Power semiconductor module and power conversion device

Abstract

A power semiconductor module (1) comprises a circuit substrate (10), a power semiconductor element (19) including a semiconductor substrate (20), and at least one joint (5). The at least one joint (5) comprises a first metal component (12) away from the semiconductor substrate (20), a second metal component (23) close to the semiconductor substrate (20), and a joint layer (15) for joining the first metal component (12) and the second metal component (23) to each other. At the same temperature, the 0.2% yield strength of the first metal component (12) is smaller than the 0.2% yield strength of the second metal component (23), and is smaller than the shear strength of the joint layer (15).

Description

Technical Field

[0001] The present invention relates to a power semiconductor module and a power conversion device. Background Art

[0002] Japanese Patent Application Publication No. 2008-41707 (Patent Document 1) discloses a semiconductor device having a semiconductor element, a metal substrate, and a bonding layer bonding the semiconductor element to the metal substrate, wherein the 0.2% yield strength of the bonding layer at the same temperature is equal to or greater than the 0.2% yield strength of the metal substrate.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2008-41707 Summary of the invention

[0006] An object of the present invention is to extend the life of a power semiconductor module and a power conversion device.

[0007] Means for solving problems

[0008] The power semiconductor module of the present invention comprises a circuit substrate, a power semiconductor element including a semiconductor substrate, and at least one joint. The at least one joint comprises a first metal member away from the semiconductor substrate, a second metal circuit member close to the semiconductor substrate, and a joint layer for joining the first metal member and the second metal member to each other. At the same temperature, the 0.2% yield strength of the first metal member is smaller than the 0.2% yield strength of the second metal member, and is smaller than the shear strength of the joint layer.

[0009] The power conversion device of the present invention comprises a main conversion circuit and a control circuit. The main conversion circuit comprises the power semiconductor module of the present invention and is configured to convert and output input power. The control circuit is configured to output a control signal for controlling the main conversion circuit to the main conversion circuit.

[0010] Effects of the Invention

[0011] The 0.2% yield strength of the first metal component is smaller than the 0.2% yield strength of the second metal component, and smaller than the shear strength of the bonding layer. Therefore, even if the power semiconductor module is subjected to a hot and cold cycle, cracks will selectively occur in the first metal component away from the semiconductor substrate. The bonding layer prevents the cracks from progressing into the power semiconductor element. It is possible to prevent cracks from occurring in the power semiconductor element. According to the power semiconductor module and the power conversion device of the present invention, the life of the power semiconductor module and the power conversion device can be extended. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a schematic plan view of the power semiconductor module according to the first embodiment.

[0013] Figure 2 The power semiconductor module of the first embodiment Figure 1 A schematic cross-sectional view along the section line II-II is shown in FIG.

[0014] Figure 3 This is a schematic cross-sectional view showing one step of the method for manufacturing the power semiconductor module according to the first embodiment.

[0015] Figure 4 The method for manufacturing a power semiconductor module according to the first embodiment is shown in FIG. Figure 3 Schematic cross-sectional view of a process subsequent to the process shown in .

[0016] Figure 5 The method for manufacturing a power semiconductor module according to the first embodiment is shown in FIG. Figure 4 Schematic cross-sectional view of a process subsequent to the process shown in .

[0017] Figure 6 The method for manufacturing a power semiconductor module according to the first embodiment is shown in FIG. Figure 5 Schematic cross-sectional view of a process subsequent to the process shown in .

[0018] Figure 7 The method for manufacturing a power semiconductor module according to the first embodiment is shown in FIG. Figure 6 Schematic cross-sectional view of a process subsequent to the process shown in .

[0019] Figure 8 This is a schematic cross-sectional view of a power semiconductor module according to the second embodiment.

[0020] Fig. 9 This is a schematic plan view of a power semiconductor module according to a third embodiment.

[0021] Fig.10 The power semiconductor module of the third embodiment Fig. 9 Schematic cross-section along the section line XX shown in .

[0022] Fig.11 This is a schematic cross-sectional view of a power semiconductor module according to a fourth embodiment.

[0023] Fig.12 This is a block diagram showing the configuration of a power conversion system according to a fifth embodiment.

[0024] (Explanation of Reference Numerals)

[0025] 1, 1b, 1c, 1d: power semiconductor module; 5: first joint; 6: second joint; 7: third joint; 10: circuit substrate; 11: insulating substrate; 11a: first main surface; 11b: second main surface; 12: circuit pattern; 13: back conductor layer; 15: first joint layer; 19: power semiconductor element; 20: semiconductor substrate; 21: gate electrode; 22: source electrode; 23: drain electrode; 24: insulating film; 25, 26, 27: lead terminal; 28 , 29: conductive wire; 30: shell; 31: heat dissipation component; 31a: third main surface; 31b: fourth main surface; 31f: convex piece; 32: metal covering layer; 35: solder layer; 35b: second bonding layer; 37: outer body; 38: sealing component; 41: conductive pad; 42: base layer; 43: third bonding layer; 100: power supply; 200: power conversion device; 201: main conversion circuit; 202: semiconductor module; 203: control circuit; 300: load. DETAILED DESCRIPTION

[0026] Hereinafter, an embodiment of the present invention will be described. In addition, the same reference numerals are attached to the same structures, and the description thereof will not be repeated.

[0027] Implementation method 1.

[0028] Reference Figure 1 and Figure 2 Next, a power semiconductor module 1 according to Embodiment 1 is described. The power semiconductor module 1 mainly includes a circuit board 10, a power semiconductor element 19, and at least one bonding portion (first bonding portion 5).

[0029] The circuit board 10 includes a circuit pattern 12. The circuit board 10 may further include an insulating substrate 11. The circuit board 10 may further include a back conductor layer 13.

[0030] The insulating substrate 11 includes a first main surface 11a facing the power semiconductor element 19 and a second main surface 11b on the opposite side of the first main surface 11a. The insulating substrate 11 is formed of an inorganic ceramic material such as aluminum oxide (Al2O3), aluminum nitride (AlN), silicon nitride (Si3N4), silicon dioxide (SiO2) or boron nitride (BN). The insulating substrate 11 may also be an insulating resin substrate such as a glass epoxy substrate.

[0031] The circuit pattern 12 is provided on the first main surface 11a of the insulating substrate 11. The circuit pattern 12 is formed of a conductive metal material such as Al, AlSi, AlCu or AlSiCu. The circuit pattern 12 may have a thickness of, for example, 0.1 mm or more and 1.0 mm or less. The back conductor layer 13 is provided on the second main surface 11b of the insulating substrate 11. The back conductor layer 13 is not particularly limited and is formed by a metal laminate in which Al foil and Cu foil are laminated on each other. The Al foil of the back conductor layer 13 is provided between the Cu foil of the back conductor layer 13 and the insulating substrate 11. The back conductor layer 13 may also be a single layer. The back conductor layer 13 may have a thickness of, for example, 0.1 mm or more and 0.6 mm or less.

[0032] The power semiconductor element 19 is not particularly limited and is a vertical metal oxide semiconductor field effect transistor (MOSFET). The power semiconductor element 19 may also be a lateral MOSFET or an insulated gate bipolar transistor (IGBT). The power semiconductor element 19 includes a semiconductor substrate 20. The semiconductor substrate 20 includes a first surface facing the circuit pattern 12 and a second surface opposite to the first surface. The first surface may also be the back surface of the semiconductor substrate 20, and the second surface may also be the front surface of the semiconductor substrate 20. The semiconductor substrate 20 is formed of a wide bandgap semiconductor material such as silicon (Si), or silicon carbide (SiC), calcium nitride (GaN) or diamond.

[0033] The power semiconductor element 19 further includes a first electrode facing the circuit pattern 12. The first electrode may also be a drain electrode 23. The first electrode (drain electrode 23) is disposed on the first surface of the semiconductor substrate 20. The power semiconductor element 19 further includes a second electrode disposed on a side away from the circuit substrate 10. The second electrode may also include a gate electrode 21 and a source electrode 22. The second electrode (gate electrode 21 and source electrode 22) is disposed on the second surface of the semiconductor substrate 20. The first electrode (drain electrode 23) and the second electrode (gate electrode 21 and source electrode 22) are formed of a conductive metal material such as AlSi, AlCu, AlSiCu or Cu. The first electrode (drain electrode 23) and the second electrode (gate electrode 21 and source electrode 22) may also have a thickness of, for example, 2 μm or more and 10 μm or less.

[0034] A barrier metal layer such as a Ti layer (not shown) may be provided on the surface of the second electrode (gate electrode 21 and source electrode 22) facing the semiconductor substrate 20. A silicide film such as a NiSi film may be provided between the semiconductor substrate 20 and the first electrode (drain electrode 23).

[0035] The power semiconductor element 19 may further include an insulating film 24. The insulating film 24 is provided on the second surface of the semiconductor substrate 20. The insulating film 24 is formed on the outer edge of the second electrode (gate electrode 21 and source electrode 22) and between the gate electrode 21 and the source electrode 22. The insulating film 24 improves the electrical insulation between the gate electrode 21 and the source electrode 22. The insulating film 24 is formed of an insulating resin such as polyimide, for example.

[0036] The power semiconductor element 19 is mounted on the circuit pattern 12 . The power semiconductor element 19 is bonded to the circuit pattern 12 via the first bonding layer 15 . Specifically, the first electrode (drain electrode 23 ) of the power semiconductor element 19 is bonded to the circuit pattern 12 via the first bonding layer 15 .

[0037] At least one joint includes a first metal member away from the semiconductor substrate 20, a second metal member close to the semiconductor substrate 20, and a joint layer that joins the first metal member and the second metal member to each other. Specifically, at least one joint includes a first joint 5. The first metal member is a circuit pattern 12, the second metal member is a first electrode (drain electrode 23), and the joint layer is a first joint layer 15. That is, the first joint 5 includes a circuit pattern 12 away from the semiconductor substrate 20, a first electrode (drain electrode 23) close to the semiconductor substrate 20, and a first joint layer 15 that joins the circuit pattern 12 and the first electrode (drain electrode 23) to each other.

[0038] At the same temperature, the 0.2% yield strength of the first metal component (circuit pattern 12) is smaller than the 0.2% yield strength of the second metal component (first electrode (drain electrode 23)). Table 1 shows the 0.2% yield strength of metal materials measured at room temperature. In Table 1, AlSi (Si 1wt%) is an AlSi alloy containing 1 weight % of Si. AlCu (Cu 0.5wt%) is an AlCu alloy containing 0.5 weight % of Cu. AlSiCu (Si 1wt%, Cu 0.5wt%) is an AlSiCu alloy containing 1 weight % of Si and 0.5 weight % of Cu. Generally, the 0.2% yield strength of a material is an indicator of the tensile strength of the material. The magnitude relationship between the 0.2% yield strength of the first metal component and the 0.2% yield strength of the second metal component remains unchanged within the operating temperature range of the power semiconductor module 1 (for example, above -55°C and less than 300°C). In this specification, the operating temperature range of the power semiconductor module 1 means a temperature range of the power semiconductor module 1 when the power semiconductor element 19 is operating or stopped.

[0039] [Table 1]

[0040]

[0041] According to Table 1, examples of combinations of metal materials that can be applied to the first metal component (circuit pattern 12) and the second metal component (first electrode (drain electrode 23)) are as follows. When the first metal component (circuit pattern 12) is formed of Al, the second metal component (first electrode (drain electrode 23)) can be formed of AlSi, AlCu, AlSiCu or Cu. When the first metal component (circuit pattern 12) is formed of AlSi, the second metal component (first electrode (drain electrode 23)) can be formed of AlCu, AlSiCu or Cu. When the first metal component (circuit pattern 12) is formed of AlCu, the second metal component (first electrode (drain electrode 23)) can be formed of AlSiCu or Cu. When the first metal component (circuit pattern 12) is formed of AlSiCu, the second metal component (first electrode (drain electrode 23)) can be formed of Cu. In one example of this embodiment, the first metal component (circuit pattern 12) is formed of Al and has a 0.2% yield strength of 30 MPa at room temperature, and the second metal component (first electrode (drain electrode 23)) is formed of AlSi (Si 1wt%) and has a 0.2% yield strength of 45 MPa at room temperature.

[0042] At the same temperature, the 0.2% yield strength of the first metal component (circuit pattern 12) is smaller than the shear strength of the bonding layer (first bonding layer 15). Specifically, at the same temperature, the 0.2% yield strength of the second metal component (first electrode (drain electrode 23)) may also be greater than the shear strength of the bonding layer (first bonding layer 15). The bonding layer (first bonding layer 15) is not particularly limited and may also be formed by a metal nanoparticle sintered body. The metal nanoparticles have, for example, a diameter of less than 10 nm. The bonding layer (first bonding layer 15) formed by the metal nanoparticle sintered body does not contain voids greater than 0.1 μm. The metal nanoparticle sintered body is obtained by sintering metal nanoparticles such as silver nanoparticles or copper nanoparticles at a low temperature of less than 300°C in an air atmosphere or a nitrogen atmosphere.

[0043] In one example of the present embodiment, the first metal component (circuit pattern 12) is formed of Al and has a 0.2% yield strength of 30 MPa at room temperature, and the bonding layer (first bonding layer 15) is formed of a silver nanoparticle sintered body and has a shear strength greater than 30 MPa and less than 40 MPa at room temperature. The silver nanoparticle sintered body having a shear strength greater than 30 MPa and less than 40 MPa is obtained, for example, by sintering silver nanoparticles at a temperature greater than 250°C and less than 300°C. In addition, the magnitude relationship between the 0.2% yield strength of the first metal component and the shear strength of the bonding layer (first bonding layer 15) remains unchanged in the operating temperature range of the power semiconductor module 1 (for example, greater than -55°C and less than 300°C).

[0044] If the sintering temperature of metal nanoparticles changes, the density (porosity) of metal nanoparticle sintered body also changes. Therefore, by adjusting the sintering temperature of metal nanoparticles, the shear strength of metal nanoparticle sintered body can be adjusted. If the load applied to silver nanoparticles changes when sintering metal nanoparticles, the density (porosity) of metal nanoparticle sintered body also changes. Therefore, the shear strength of metal nanoparticle sintered body can also be adjusted by adjusting this load.

[0045] The bonding layer (first bonding layer 15) may have a thickness of, for example, more than 20 μm, or more than 35 μm. Therefore, the mechanical strength of the bonding layer (first bonding layer 15) is improved, and the generation of cracks in the bonding layer (first bonding layer 15) can be suppressed. Even if a hot and cold cycle is applied to the power semiconductor module 1, cracks can be selectively generated in the first metal component (circuit pattern 12) away from the semiconductor substrate 20. The bonding layer (first bonding layer 15) may have a thickness of, for example, less than 100 μm, or less than 50 μm. There is no need to form a special bonding layer (first bonding layer 15), so the increase in the cost of the power semiconductor module 1 can be suppressed.

[0046] The power semiconductor module 1 may further include lead terminals 25, 26, and 27. The lead terminals 25, 26, and 27 are formed of a metal material such as Cu or Al. The lead terminals 25, 26, and 27 are bonded to the circuit pattern 12. Specifically, the lead terminals 25, 26, and 27 are ultrasonically bonded to the circuit pattern 12. The lead terminal 26 is electrically connected to the first electrode (drain electrode 23) of the power semiconductor element 19 via the circuit pattern 12. The lead terminal 26 may also be a drain terminal.

[0047] The power semiconductor module 1 may further include conductive wires 28 and 29. The conductive wires 28 and 29 are formed of a metal material such as Al or Cu. The conductive wires 28 and 29 may be formed of the same metal material. For example, the conductive wires 28 and 29 may be formed of Al. The conductive wires 28 and 29 may be formed of different materials. The conductive wire 28 may be formed of Cu, and the conductive wire 29 may be formed of Al.

[0048] The lead terminal 25 is electrically connected to the second electrode (gate electrode 21) of the power semiconductor element 19 via the conductive wire 28. The lead terminal 25 may also be a gate terminal. The lead terminal 27 is electrically connected to the second electrode (source electrode 22) of the power semiconductor element 19 via the conductive wire 29. The lead terminal 27 may also be a source terminal. In the power semiconductor element 19, the current flowing through the source electrode 22 is larger than the current flowing through the gate electrode 21. Therefore, the conductive wire 29 may also have a larger diameter than the conductive wire 28. The number of conductive wires 29 may also be greater than the number of conductive wires 28.

[0049] The power semiconductor module 1 may further include a case 30. The case 30 accommodates the power semiconductor element 19 and the circuit substrate 10. The case 30 may include a heat dissipation member 31 and a peripheral body 37. The circuit substrate 10 is bonded to the heat dissipation member 31. The heat dissipation member 31 diffuses the heat generated in the power semiconductor element 19 to the outside of the power semiconductor module 1. The heat dissipation member 31 may be formed of a metal material such as aluminum, for example.

[0050] Specifically, the heat dissipation component 31 includes a third main surface 31a facing the circuit substrate 10 and a fourth main surface 31b on the opposite side of the third main surface 31a. A metal coating layer 32 is provided on the third main surface 31a of the heat dissipation component 31. The metal coating layer 32 may also be a Ni-P plated layer. The back conductor layer 13 of the circuit substrate 10 and the metal coating layer 32 are bonded to each other through a solder layer 35. The solder layer 35 may also be formed of, for example, a SnAgCu-based lead-free solder. The heat dissipation component 31 may also include a plurality of convex pieces 31f. The plurality of convex pieces 31f protrude from the fourth main surface 31b. The plurality of convex pieces 31f increase the heat dissipation capacity of the heat dissipation component 31.

[0051] The outer casing 37 is fixed to the heat dissipation member 31 using a fixing member such as a screw or an adhesive. The outer casing 37 may be formed of an insulating resin such as polyphenylene sulfide (PPS) resin, epoxy resin, polyimide resin, or acrylic resin.

[0052] A sealing member 38 is provided in at least a portion of the inner space of the case 30. The sealing member 38 seals the power semiconductor element 19. The sealing member 38 may further seal the ends of the lead terminals 25, 26, and 27 connected to the circuit pattern 12. The sealing member 38 may further seal the circuit substrate 10. The sealing member 38 may be formed of an insulating resin such as a silicone resin, an epoxy resin, a urethane resin, a polyimide resin, a polyamide resin, or an acrylic resin.

[0053] The sealing member 38 may also include fillers such as particles. The fillers may also be dispersed in the insulating resin. The fillers may be formed of inorganic ceramic materials such as silicon dioxide (SiO2), aluminum oxide (Al2O3), aluminum nitride (AlN), boron nitride (BN), silicon nitride (Si3N4), diamond (C), silicon carbide (SiC) or boron oxide (B2O3). By adding fillers to the insulating resin, the thermal expansion coefficient of the sealing member 38 can be adjusted. The fillers may also have a higher thermal conductivity than the insulating resin material that is the main component of the sealing member 38, and may also improve the thermal conductivity of the sealing member 38.

[0054] Reference Figures 1 to 7 , a method for manufacturing the power semiconductor module 1 according to the first embodiment is described.

[0055] like Figure 3 As shown, the manufacturing method of the power semiconductor module 1 of the present embodiment comprises: using the first bonding layer 15, the power semiconductor element 19 is bonded to the circuit pattern 12. Specifically, a metal nanoparticle paste such as a silver nanoparticle paste is applied on the circuit pattern 12. The metal nanoparticle paste has a thickness of, for example, 20 μm to 100 μm. The metal nanoparticle paste is temporarily sintered at a first temperature of, for example, 100° C. to 200° C. to obtain a metal nanoparticle temporarily sintered body.

[0056] A power semiconductor element 19 is placed on the temporary sintered body of metal nanoparticles. The first electrode (drain electrode 23) of the power semiconductor element 19 contacts the temporary sintered body of metal nanoparticles. A load is applied to the power semiconductor element 19 to position the power semiconductor element 19 relative to the temporary sintered body of metal nanoparticles. The load is, for example, greater than 1 MPa and less than 10 MPa. Application of the load to the power semiconductor element 19 is stopped. The temporary sintered body of metal nanoparticles is sintered at a second temperature higher than the first temperature, for example, to obtain a first bonding layer 15 formed by the sintered body of metal nanoparticles. The second temperature may be, for example, less than 300°C or less than 250°C. The sintering time at the second temperature is, for example, greater than 5 minutes and less than 60 minutes. Thus, the first electrode (drain electrode 23) of the power semiconductor element 19 is bonded to the circuit pattern 12 using the first bonding layer 15.

[0057] like Figure 4 As shown, the method for manufacturing the power semiconductor module 1 of the present embodiment includes: bonding the lead terminals 25, 26, 27 to the circuit pattern 12. Specifically, the lead terminals 25, 26, 27 are ultrasonically bonded to the circuit pattern 12. Figure 5As shown, the method for manufacturing the power semiconductor module 1 of this embodiment includes bonding conductive wires 28 and 29 to the second electrodes (gate electrode 21 and source electrode 22) of the power semiconductor element 19 and the lead terminals 25 and 27. The conductive wires 28 and 29 may be bonded using a wedge bonder.

[0058] like Figure 6 and Figure 7 As shown, the manufacturing method of the power semiconductor module 1 of this embodiment includes: accommodating the power semiconductor element 19 and the circuit substrate 10 in the case 30. Specifically, as Figure 6 As shown in FIG. 1 , the circuit substrate 10 is bonded to the heat dissipation member 31. Specifically, the back conductor layer 13 of the circuit substrate 10 and the metal cover layer 32 provided on the third main surface 31a of the heat dissipation member 31 are bonded to each other through the solder layer 35. Then, as shown in FIG. Figure 7 As shown, the peripheral body 37 is fixed to the heat dissipation member 31. Specifically, the peripheral body 37 is fixed to the heat dissipation member 31 using an adhesive and screws.

[0059] Then, the manufacturing method of the power semiconductor module 1 of the present embodiment comprises: using a sealing member 38 to seal the power semiconductor element 19. Specifically, a sealing material is provided in at least a portion of the internal space of the shell 30. The sealing material is subjected to a degassing treatment. The sealing material is heated to be hardened. Thus, a sealing member 38 that seals the power semiconductor element 19 is obtained. The sealing member 38 may further seal the ends of the lead terminals 25, 26, and 27 connected to the circuit pattern 12. The sealing member 38 may further seal the circuit substrate 10. Thus, Figure 1 and Figure 2 A power semiconductor module 1 is shown.

[0060] The effects of the power semiconductor module 1 according to the present embodiment will be described.

[0061] The power semiconductor module 1 of the present embodiment includes a circuit substrate 10, a power semiconductor element 19 including a semiconductor substrate 20, and at least one joint (first joint 5). The at least one joint (first joint 5) includes a first metal member (circuit pattern 12) away from the semiconductor substrate 20, a second metal member (first electrode (drain electrode 23)) close to the semiconductor substrate 20, and a joint layer (first joint layer 15) that joins the first metal member (circuit pattern 12) and the second metal member (first electrode (drain electrode 23)) to each other. At the same temperature, the 0.2% yield strength of the first metal member (circuit pattern 12) is smaller than the 0.2% yield strength of the second metal member (first electrode (drain electrode 23)), and is smaller than the shear strength of the joint layer (first joint layer 15).

[0062] If the power semiconductor element 19 is working, the temperature of the power semiconductor module 1 rises, and the first metal component (circuit pattern 12) and the second metal component (first electrode (drain electrode 23)) thermally expand. If the temperature of the power semiconductor module 1 rises, it can be considered that tensile stress is applied to the first metal component (circuit pattern 12) and the second metal component (first electrode (drain electrode 23)). In addition, in the case where the first metal component (circuit pattern 12) and the second metal component (first electrode (drain electrode 23)) are formed of different materials, the thermal expansion coefficient of the first metal component (circuit pattern 12) is different from the thermal expansion coefficient of the second metal component (first electrode (drain electrode 23)). The bonding layer (first bonding layer 15) is arranged between the first metal component (circuit pattern 12) and the second metal component (first electrode (drain electrode 23)), so shear stress acts on the bonding layer (first bonding layer 15).

[0063] The 0.2% yield strength of the first metal component (circuit pattern 12) is smaller than the 0.2% yield strength of the second metal component (first electrode (drain electrode 23)), and smaller than the shear strength of the bonding layer (first bonding layer 15). Therefore, even if a hot and cold cycle is applied to the power semiconductor module 1, cracks are selectively generated in the first metal component (circuit pattern 12) away from the semiconductor substrate 20. The bonding layer (first bonding layer 15) prevents the cracks from progressing to the power semiconductor element 19. Thus, the occurrence of cracks in the power semiconductor element 19 can be prevented. The life of the power semiconductor module 1 can be extended.

[0064] In the power semiconductor module 1 of the present embodiment, at the same temperature, the 0.2% yield strength of the second metal member (the first electrode (drain electrode 23)) can also be greater than the shear strength of the bonding layer (the first bonding layer 15). Therefore, even if a crack occurs in the first metal member (circuit pattern 12) away from the semiconductor substrate 20, the second metal member (the first electrode (drain electrode 23)) can prevent the crack from progressing to the power semiconductor element 19. Thus, the occurrence of cracks in the power semiconductor element 19 can be prevented. The life of the power semiconductor module 1 can be extended.

[0065] In the power semiconductor module 1 of the present embodiment, the circuit substrate 10 includes a circuit pattern 12. The power semiconductor element 19 further includes a first electrode (drain electrode 23) facing the circuit pattern 12. At least one joint includes a first joint 5. The first joint 5 includes the circuit pattern 12 as a first metal component, the first electrode (drain electrode 23) as a second metal component, and the first bonding layer 15 as a bonding layer. Therefore, even if the power semiconductor module 1 is subjected to a hot and cold cycle, cracks are selectively generated in the circuit pattern 12 away from the semiconductor substrate 20. The first bonding layer 15 and the first electrode (drain electrode 23) prevent the cracks from progressing to the semiconductor substrate 20 of the power semiconductor element 19. Thus, it is possible to prevent cracks from occurring in the power semiconductor element 19. The life of the power semiconductor module 1 can be extended.

[0066] In the power semiconductor module 1 of the present embodiment, the bonding layer (first bonding layer 15) is formed by a metal nanoparticle sintered body. By adjusting the sintering temperature of the metal nanoparticles, etc., the shear strength of the metal nanoparticle sintered body can be adjusted. The bonding layer (first bonding layer 15) formed by the metal nanoparticle sintered body can expand the material options of the first metal component (circuit pattern 12) and the second metal component (first electrode (drain electrode 23)). Therefore, a high-performance and inexpensive power semiconductor module 1 can be obtained.

[0067] Implementation method 2.

[0068] Reference Figure 8 A power semiconductor module 1 b according to Embodiment 2 will be described. The power semiconductor module 1 b according to this embodiment has the same structure as the power semiconductor module 1 according to Embodiment 1, but is mainly different in the following points.

[0069] In the power semiconductor module 1b, the back conductor layer 13 is a single layer. In one example of the present embodiment, the back conductor layer 13 may be formed of, for example, Cu. The back conductor layer 13 may be a laminated body as in the first embodiment.

[0070] In the power semiconductor module 1b, the metal cover layer 32 and the solder layer 35 (see Figure 2), the circuit substrate 10 is bonded to the heat dissipation component 31 using the second bonding layer 35b. The second bonding layer 35b may have a thickness of, for example, greater than 20 μm and less than 100 μm. The second bonding layer 35b is not particularly limited, but may also be formed by a metal nanoparticle sintered body. The metal nanoparticles may have a diameter of, for example, less than 10 nm. The bonding layer (second bonding layer 35b) formed by the metal nanoparticle sintered body does not contain voids greater than 0.1 μm. The metal nanoparticle sintered body is obtained by, for example, sintering metal nanoparticles such as silver nanoparticles or copper nanoparticles at a low temperature of less than 300°C in an air atmosphere or a nitrogen atmosphere.

[0071] At least one joint portion includes a second joint portion 6. The second joint portion 6 includes a heat dissipation member 31 as a first metal member, a back conductor layer 13 as a second metal member, and a second joint layer 35b as a joint layer. At the same temperature, the 0.2% yield strength of the first metal member (heat dissipation member 31) is smaller than the 0.2% yield strength of the second metal member (back conductor layer 13), and is smaller than the shear strength of the joint layer (second joint layer 35b). Specifically, at the same temperature, the 0.2% yield strength of the second metal member (back conductor layer 13) may also be greater than the shear strength of the joint layer (second joint layer 35b). In an example of the present embodiment, the heat dissipation member 31 is formed of Al, the back conductor layer 13 is formed of Cu, and the second joint layer 35b is formed of a silver nanoparticle sintered body. The shear strength of the second joint layer 35b (silver nanoparticle sintered body) at room temperature is, for example, greater than 30 MPa and less than 40 MPa.

[0072] The 0.2% yield strength of the first metal member (heat dissipation member 31) in the second joint 6 may also be lower than the 0.2% yield strength of the first metal member (circuit pattern 12) in the first joint 5. Therefore, when the power semiconductor module 1b is subjected to a cold and hot cycle, cracks occur earlier in the first metal member (heat dissipation member 31) in the second joint 6 that is further away from the power semiconductor element 19 than in the first metal member (circuit pattern 12) in the first joint 5. The time until the crack reaches the power semiconductor element 19 can be extended. The life of the power semiconductor module 1b can be extended.

[0073] The bonding layer (second bonding layer 35b) may have a thickness of, for example, more than 20 μm, or more than 35 μm. Therefore, the mechanical strength of the bonding layer (second bonding layer 35b) is improved, and the generation of cracks in the bonding layer (second bonding layer 35b) can be suppressed. Even if a hot and cold cycle is applied to the power semiconductor module 1b, cracks can be selectively generated in the first metal component (heat dissipation component 31) away from the power semiconductor element 19 (semiconductor substrate 20). The bonding layer (second bonding layer 35b) may have a thickness of, for example, less than 100 μm, or less than 50 μm. There is no need to form a special bonding layer (second bonding layer 35b), so the increase in the cost of the power semiconductor module 1b can be suppressed.

[0074] The manufacturing method of the power semiconductor module 1b of the second embodiment has the same steps as the manufacturing method of the power semiconductor module 1 of the first embodiment, but is different in the step of bonding the circuit substrate 10 to the heat dissipation member 31. In the manufacturing method of the power semiconductor module 1b of the present embodiment, bonding the circuit substrate 10 to the heat dissipation member 31 includes: bonding the back conductor layer 13 of the circuit substrate 10 and the heat dissipation member 31 (the third main surface 31a) to each other via the second bonding layer 35b.

[0075] Specifically, a metal nanoparticle paste such as a silver nanoparticle paste is applied on the third main surface 31a of the heat dissipation member 31. The metal nanoparticle paste has a thickness of, for example, 20 μm to 100 μm. The metal nanoparticle paste is temporarily sintered at a first temperature of, for example, 100° C. to 200° C. to obtain a metal nanoparticle temporarily sintered body.

[0076] The back conductor layer 13 of the circuit substrate 10 is placed on the temporary sintered body of metal nanoparticles. The back conductor layer 13 of the circuit substrate 10 is in contact with the temporary sintered body of metal nanoparticles. A load is applied to the circuit substrate 10 to position the circuit substrate 10 relative to the temporary sintered body of metal nanoparticles. The load is, for example, greater than 1 MPa and less than 10 MPa. Stop applying the load to the circuit substrate 10. The temporary sintered body of metal nanoparticles is sintered at a second temperature higher than the first temperature, for example, to obtain a second bonding layer 35b formed by the sintered body of metal nanoparticles. The second temperature may be, for example, less than 300°C or less than 250°C. The sintering time at the second temperature is, for example, greater than 5 minutes and less than 60 minutes. Thus, the back conductor layer 13 of the circuit substrate 10 is bonded to the third main surface 31a of the heat dissipation component 31 using the second bonding layer 35b.

[0077] The power semiconductor module 1 b of the present embodiment achieves the following effects in addition to the effects of the power semiconductor module 1 of the first embodiment.

[0078] The power semiconductor module 1b of the present embodiment further includes a heat dissipation member 31. The circuit substrate 10 includes an insulating substrate 11, a circuit pattern 12, and a back conductor layer 13. The insulating substrate 11 includes a first main surface 11a facing the power semiconductor element 19 and a second main surface 11b on the opposite side of the first main surface 11a. The circuit pattern 12 is provided on the first main surface 11a of the insulating substrate 11. The back conductor layer 13 is provided on the second main surface 11b of the insulating substrate 11. At least one bonding portion includes a second bonding portion 6. The second bonding portion 6 includes a heat dissipation member 31 as a first metal member, a back conductor layer 13 as a second metal member, and a second bonding layer 35b as a bonding layer.

[0079] If the power semiconductor element 19 is operated, the temperature of the power semiconductor module 1b rises, and the first metal member (heat dissipation member 31) and the second metal member (back conductor layer 13) thermally expand. If the temperature of the power semiconductor module 1b rises, it can be considered that tensile stress is applied to the first metal member (heat dissipation member 31) and the second metal member (back conductor layer 13). In addition, when the first metal member (heat dissipation member 31) and the second metal member (back conductor layer 13) are formed of different materials, the thermal expansion coefficient of the first metal member (heat dissipation member 31) is different from the thermal expansion coefficient of the second metal member (back conductor layer 13). The bonding layer (second bonding layer 35b) is arranged between the first metal member (heat dissipation member 31) and the second metal member (back conductor layer 13), so shear stress acts on the bonding layer (second bonding layer 35b).

[0080] The 0.2% yield strength of the first metal member (heat dissipation member 31) is smaller than the 0.2% yield strength of the second metal member (back conductor layer 13), and smaller than the shear strength of the bonding layer (second bonding layer 35b). Therefore, even if a hot and cold cycle is applied to the power semiconductor module 1b, cracks are selectively generated in the first metal member (heat dissipation member 31) away from the semiconductor substrate 20. The bonding layer (second bonding layer 35b) and the second metal member (back conductor layer 13) prevent the cracks from progressing to the power semiconductor element 19. Thus, it is possible to prevent cracks from occurring in the power semiconductor element 19. The life of the power semiconductor module 1b can be extended.

[0081] In the power semiconductor module 1b of this embodiment, the 0.2% yield strength of the second metal member (back conductor layer 13) can also be greater than the shear strength of the bonding layer (second bonding layer 35b) at the same temperature. Therefore, even if a crack occurs in the first metal member (heat dissipation member 31) away from the semiconductor substrate 20, the second metal member (back conductor layer 13) can prevent the crack from progressing to the power semiconductor element 19. Thus, it is possible to prevent cracks from occurring in the power semiconductor element 19. The life of the power semiconductor module 1b can be extended.

[0082] In the power semiconductor module 1b of the present embodiment, the power semiconductor element 19 further includes a first electrode (drain electrode 23) facing the circuit pattern 12. At least one joint further includes a first joint 5. The first joint 5 includes the circuit pattern 12 as a first metal member, the first electrode (drain electrode 23) as a second metal member, and a first joint layer 15 as a joint layer.

[0083] That is, the power semiconductor module 1b has a plurality of joints (a first joint 5 and a second joint 6). Each of the plurality of joints (the first joint 5 and the second joint 6) includes a first metal member (a circuit pattern 12 and a heat dissipation member 31) away from the semiconductor substrate 20, a second metal member (a first electrode (drain electrode 23) and a back conductor layer 13) close to the semiconductor substrate 20, and a joint layer (a first joint layer 15 and a second joint layer 35b) that joins the first metal member (a circuit pattern 12 and a heat dissipation member 31) and the second metal member (a first electrode (drain electrode 23) and a back conductor layer 13) to each other. At the same temperature, the 0.2% yield strength of the first metal member (the circuit pattern 12 and the heat dissipation member 31) is smaller than the 0.2% yield strength of the second metal member (the first electrode (drain electrode 23) and the back conductor layer 13), and is smaller than the shear strength of the joint layer (the first joint layer 15 and the second joint layer 35b).

[0084] Therefore, the thermal stress and thermal strain generated in the power semiconductor module 1b can be borne by the multiple joints (the first joint 5 and the second joint 6). The thermal stress and thermal strain acting on each of the multiple joints (the first joint 5 and the second joint 6) are reduced. The progress of cracks in the weakest part among the multiple joints (the first joint 5 and the second joint 6) can be reduced. The life of the power semiconductor module 1b can be further extended.

[0085] Implementation method 3.

[0086] Reference Fig. 9 and Fig.10A power semiconductor module 1c according to Embodiment 3 will be described. The power semiconductor module 1c according to this embodiment has the same structure as the power semiconductor module 1 according to Embodiment 1, but is mainly different in the following points.

[0087] The power semiconductor module 1c further includes a conductive pad 41. Fig. 9 As shown in FIG. 1 , when the second electrode (source electrode 22) is viewed from above (when the first main surface 11a of the insulating substrate 11 is viewed from above), the conductive pad 41 has a larger area than the second electrode (source electrode 22). Therefore, even if the conductive wire 29 has a larger diameter than the conductive wire 28 or the number of the conductive wires 29 is greater than the number of the conductive wires 28, the conductive wire 29 can be bonded to the conductive pad 41 more easily.

[0088] In addition, the conductive pad 41 has a larger volume than the second electrode (source electrode 22). The conductive pad 41 has a larger heat capacity than the second electrode (source electrode 22). Therefore, the heat generated in the power semiconductor element 19 can be diffused from the conductive pad 41. The conductive pad 41 is thicker than the second electrode (source electrode 22). The conductive pad 41 (excluding the base layer 42) is formed of Cu, for example. The conductive pad 41 (excluding the base layer 42) may also have a thickness of, for example, 0.1 mm or more and 2.0 mm or less.

[0089] The conductive pad 41 includes a conductive pad portion facing the power semiconductor element 19. The conductive pad portion may also be the base layer 42. The conductive pad portion (base layer 42) is formed of, for example, Al. The conductive pad 41 may also be formed of a single metal material. The thickness of the conductive pad portion (base layer 42) is smaller than the thickness of the conductive pad 41 (excluding the base layer 42). The conductive pad portion (base layer 42) may also have a thickness of, for example, 2 μm or more and 200 μm or less.

[0090] At least one bonding portion includes a third bonding portion 7. The third bonding portion 7 includes a conductive pad portion (base layer 42) as a first metal component, a second electrode (source electrode 22) as a second metal component, and a third bonding layer 43 as a bonding layer. The third bonding layer 43 may have a thickness of, for example, more than 20 μm and less than 100 μm. The third bonding layer 43 is not particularly limited, but may also be formed by a metal nanoparticle sintered body. The metal nanoparticles have, for example, a diameter of less than 10 nm. The bonding layer (third bonding layer 43) formed by the metal nanoparticle sintered body does not include voids greater than 0.1 μm. The metal nanoparticle sintered body is obtained by sintering metal nanoparticles such as silver nanoparticles or copper nanoparticles at a low temperature of less than 300°C in an air atmosphere or a nitrogen atmosphere.

[0091] At the same temperature, the 0.2% yield strength of the first metal component (conductive pad portion (base layer 42)) is smaller than the 0.2% yield strength of the second metal component (second electrode (source electrode 22)), and smaller than the shear strength of the bonding layer (third bonding layer 43). Specifically, at the same temperature, the 0.2% yield strength of the second metal component (second electrode (source electrode 22)) may also be greater than the shear strength of the bonding layer (third bonding layer 43). In one example of the present embodiment, the conductive pad portion (base layer 42) is formed of Al, the second electrode (source electrode 22) is formed of AlSi (Si 1wt%), and the third bonding layer 43 is formed of a silver nanoparticle sintered body. The shear strength of the third bonding layer 43 (silver nanoparticle sintered body) at room temperature is greater than 30MPa and less than 40MPa.

[0092] The bonding layer (third bonding layer 43) may have a thickness of, for example, more than 20 μm, or more than 35 μm. Therefore, the mechanical strength of the bonding layer (third bonding layer 43) is improved, and the generation of cracks in the bonding layer (third bonding layer 43) can be suppressed. Even if the power semiconductor module 1c is subjected to a hot and cold cycle, cracks can be selectively generated in the first metal component (conductive pad portion (base layer 42)) away from the semiconductor substrate 20. The bonding layer (third bonding layer 43) may have a thickness of, for example, less than 100 μm, or less than 50 μm. There is no need to form a special bonding layer (third bonding layer 43), so the increase in the cost of the power semiconductor module 1c can be suppressed.

[0093] The manufacturing method of the power semiconductor module 1c of the third embodiment has the same steps as the manufacturing method of the power semiconductor module 1 of the first embodiment, but mainly differs in the following aspects. The manufacturing method of the power semiconductor module 1c of the present embodiment further comprises: using the third bonding layer 43 to bond the conductive pad 41 to the power semiconductor element 19. It is also possible to bond the conductive pad 41 to the power semiconductor element 19 using the third bonding layer 43 after bonding the power semiconductor element 19 to the circuit pattern 12 using the first bonding layer 15. It is also possible to bond the conductive pad 41 to the power semiconductor element 19 using the third bonding layer 43 before bonding the lead terminals 25, 26, 27 to the circuit pattern 12.

[0094] Specifically, a metal nanoparticle paste such as a silver nanoparticle paste is applied on the second electrode (source electrode 22) of the power semiconductor element 19. The metal nanoparticle paste has a thickness of, for example, 20 μm or more and 100 μm or less. The metal nanoparticle paste is temporarily sintered at a first temperature of, for example, 100° C. or more and 200° C. or less to obtain a metal nanoparticle temporarily sintered body.

[0095] A conductive pad 41 is placed on the temporary sintered body of metal nanoparticles. The conductive pad portion (base layer 42) contacts the temporary sintered body of metal nanoparticles. A load is applied to the conductive pad 41 to position the conductive pad 41 relative to the temporary sintered body of metal nanoparticles. The load is, for example, greater than 1 MPa and less than 10 MPa. Stop applying the load to the conductive pad 41. The temporary sintered body of metal nanoparticles is sintered at a second temperature that is, for example, higher than the first temperature to obtain a third bonding layer 43 formed by the metal nanoparticle sintered body. The second temperature may be, for example, less than 300°C or less than 250°C. The sintering time at the second temperature is, for example, greater than 5 minutes and less than 60 minutes. Thus, the conductive pad portion (base layer 42) of the conductive pad 41 is bonded to the second electrode (source electrode 22) of the power semiconductor element 19 using the third bonding layer 43.

[0096] The method for manufacturing the power semiconductor module 1 c of the present embodiment includes bonding the conductive wire 29 to the conductive pad 41 instead of the second electrode (source electrode 22 ) of the power semiconductor element 19 .

[0097] The effects of the power semiconductor module 1 c according to the present embodiment will be described.

[0098] The power semiconductor module 1c of the present embodiment further includes a conductive pad 41 including a conductive pad portion (base layer 42) facing the power semiconductor element 19. The power semiconductor element 19 further includes a second electrode (source electrode 22) provided on a side away from the circuit substrate 10. When the second electrode (source electrode 22) is viewed from above, the conductive pad 41 has a larger area than the second electrode (source electrode 22). At least one joint includes a third joint 7. The third joint 7 includes a conductive pad portion (base layer 42) as a first metal member, a second electrode (source electrode 22) as a second metal member, and a third joint layer 43 as a joint layer.

[0099] If the power semiconductor element 19 is working, the temperature of the power semiconductor module 1c rises, and the first metal component (conductive pad portion (base layer 42)) and the second metal component (second electrode (source electrode 22)) thermally expand. If the temperature of the power semiconductor module 1c rises, it can be considered that tensile stress is applied to the first metal component (conductive pad portion (base layer 42)) and the second metal component (second electrode (source electrode 22)). In addition, in the case where the first metal component (conductive pad portion (base layer 42)) and the second metal component (second electrode (source electrode 22)) are formed of different materials, the thermal expansion coefficient of the first metal component (conductive pad portion (base layer 42)) is different from the thermal expansion coefficient of the second metal component (second electrode (source electrode 22)). The bonding layer (third bonding layer 43) is arranged between the first metal component (conductive pad portion (base layer 42)) and the second metal component (second electrode (source electrode 22)), so shear stress acts on the bonding layer (third bonding layer 43).

[0100] The 0.2% yield strength of the first metal component (conductive pad portion (base layer 42)) is smaller than the 0.2% yield strength of the second metal component (second electrode (source electrode 22)), and smaller than the shear strength of the bonding layer (third bonding layer 43). Therefore, even if a hot and cold cycle is applied to the power semiconductor module 1c, cracks are selectively generated in the first metal component (conductive pad portion (base layer 42)) away from the semiconductor substrate 20. The bonding layer (third bonding layer 43) prevents the cracks from progressing to the power semiconductor element 19. Thus, it is possible to prevent cracks from occurring in the power semiconductor element 19. The life of the power semiconductor module 1c can be extended.

[0101] In the power semiconductor module 1c of this embodiment, the 0.2% yield strength of the second metal member (the second electrode (source electrode 22)) can also be greater than the shear strength of the bonding layer (the third bonding layer 43) at the same temperature. Therefore, even if a crack occurs in the first metal member (the conductive pad portion (base layer 42)) away from the semiconductor substrate 20, the second metal member (the second electrode (source electrode 22)) can prevent the crack from progressing to the power semiconductor element 19. Thus, it is possible to prevent cracks from occurring in the power semiconductor element 19. The life of the power semiconductor module 1c can be extended.

[0102] When the second electrode (source electrode 22) is viewed from above, the conductive pad 41 has a larger area than the second electrode (source electrode 22). Therefore, even if the diameter of the conductive wire 29 is increased, the conductive wire 29 can be easily bonded to the conductive pad 41. By increasing the diameter of the conductive wire 29, the resistance in the connection portion between the second electrode (source electrode 22) and the conductive wire 29 can be reduced. The heat generated in the connection portion can be reduced. The thermal stress and thermal strain generated in the power semiconductor module 1c during the hot and cold cycle can be reduced. The life of the power semiconductor module 1c can be extended.

[0103] The conductive pad 41 diffuses the heat generated in the power semiconductor element 19 to the outside of the power semiconductor element 19. The operating temperature of the power semiconductor element 19 can be reduced. If the temperature of the power semiconductor element 19 is reduced, the short-circuit resistance of the power semiconductor element 19 is improved. Therefore, the life of the power semiconductor module 1c can be extended.

[0104] In the power semiconductor module 1c of the present embodiment, the power semiconductor element 19 further includes a first electrode (drain electrode 23) facing the circuit pattern 12. At least one joint further includes a first joint 5. The first joint 5 includes the circuit pattern 12 as a first metal member, the first electrode (drain electrode 23) as a second metal member, and a first joint layer 15 as a joint layer.

[0105] That is, the power semiconductor module 1c has a plurality of joints (a first joint 5 and a third joint 7). Each of the plurality of joints (the first joint 5 and the third joint 7) includes a first metal member (a circuit pattern 12 and a conductive pad portion (base layer 42)) away from the semiconductor substrate 20, a second metal member (a first electrode (drain electrode 23) and a back conductor layer 13) close to the semiconductor substrate 20, and a joint layer (a first joint layer 15 and a second joint layer 35b) that joins the first metal member (circuit pattern 12 and heat dissipation member 31) and the second metal member (a first electrode (drain electrode 23) and a second electrode (source electrode 22)) to each other. At the same temperature, the 0.2% yield strength of the first metal component (circuit pattern 12, conductive pad portion (base layer 42)) is smaller than the 0.2% yield strength of the second metal component (first electrode (drain electrode 23), second electrode (source electrode 22)), and is smaller than the shear strength of the bonding layer (first bonding layer 15, third bonding layer 43).

[0106] Therefore, the thermal stress and thermal strain generated in the power semiconductor module 1c can be borne by the multiple joints (the first joint 5 and the third joint 7). The thermal stress and thermal strain acting on each of the multiple joints (the first joint 5 and the third joint 7) are reduced. The progress of cracks in the weakest part of the multiple joints (the first joint 5 and the third joint 7) can be reduced. The life of the power semiconductor module 1c can be further extended.

[0107] Implementation method 4.

[0108] Reference Fig.11 The power semiconductor module 1d of the fourth embodiment is described. The power semiconductor module 1d of the present embodiment has the same structure as the power semiconductor module 1b of the second embodiment, but is different from the power semiconductor module 1b of the second embodiment mainly in the following aspects. The power semiconductor module 1d also has a conductive pad 41 as in the third embodiment. In the power semiconductor module 1d, the conductive pad 41 is bonded to the second electrode (source electrode 22) of the power semiconductor element 19 using the third bonding layer 43 of the third embodiment. In the power semiconductor module 1d, the conductive wire 29 is bonded to the conductive pad 41 as in the third embodiment.

[0109] The manufacturing method of the power semiconductor module 1d of the fourth embodiment has the same steps as the manufacturing method of the power semiconductor module 1b of the second embodiment, but is mainly different in the following aspects. The manufacturing method of the power semiconductor module 1d of this embodiment is similar to the third embodiment, and further includes: using the third bonding layer 43 to bond the conductive pad 41 to the power semiconductor element 19. The manufacturing method of the power semiconductor module 1d of this embodiment is similar to the third embodiment, and includes: bonding the conductive wire 29 to the conductive pad 41.

[0110] The power semiconductor module 1d of the present embodiment has the following effects in addition to the effects of the power semiconductor modules 1, 1b, and 1c of embodiments 1 to 3. In the power semiconductor module 1d of the present embodiment, the thermal stress and thermal strain occurring in the power semiconductor module 1d can be borne by a plurality of joints (the first joint 5, the second joint 6, and the third joint 7). The thermal stress and thermal strain acting on each of the plurality of joints (the first joint 5, the second joint 6, and the third joint 7) are reduced. Therefore, the progression of cracks in the weakest portion of the plurality of joints (the first joint 5, the second joint 6, and the third joint 7) can be reduced. The life of the power semiconductor module 1d can be further extended.

[0111] Implementation method 5.

[0112] In this embodiment, any of the power semiconductor modules 1, 1b, 1c, and 1d of Embodiments 1 to 4 is applied to a power conversion device. The power conversion device 200 of this embodiment is not particularly limited, but a three-phase inverter is described below.

[0113] Fig.12 The power conversion system shown includes a power supply 100, a power conversion device 200, and a load 300. The power supply 100 is a DC power supply that provides DC power to the power conversion device 200. The power supply 100 is not particularly limited, but for example, it may include a DC system, a solar cell or a storage battery, and may also include a rectifier circuit or an AC / DC converter connected to an AC system. The power supply 100 may also include a DC / DC converter that converts the DC power output from the DC system into other DC power.

[0114] The power conversion device 200 is a three-phase inverter connected between the power source 100 and the load 300, converts the DC power provided by the power source 100 into AC power, and provides the AC power to the load 300. Fig.12 As shown, a main conversion circuit 201 that converts DC power into AC power and outputs the AC power and a control circuit 203 that outputs a control signal for controlling the main conversion circuit 201 to the main conversion circuit 201 are provided.

[0115] Load 300 is a three-phase motor driven by AC power supplied from power converter 200. Load 300 is not particularly limited, and is a motor installed in various electrical devices, such as a motor for hybrid vehicles, electric vehicles, railway vehicles, elevators, or air conditioners.

[0116] The following describes the details of the power conversion device 200. The main conversion circuit 201 includes a switching element (not shown) and a return diode (not shown). The switching element switches the voltage provided from the power supply 100, thereby the main conversion circuit 201 converts the DC power provided from the power supply 100 into AC power and provides it to the load 300. The specific circuit structure of the main conversion circuit 201 is various, but the main conversion circuit 201 of this embodiment is a 2-level three-phase full-bridge circuit, which can include 6 switching elements and 6 return diodes connected in anti-parallel with each switching element. In at least one of the switching elements and return diodes of the main conversion circuit 201, any power semiconductor module of the power semiconductor modules 1, 1b, 1c, and 1d of the above-mentioned embodiments 1 to 4 is applied. With respect to the 6 switching elements, every two switching elements are connected in series to form upper and lower branches, and each upper and lower branch constitutes each phase (U phase, V phase, and W phase) of the full-bridge circuit. Then, the output terminals of each upper and lower branch, that is, the three output terminals of the main conversion circuit 201 are connected to the load 300.

[0117] In addition, the main conversion circuit 201 is provided with a driving circuit (not shown) for driving each switching element. The driving circuit may be built into the semiconductor module 202, or may be provided independently of the semiconductor module 202. The driving circuit generates a driving signal for driving the switching element included in the main conversion circuit 201, and provides the driving signal to the control electrode of the switching element of the main conversion circuit 201. Specifically, according to the control signal from the control circuit 203, a driving signal for turning the switching element into an on state and a driving signal for turning the switching element into an off state are output to the control electrode of each switching element. When the switching element is maintained in an on state, the driving signal is a voltage signal (on signal) above the threshold voltage of the switching element, and when the switching element is maintained in an off state, the driving signal becomes a voltage signal (off signal) below the threshold voltage of the switching element.

[0118] The control circuit 203 controls the switch elements of the main conversion circuit 201 to provide the desired power to the load 300. Specifically, based on the power to be provided to the load 300, the time (on time) at which each switch element of the main conversion circuit 201 should be in the on state is calculated. For example, the main conversion circuit 201 can be controlled by pulse width modulation (PWM) control that modulates the on time of the switch element according to the voltage to be output. Then, a control instruction (control signal) is output to the drive circuit of the main conversion circuit 201, so that at each time point, an on signal is output for the switch element that should be in the on state and an off signal is output for the switch element that should be in the off state. The drive circuit outputs an on signal or an off signal to the control electrode of each switch element as a drive signal according to the control signal.

[0119] In the power conversion device 200 of the present embodiment, any of the power semiconductor modules 1, 1b, 1c, and 1d of Embodiments 1 to 4 is applied as the semiconductor module 202 included in the main conversion circuit 201. Therefore, the power conversion device 200 of the present embodiment has improved reliability.

[0120] In this embodiment, an example of applying the present invention to a 2-level three-phase inverter is described, but the present invention is not limited thereto and can be applied to various power conversion devices. In this embodiment, a 2-level power conversion device is used, but a 3-level power conversion device or a multi-level power conversion device may be used. In the case where the power conversion device provides power to a single-phase load, the present invention may also be applied to a single-phase inverter. In the case where the power conversion device provides power to a DC load, etc., the present invention may also be applied to a DC / DC converter or an AC / DC converter.

[0121] The power conversion device to which the present invention is applied is not limited to the case where the load is a motor, and can be assembled, for example, in a power supply device for an electric discharge machine or a laser processing machine, or a power supply device for an induction heating cooker or a contactless power supply system. The power conversion device to which the present invention is applied can be used as a power conditioner for a solar power generation system or a power storage system.

[0122] It should be recognized that the embodiments 1-5 disclosed this time are illustrative in all aspects and not restrictive. At least two of the embodiments 1-5 disclosed this time can be combined as long as there is no contradiction. The scope of the present invention is not shown by the above description but by the claims, and it is intended to include all changes within the meaning and scope equivalent to the claims.

Claims

1. A power semiconductor module comprising: Circuit board; A power semiconductor device comprising a semiconductor substrate; and at least one joint, The at least one bonding portion includes a first metal member away from the semiconductor substrate, a second metal member close to the semiconductor substrate, and a bonding layer bonding the first metal member and the second metal member to each other. At the same temperature, the 0.2% yield strength of the first metal component is less than the 0.2% yield strength of the second metal component, and is less than the shear strength of the bonding layer. The circuit substrate includes a circuit pattern. The power semiconductor element further includes a first electrode provided on a surface of the semiconductor substrate facing the circuit pattern. The at least one joining portion includes a first joining portion, The first bonding portion includes the circuit pattern as the first metal member, the first electrode as the second metal member, and a first bonding layer as the bonding layer. The first bonding layer is used to connect the first electrode of the power semiconductor element to the circuit pattern of the circuit substrate.

2. The power semiconductor module according to claim 1, wherein: At the same temperature, the 0.2% yield strength of the second metal member is greater than the shear strength of the bonding layer.

3. A power semiconductor module comprising: Circuit board; A power semiconductor component, comprising a semiconductor substrate; at least one engaging portion; and heat dissipation components, The at least one bonding portion includes a first metal member away from the semiconductor substrate, a second metal member close to the semiconductor substrate, and a bonding layer bonding the first metal member and the second metal member to each other. At the same temperature, the 0.2% yield strength of the first metal component is less than the 0.2% yield strength of the second metal component, and is less than the shear strength of the bonding layer. The circuit substrate comprises an insulating substrate, a circuit pattern and a back conductor layer. The insulating substrate includes a first main surface facing the power semiconductor element and a second main surface opposite to the first main surface. The circuit pattern is arranged on the first main surface, The back conductor layer is provided on the second main surface, The at least one joining portion includes a second joining portion, The second bonding portion includes the heat dissipation member as the first metal member, the back conductor layer as the second metal member, and a second bonding layer as the bonding layer. The second bonding layer is used to connect the back surface conductor layer of the circuit board to the heat dissipation member.

4. The power semiconductor module according to claim 3, wherein: At the same temperature, the 0.2% yield strength of the second metal member is greater than the shear strength of the bonding layer.

5. The power semiconductor module according to claim 3, wherein: The power semiconductor element further includes a first electrode facing the circuit pattern. The at least one joining portion further comprises a first joining portion, The first joining portion includes the circuit pattern as the first metal member, the first electrode as the second metal member, and a first joining layer as the joining layer.

6. A power semiconductor module comprising: Circuit board; A power semiconductor component, comprising a semiconductor substrate; at least one engaging portion; and Conductive pads, The at least one bonding portion includes a first metal member away from the semiconductor substrate, a second metal member close to the semiconductor substrate, and a bonding layer bonding the first metal member and the second metal member to each other. At the same temperature, the 0.2% yield strength of the first metal component is less than the 0.2% yield strength of the second metal component, and is less than the shear strength of the bonding layer. The conductive pad includes a conductive pad portion facing the power semiconductor element, The power semiconductor element further includes a second electrode disposed on a side away from the circuit substrate. When the second electrode is viewed from above, the conductive pad has an area larger than that of the second electrode. The at least one joining portion includes a third joining portion, The third bonding portion includes the conductive pad portion as the first metal member, the second electrode as the second metal member, and a third bonding layer as the bonding layer. The third bonding layer is used to connect the second electrode as the second metal member to the conductive pad portion.

7. The power semiconductor module according to any one of claims 1 to 6, wherein: The bonding layer is formed of a sintered metal nanoparticle body.

8. The power semiconductor module according to any one of claims 1 to 6, wherein: The first metal member is formed of Al, The second metal member is formed of AlSi, AlCu, AlSiCu or Cu.

9. A power conversion device comprising: A main conversion circuit, comprising the power semiconductor module according to any one of claims 1 to 8, wherein the main conversion circuit converts input power and outputs the converted power; and The control circuit outputs a control signal for controlling the main conversion circuit to the main conversion circuit.

Images