed of a base plate and a plurality of fins. The fins are, for example, pin fins.

[0097] Therefore, when the insulating substrate is joined to the base plate of the heat sink, a large thermal stress occurs at the joint between the insulating substrate and the base plate, and the insulating substrate and the base plate are likely to warp. When the warp occurs, the positions of the tips of the fins of the heat sink vary. Therefore, when the base plate is warped, an excessively large gap occurs between the tips of the fins and the inner bottom surface of the water-cooled jacket when the water-cooled jacket is attached. This causes a problem that the water flow in the water-cooled jacket is not as designed, and the cooling performance is reduced.

[0098] In addition, if there is an excessively large gap between the tips of the fins and the inner bottom surface of the water-cooled jacket in this installation state, the flow of the cooling water may differ from the designed flow. If this occurs, the heat dissipation performance of the module will decrease. Therefore, it is required that the positions of the tips of the fins are aligned in the longitudinal direction of the fins.

[0099] In related configuration A, different cooling performance is set in multiple parts of the module by flowing more cooling water in the center of the module. In related configuration A, the height of multiple fins on the base plate included in the module is configured to change in stages.

[0100] For example, the fins are configured so that the height of the fins increases as the fins are closer to the center fin. In other words, the height of the fins is reduced as the fins are closer to the end fin. The center fin is a fin that is located in the center of the fins. The end fin is a fin that is located at the end of the fins.

[0101] When the base plate of the module of related configuration A is attached to a water-cooled jacket, the shape of the inner bottom surface of the water-cooled jacket must also be changed based on the height of each fin of the base plate, which causes a problem that the module of related configuration A cannot be used as a versatile module.

[0102] The inner bottom surface of the water-cooled jacket is a flat surface, so the tips of the multiple fins are required to be aligned in the same plane.

[0103] Related configuration B discloses a configuration that takes into consideration warping of the base plate. However, related configuration B has a problem in that warping of the base plate is not eliminated. Therefore, when warping exists in the base plate, related configuration B cannot be applied to a configuration that uses a water-cooling jacket.

[0104] Therefore, the semiconductor module 100 of this embodiment has a configuration for achieving the above-mentioned effects, and therefore, the semiconductor module 100 of this embodiment can solve the above-mentioned problems.

[0105] Moreover, SiC semiconductor elements made of silicon carbide (SiC) have a high operating temperature and excellent power conversion efficiency. For this reason, SiC semiconductor elements have become mainstream semiconductor elements in recent years. Thus, there is a demand for a semiconductor module capable of mounting a SiC semiconductor element. The semiconductor module 100 of the present embodiment has a configuration for achieving the above-mentioned effects. Therefore, it is possible to apply a SiC semiconductor element as the semiconductor element S1 mounted on the semiconductor module 100.

[0106] As a result, it is possible to provide a semiconductor module that can be used in various situations where power generation, power transmission, efficient energy utilization, energy regeneration, and the like are performed.

[0107] In the present embodiment, the fins 71 are different in length, but the present invention is not limited to this. In the manufacturing method Pr, the fins 71 may be the same in length (hereinafter, referred to as "variant configuration A").

[0108] In the modified configuration A, the polishing process is performed at a specific timing in the manufacturing method Pr. The specific timing is, for example, the timing after the insulating substrate 10 with elements mounted thereon is bonded to the base plate 70 in a substrate bonding process. The specific timing is also, for example, the timing after the resin 8 injected into the inside of the case 5 is hardened in a sealing process. The polishing process is a process for polishing the tips of the multiple fins 71 having different fin lengths so that the tips of the multiple fins 71 are aligned on the same plane.

[0109] In the present embodiment, the material constituting base material 11 of insulating substrate 10 is not limited to aluminum nitride. Base material 11 may be made of, for example, silicon nitride, alumina, or the like.

[0110] In the present embodiment, the material constituting the conductor layers 12 and 13 is not limited to copper. The material constituting the conductor layers 12 and 13 may be, for example, a material having good solder wettability. The material constituting the conductor layers 12 and 13 may be, for example, aluminum with nickel plating on the surface of the aluminum.

[0111] In the present embodiment, the material constituting the base plate 70 is not limited to an aluminum alloy, but may be made of copper, a copper alloy, or the like.

[0112] Furthermore, in this embodiment, the shape of the fins 71 is not limited to a cylinder, but may be, for example, a hexagonal cylinder, an elliptical cylinder, a flat plate, or the like.

[0113] In the present embodiment, the fins 71 having different lengths may be formed by, for example, polishing. Note that, by polishing, a slope may be formed at the tip of the fin 71.

[0114] In addition, in this embodiment, the material constituting the semiconductor element S1 is not limited to silicon. The material constituting the semiconductor element S1 may be, for example, a wide band gap semiconductor material such as silicon carbide, silicon carbide (SiC), gallium nitride, diamond, etc. The wide band gap semiconductor material is a material having a band gap wider than that of silicon.

[0115] In addition, in this embodiment, the composition ratio of the solder as the bonding materials b1, b2, etc. is expressed as "96.5% tin, 3% silver, 0.5% copper" and the melting point of the solder is 217°C, but this is not limited to this. For example, the composition ratio of the solder as the bonding materials b1, b2, etc. may be expressed as "99.3% tin, 0.7% copper" and the melting point of the solder may be 224°C. For example, the composition ratio of the solder as the bonding materials b1, b2, etc. may be expressed as "95% tin, 5% antimony" and the melting point of the solder may be 240°C.

[0116] In addition, a part of the solder, which is the bonding material b1, b2, etc., may be a bonding material other than solder (hereinafter, also referred to as a "non-solder material"). The non-solder material is, for example, a silver epoxy adhesive, a silver sintering material, a brazing material, etc.

[0117] Furthermore, the material constituting the wires W1 and W2 is not limited to aluminum. The material constituting the wires W1 and W2 may be, for example, an aluminum alloy, copper, or the like. The aluminum alloy contains a small amount of additive. The additive is, for example, iron.

[0118] Furthermore, the material constituting the case 5 is not limited to PPS resin. The material constituting the case 5 may be, for example, LCP (Liquid Crystal Polymer) resin. By making the case 5 out of LCP resin, the heat resistance of the case 5 can be improved.

[0119] The material constituting the electrode 6 is not limited to copper. The material constituting the electrode 6 may be, for example, copper with nickel plating on the surface of the copper. The material constituting the electrode 6 may be, for example, a copper alloy. The material constituting the electrode 6 may be, for example, aluminum with nickel plating on the surface of the aluminum.

[0120] Furthermore, the resin 8 is not limited to the epoxy resin in which a silica filler is dispersed in the epoxy resin. The resin 8 may be, for example, the epoxy resin in which a filler such as alumina is dispersed in the epoxy resin. The resin 8 may be, for example, the epoxy resin in which a silicone resin is mixed into the epoxy resin. The resin 8 may be, for example, composed of only a silicone resin.

[0121] <Variation 1> (composition) The configuration of this modification is applied to the first embodiment. Hereinafter, the configuration of this modification is also referred to as "configuration Ctm1." The configuration Ctm1 includes a configuration Ctm1a and a configuration Ctm1b. The configuration Ctm1a is a configuration in which the base plate 70 has a plurality of different thicknesses. The configuration Ctm1b is a configuration in which a groove is provided in the base plate 70.

[0122] Fig. 5 is a cross-sectional view of a semiconductor module 100 having a configuration Ctm1 of Modification 1. The semiconductor module 100 in Fig. 5 is a modified version of the semiconductor module 100 in Fig. 1(a). Specifically, the semiconductor module 100 in Fig. 5 is the semiconductor module 100 in Fig. 1(a) to which the configurations Ctm1a and Ctm1b are applied.

[0123] Hereinafter, the portion of the base plate 70 to which the insulating substrate 10 is bonded is also referred to as "substrate bonding portion 70c" or "substrate bonding portion." In Fig. 5, the substrate bonding portion 70c of the base plate 70 is a part of the base plate 70 to which the insulating substrate 10 is bonded by bonding material b2. The substrate bonding portion 70c is the center of the base plate 70.

[0124] In the following description, the portion of the base plate 70 around the substrate bonding portion 70c is also referred to as the "substrate non-bonding portion 70e" or the "substrate non-bonding portion." The substrate non-bonding portion 70e of the base plate 70 is the peripheral portion of the base plate 70. The base plate 70 has the substrate bonding portion 70c and the substrate non-bonding portion 70e.

[0125] The shape of the substrate non-bonded portion 70e in plan view is a closed loop. Hereinafter, the rectangular shape of the base plate 70 in plan view is also referred to as a "rectangle A." The substrate non-bonded portion 70e is a peripheral portion of the base plate 70 that corresponds to the peripheral portion of the rectangle A.

[0126] 5 shows the heat sink H1 in an attached state. In the attached state, the water-cooled jacket 80 is attached to the peripheral portion of the back surface 7r of the base plate 70 by an O-ring (not shown). The peripheral portion of the back surface 7r of the base plate 70 is the substrate non-bonding portion 70e of the base plate 70. That is, in the attached state, the water-cooled jacket 80 is attached to the substrate non-bonding portion 70e, which is the peripheral portion of the base plate 70, by an O-ring (not shown). Since an O-ring is used to attach the water-cooled jacket 80, it is desirable that the substrate non-bonding portion 70e has high flatness.

[0127] The base plate 70 in FIG. 1( a ) has the same thickness throughout the entire base plate 70 .

[0128] On the other hand, the base plate 70 of this modified example shown in Fig. 5 has a plurality of different thicknesses. Specifically, in the configuration Ctm1a of this modified example, the substrate non-bonded portion 70e has a plate thickness portion M7. The plate thickness portion M7 is a portion to which the water-cooling jacket 80 is attached. The plate thickness portion M7 is a part of the substrate non-bonded portion 70e. Note that the plate thickness portion M7 may be the entire substrate non-bonded portion 70e.

[0129] In the configuration Ctm1a, the thickness of the plate thick portion M7 of the substrate non-bonding portion 70e is thicker than the thickness of the substrate bonding portion 70c. That is, in this modification, the thickness of at least a part of the substrate non-bonding portion 70e is thicker than the thickness of the substrate bonding portion 70c. The thickness of the plate thick portion M7 is, for example, 1.3 times or more the thickness of the substrate bonding portion 70c. The plate thick portion M7 protrudes from the main surface 7s side of the base plate 70. The plate thick portion M7 may protrude from the back surface 7r side of the base plate 70.

[0130] The above-described configuration Ctm1a can suppress the occurrence of defects caused by the warp A of the base plate 70 during the substrate bonding process. For example, the defect is a defect in which the plate thick portion M7 of the substrate non-bonding portion 70e is deformed. Therefore, the flatness of the plate thick portion M7 of the substrate non-bonding portion 70e can be ensured.

[0131] Further, a groove V1 is provided in the substrate non-bonded portion 70e of the base plate 70 in the configuration Ctm1b of this modified example. Specifically, the groove V1 is provided in the upper surface of the substrate non-bonded portion 70e of the base plate 70. As a result, the portion of the substrate non-bonded portion 70e where the groove V1 is provided is thinner than the substrate bonded portion 70c.

[0132] The presence of the groove V1 can suppress the occurrence of defects caused by warpage A of the base plate 70 during the substrate bonding process. For example, the defect is a defect in which stress is applied to the entire substrate non-bonding portion 70e, causing warpage throughout the entire substrate non-bonding portion 70e.

[0133] (summary) As described above, according to this modification, the thickness of at least a part of the substrate non-bonding portion 70e is greater than the thickness of the substrate bonding portion 70c. Therefore, even if warpage A occurs in the base plate 70 during the substrate bonding process, the flatness of the plate thick portion M7 of the substrate non-bonding portion 70e can be ensured.

[0134] Moreover, according to this modification, a groove V1 is provided in the substrate non-bonding portion 70e of the base plate 70. Therefore, even if warpage A occurs in the base plate 70 in the substrate bonding process, the flatness of the plate thickness portion M7 of the substrate non-bonding portion 70e can be ensured.

[0135] 5 has both the configuration Ctm1a and the configuration Ctm1b. The semiconductor module 100 may have only one of the configuration Ctm1a and the configuration Ctm1b. That is, the substrate non-bonding portion 70e of the base plate 70 may have only one of the plate thickness portion M7 and the groove V1.

[0136] The plate thickness portion M7 and / or the groove V1 are provided over the entire substrate non-joined portion 70e, which is in the form of a closed loop.

[0137] In addition, both or one of the thick plate portion M7 and the groove V1 may be provided in a part of the closed-loop non-bonded portion 70e. For example, both or one of the thick plate portion M7 and the groove V1 may be provided discretely in the closed-loop non-bonded portion 70e.

[0138] Specifically, the plate thickness portion M7 and / or the groove V1 may be provided, for example, only on some of the four sides of the rectangle A that is the shape of the base plate 70. Also, the plate thickness portion M7 and / or the groove V1 may be provided, for example, only on the corners of the rectangle A that is the shape of the base plate 70.

[0139] In addition, in a configuration in which the groove V1 is provided over the entire substrate non-bonding portion 70e, which is a closed loop, the rigidity of the base plate 70 may decrease. Therefore, the groove V1 is preferably provided in the substrate non-bonding portion 70e of the base plate 70 so as to suppress a decrease in the rigidity of the base plate 70. Therefore, the groove V1 is preferably provided, for example, only on some of the four sides of the rectangle A that is the shape of the base plate 70. Also, the groove V1 is preferably provided, for example, only on the corners of the rectangle A that is the shape of the base plate 70.

[0140] <Variation 2> FIG. 6 is a diagram for explaining a manufacturing method of the semiconductor module 100 according to the second modification, and shows a state before the base plate 70 and the insulating substrate 10 are bonded. FIG. 6(a) is a plan view of the semiconductor module 100 according to the second modification. FIG. 6(b) is a B-B' cross-sectional view of FIG. 6(a). The B-B' cross-section is a cross-section near the center of a cross-section parallel to the short side of the insulating substrate 10. FIG. 6(c) is a C-C' cross-sectional view of FIG. 6(a). The C-C' cross-section is a cross-section near an end of a cross-section parallel to the short side of the insulating substrate 10. FIG. 6(d) is a D-D' cross-sectional view of FIG. 6(a). The D-D' cross-section is a cross-section parallel to the long side of the insulating substrate 10.

[0141] In many cases, the insulating substrate 10 is rectangular in plan view. Therefore, the warpage that occurs in the insulating substrate 10 after bonding to the base plate 70 becomes larger in the direction parallel to the long side. Specifically, in the direction parallel to the long side of the insulating substrate 10, a cylindrical warpage like a part of the side of a cylinder occurs as shown in FIG. 6(e). Strictly speaking, a slight warpage also occurs in the direction parallel to the short side of the insulating substrate 10, so that the insulating substrate 10 as a whole has a three-dimensional curved (spherical) warpage as shown in FIG. 6(f). Therefore, before bonding the base plate 70 and the insulating substrate 10, it is necessary to align the tips of the fins 71 of the base plate 70 in a three-dimensional curved shape. However, since it is difficult to manufacture the tips of the fins 71 of the base plate 70 in a three-dimensional curved shape, the productivity can be improved by finishing the tips of the fins 71 of the base plate 70 in a quadratic curved shape.

[0142] In order to finish the tips of the fins 71 of the base plate 70 with a quadratic curved surface, it is necessary to provide a difference in height between the fins 71 so that the tips of the fins 71 form an arc in a cross section parallel to the long side of the insulating substrate 10 (see FIG. 6(d)). Specifically, in a cross section parallel to the short side of the insulating substrate 10, near the center (see FIG. 6(b)), all the fins 71H have a long fin length (L2), and near the end (see FIG. 6(c)), all the fins 71L have a short fin length (L1). This makes it possible to align the tips of the fins 71 to be generally flush with each other with high productivity, even if warping occurs in the base plate 70 after bonding the base plate 70 and the insulating substrate 10.

[0143] In this way, when the base plate 70 with the fin length adjusted (if the base plate 70 is made of aluminum, the expansion coefficient is 21 ppm / K) and the insulating substrate 10 (if the base material 11 of the insulating substrate 10 is made of silicon nitride, the expansion coefficient of the base material 11 is 3 ppm / K) are bonded with the bonding material b2, warping occurs due to the difference in their respective expansion coefficients, and the tips of the fins 71 become aligned in the same plane.

[0144] <Embodiment 2> (composition) Fig. 7 is a cross-sectional view of a semiconductor module 100A according to embodiment 2. Fig. 7 shows a water-cooling jacket 80 that is not included in the semiconductor module 100A.

[0145] 1(a) in that a frame 6c is provided instead of the wire W1. Other configurations of the semiconductor module 100A are similar to those of the semiconductor module 100. Below, the semiconductor module 100A will be described, focusing mainly on the differences from the semiconductor module 100.

[0146] The frame 6c is a conductive member. The frame 6c has a plate shape. The frame 6c is bent. The frame 6c has a thickness of, for example, 0.64 mm. The frame 6c is made of, for example, copper.

[0147] A bonding material b4 is provided on each of the electrode 6a, the semiconductor element S1a, and the main terminals of the semiconductor element S1b. Each of the electrode 6a, the semiconductor element S1a, and the semiconductor element S1b is connected to the frame 6c via the bonding material b4. Therefore, the main terminals of the semiconductor element S1a and the semiconductor element S1b are connected to the electrode 6a provided on the case 5 by the frame 6c and the bonding material b4. This forms a circuit.

[0148] The configuration of the bonding material b4 is the same as the configuration of the bonding material b2. The bonding material b4 is, for example, solder. The material constituting the bonding material b4 is the same as the material constituting the bonding material b2.

[0149] (Manufacturing method) Next, an example of a manufacturing method for the semiconductor module 100A will be described with reference to Figures 2, 3, and 8. Hereinafter, the manufacturing method for the semiconductor module 100A will also be referred to as "manufacturing method Pra." Except for some processing, the manufacturing method Pra is similar to the manufacturing method Pr for the semiconductor module 100. Figures 3 and 8 are cross-sectional views for explaining the manufacturing method Pra for the semiconductor module 100A according to the second embodiment.

[0150] Here, the method Pra for manufacturing the semiconductor module 100A will be described, focusing mainly on the differences from the method Pr for manufacturing the semiconductor module 100 in the first embodiment.

[0151] In the manufacturing method Pra, an element mounting step is performed (step S110) in the same manner as in the embodiment 1. Through the element mounting step, the insulating substrate 10 is in an element-mounted state as shown in FIG.

[0152] Next, a substrate bonding step is performed (step S120) in the same manner as in the first embodiment. In the substrate bonding step, the insulating substrate 10 with elements mounted thereon is positioned and a heat treatment A is performed in the same manner as in the first embodiment. As a result, as shown in FIG. 3(b), the insulating substrate 10 with elements mounted thereon is bonded to the main surface 7s of the base plate 70 by the bonding material b2. During the period in which the insulating substrate 10 with elements mounted thereon is bonded to the base plate 70, the aforementioned warpage A occurs in the base plate 70 due to the aforementioned difference in expansion coefficient.

[0153] Next, a case joining step is performed (step S130) in the same manner as in the first embodiment. In the case joining step, the case 5 is joined to the peripheral portion of the main surface 7s of the base plate 70 via the joining material b3, as shown in FIG.

[0154] Next, an electrode connecting step is performed (step S140). In the electrode connecting step of the manufacturing method Pra, as shown in Fig. 8(b), the electrodes 6 are connected to the semiconductor element S1 by a frame 6c, a bonding material b4, a wire W2, and the like.

[0155] Specifically, in the electrode connection step of the manufacturing method Pra, the semiconductor element S1a and the semiconductor element S1b are connected to the electrode 6a, which is an external electrode, by the frame 6c and the bonding material b4. Also, the gate electrode g1 (not shown) of the semiconductor element S1b is connected to the electrode 6b, which is a signal electrode, by the wire W2. That is, the gate electrode g1 (not shown) of the semiconductor element S1b is connected to the electrode 6b by wire bonding using the wire W2.

[0156] Next, a sealing step is performed (step S150) in the same manner as in the first embodiment. In the sealing step, the inside of the case 5 is filled with the resin 8.

[0157] In this manner, the semiconductor module 100A shown in FIG. 8(b) is manufactured.

[0158] (summary) As described above, according to the present embodiment, the main terminals of the semiconductor element S1a and the semiconductor element S1b are connected to the electrodes 6a provided on the case 5 by the frame 6c and the bonding material b4. Therefore, the semiconductor module 100A using the frame 6c can also achieve the same effect as that of the first embodiment. For example, this effect is that it is possible to suppress a decrease in the heat dissipation performance of the semiconductor module 100A when it is attached.

[0159] The configuration of the semiconductor module 100A of the present embodiment is not limited to the above configuration. For example, the frame 6c is not limited to a frame made of copper. The frame 6c may be made of, for example, a 42 alloy metallized for applying solder. The frame 6c may also be made of aluminum.

[0160] Furthermore, for example, the insulating substrate 10 is not limited to a ceramic substrate, and may be, for example, a glass epoxy substrate having a conductor layer formed on the surface.

[0161] <Modification 3> (composition) The configuration of this modification is applied to the second embodiment. Hereinafter, the configuration of this modification is also referred to as "configuration Ctm2." The configuration Ctm2 is a configuration that uses a sealing resin formed by transfer molding.

[0162] Fig. 9 is a cross-sectional view of a semiconductor module 100B having a configuration Ctm2 of Modification 3. Fig. 9 shows a water-cooling jacket 80 that is not included in the semiconductor module 100B. The semiconductor module 100B is a modification of the semiconductor module 100A of Fig. 7.

[0163] 7 in that the semiconductor module 100B includes a resin 8A instead of the case 5 and the resin 8, and electrodes 6af and 6bf instead of the electrodes 6a and 6b. Other configurations of the semiconductor module 100B are similar to those of the semiconductor module 100A.

[0164] The following describes the semiconductor module 100B, focusing mainly on the differences from the semiconductor module 100A. The semiconductor module 100A uses electrodes 6a and 6b provided on the case 5 by insert molding.

[0165] On the other hand, in the semiconductor module 100B, the electrodes 6af and 6bf are provided in the resin 8A as the sealing resin by transfer molding using a mold.

[0166] The resin 8A mainly seals the insulating substrate 10, the semiconductor elements S1, the electrodes 6af, 6bf, the frame 6c, the wires W2, and the like.

[0167] The electrodes 6af and 6bf are parts of a lead frame. The thickness of the lead frame is, for example, 0.64 mm. Each of the electrodes 6af and 6bf has an elongated shape. Each of the electrodes 6af and 6bf is bent. Each of the electrodes 6af and 6bf is made of, for example, copper. The electrode 6af is an external electrode. The electrode 6bf is a signal electrode.

[0168] The electrode 6af, the semiconductor element S1a, and the main terminals of the semiconductor element S1b are each provided with a bonding material b4. The electrode 6af, the semiconductor element S1a, and the semiconductor element S1b are each connected to the frame 6c via the bonding material b4. Therefore, the main terminals of the semiconductor element S1a and the semiconductor element S1b are connected to the electrode 6af provided on the case 5 by the frame 6c and the bonding material b4.

[0169] A gate electrode g1 (not shown) of the semiconductor element S1b is connected to an electrode 6bf by a wire W2.

[0170] (summary) As described above, the semiconductor module 100B having the configuration Ctm2 of this modified example also provides the same effects as those of the first embodiment. For example, the effect is that it is possible to suppress a decrease in the heat dissipation performance of the semiconductor module 100B when it is attached.

[0171] <Embodiment 3> (composition) Fig. 10 is a cross-sectional view of a semiconductor module 100C according to embodiment 3. Fig. 10 shows a water-cooling jacket 80 that is not included in the semiconductor module 100C. Fig. 11 is a plan view of the semiconductor module 100C according to embodiment 3. In Fig. 11, resin 8 as a sealing resin is not shown in order to make the configuration of the semiconductor module 100C easier to understand.

[0172] 1 mainly differs in that the semiconductor module 100C includes a plurality of insulating substrates 10. Other configurations of the semiconductor module 100C are similar to those of the semiconductor module 100. Below, the semiconductor module 100C will be described, focusing mainly on the differences from the semiconductor module 100.

[0173] 10 and 11, a configuration in which a semiconductor module 100C includes two insulating substrates 10 is shown as an example.

[0174] The case 5 of this embodiment differs from the case 5 of Fig. 1 mainly in the size of the case 5. The outline shape of the case 5 in a plan view is rectangular. The size of the rectangle that is the shape of the case 5 is expressed as "100 mm x 70 mm", for example. Electrodes 6a and 6b are provided on the case 5 by insert molding.

[0175] The heat sink H1 of this embodiment is a water-cooled heat sink. The heat sink H1 of this embodiment differs from the heat sink H1 of FIG.

[0176] The shape of the base plate 70 in a plan view is rectangular. The size of the rectangle that is the shape of the base plate 70 in this embodiment is expressed as, for example, "100 mm x 70 mm."

[0177] The configuration of each insulating substrate 10 in this embodiment is similar to the configuration of the insulating substrate 10 in the semiconductor module 100 .

[0178] Two insulating substrates 10 are bonded to the main surface 7s of the base plate 70 via a bonding material b2. That is, the two insulating substrates 10 are bonded to the main surface 7s of the base plate 70.

[0179] Hereinafter, the state of the base plate 70 in a situation where a plurality of insulating substrates 10 are bonded to the main surface 7s of the base plate 70 is also referred to as a "bonded state." Fig. 10 shows the base plate 70 in the bonded state. The bonded state in this embodiment is the state of the base plate 70 in a situation where two insulating substrates 10 are bonded to the main surface 7s of the base plate 70.

[0180] In the following description, the state of the base plate 70 in a situation where the insulating substrates 10 are not bonded to the main surface 7s of the base plate 70 will also be referred to as an “unbonded state.” Fig. 12 is a cross-sectional view showing a heat sink H1 having a base plate 70 in an unbonded state.

[0181] The linear expansion coefficient of each insulating substrate 10 is smaller than the linear expansion coefficient of the base plate 70. The linear expansion coefficient of each insulating substrate 10 is, for example, a value included in the range from 5 ppm / K to 8 ppm / K. The linear expansion coefficient of the base plate 70 is, for example, 23 ppm / K. As described above, the difference between the linear expansion coefficient of each insulating substrate 10 and the linear expansion coefficient of the base plate 70 is also referred to as the "expansion coefficient difference."

[0182] Hereinafter, the two insulating substrates 10 included in the semiconductor module 100C will also be referred to as insulating substrate 10a and insulating substrate 10b, respectively. The semiconductor module 100C includes insulating substrate 10a and insulating substrate 10b. The insulating substrate 10a and insulating substrate 10b are bonded to a main surface 7s of a base plate 70.

[0183] In the process of manufacturing the semiconductor module 100C, when the insulating substrate 10a is bonded to the main surface 7s of the base plate 70, a difference in expansion coefficient causes a warp Ac in the base plate 70. The warp Ac is an upwardly convex warp.

[0184] Furthermore, when the insulating substrate 10b is bonded to the main surface 7s of the base plate 70 during the manufacturing process of the semiconductor module 100C, a warp Bc occurs in the base plate 70 due to the difference in expansion coefficient. The warp Bc is a warp that expresses an upward convexity. As described above, FIG. 10 shows the base plate 70 in a bonded state. The base plate 70 in the bonded state is warped. Hereinafter, the state of the warped base plate 70 is also referred to as a "warped state." FIG. 10 shows the base plate 70 in a warped state.

[0185] Insulating substrate 10a includes base material 11, conductor layer 12, and conductor layer 13. The entire conductor layer 12 of insulating substrate 10a has the same potential. Three pairs of semiconductor elements S1a, S1b are mounted on conductor layer 12 of insulating substrate 10a.

[0186] Furthermore, in the insulating substrate 10a, the main terminals of the semiconductor element S1a and the semiconductor element S1b are connected to the electrode 6a provided on the case 5 by the wire W1. This forms a circuit using the semiconductor element S1a and the semiconductor element S1b. The circuit is formed, for example, as a 6-in-1 module.

[0187] The insulating substrate 10b includes a base material 11, four conductor layers 12, and a conductor layer 13. The four conductor layers 12 include three conductor layers 12 on which semiconductor elements S1a and S1b are mounted. That is, the three conductor layers 12 each have a semiconductor element S1a or S1b mounted thereon. This forms a circuit using the semiconductor element S1b.

[0188] Furthermore, in the insulating substrate 10b, the gate electrode g1 of the semiconductor element S1b is connected to the electrode 6b provided on the case 5 by a wire W2. Specifically, the gate electrode g1 of the semiconductor element S1b is connected to the electrode 6b by wire bonding using the wire W2. This forms a circuit using the semiconductor element S1b.

[0189] In addition, a case 5 is bonded to the main surface 7s of the base plate 70 via a bonding material b3. The case 5 encloses the insulating substrates 10a and 10b, the multiple semiconductor elements S1, the wires W1 and W2, etc. Inside the case 5, a resin 8 is provided.

[0190] In addition, a plurality of fins 71 are formed on the rear surface 7r of the base plate 70. In a plan view, the plurality of fins 71 are arranged, for example, in a matrix. As described above, the base plate 70 in the joined state shown in FIG. 10 is warped.

[0191] The height of each fin 71 is, for example, within a range of 4.5 mm to 5 mm. The height of a fin 71 is the length of the fin 71 in the longitudinal direction.

[0192] Moreover, the heat sink H1 in an attached state is shown in Fig. 10. In the following, the state in which the water-cooling jacket 80 is attached to the base plate 70 of the heat sink H1 of this embodiment is also referred to as an "attached state."

[0193] In the attached state, a water-cooling jacket 80 is attached to the peripheral edge of the rear surface 7r of the base plate 70.

[0194] The water-cooled jacket 80 in Figure 10 is different from the water-cooled jacket 80 in Figure 1(a) in terms of size. Other configurations of the water-cooled jacket 80 in Figure 10 are similar to those of the water-cooled jacket 80 in Figure 1(a).

[0195] In the attached state, the multiple fins 71 of the heat sink H1 of the present embodiment are accommodated in the internal space R8. In addition, in the attached state, the tips of the multiple fins 71 face the internal bottom surface 8s. In addition, in the attached state, a gap exists between the tip of each fin 71 and the internal bottom surface 8s. In addition, in the attached state, the internal space R8 is filled with cooling water. In addition, in the attached state, the cooling water flows in the internal space R8 filled with the cooling water.

[0196] The semiconductor module 100C, in which the water-cooling jacket 80 is attached to the heat sink H1 of the semiconductor module 100C, has a predetermined heat dissipation performance.

[0197] Hereinafter, the region of the rear surface 7r of the base plate 70 that overlaps with the insulating substrate 10a in a plan view is also referred to as "region R1a." The region R1a of the rear surface 7r is the region that overlaps with the insulating substrate 10a in a plan view. In FIG. 10, the region R1a of the rear surface 7r is, for example, below the insulating substrate 10a.

[0198] In the following description, the region of the rear surface 7r of the base plate 70 that overlaps with the insulating substrate 10b in a plan view is also referred to as "region R1b." The region R1b of the rear surface 7r is the region that overlaps with the insulating substrate 10b in a plan view. In FIG. 9, the region R1b of the rear surface 7r is, for example, below the insulating substrate 10b.

[0199] In the following description, the region of the rear surface 7r of the base plate 70 that does not overlap with the insulating substrate 10a and the insulating substrate 10b in a plan view is also referred to as "region R2." In the present embodiment, the region R2 of the rear surface 7r is a region that does not overlap with the insulating substrate 10a and the insulating substrate 10b in a plan view. In FIG. 10, the region R2 of the rear surface 7r is, for example, the peripheral portion of the rear surface 7r. In FIG. 10, the region R2 of the rear surface 7r is, for example, a region between the region R1a and the region R1b of the rear surface 7r. The rear surface 7r of the base plate 70 has the region R1a, the region R2, and the region R1b.

[0200] The warped base plate 70 shown in Fig. 10 has a warp. That is, the back surface 7r of the warped base plate 70 has a warp. In the following, the area of ​​the back surface 7r of the warped base plate 70 where the warp exists is also referred to as a "warped area." In the following, the area of ​​the back surface 7r of the warped base plate 70 where the warp does not exist is also referred to as a "non-warped area."

[0201] The base plate 70 of the present embodiment is a base plate having warps at a plurality of locations on the base plate 70. Specifically, the rear surface 7r of the base plate 70 has warps Ac and Bc.

[0202] As described above, the difference between the position of the warped region in the thickness direction of the base plate 70 and the position of the non-warped region in the thickness direction of the base plate 70 is also referred to as the "region height difference." The region height difference is, for example, a value in the range of 0.1 mm to 0.5 mm.

[0203] As described above, the largest value among the different values ​​of the regional height difference is also referred to as the “maximum height difference.” As described above, the region having the maximum height difference on the rear surface 7r of the warped base plate 70 is also referred to as the “maximum height difference region.”

[0204] In the present embodiment, as an example, the maximum height difference region is the center of the region R1a of the back surface 7r of the base plate 70 in Fig. 10 and the center of the region R1b of the back surface 7r. The maximum height difference of the maximum height difference region of the back surface 7r of the base plate 70 is, for example, 0.5 mm.

[0205] The above-mentioned warp Ac present in the base plate 70 is a warp that expresses an upward convexity. The warp Ac is a warp that exists below the insulating substrate 10a and has its apex at the center of the region R1a of the back surface 7r. The above-mentioned warp Bc present in the base plate 70 is a warp that expresses an upward convexity. The warp Bc is a warp that exists below the insulating substrate 10b and has its apex at the center of the region R1b of the back surface 7r.

[0206] The tips of the fins 71 of the heat sink H1 of the present embodiment are aligned on the same plane. The expression "the tips of the fins 71 are aligned on the same plane" also means that the tips of the fins 71 are aligned on approximately the same plane.

[0207] As described above, the length of the fin 71 in the longitudinal direction of the fin 71 is also referred to as the "fin length." The fins 71 of the heat sink H1 of the present embodiment are configured so that the fin lengths differ stepwise. For example, the fins 71 are configured so that the fin lengths of the fins 71 are longer as the fins 71 are closer to the maximum height difference region of the rear surface 7r.

[0208] In the following, the fin 71 having the longest fin length among the multiple fins 71 of the heat sink H1 of the present embodiment is also referred to as "fin 71H." The fin length of fin 71H is expressed as "L2." In addition, in the following, the fin 71 having the shortest fin length among the multiple fins 71 of the heat sink H1 of the present embodiment is also referred to as "fin 71L." The fin length of fin 71L is expressed as "L1."

[0209] The fins 71 of the heat sink H1 in FIG. 10 include a plurality of fins 71H and a plurality of fins 71L.

[0210] In the following, in order to make the configuration of the multiple fins 71 easier to understand, a configuration in which the number of fins 71H included in the multiple fins 71 of the heat sink H1 in Fig. 10 is two will be described. In this configuration, the multiple fins 71 of the heat sink H1 include two fins 71H.

[0211] One of the two fins 71H is formed in the center of the region R1a on the rear surface 7r of the base plate 70. The other of the two fins 71H is formed in the center of the region R1b on the rear surface 7r of the base plate 70.

[0212] The fins 71L are formed in the region R2, the peripheral portion of the region R1a, and the peripheral portion of the region R1b of the rear surface 7r of the base plate 70. As described above, in the present embodiment, the region R2 of the rear surface 7r is a region of the rear surface 7r of the base plate 70 that does not overlap with the insulating substrate 10a and the insulating substrate 10b in a plan view.

[0213] The fins 71L may be formed in part of the region R2, the peripheral portion of the region R1a, and the peripheral portion of the region R1b of the rear surface 7r. For example, the fins 71L may not be formed in the peripheral portion of the region R1a and the peripheral portion of the region R1b, and the fins 71L may be formed in the region R2 of the rear surface 7r. Also, for example, the fins 71L may not be formed in the region R2 of the rear surface 7r, and the fins 71L may be formed in the peripheral portion of the region R1a and the peripheral portion of the region R1b.

[0214] The fin length L2 of the fin 71H formed in the center of the region R1a of the back surface 7r of the base plate 70 is longer than the fin length L1 of the fin 71L. The fin length L2 of the fin 71H formed in the center of the region R1b of the back surface 7r of the base plate 70 is longer than the fin length L1 of the fin 71L.

[0215] The fin 71H formed in the center of the region R1 of the rear surface 7r of the base plate 70 has a fin length of, for example, 5 mm. As described above, the maximum height difference of the maximum height difference region of the rear surface 7r of the base plate 70 is, for example, 0.5 mm. Therefore, the fin length of the fin 71L is 4.5 mm.

[0216] Therefore, as described above, the tips of the fins 71 of the heat sink H1 are arranged on approximately the same plane. "Almost the same plane" means the same plane with a tolerance. The tolerance is, for example, a value in the range from -0.2 mm to 0.2 mm.

[0217] In this embodiment, due to the above-mentioned configuration of the multiple fins 71, in the attached state, the tips of the multiple fins 71 are aligned on the same plane parallel to the inner bottom surface 8s of the water-cooled jacket 80. In addition, in the attached state, the gap between the tips of the multiple fins 71 and the inner bottom surface 8s of the water-cooled jacket 80 is 0.2 mm or less.

[0218] (summary) As described above, according to the present embodiment, in the semiconductor module 100C using the base plate 70 having warpage in multiple places, the tips of the multiple fins 71 are aligned on the same plane. Therefore, the semiconductor module 100C using the base plate 70 having warpage in multiple places can also achieve the same effect as in the first embodiment. For example, this effect is that it is possible to suppress a decrease in the heat dissipation performance of the semiconductor module 100C when it is attached.

[0219] Although the semiconductor module 100C of the present embodiment is configured to include two insulating substrates 10, the present invention is not limited to this. The number of insulating substrates 10 included in the semiconductor module 100C is not limited to two, and may be three or more.

[0220] As an example, the semiconductor module 100C may be configured to include six insulating substrates 10. In this configuration, for example, each of the six insulating substrates 10 has a pair of semiconductor elements S1a, S1b mounted thereon.

[0221] Also, the semiconductor module 100C may be configured to include, for example, four insulating substrates 10. In this configuration, for example, as shown in FIG. 11, three pairs of semiconductor elements S1a, S1b are mounted on the conductor layer 12 of an insulating substrate 10a, which is one insulating substrate 10. The entire conductor layer 12 of the insulating substrate 10a has the same potential. In this configuration, one pair of semiconductor elements S1a, S1b is mounted on each of the three insulating substrates 10. The pair of semiconductor elements S1a, S1b is, for example, the semiconductor elements S1a, S1b mounted on each of the three conductor layers 12 of the insulating substrate 10b in FIG. 11.

[0222] <Fourth embodiment> Here, a power conversion device to which any one of the above-mentioned semiconductor modules 100, 100A, 100B, and 100C is applied will be described. Although the present disclosure is not limited to a specific power conversion device, a case in which any one of the semiconductor modules 100, 100A, 100B, and 100C is applied to a three-phase inverter will be described below as a fourth embodiment.

[0223] Fig. 13 is a block diagram showing a configuration of a power conversion system to which a power conversion device according to embodiment 4 is applied. The power conversion system shown in Fig. 13 includes a power source Pw1, a power conversion device 200, and a load 300. The power source Pw1 is a DC power source. The power source Pw1 supplies DC power to the power conversion device 200. The power source Pw1 is made up of various elements. The power source Pw1 can be made up of, for example, a DC system, a solar cell, a storage battery, or the like.

[0224] The power supply Pw1 may be configured with a rectifier circuit or an AC / DC converter connected to an AC system, or may be configured with a DC / DC converter that converts DC power output from a DC system into a predetermined power.

[0225] The power conversion device 200 is a three-phase inverter connected between a power source Pw1 and a load 300. The power conversion device 200 converts DC power supplied from the power source Pw1 into AC power and supplies the AC power to the load 300. As shown in FIG. 13, the power conversion device 200 includes a main conversion circuit 201 and a control circuit 203. The main conversion circuit 201 converts and outputs power input to the main conversion circuit 201. Specifically, the main conversion circuit 201 converts DC power into AC power and outputs the AC power.

[0226] The control circuit 203 outputs a control signal for controlling the main conversion circuit 201 to the main conversion circuit 201 .

[0227] The load 300 is a three-phase motor driven by AC power supplied from the power conversion device 200. The load 300 is not limited to a specific application, but is a motor mounted on various electric devices. The load 300 is used as a motor for a hybrid vehicle, an electric vehicle, a railroad car, an elevator, or an air conditioner, for example.

[0228] The power conversion device 200 will be described in detail below. The main conversion circuit 201 includes switching elements (not shown) and free wheel diodes (not shown). The switching elements switch to convert DC power supplied from the power source Pw1 into AC power, and the AC power is supplied to the load 300. There are various specific circuit configurations for the main conversion circuit 201. The main conversion circuit 201 according to this embodiment is a two-level three-phase full bridge circuit. The main conversion circuit 201 is composed of, for example, six switching elements and six free wheel diodes. The six switching elements are connected in anti-parallel to the six free wheel diodes.

[0229] At least one of the switching elements and free wheel diodes of the main conversion circuit 201 is configured by a semiconductor module 202. The semiconductor module 202 corresponds to any one of the above-mentioned semiconductor modules 100, 100A, 100B, and 100C. That is, the main conversion circuit 201 has a semiconductor module 202 that corresponds to any one of the semiconductor modules 100, 100A, 100B, and 100C.

[0230] The main conversion circuit 201 includes three upper and lower arms configured using six switching elements. Each of the three upper and lower arms is configured with two switching elements connected in series. The three upper and lower arms correspond to the U phase, V phase, and W phase of the full-bridge circuit, respectively. The output terminals of the three upper and lower arms correspond to the three output terminals of the main conversion circuit 201. The three output terminals of the main conversion circuit 201 are connected to a load 300.

[0231] The main conversion circuit 201 also includes a drive circuit (not shown) that drives each switching element. The drive circuit may be built into the semiconductor module 202. The main conversion circuit 201 may also include a drive circuit separate from the semiconductor module 202.

[0232] The drive circuit generates drive signals for driving the switching elements of the main conversion circuit 201, and supplies the drive signals to the control electrodes of the switching elements of the main conversion circuit 201. Specifically, the drive circuit outputs, to the control electrodes of each switching element, a drive signal for turning the switching element on and a drive signal for turning the switching element off, in accordance with a control signal from a control circuit 203, which will be described later.

[0233] When the switching element is maintained in the on state, the drive signal is a voltage signal equal to or greater than the threshold voltage of the switching element (i.e., an on signal). When the switching element is maintained in the off state, the drive signal is a voltage signal less than the threshold voltage of the switching element (i.e., an off signal).

[0234] The control circuit 203 controls the switching elements of the main conversion circuit 201 so that a desired power is supplied to the load 300. Specifically, the control circuit 203 calculates an on-time, which is the time during which each switching element of the main conversion circuit 201 should be in an on-state, based on the power to be supplied to the load 300. The control circuit 203 can control the main conversion circuit 201 by, for example, PWM control. The PWM control is a control that modulates the on-time of the switching elements according to the voltage to be output.

[0235] The control circuit 203 outputs a control signal as a control command to the drive circuit included in the main conversion circuit 201. The control signal is a signal for outputting an ON signal to a switching element that should be in an ON state at each time point. The control signal is also a signal for outputting an OFF signal to a switching element that should be in an OFF state at each time point. The drive circuit outputs an ON signal or an OFF signal to the control electrode of each switching element as a drive signal in accordance with the control signal.

[0236] In the power conversion device according to the present embodiment, at least one of the switching elements and free wheel diodes of the main conversion circuit 201 is configured by a semiconductor module 202. The semiconductor module 202 corresponds to any one of the above-mentioned semiconductor modules 100, 100A, 100B, and 100C. Therefore, the high reliability of the semiconductor module 202 can improve the reliability of the power conversion device.

[0237] In this embodiment, an example of applying any one of semiconductor modules 100, 100A, 100B, and 100C to a two-level three-phase inverter has been described, but the present disclosure is not limited to this, and any one of semiconductor modules 100, 100A, 100B, and 100C can be applied to various power conversion devices.

[0238] In addition, in the present embodiment, a two-level power conversion device is used, but a three-level or multi-level power conversion device may be used. When supplying power to a single-phase load, any of the semiconductor modules 100, 100A, 100B, and 100C may be applied to a single-phase inverter. When supplying power to a DC load or the like, any of the semiconductor modules 100, 100A, 100B, and 100C may be applied to a DC / DC converter or an AC / DC converter.

[0239] Moreover, the configuration of the power conversion device to which any of the semiconductor modules 100, 100A, 100B, and 100C is applied is not limited to the configuration in which the load 300 is an electric motor. The load 300 may be, for example, a power supply device for an electric discharge machine, a laser processing machine, an induction heating cooker, or a non-contact power supply system. Moreover, the power conversion device to which any of the semiconductor modules 100, 100A, 100B, and 100C is applied may be used as a power conditioner for a solar power generation system, a power storage system, or the like.

[0240] (Other variations) It should be noted that the embodiments and modifications may be freely combined, and the embodiments and modifications may be modified or omitted as appropriate.

[0241] For example, any one of the semiconductor modules 100, 100A, 100B, and 100C is not limited to a power semiconductor module. Any one of the semiconductor modules 100, 100A, 100B, and 100C may be, for example, a semiconductor module that operates at a low voltage.

[0242] Also, for example, the number of fins 71H included in the multiple fins 71 of the heat sink H1 in Fig. 10 is two, but this is not limited to this. The number of fins 71H included in the multiple fins 71 of the heat sink H1 in Fig. 10 may be three or more.

[0243] Although the present disclosure has been described in detail, the above description is illustrative in all respects and is not restrictive. It is understood that countless variations not illustrated can be envisioned.

[0244] Various aspects of the present disclosure are summarized below as appendices.

[0245] (Appendix 1) A semiconductor module, A semiconductor element; an insulating substrate on which the semiconductor element is mounted; a heat sink; The heat sink is A plurality of fins; A base plate, The base plate has a main surface and a back surface, The back surface of the base plate is a surface of the base plate opposite to the main surface, the insulating substrate is bonded to the main surface of the base plate, the base plate is warped based on a difference in coefficient of expansion between the base plate and the insulating substrate, the plurality of fins are formed on the back surface of the warped base plate, The tips of the fins are aligned on the same plane. Semiconductor module.

[0246] (Appendix 2) Each of the fins has an elongated shape. 2. The semiconductor module of claim 1.

[0247] (Appendix 3) When the long side direction of the insulating substrate is the X-axis and the short side direction of the insulating substrate is the Y-axis, In the cross-sectional view of the X-axis, the length of the fin gradually increases toward the center, In the cross-sectional view of the Y axis, the fins have the same length. 2. The semiconductor module of claim 1.

[0248] (Appendix 4) the plurality of fins includes a first fin and a second fin, The back surface of the base plate has a first region and a second region, the first region overlaps with the insulating substrate in a plan view, the second region is a region that does not overlap with the insulating substrate in a plan view, the first fin is formed in a central portion of the first region on the back surface of the base plate, the second fin is formed on both or one of the second region and a peripheral portion of the first region on the rear surface of the base plate, A length of the first fin in a longitudinal direction of the first fin is longer than a length of the second fin in a longitudinal direction of the second fin. 2. The semiconductor module of claim 1.

[0249] (Appendix 5) The base plate of the heat sink is a substrate bonding portion to which the insulating substrate is bonded; and a substrate non-bonded portion which is a peripheral portion of the substrate bonded portion. 5. The semiconductor module according to claim 1 .

[0250] (Appendix 6) The thickness of at least a part of the non-bonded portion of the substrate is greater than the thickness of the bonded portion of the substrate. 6. The semiconductor module according to claim 5.

[0251] (Appendix 7) A groove is provided in the non-substrate-joined portion of the base plate of the heat sink. 7. The semiconductor module according to claim 5 or 6.

[0252] (Appendix 8) The semiconductor module further comprises: A plurality of insulating substrates including the insulating substrate are provided, The insulating substrates include: A first insulating substrate which is the insulating substrate; a second insulating substrate; the first insulating substrate and the second insulating substrate are bonded to the main surface of the base plate, the plurality of fins includes a first fin, a second fin, and a third fin, The rear surface of the base plate has a first region, a second region, and a third region, the first region overlaps with the first insulating substrate in a plan view, the second region is a region that does not overlap with the first insulating substrate and the second insulating substrate in a plan view, the third region overlaps with the second insulating substrate in a plan view, the first fin is formed in a central portion of the first region on the back surface of the base plate, the third fin is formed in a central portion of the third region on the back surface of the base plate, the second fin is formed in all or a part of the second region, a peripheral portion of the first region, and a peripheral portion of the third region on the rear surface of the base plate, a length of the first fin in a longitudinal direction of the first fin is longer than a length of the second fin in a longitudinal direction of the second fin; A length of the third fin in a longitudinal direction of the third fin is longer than a length of the second fin in a longitudinal direction of the second fin. 2. The semiconductor module of claim 1.

[0253] (Appendix 9) A main conversion circuit having the semiconductor module according to any one of appendix 1 to 8, which converts input power and outputs the converted power; a control circuit that outputs a control signal for controlling the main conversion circuit to the main conversion circuit; Power conversion equipment.

[0254] (Appendix 10) an element mounting step of mounting a semiconductor element on an insulating substrate; a substrate bonding step of bonding the insulating substrate to a heat sink having a plurality of fins and a base plate; Equipped with the base plate has a flat main surface that is bonded to the insulating substrate, The plurality of fins are provided on a surface of the base plate opposite to the main surface, and are gradually longer toward the center, In the substrate bonding step, after warping occurs due to a difference in expansion coefficient between the insulating substrate and the heat sink, the tips of the fins are aligned on the same plane. A method for manufacturing a semiconductor module.

[0255] (Appendix 11) Before the substrate bonding step, when the long side direction of the insulating substrate is the X-axis and the short side direction of the insulating substrate is the Y-axis, In the cross-sectional view of the X-axis, the length of the fin gradually increases toward the center, In the cross-sectional view of the Y axis, the fins have the same length. A method for manufacturing the semiconductor module described in appendix 10. [Explanation of symbols]

[0256] 5 case, 6, 6a, 6b, 6af, 6bf electrodes, 8, 8A resin, 10, 10a, 10b insulating substrate, 71, 71H, 71L fins, 70 base plate, 80 water-cooled jacket, 100, 100A, 100B, 100C, 202 semiconductor module, 200 power conversion device, 201 main conversion circuit, 203 control circuit, H1 heat sink, S1, S1a, S1b semiconductor element, V1 groove, W1, W2 wire.

Claims

1. A semiconductor module, comprising: A semiconductor element; an insulating substrate on which the semiconductor element is mounted; a heat sink; The heat sink is A plurality of fins; A base plate, The base plate has a main surface and a back surface, The back surface of the base plate is a surface of the base plate opposite to the main surface, the insulating substrate is bonded to the main surface of the base plate, the base plate is warped based on a difference in coefficient of expansion between the base plate and the insulating substrate, the plurality of fins are formed on the back surface of the warped base plate, The tips of the fins are aligned on the same plane. Semiconductor module.

2. Each of the fins has an elongated shape. The semiconductor module according to claim 1 .

3. When the long side direction of the insulating substrate is the X-axis and the short side direction of the insulating substrate is the Y-axis, In the cross-sectional view of the X-axis, the length of the fin gradually increases toward the center, In the cross-sectional view of the Y axis, the lengths of the fins are the same. The semiconductor module according to claim 1 .

4. The plurality of fins includes a first fin and a second fin, The rear surface of the base plate has a first region and a second region, the first region overlaps with the insulating substrate in a plan view, the second region is a region that does not overlap with the insulating substrate in a plan view, the first fin is formed in a central portion of the first region on the back surface of the base plate, the second fin is formed on both or one of the second region and a peripheral portion of the first region on the rear surface of the base plate, A length of the first fin in a longitudinal direction of the first fin is longer than a length of the second fin in a longitudinal direction of the second fin. The semiconductor module according to claim 1 .

5. The base plate of the heat sink is a substrate bonding portion to which the insulating substrate is bonded; and a substrate non-bonded portion which is a peripheral portion of the substrate bonded portion. The semiconductor module according to claim 1 .

6. The thickness of at least a part of the non-bonded portion of the substrate is greater than the thickness of the bonded portion of the substrate. The semiconductor module according to claim 5 .

7. A groove is provided in the non-substrate-joined portion of the base plate of the heat sink.

7. The semiconductor module according to claim 5.

8. The semiconductor module further comprises: A plurality of insulating substrates including the insulating substrate are provided, The insulating substrates include: A first insulating substrate which is the insulating substrate; a second insulating substrate; the first insulating substrate and the second insulating substrate are bonded to the main surface of the base plate, the plurality of fins includes a first fin, a second fin, and a third fin, The rear surface of the base plate has a first region, a second region, and a third region, the first region overlaps with the first insulating substrate in a plan view, the second region is a region that does not overlap with the first insulating substrate and the second insulating substrate in a plan view, the third region overlaps with the second insulating substrate in a plan view, the first fin is formed in a central portion of the first region on the back surface of the base plate, the third fin is formed in a central portion of the third region on the rear surface of the base plate, the second fin is formed in all or a part of the second region, a peripheral portion of the first region, and a peripheral portion of the third region on the rear surface of the base plate, A length of the first fin in a longitudinal direction of the first fin is longer than a length of the second fin in a longitudinal direction of the second fin, A length of the third fin in a longitudinal direction of the third fin is longer than a length of the second fin in a longitudinal direction of the second fin. The semiconductor module according to claim 1 .

9. a main conversion circuit having the semiconductor module according to any one of claims 1 to 8, which converts input power and outputs the converted power; a control circuit that outputs a control signal for controlling the main conversion circuit to the main conversion circuit; Power conversion equipment.

10. an element mounting step of mounting a semiconductor element on an insulating substrate; a substrate bonding step of bonding the insulating substrate to a heat sink having a plurality of fins and a base plate; Equipped with the base plate has a flat main surface that is bonded to the insulating substrate, The plurality of fins are provided on a surface of the base plate opposite to the main surface, and are gradually longer toward the center, In the substrate bonding step, after warping occurs due to a difference in expansion coefficient between the insulating substrate and the heat sink, the tips of the fins are aligned on the same plane. A method for manufacturing a semiconductor module.

11. Before the substrate bonding step, when the long side direction of the insulating substrate is the X-axis and the short side direction of the insulating substrate is the Y-axis, In the cross-sectional view of the X-axis, the length of the fin gradually increases toward the center, In the cross-sectional view of the Y axis, the lengths of the fins are the same. The method for manufacturing a semiconductor module according to claim 10 .

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