Semiconductor module and power conversion device

Abstract

A semiconductor module (1) includes a first power semiconductor element (20), a conductive wire (35), and a resin film (40). The conductive wire (35) is bonded to a surface (22a) of a first front surface electrode (22) of the first power semiconductor element (20). The resin film (40) is continuously formed on at least one of an end (30a) or an end (30b) of a first bonding portion (30) between the first front surface electrode (22) and the conductive wire (35) in the length direction of the conductive wire (35), the surface (22a) of the first front surface electrode (22), and the surface (35a) of the conductive wire (35). The elastic elongation of the resin film (40) is 4.5% or more and 10.0% or less.

Description

Technical Field

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

[0002] Japanese Patent Publication No. 2017-147327 (Patent Document 1) discloses a semiconductor device having a power semiconductor element, a wire, a resin layer, and a gel filling material. The wire is bonded to an electrode of the power semiconductor element. The resin layer covers a bonded portion between the electrode of the power semiconductor element and the wire. The gel filling material seals the power semiconductor element, the wire, and the resin layer.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2017-147327 Summary of the invention

[0006] Problems to be solved by the invention

[0007] In the semiconductor device disclosed in Patent Document 1, thermal stress is repeatedly applied to the joint between the electrode and the wire of the power semiconductor element during use of the semiconductor device. Therefore, sometimes the resin layer peels off from at least one of the electrode, the wire, or the joint between the electrode and the wire of the power semiconductor element, cracks occur in the joint between the electrode and the wire of the power semiconductor element, or the wire peels off from the electrode of the power semiconductor element. The present disclosure is made in view of the above-mentioned problems, and its purpose is to provide a semiconductor module and a power conversion device with improved reliability.

[0008] Means for solving problems

[0009] The semiconductor module disclosed in the present invention comprises a first power semiconductor element, a conductive wire and a resin film. The first power semiconductor element comprises a first electrode. The conductive wire is bonded to a first surface of the first electrode. The resin film is continuously formed on a first end of a first bonding portion between the first electrode and the conductive wire in a longitudinal direction of the conductive wire, a first surface of the first electrode and a second surface of the conductive wire. The elastic elongation of the resin film is 4.5% or more and 10.0% or less.

[0010] The power conversion device of the present disclosure includes a main conversion circuit and a control circuit. The main conversion circuit includes the semiconductor module of the present disclosure 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.

[0011] Effects of the Invention

[0012] The elastic elongation of the resin film is 4.5% or more, so the resin film can follow the thermal expansion and thermal contraction of components constituting the semiconductor module, such as the first electrode and the conductive wire of the first power semiconductor element. The resin film does not peel off from the first end of the first joint, the surface of the first electrode, and the surface of the conductive wire. The resin film continuously alleviates the thermal stress applied to the first joint. The resin film can prevent cracks from occurring in the first joint or the conductive wire from peeling off from the first electrode. The life of the semiconductor module and the power conversion device is prolonged, and the semiconductor module and the power conversion device have improved reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a schematic cross-sectional view of the semiconductor module according to the first and second embodiments.

[0014] Figure 2 The semiconductor module of the first and second embodiments, Figure 1 A schematic partial enlarged cross-sectional view of region II is shown.

[0015] Figure 3 The semiconductor module of the first and second embodiments, Figure 1 A schematic partial enlarged cross-sectional view of region III is shown.

[0016] Figure 4 This is a diagram showing the definition of elastic elongation of a resin film.

[0017] Figure 5 It is a graph showing the power cycle life of the semiconductor modules of Comparative Examples A to C and the semiconductor modules of Examples D to G.

[0018] Figure 6 This is a schematic partial enlarged cross-sectional view of a semiconductor module according to a third embodiment.

[0019] Figure 7 This is a schematic cross-sectional view of a semiconductor module according to a fourth embodiment.

[0020] Figure 8 This is a block diagram showing the configuration of a power conversion system according to a fifth embodiment.

[0021] (Explanation of Reference Numerals)

[0022] 1, 1a, 1b, 1c: semiconductor module; 10: insulating circuit substrate; 11: insulating substrate; 12: conductive circuit pattern; 13: conductive plate; 20: first power semiconductor element; 21: first back electrode; 22: first front electrode; 22a: surface; 23: first guard ring; 25: second power semiconductor element; 26: second back electrode; 27: second front electrode; 27a: surface; 28: second guard ring; 30: first joint; 30a, 30b: end; 31: second joint; 31 a, 31b: end; 32: first electrode terminal; 32c: first lead terminal; 33: second electrode terminal; 33c: second lead terminal; 35, 36, 37: conductive wire; 35a: surface; 40: resin film; 43: rough surface; 45: shell; 46: bottom plate; 47: outer body; 50, 50a: sealing member; 55: heat sink; 56: insulating plate; 57: heat sink; 100: power supply; 200: power conversion device; 201: main conversion circuit; 203: control circuit; 300: load power supply. DETAILED DESCRIPTION

[0023] Hereinafter, the embodiment of the present disclosure will be described. In addition, the same reference numerals are given to the same configurations, and the description thereof will not be repeated.

[0024] Implementation method 1.

[0025] Reference Figures 1 to 3 , a semiconductor module 1 according to Embodiment 1 is described. The semiconductor module 1 mainly includes a first power semiconductor element 20, a second power semiconductor element 25, conductive wires 35, 36, a resin film 40, a first electrode terminal 32, and a second electrode terminal 33. The semiconductor module 1 may further include an insulating circuit substrate 10, a housing 45, and a sealing member 50.

[0026] The insulating circuit substrate 10 includes an insulating substrate 11. The insulating substrate 11 includes a front surface and a back surface opposite to the front surface. The insulating substrate 11 is formed of a ceramic material such as aluminum oxide (Al2O3), aluminum nitride (AlN) or silicon nitride (Si3N4). The insulating circuit substrate 10 includes a conductive circuit pattern 12 and a conductive plate 13. The conductive circuit pattern 12 is provided on the front surface of the insulating substrate 11. The conductive plate 13 is provided on the back surface of the insulating substrate 11. The conductive circuit pattern 12 and the conductive plate 13 are formed of a metal material such as copper (Cu) or aluminum (Al).

[0027] The first power semiconductor element 20 is, for example, a switch element such as an insulated gate bipolar transistor (IGBT) or a metal oxide semiconductor field effect transistor (MOSFET) or a diode such as a freewheeling diode. The first power semiconductor element 20 is mainly formed of a semiconductor material such as silicon, silicon carbide, gallium nitride or diamond.

[0028] The first power semiconductor element 20 includes a first back electrode 21 and a first front surface electrode 22. The first back electrode 21 is provided on the first back surface of the first power semiconductor element 20. The first back electrode 21 is bonded to the conductive circuit pattern 12 using a conductive bonding member (not shown) such as solder or a metal nanoparticle sintered body. The first front surface electrode 22 is provided on the first front surface of the first power semiconductor element 20 on the opposite side to the first back surface. The first front surface electrode 22 and the second back surface electrode are formed of, for example, aluminum or an Al alloy containing Si.

[0029] The first power semiconductor element 20 may further include a first guard ring 23. The first guard ring 23 is disposed in a peripheral region of the first front surface of the first power semiconductor element 20. When the first front surface is viewed from above, the first guard ring 23 surrounds the first front surface electrode 22. The first guard ring 23 is formed of, for example, the same conductive material as the first front surface electrode 22.

[0030] The second power semiconductor element 25 is, for example, a switch element such as an insulated gate bipolar transistor (IGBT) or a metal oxide semiconductor field effect transistor (MOSFET) or a diode such as a freewheeling diode. The second power semiconductor element 25 is mainly formed of a semiconductor material such as silicon, silicon carbide, gallium nitride or diamond.

[0031] The second power semiconductor element 25 includes a second back electrode 26 and a second front electrode 27. The second back electrode 26 is provided on the second back surface of the second power semiconductor element 25. The second back electrode 26 is bonded to the conductive circuit pattern 12 using a conductive bonding member (not shown) such as solder or a metal nanoparticle sintered body. The second front electrode 27 is provided on the second front surface of the second power semiconductor element 25 on the opposite side to the second back surface. The second front electrode 27 and the second back electrode 26 are formed of, for example, aluminum or an Al alloy containing Si.

[0032] The second power semiconductor element 25 may further include a second guard ring 28. The second guard ring 28 is disposed in a peripheral region of the second front surface of the second power semiconductor element 25. When the second front surface is viewed from above, the second guard ring 28 surrounds the second front surface electrode 27. The second guard ring 28 is formed of, for example, the same conductive material as the second front surface electrode 27.

[0033] The first electrode terminal 32 and the second electrode terminal 33 are provided in the outer shell 47 constituting the case 45. The first electrode terminal 32 and the second electrode terminal 33 are formed of a metal material such as copper or aluminum.

[0034] like Figure 1 and Figure 2 As shown, the conductive wire 35 is bonded to the surface 22a of the first front surface electrode 22. The conductive wire 35 is bonded to the first front surface electrode 22 of the first power semiconductor element 20 in the first bonding portion 30 by wire bonding. The first bonding portion 30 is a bonding surface between the surface 22a of the first front surface electrode 22 and the surface 35a of the conductive wire 35. Figure 1 and Figure 3 As shown, the conductive wire 35 is bonded to the surface 27a of the second front surface electrode 27. The conductive wire 35 is bonded to the second front surface electrode 27 of the second power semiconductor element 25 in the second bonding portion 31 by wire bonding. The second bonding portion 31 is a bonding surface between the surface 27a of the second front surface electrode 27 and the surface 35a of the conductive wire 35. The conductive wire 35 is bonded to the first electrode terminal 32 by wire bonding.

[0035] The conductive wire 36 is bonded to the second electrode terminal 33 and the conductive circuit pattern 12 by wire bonding. The conductive wires 35 and 36 are formed of, for example, copper, iron, nickel, cobalt, aluminum, or an alloy thereof.

[0036] The resin film 40 has electrical insulation properties. Figure 2 As shown, the resin film 40 is continuously formed in the length direction ( Figure 2 The resin film 40 is formed continuously on the end 30a of the first joint portion 30 between the first front surface electrode 22 and the conductive wire 35 in the left-right direction of the conductive wire 35, the surface 22a of the first front surface electrode 22, and the surface 35a of the conductive wire 35. The resin film 40 is formed continuously on the end 30b of the first joint portion 30 between the first front surface electrode 22 and the conductive wire 35, the surface 22a of the first front surface electrode 22, and the surface 35a of the conductive wire 35 in the length direction of the conductive wire 35.

[0037] like Figure 3 As shown, the resin film 40 is continuously formed on the end 31a of the second joint 31 between the second front surface electrode 27 and the conductive wire 35 in the length direction of the conductive wire 35, the surface 27a of the second front surface electrode 27, and the surface 35a of the conductive wire 35. The resin film 40 is continuously formed on the end 31b of the second joint 31 between the second front surface electrode 27 and the conductive wire 35 in the length direction of the conductive wire 35, the surface 27a of the second front surface electrode 27, and the surface 35a of the conductive wire 35.

[0038] like Figure 1 As shown, the resin film 40 may also be formed on the entire conductive wire 35 between the first joint portion 30 and the second joint portion 31. The resin film 40 is continuously formed on at least one of the ends of the joint between the first electrode terminal 32 and the conductive wire 35 in the length direction of the conductive wire 35, the surface of the first electrode terminal 32, and the surface 35a of the conductive wire 35. The resin film 40 is continuously formed on at least one of the ends of the joint between the second electrode terminal 33 and the conductive wire 36 in the length direction of the conductive wire 36, the surface of the second electrode terminal 33, and the surface of the conductive wire 36. The resin film 40 is continuously formed on at least one of the ends of the joint between the conductive circuit pattern 12 and the conductive wire 36 in the length direction of the conductive wire 36, the surface of the conductive circuit pattern 12, and the surface of the conductive wire 36. The resin film 40 may also be formed on the entire conductive wires 35, 36.

[0039] like Figure 1 As shown, the resin film 40 also covers the first guard ring 23 and the second guard ring 28. The resin film 40 contacts the sealing member 50 and the first guard ring 23. The resin film 40 contacts the sealing member 50 and the second guard ring 28.

[0040] The resin film 40 may be further formed on the surface of the insulating circuit substrate 10 exposed from the first power semiconductor element 20 and the second power semiconductor element 25. The resin film 40 may be further formed on the portion of the first electrode terminal 32 that is bonded to the conductive wire 35. The resin film 40 may be further formed on the portion of the second electrode terminal 33 that is bonded to the conductive wire 36. The resin film 40 may be further formed on the surface of the bottom plate 46 exposed from the insulating circuit substrate 10. The resin film 40 may be further formed on the surface of the outer peripheral body 47 between the electrode terminals (the first electrode terminal 32, the second electrode terminal 33) and the bottom plate 46. The resin film 40 is formed, for example, using a dispensing method, an electrodeposition method, an electrostatic coating method, a spin coating method, an immersion method, or a spray coating method.

[0041] The resin film 40 is softer than the first front surface electrode 22, the second front surface electrode 27 and the conductive wires 35 and 36. The elastic elongation rate of the resin film 40 is 4.5% or more and 10.0% or less. The elastic elongation rate of the resin film 40 is determined by the yield point of the resin film 40 (refer to Figure 4 ) is defined by the strain rate of the resin film 40 at the point where the film is stretched. The plastic elongation rate of the resin film 40 is different from the elastic elongation rate of the resin film 40. The plastic elongation rate of the resin film 40 is determined by the breaking point of the resin film 40 (refer to Figure 4 ) is defined by the strain rate of the resin film 40 at the resin film 40. The resin film 40 is formed of, for example, a polyimide resin, an epoxy resin, or a silicone resin. An example of an epoxy resin applied to the resin film 40 is a bottom filler of U8443-14 manufactured by NAMICSCORPORATION. An example of a silicone resin applied to the resin film 40 is a silicone resin of KE-210 manufactured by Shin-Etsu Silicones.

[0042] The shear bonding strength of the resin film 40 for the conductive wires 35 and 36 is 8.0 MPa or more and 13.0 MPa or less. The shear bonding strength of the resin film 40 for the first front surface electrode 22 of the first power semiconductor element 20 is 8.0 MPa or more and 13.0 MPa or less. The shear bonding strength of the resin film 40 for the second front surface electrode 27 of the second power semiconductor element 25 is 8.0 MPa or more and 13.0 MPa or less. In this specification, the shear bonding strength of the first member for the second member is the tensile stress when the first member is peeled off from the second member when tensile stress is applied to the first member and the second member in the direction of the bonding interface between the first member and the second member and in the opposite directions. The shear bonding strength is measured according to the method specified in Japanese Industrial Standard (JIS) K6850.

[0043] The resin film 40 having an elastic elongation of 4.5% or more and 10.0% or less and a shear bonding strength of 8.0 MPa or more and 13.0 MPa or less is formed, for example, of a polyimide resin defined by the following chemical structural formula (I). The polyimide resin is obtained by polymerizing an acid dihydrate containing an alkyl group and a diamine containing a benzene ring, an ether bond, and an alkyl group. Here, R1 represents C n H 2n+1 (n is a natural number), R2 represents C m H 2m+1 (m is a natural number). The molecular chain of the polyimide resin specified by the following chemical structural formula (I) is long, and the molecular chain can rotate with the ether bond as a starting point. Therefore, the polyimide resin specified by the following chemical structural formula (I) is soft and has high shear bonding strength.

[0044] [Chemical formula 1]

[0045]

[0046] The housing 45 includes a bottom plate 46 and a peripheral body 47. The bottom plate 46 is formed of, for example, a metal such as copper or aluminum, or an alloy such as aluminum-silicon carbide alloy (AlSiC) or copper-molybdenum alloy (CuMo). The conductive plate 13 of the insulating circuit substrate 10 is bonded to the bottom plate 46. The bottom plate 46 can function as a heat sink. In a modified example of the present embodiment, the bottom plate 46 can be omitted and the conductive plate 13 can perform the function of the bottom plate 46 of the present embodiment.

[0047] The outer body 47 has electrical insulation properties. The outer body 47 is formed of an electrical insulating resin such as polyphenylene sulfide (PPS) resin or polybutylene terephthalate (PBT) resin. The bottom plate 46 and the outer body 47 are bonded to each other using an adhesive (not shown). The adhesive is formed of, for example, silicone resin or epoxy resin.

[0048] The sealing member 50 seals the first power semiconductor element 20, the second power semiconductor element 25, the conductive circuit pattern 12, the conductive wires 35, 36 and the resin film 40. The sealing member 50 can further seal the insulating substrate 11. In the present embodiment, the sealing member 50 is formed of a gel such as silicone gel. The second tensile elastic modulus of the gel forming the sealing member 50 is lower than the first tensile elastic modulus of the resin material forming the resin film 40. In this specification, the tensile elastic modulus is measured by the tensile test specified in JISK7161.

[0049] Reference Figure 5 The operation of the semiconductor module 1 according to the present embodiment will be described while comparing it with a comparative example. Figure 5 The power cycle life of the semiconductor modules of Comparative Examples A to C and the semiconductor modules 1 of Examples D to G are shown. The semiconductor module of Comparative Example A has the same structure as the semiconductor module 1 of the present embodiment, but does not include the resin film 40. The semiconductor modules of Comparative Examples B and C have the same structure as the semiconductor module 1 of the present embodiment, but the resin film 40 included in the semiconductor modules of Comparative Examples B and C is a polyimide resin film having an elastic elongation of less than 4.5%. In the semiconductor modules 1 of Examples D to G, the resin film 40 is a polyimide resin film having an elastic elongation of 4.5% or more. The resin film 40 in the semiconductor module 1 of Example G is a polyimide resin film represented by the above-mentioned chemical structural formula (I).

[0050] The power cycle test of the semiconductor module 1 is a test in which a first step of causing a current to flow through the first power semiconductor element 20 or the second power semiconductor element 25 and a second step of not causing a current to flow through the first power semiconductor element 20 and the second power semiconductor element 25 are repeated alternately, and the life (power cycle life) of the semiconductor module 1 is measured. Figure 5 As shown, the power cycle life of the semiconductor module 1 is correlated with the elastic elongation of the resin film 40 .

[0051] Specifically, in the case where the semiconductor module does not include the resin film 40 (Comparative Example A) or in the case where the semiconductor module includes the resin film 40 having an elastic elongation of less than 4.5% (Comparative Examples B and C), the power cycle life of the semiconductor module is short. The reason is as follows. During the power cycle test of the semiconductor module, components constituting the semiconductor module such as the first front surface electrode 22, the second front surface electrode 27 and the conductive wire 35 repeatedly undergo thermal expansion and thermal contraction. Therefore, thermal stress is repeatedly applied to the first joint 30 between the first front surface electrode 22 and the conductive wire 35 and the second joint 31 between the second front surface electrode 27 and the conductive wire 35. The semiconductor module of Comparative Example A does not include the resin film 40, so due to the thermal stress, cracks occur in the first joint 30 or the second joint 31, or the conductive wire 35 is peeled off from the first front surface electrode 22 or the second front surface electrode 27. Therefore, the power cycle life of the semiconductor module of Comparative Example A is the shortest.

[0052] In the semiconductor modules of Comparative Examples B and C, the elastic elongation of the resin film 40 is less than 4.5%, which is relatively small. Therefore, the resin film 40 cannot fully follow the thermal expansion and thermal contraction of the components constituting the semiconductor module 1, such as the first front surface electrode 22, the second front surface electrode 27, and the conductive wire 35. The resin film 40 peels off from the ends 30a, 30b of the first joint 30, the ends 31a, 31b of the second joint 31, the surface 22a of the first front surface electrode 22, the surface 27a of the second front surface electrode 27, or the surface 35a of the conductive wire 35 with a small number of power cycles. The resin film 40 becomes unable to relax the thermal stress applied to the first joint 30 and the second joint 31 with a small number of power cycles. Due to the thermal stress, cracks occur in the first joint 30 or the second joint 31, or the conductive wire 35 peels off from the first front surface electrode 22 or the second front surface electrode 27. Therefore, the power cycle life of the semiconductor modules of Comparative Examples B and C is longer than that of the semiconductor module of Comparative Example A, but the power cycle life of the semiconductor modules of Comparative Examples B and C is still relatively short.

[0053] In contrast, when the semiconductor module 1 includes the resin film 40 having an elastic elongation of 4.5% or more and 10% or less (Examples D to G), the power cycle life of the semiconductor module 1 increases sharply as the elastic elongation of the resin film 40 increases. The reason is as follows. In the semiconductor modules 1 of Examples D to G, the elastic elongation of the resin film 40 is 4.5% or more, so the resin film 40 can fully follow the thermal expansion and thermal contraction of the components constituting the semiconductor module 1 such as the first front surface electrode 22, the second front surface electrode 27, and the conductive wire 35. The resin film 40 does not peel off from the ends 30a, 30b of the first bonding portion 30, the ends 31a, 31b of the second bonding portion 31, the surface 22a of the first front surface electrode 22, the surface 27a of the second front surface electrode 27, and the surface 35a of the conductive wire 35 at a greater number of power cycles. The resin film 40 can alleviate the thermal stress applied to the first bonding portion 30 and the second bonding portion 31 at a greater number of power cycles. The resin film 40 can prevent cracks from occurring in the first bonding portion 30 or the second bonding portion 31 due to thermal stress or the conductive wire 35 from peeling off from the first front surface electrode 22 or the second front surface electrode 27. The semiconductor modules 1 of Examples D to G have a long power cycle life.

[0054] The effects of the semiconductor module 1 according to the present embodiment will be described.

[0055] The semiconductor module 1 of the present embodiment includes a first power semiconductor element 20, a conductive wire 35, and a resin film 40. The first power semiconductor element 20 includes a first electrode (first front surface electrode 22). The conductive wire 35 is bonded to the first surface (surface 22a) of the first electrode (first front surface electrode 22). The resin film 40 is continuously formed on the first end (at least one of the end 30a or the end 30b) of the first bonding portion 30 between the first electrode (first front surface electrode 22) and the conductive wire 35 in the length direction of the conductive wire 35, the first surface (surface 22a) of the first electrode (first front surface electrode 22), and the second surface (surface 35a) of the conductive wire 35. The elastic elongation of the resin film 40 is 4.5% or more and 10.0% or less.

[0056] The elastic elongation of the resin film 40 is 4.5% or more, so the resin film 40 can follow the thermal expansion and thermal contraction of the components constituting the semiconductor module 1, such as the first electrode (first front surface electrode 22) of the first power semiconductor element 20 and the conductive wire 35. The resin film 40 does not peel off from the first end (at least one of the end 30a or the end 30b) of the first joint 30, the first surface (surface 22a) of the first electrode (first front surface electrode 22), and the second surface (surface 35a) of the conductive wire 35. The resin film 40 continuously relaxes the thermal stress applied to the first joint 30. The resin film 40 can prevent cracks from occurring in the first joint 30 or the conductive wire 35 from peeling off from the first electrode (first front surface electrode 22). The life of the semiconductor module 1 is prolonged, and the semiconductor module 1 has improved reliability.

[0057] In the semiconductor module 1 of the present embodiment, the shear adhesive strength of the resin film 40 with respect to the conductive wire 35 is 8.0 MPa or more and 13.0 MPa or less.

[0058] The shear bonding strength of the resin film 40 for the conductive wire 35 is 8.0 MPa or more, so the resin film 40 is further difficult to be peeled off from the surface 35a of the conductive wire 35 during use of the semiconductor module 1. The resin film 40 continuously relieves the thermal stress applied to the first joint 30. The resin film 40 can prevent cracks from occurring in the first joint 30 or the conductive wire 35 from being peeled off from the first electrode (first front surface electrode 22). The life of the semiconductor module 1 is prolonged, and the semiconductor module 1 has improved reliability.

[0059] The shear bonding strength of the resin film 40 for the conductive wire 35 is 13.0 MPa or less, so even if the conductive wire 35 is bonded to the first electrode (first front surface electrode 22) of the first power semiconductor element 20, the thickness of the conductive wire 35 in the first joint 30 and its periphery will not be excessively reduced. It is possible to prevent the conductive wire 35 from being disconnected when thermal stress is applied to the conductive wire 35 during use of the semiconductor module 1. The life of the semiconductor module 1 is prolonged, and the semiconductor module 1 has improved reliability.

[0060] The semiconductor module 1 of the present embodiment further includes a sealing member 50. The sealing member 50 seals the first power semiconductor element 20, the conductive wire 35, and the resin film 40. The sealing member 50 is formed of gel. The second tensile elastic modulus of the gel is lower than the first tensile elastic modulus of the resin material forming the resin film 40. Even if the sealing member 50 is formed of gel, the life of the semiconductor module 1 is prolonged due to the provision of the resin film 40, and the semiconductor module 1 has improved reliability.

[0061] In the semiconductor module 1 of the present embodiment, the first power semiconductor element 20 includes a guard ring (first guard ring 23 ). The resin film 40 covers the guard ring (first guard ring 23 ) and is in contact with the sealing member 50 and the guard ring (first guard ring 23 ).

[0062] A guard ring (first guard ring 23) is provided in the peripheral area of ​​the first power semiconductor element 20, so the insulation withstand voltage of the first power semiconductor element 20 is improved. Furthermore, the resin film 40 prevents the sealing member 50 from peeling off from the guard ring (first guard ring 23) and forming a cavity between the sealing member 50 and the guard ring (first guard ring 23). Therefore, the insulation withstand voltage of the first power semiconductor element 20 is improved. The semiconductor module 1 has improved reliability.

[0063] The semiconductor module 1 of the present embodiment further includes a second power semiconductor element 25. The second power semiconductor element 25 includes a second electrode (second front surface electrode 27). The conductive wire 35 is bonded to the third surface (surface 27a) of the second electrode (second front surface electrode 27). The resin film 40 is continuously formed on the second end (at least one of the end 31a or the end 31b) of the second bonding portion 31 between the second electrode (second front surface electrode 27) and the conductive wire 35, the third surface (surface 27a) of the second electrode (second front surface electrode 27), and the second surface (surface 35a) of the conductive wire 35, and is formed on the entire conductive wire 35 between the first bonding portion 30 and the second bonding portion 31.

[0064] The resin film 40 is continuously formed on the second end (at least one of the end 31a or the end 31b) of the second joint portion 31 between the second electrode (the second front surface electrode 27) of the second power semiconductor element 25 and the conductive wire 35, the third surface (surface 27a) of the second electrode (the second front surface electrode 27), and the second surface (surface 35a) of the conductive wire 35. Therefore, the resin film 40 can follow the thermal expansion and thermal contraction of the components constituting the semiconductor module 1 such as the second electrode (the second front surface electrode 27) of the second power semiconductor element 25 and the conductive wire 35. The resin film 40 does not peel off from the second end (at least one of the end 31a or the end 31b) of the second joint portion 31, the third surface (surface 27a) of the second electrode (the second front surface electrode 27), and the second surface (surface 35a) of the conductive wire 35. The resin film 40 continuously relaxes the thermal stress applied to the second joint portion 31. The resin film 40 can prevent cracks from occurring in the second joint portion 31 or the conductive wire 35 from peeling off from the second electrode (the second front surface electrode 27). The life of the semiconductor module 1 is prolonged, and the semiconductor module 1 has improved reliability.

[0065] The resin film 40 forms the entirety of the conductive wire 35 between the first joint portion 30 and the second joint portion 31. Therefore, the resin film 40 is further difficult to peel off from the second surface (surface 35a) of the conductive wire 35. The resin film 40 can prevent cracks from occurring at the first joint portion 30 and the second joint portion 31 or the conductive wire 35 from peeling off from the first electrode (first front surface electrode 22) and the second electrode (second front surface electrode 27). The life of the semiconductor module 1 is prolonged, and the semiconductor module 1 has improved reliability.

[0066] Implementation method 2.

[0067] Reference Figures 1 to 3 A semiconductor module 1a according to a second embodiment will be described. The semiconductor module 1a according to the present embodiment has the same structure as the semiconductor module 1 according to the first embodiment, but is mainly different in the following points.

[0068] The semiconductor module 1a is provided with a sealing member 50a instead of the sealing member 50 of the first embodiment. The sealing member 50a is formed of a thermosetting resin. The thermosetting resin mainly includes, for example, epoxy resin, urethane resin, polyimide resin or acrylic resin. The third tensile elastic modulus of the thermosetting resin is higher than the first tensile elastic modulus of the resin material forming the resin film 40. The thermosetting resin is harder than the resin film 40 and the sealing member 50 formed of gel (the first embodiment). Therefore, the sealing member 50a formed of the thermosetting resin (the present embodiment) constrains the conductive wire 35 more strongly than the resin film 40 and the sealing member 50 formed of gel (the first embodiment).

[0069] The semiconductor module 1 a of the present embodiment has the following effects in addition to the effects of the semiconductor module 1 of the first embodiment.

[0070] The semiconductor module 1a of this embodiment further includes a sealing member 50a. The sealing member 50a seals the first power semiconductor element 20, the conductive wire 35, and the resin film 40. The sealing member 50a is formed of a thermosetting resin. The third tensile modulus of the thermosetting resin is higher than the first tensile modulus of the resin material forming the resin film 40.

[0071] The thermosetting resin is harder than the resin film 40 and the sealing member 50 (embodiment 1) formed of gel. Therefore, the sealing member 50a (present embodiment) formed of the thermosetting resin constrains the conductive wire 35 more strongly than the resin film 40 and the sealing member 50 (embodiment 1) formed of gel. It is possible to prevent cracks from occurring in the first joint 30 due to thermal stress or the conductive wire 35 from peeling off from the first electrode (first front surface electrode 22). The life of the semiconductor module 1a is prolonged, and the semiconductor module 1a has improved reliability.

[0072] Implementation method 3.

[0073] Reference Figure 6 A semiconductor module 1b according to a third embodiment will be described. The semiconductor module 1b according to the present embodiment has the same structure as the semiconductor module 1 according to the first embodiment, but is mainly different in the following points.

[0074] like Figure 6 As shown, a rough surface 43 is formed on at least one of the surface 22a of the first front surface electrode 22 of the first power semiconductor element 20 or the surface 35a of the conductive wire 35. Specifically, the rough surface 43 is provided on both the surface 22a of the first front surface electrode 22 of the first power semiconductor element 20 and the surface 35a of the conductive wire 35. The rough surface 43 may be connected to the ends 30a, 30b of the first joint 30. Although not shown, a rough surface 43 may also be formed on at least one of the surface 27a of the second front surface electrode 27 of the second power semiconductor element 25 or the surface 35a of the conductive wire 35. Specifically, the rough surface 43 may be provided on both the surface 27a of the second front surface electrode 27 of the second power semiconductor element 25 and the surface 35a of the conductive wire 35. The rough surface 43 may be connected to the ends 31a, 31b of the second joint 31. The resin film 40 is formed on the rough surface 43.

[0075] The semiconductor module 1 b of the present embodiment has the following effects in addition to the effects of the semiconductor module 1 of the first embodiment.

[0076] In the semiconductor module 1b of the present embodiment, a rough surface 43 is formed on at least one of the first surface (surface 22a) of the first electrode (first front surface electrode 22) of the first power semiconductor element 20 or the second surface (surface 35a) of the conductive wire 35. The resin film 40 is formed on the rough surface 43. Therefore, it is possible to prevent the resin film 40 from being peeled off from at least one of the first surface (surface 22a) of the first electrode (first front surface electrode 22) of the first power semiconductor element 20 or the second surface (surface 35a) of the conductive wire 35. The power cycle life of the semiconductor module 1b becomes longer, and the semiconductor module 1b has improved reliability.

[0077] Implementation method 4.

[0078] Reference Figure 7 , a semiconductor module 1c of Embodiment 4 is described. The semiconductor module 1c of this embodiment has the same structure and the same effect as the semiconductor module 1 of Embodiment 1, but is mainly different in the type of semiconductor module. Specifically, the semiconductor module 1c is a transfer molding type semiconductor module. The sealing member 50 is formed using a transfer molding method.

[0079] Instead of insulating circuit substrate 10 and bottom plate 46 (see Figure 1 ), the semiconductor module 1c includes a heat sink 55, an insulating plate 56, and a heat sink 57. Figure 1 ), the semiconductor module 1c includes a first lead terminal 32c and a second lead terminal 33c. The semiconductor module 1c also includes a conductive wire 37.

[0080] The first power semiconductor element 20 and the second power semiconductor element 25 are fixed to the front surface of the heat sink 55. For example, the first power semiconductor element 20 and the second power semiconductor element 25 are bonded to the front surface of the heat sink 55 using a conductive bonding member such as solder or a metal nanoparticle sintered body. The heat sink 55 diffuses the heat generated from the first power semiconductor element 20 and the second power semiconductor element 25. The heat sink 55 is formed of a material having high thermal conductivity such as copper, aluminum, or graphite.

[0081] A heat sink 57 is provided on the back surface of the heat sink 55 via an insulating plate 56. The heat sink 57 is formed of, for example, a metal such as copper or aluminum, or an alloy such as aluminum-silicon carbide alloy (AlSiC) or copper-molybdenum alloy (CuMo).

[0082] The insulating plate 56 electrically insulates the heat sink 55 from the heat sink 57. The insulating plate 56 transfers heat generated from the first power semiconductor element 20 and the second power semiconductor element 25 and transferred to the heat sink 55 to the heat sink 57. The insulating plate 56 is formed of a ceramic material such as silicon nitride (Si3N4), aluminum nitride (AlN), aluminum oxide (Al2O3), or zirconium (Zr)-containing aluminum oxide, for example.

[0083] The insulating plate 56 may be, for example, a resin insulating plate in which powder is dispersed. The powder may have a higher thermal conductivity than the resin constituting the base material of the resin insulating plate. The powder may be, for example, a ceramic powder formed of ceramics such as aluminum oxide (Al2O3), silicon dioxide (SiO2), aluminum nitride (AlN), boron nitride (BN) or silicon nitride (Si3N4). The powder may also be formed of diamond (C), silicon carbide (SiC) or boron oxide (B2O3). The powder may also be a powder made of a resin such as silicone resin or acrylic resin. The base material of the resin insulating plate may be, for example, epoxy resin, polyimide resin, silicone resin or acrylic resin.

[0084] In the semiconductor module 1c, the conductive wire 35 is bonded to the first front surface electrode 22 of the first power semiconductor element 20 and the second front surface electrode 27 of the second power semiconductor element 25, but is not bonded to the first lead terminal 32c. The conductive wire 36 is bonded to the first front surface electrode 22 and the second lead terminal 33c of the first power semiconductor element 20. The conductive wire 37 is bonded to the second front surface electrode 27 and the first lead terminal 32c of the second power semiconductor element 25.

[0085] The resin film 40 is formed not only on the conductive wires 35 and 36, but also on the conductive wire 37. Specifically, the resin film 40 is continuously formed on at least one of the ends of the joint between the first front surface electrode 22 and the conductive wire 36 in the length direction of the conductive wire 36, the surface of the first front surface electrode 22, and the surface of the conductive wire 36. The resin film 40 is continuously formed on at least one of the ends of the joint between the first lead terminal 32c and the conductive wire 36 in the length direction of the conductive wire 36, the surface of the first lead terminal 32c, and the surface of the conductive wire 36. The resin film 40 is continuously formed on at least one of the ends of the joint between the second front surface electrode 27 and the conductive wire 37 in the length direction of the conductive wire 37, the surface of the second front surface electrode 27, and the surface of the conductive wire 37. The resin film 40 is continuously formed on at least one of the ends of the joint between the second lead terminal 33c and the conductive wire 37 in the length direction of the conductive wire 37, the surface of the second lead terminal 33c, and the surface of the conductive wire 37. The resin film 40 may also be formed on the entire conductive wire 37.

[0086] Implementation method 5.

[0087] In this embodiment, any semiconductor module of the semiconductor modules 1, 1a, 1b, and 1c of the above-mentioned embodiments to Embodiment 4 is applied to a power conversion device. The present disclosure is not limited to a specific power conversion device, but the following is a description of the case where any semiconductor module of the semiconductor modules 1, 1a, 1b, and 1c of the present disclosure is applied to a three-phase inverter as Embodiment 5.

[0088] Figure 8 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, and 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 connected to an AC system, and an AC / DC converter. The power supply 100 may also include a DC / DC converter that converts the DC power output from the DC system into another DC power.

[0089] The power conversion device 200 is a three-phase inverter connected between the power source 100 and the load 300, which converts the DC power provided by the power source 100 into AC power and provides the AC power to the load 300. Figure 8 The diagram includes 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 .

[0090] Load 300 is a three-phase motor driven by AC power supplied from power converter 200. Load 300 is not limited to a specific use, and is a motor mounted on various electrical devices, such as a motor for hybrid vehicles, electric vehicles, railway vehicles, elevators, or air conditioners.

[0091] The power conversion device 200 is described in detail below. The main conversion circuit 201 includes a switching element (not shown) and a freewheeling diode (not shown). The switching element switches the voltage provided from the power supply 100, whereby 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 has various structures, 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 freewheeling diodes connected in anti-parallel to each switching element. At least one of each switching element and each freewheeling diode of the main conversion circuit 201 is a switching element or a freewheeling diode included in a semiconductor module 202 corresponding to the semiconductor module 1, 1a, 1b, 1c of any of the above-mentioned embodiments 1 to 4. With respect to the 6 switching elements, every two switching elements are connected in series to form upper and lower arms, and each upper and lower arm constitutes each phase (U phase, V phase, W phase) of the full-bridge circuit. Then, the output terminals of the upper and lower arms, that is, the three output terminals of the main conversion circuit 201 are connected to the load 300 .

[0092] 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 separately from 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.

[0093] 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) for each switch element of the main conversion circuit 201 to 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 to output an on signal to the switch element that should be in the on state at each time point, and output an off signal to the switch element that should be in the off state. The drive circuit outputs an on signal or an off signal as a drive signal to the control electrode of each switch element according to the control signal.

[0094] In the power conversion device 200 of this embodiment, any of the semiconductor modules 1, 1a, 1b, and 1c of Embodiments 1 to 4 is applied as the semiconductor module 202 constituting the main conversion circuit 201. Therefore, the power conversion device 200 of this embodiment can achieve improved reliability.

[0095] In this embodiment, an example of applying the present disclosure to a 2-level three-phase inverter is described, but it 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 can also be used. In the case where the power conversion device provides power to a single-phase load, the present disclosure can 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 disclosure can also be applied to a DC / DC converter or an AC / DC converter.

[0096] The power conversion device to which the present disclosure is applied is not limited to the case where the load is a motor, and can also be used as 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 disclosure is applied can also be used as a power conditioner for a solar power generation system or a power storage system.

Claims

1. A semiconductor module comprising: A first power semiconductor element comprising a first electrode; a conductive wire bonded to the first surface of the first electrode; and a resin film continuously formed on a first end portion of a first joint between the first electrode and the conductive wire, the first surface of the first electrode, and a second surface of the conductive wire in a length direction of the conductive wire, The resin film has an elastic elongation of 4.5% or more and 10.0% or less.

2. The semiconductor module according to claim 1, wherein: The resin film is formed of polyimide resin, epoxy resin or silicone resin.

3. The semiconductor module according to claim 1, wherein: The resin film is formed of a resin material formed by polymerizing an acid dihydrate including an alkyl group and a diamine including a benzene ring, an ether bond, and an alkyl group.

4. The semiconductor module according to any one of claims 1 to 3, wherein: The shear adhesive strength of the resin film to the conductive wire is 8.0 MPa or more and 13.0 MPa or less.

5. The semiconductor module according to claim 1 or 2, further comprising: a sealing member that seals the first power semiconductor element, the conductive wire, and the resin film, The sealing member is formed of gel, The second tensile elastic modulus of the gel is lower than the first tensile elastic modulus of the resin material forming the resin film.

6. The semiconductor module according to claim 5, wherein: The gel is a silicone gel.

7. The semiconductor module according to claim 1 or 2, further comprising: a sealing member that seals the first power semiconductor element, the conductive wire, and the resin film, The sealing member is formed of a thermosetting resin, The third tensile elastic modulus of the thermosetting resin is higher than the first tensile elastic modulus of the resin material forming the resin film.

8. The semiconductor module according to claim 7, wherein: The thermosetting resin mainly includes epoxy resin, urethane resin, polyimide resin, polyamide resin or acrylic resin.

9. The semiconductor module according to claim 5, wherein: The first power semiconductor element comprises a guard ring, The resin film covers the protection ring and is in contact with the sealing member and the protection ring.

10. The semiconductor module according to claim 7, wherein: The first power semiconductor element comprises a guard ring, The resin film covers the protection ring and is in contact with the sealing member and the protection ring.

11. The semiconductor module according to any one of claims 1 to 3, wherein: A rough surface is formed on at least one of the first surface or the second surface, The resin film is formed on the rough surface.

12. The semiconductor module according to any one of claims 1 to 3, wherein: The conductive wire is formed of copper, iron, nickel, cobalt, aluminum or alloys thereof.

13. The semiconductor module according to any one of claims 1 to 3, further comprising: The second power semiconductor element comprises a second electrode, The conductive wire is bonded to the third surface of the second electrode, The resin film is continuously formed on the second end of the second joining portion between the second electrode and the conductive wire, the third surface of the second electrode, and the second surface of the conductive wire, and the resin film is formed on the entirety of the conductive wire between the first joining portion and the second joining portion.

14. A power conversion device comprising: A main conversion circuit, comprising the semiconductor module according to any one of claims 1 to 13, the main conversion circuit converting input power and outputting the converted power; and The control circuit outputs a control signal for controlling the main conversion circuit to the main conversion circuit.

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