semiconductor devices

Abstract

The semiconductor device includes a semiconductor element (30) having an emitter electrode formed on the surface and a collector electrode formed on the back surface. The collector electrode is connected to a heat sink (40) arranged on the back side of the semiconductor element (30) via solder (80). A plurality of wire pieces (90) are provided in the solder joint portion. All the wire pieces (90) are joined to the mounting surface (40a) of the heat sink (40) and protrude toward the semiconductor element (30). The solder (80) has a central region (80a) that overlaps with the central portion of the semiconductor element (30) including the element center (30c) when viewed from above, and a peripheral region (80b) that surrounds the central region (80a). In the peripheral region, at least four or more wire pieces are arranged corresponding to the four corners of the semiconductor element (30). At least one of the wire pieces extends toward the element center when viewed from above.

Description

[0001] Cross-reference to related applications

[0002] This application is based on patent application No. 2019-184066 filed in Japan on October 4, 2019, and patent application No. 2020-158041 filed in Japan on September 22, 2020, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0003] The disclosure in this specification relates to a semiconductor device. Background Art

[0004] Patent Document 1 discloses a Ni ball with a sufficient solder thickness. In the present specification, the descriptions of the prior art documents are incorporated by reference for the explanation of the technical elements.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent No. 5510623 Summary of the Invention

[0008] Ni balls are limited in their applicability. For example, in solder die bonding, Ni balls melt significantly in the solder melting furnace. This can lead to a potential failure to maintain the minimum guaranteed thickness of the solder (bonding component). Further improvements are required for semiconductor devices based on these and other considerations.

[0009] One object of the disclosure is to provide a semiconductor device with higher reliability.

[0010] The semiconductor device disclosed herein comprises:

[0011] A semiconductor element having a surface electrode and a back electrode as main electrodes, wherein the surface electrode is formed on the surface, and the back electrode is formed on the back surface opposite to the surface in the plate thickness direction and has an area larger than that of the surface electrode;

[0012] a joining member sandwiched between the first opposing surface and the second opposing surface to form a joining portion;

[0013] a wiring member electrically connected to the main electrode via a bonding member; and

[0014] A plurality of wire pieces are arranged in the joint member, fixed to the first opposing surface and protruding from the first opposing surface,

[0015] The wiring member includes a back wiring member disposed on the back side and connected to the back electrode.

[0016] The bonding member includes a back-side bonding member that forms a bonding portion between the back electrode and the back-side wiring member and is provided with a plurality of wiring pieces.

[0017] The back-side bonding member includes: a central region overlapping with a central portion of the semiconductor element including the element center when viewed from above along the plate thickness direction; and a peripheral region including a portion overlapping with a peripheral portion of the semiconductor element surrounding the central portion and surrounding the central region.

[0018] In the peripheral area, at least four or more wire pieces are arranged corresponding to the four corners of the semiconductor element.

[0019] At least one of the wire pieces extends toward the center of the element when viewed from above.

[0020] According to the disclosed semiconductor device, the wire piece is fixed to the first opposing surface. The wire piece protruding from the first opposing surface ensures the thickness of the bonding component. Even if warping occurs in a semiconductor element having main electrodes on both sides, the wire piece provided in the peripheral area can ensure the thickness of the bonding component. Furthermore, the wire piece extending toward the center of the element is less likely to hinder solder flow when it wets and spreads. As a result, a highly reliable semiconductor device can be provided.

[0021] The various embodiments disclosed in this specification employ different technical means to achieve their respective objectives. The claims and the reference numerals within parentheses therein are provided for illustrative purposes to indicate the correspondence between the embodiments described below and are not intended to limit the scope of the invention. The objectives, features, and effects disclosed in this specification will become more apparent with reference to the detailed description and accompanying drawings that follow. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a circuit diagram of a power conversion device to which the semiconductor device according to the first embodiment is applied.

[0023] Figure 2 It is a top view of a semiconductor device.

[0024] Figure 3 It is along Figure 2 Cross-sectional view along line III-III.

[0025] Figure 4 It is along Figure 2 Cross-sectional view along line IV-IV.

[0026] Figure 5 It is a top view with the sealing resin body omitted.

[0027] Figure 6 It is a top view with the heat sink on the emitter electrode side omitted.

[0028] Figure 7 It is a top view showing the positional relationship between the semiconductor element and the wiring sheet.

[0029] Figure 8 It is a three-dimensional diagram showing the arrangement of the wire pieces.

[0030] Figure 9 It is along Figure 7 Cross-sectional view of line IX-IX.

[0031] Figure 10 This is a perspective view showing the warping of a semiconductor element and the effect of a wire sheet.

[0032] Figure 11 It is a plan view showing the height of the wiring piece in the semiconductor device according to the second embodiment.

[0033] Figure 12 It is a plan view showing the positional relationship between the semiconductor element and the wiring sheet in the semiconductor device according to the third embodiment.

[0034] Figure 13 It is along Figure 12 Cross-sectional view along line XIII-XIII.

[0035] Figure 14 This is a cross-sectional view when a semiconductor element is arranged at an angle.

[0036] Figure 15 It is a plan view showing the arrangement of wire segments in a semiconductor device according to a fourth embodiment.

[0037] Figure 16 It is a top view showing a modified example.

[0038] Figure 17 It is a plan view showing the positional relationship between the semiconductor element and the wiring sheet in the semiconductor device according to the fifth embodiment.

[0039] Figure 18 It is a top view showing the arrangement of the wire pieces.

[0040] Figure 19 It is along Figure 17 Cross-sectional view of line XIX-XIX.

[0041] Figure 20 It is a top view showing a modified example.

[0042] Figure 21 It is a plan view showing the positional relationship between the semiconductor element and the wiring sheet in the semiconductor device according to the sixth embodiment.

[0043] Figure 22 This is a schematic cross-sectional view showing the influence of the positional relationship between upper and lower wire pieces.

[0044] Figure 23 This is a schematic cross-sectional view showing a stacked structure of one arm in a semiconductor device according to a seventh embodiment.

[0045] Figure 24 It is a plan view showing the arrangement of wire pieces in each solder.

[0046] Figure 25 A diagram illustrating the difference in terminals between the semiconductor device of the eighth embodiment and the comparative example.

[0047] Figure 26 It is a perspective view showing an example of a connection structure between a semiconductor element and a heat sink in a semiconductor device according to a ninth embodiment.

[0048] Figure 27 It is along Figure 26 Cross-sectional view of line XXVII-XXVII.

[0049] Figure 28 It is a three-dimensional diagram showing a line piece.

[0050] Figure 29 This is a cross-sectional view showing another example of a wire piece.

[0051] Figure 30 It is a cross-sectional view showing a method for manufacturing a semiconductor device.

[0052] Figure 31 It is a cross-sectional view showing a method for manufacturing a semiconductor device.

[0053] Figure 32 It is a cross-sectional view showing a method for manufacturing a semiconductor device.

[0054] Figure 33 It is a cross-sectional view showing a method for manufacturing a semiconductor device.

[0055] Figure 34 It is a cross-sectional view showing a method for manufacturing a semiconductor device.

[0056] Figure 35 This is a cross-sectional view showing an example of a semiconductor element without warpage.

[0057] Figure 36 This is a cross-sectional view showing an example of a semiconductor element in which an upwardly convex warpage occurs.

[0058] Figure 37 This is a cross-sectional view showing an example of a semiconductor element in which downwardly convex warping occurs.

[0059] Figure 38 This is a cross-sectional view showing the effect of having flat portions at both ends.

[0060] Figure 39 is a cross-sectional view showing another example of a semiconductor device.

[0061] Figure 40 1 and 2 are simulation results showing the relationship between the volume of the wire piece and the solder strain in the semiconductor device according to the tenth embodiment.

[0062] Figure 41 This is a diagram showing the structure of a wire sheet.

[0063] Figure 42 This is a cross-sectional view for explaining the height of the wire piece between the collector electrode and the heat sink.

[0064] Figure 43 This is a cross-sectional view for explaining the height of the wire piece between the emitter electrode and the terminal.

[0065] Figure 44 It is a cross-sectional view showing a method for manufacturing a wire sheet.

[0066] Figure 45 It is a cross-sectional view showing a method for manufacturing a wire sheet.

[0067] Figure 46 This is a cross-sectional view showing a method for manufacturing a wire sheet.

[0068] Figure 47 It is a cross-sectional view showing a method for manufacturing a wire sheet.

[0069] Figure 48 This is a cross-sectional view showing a method for manufacturing a wire sheet. DETAILED DESCRIPTION

[0070] Hereinafter, multiple embodiments will be described based on the accompanying drawings. In multiple embodiments, functionally and / or structurally corresponding parts and / or associated parts may be denoted by the same reference numerals. For corresponding parts and / or associated parts, reference may be made to the description of other embodiments.

[0071] (First embodiment)

[0072] First, based on Figure 1 , a power conversion device using a semiconductor device is described.

[0073] Power conversion device

[0074] Figure 1 The power converter 1 shown is mounted on, for example, an electric vehicle or a hybrid vehicle. The power converter 1 converts power between a DC power supply 2 and a motor generator 3. The power converter 1, the DC power supply 2, and the motor generator 3 together constitute a vehicle drive system.

[0075] DC power supply 2 is a rechargeable secondary battery such as a lithium-ion battery or a nickel-metal hydride battery. Motor generator 3 is a three-phase AC rotating electrical machine. Motor generator 3 functions as the vehicle's driving source, or as an electric motor. Motor generator 3 functions as a generator during regeneration.

[0076] The power conversion device 1 includes a smoothing capacitor 4 and an inverter 5 serving as a power converter. The positive terminal of the smoothing capacitor 4 is connected to the positive electrode, which is the high-potential side electrode, of the DC power supply 2, and the negative terminal is connected to the negative electrode, which is the low-potential side electrode, of the DC power supply 2. The inverter 5 converts input DC power into three-phase AC power of a predetermined frequency and outputs it to the motor generator 3. The inverter 5 converts the AC power generated by the motor generator 3 into DC power. The inverter 5 is a DC-AC converter.

[0077] The inverter 5 is configured with three-phase upper and lower arm circuits 6. The upper and lower arm circuits 6 are sometimes referred to as legs. Each phase of the upper and lower arm circuits 6 has two arms 6H and 6L connected in series between a high-potential power line 7, which serves as the positive-side power line, and a low-potential power line 8, which serves as the negative-side power line. In each phase of the upper and lower arm circuits 6, the connection point between the upper arm 6H and the lower arm 6L is connected to an output line 9 to the motor generator 3.

[0078] In this embodiment, an n-channel insulated gate bipolar transistor 6i (hereinafter referred to as IGBT6i) is used as a switching element constituting each arm. FWD6d, which serves as a reflux diode, is connected in reverse parallel to each other in the IGBT6i. The upper and lower arm circuits 6 of one phase have two IGBT6i. In the upper arm 6H, the collector electrode of the IGBT6i is connected to the high potential power line 7. In the lower arm 6L, the emitter electrode of the IGBT6i is connected to the low potential power line 8. Moreover, the emitter electrode of the IGBT6i in the upper arm 6H and the collector electrode of the IGBT6i in the lower arm 6L are connected to each other.

[0079] In addition to the smoothing capacitor 4 and inverter 5 described above, the power conversion device 1 may further include a converter (a power converter separate from the inverter 5), a drive circuit for the switching elements that constitute the inverter 5 and the converter, a filter capacitor, and the like. The converter is a DC-DC converter that converts a DC voltage into a DC voltage of a different value. The converter is provided between the DC power supply 2 and the smoothing capacitor 4. The filter capacitor is connected in parallel to the DC power supply 2. For example, the filter capacitor removes power supply noise from the DC power supply 2.

[0080] Semiconductor devices

[0081] Next, based on Figures 2 to 6 , an example of a semiconductor device is described. Figure 3 、 Figure 4 It is along Figure 2 Cross-sectional views along lines III-III and IV-IV. Figure 5 is relative to Figure 2 The sealing resin body is omitted from the drawing. Figure 6 is relative to Figure 5 The heat sink on the emitter electrode side is omitted from the illustration. For some components constituting the semiconductor device, reference numerals are suffixed with "H" to indicate the upper arm 6H side, and "L" to indicate the lower arm 6L side. For other components, for convenience, the upper arm 6H and lower arm 6L are given the same reference numerals.

[0082] Hereinafter, the thickness direction of the semiconductor element is referred to as the Z direction, and a direction perpendicular to the Z direction, specifically, the direction in which the two semiconductor elements are arranged, is referred to as the X direction. Furthermore, the direction perpendicular to both the Z and X directions is referred to as the Y direction. Unless otherwise specified, the shape viewed from above in the Z direction, in other words, the shape along the XY plane defined by the X and Y directions, is referred to as the planar shape. Furthermore, the view viewed from above in the Z direction is simply referred to as the "top view."

[0083] like Figures 2 to 6 As shown, semiconductor device 10 includes sealing resin body 20, semiconductor element 30, heat sink 40, heat sink 50, terminal 55, connector 60-62, main terminals 70-72, and signal terminal 75. Semiconductor device 10 constitutes the upper and lower arm circuits 6 of one phase described above.

[0084] The sealing resin body 20 seals a portion of the other elements constituting the semiconductor device 10. The remaining portions of the other elements are exposed outside the sealing resin body 20. The sealing resin body 20 is made of, for example, epoxy resin. The sealing resin body 20 is formed, for example, by transfer molding. Figures 2 to 4 As shown, the sealing resin body 20 has a generally rectangular shape in plan view. The sealing resin body 20 has a front surface 20a and a back surface 20b opposite to the front surface 20a in the Z direction. The front surface 20a and the back surface 20b are, for example, flat surfaces.

[0085] Semiconductor element 30 is formed on a semiconductor substrate made of silicon (Si) or a wide-bandgap semiconductor with a wider bandgap than silicon. Examples of wide-bandgap semiconductors include silicon carbide (SiC), gallium nitride (GaN), gallium oxide (Ga2O3), and diamond. Semiconductor element 30 is sometimes referred to as a semiconductor chip.

[0086] The element has a vertical structure so that the main current flows in the Z direction. As a vertical element, an IGBT, a MOSFET, a diode, etc. can be used. In this embodiment, as a vertical element, an IGBT6i and a FWD6d forming one arm are formed. The vertical element is an RC (Reverse Conducting)-IGBT. The semiconductor element 30 has a gate electrode not shown. The gate electrode has a trench structure, for example. The semiconductor element 30 has the main electrodes of the element on both sides in the thickness direction of the semiconductor element 30, that is, in the Z direction. Specifically, as the main electrodes, an emitter electrode 31 is provided on the surface side and a collector electrode 32 is provided on the back side. The emitter electrode 31 also serves as the anode electrode of the FWD6d. The collector electrode 32 also serves as the cathode electrode of the FWD6d. The emitter electrode 31 is equivalent to the surface electrode, and the collector electrode 32 is equivalent to the back electrode.

[0087] The semiconductor element 30 is in a generally rectangular shape in plan view. Figure 6 As shown, semiconductor element 30 has a bonding pad 33 formed on its surface at a position different from emitter electrode 31. Both emitter electrode 31 and bonding pad 33 are exposed from a protective film (not shown) on the surface of the semiconductor substrate. Emitter electrode 31 is formed on a portion of the surface of semiconductor element 30. Collector electrode 32 is formed on substantially the entire back surface. When viewed from above, collector electrode 32 is larger in area than emitter electrode 31.

[0088] The pad 33 is an electrode for signals. The pad 33 is electrically separated from the emitter electrode 31. The pad 33 is formed at the end portion on the side opposite to the formation region of the emitter electrode 31 in the Y direction. The pad 33 includes a gate pad 33g for the gate electrode. In this embodiment, the semiconductor element 30 has five pads 33. Specifically, there are the gate pad 33g and the Kelvin emitter for detecting the potential of the emitter electrode 31, the current sensing, the anode potential of the temperature sensor (thermosensitive diode) for detecting the temperature of the semiconductor element 30, and the cathode potential. The five pads 33 are concentrated on one end side in the Y direction of the semiconductor element 30, which is roughly rectangular in plan view, and are arranged in the X direction.

[0089] The semiconductor device 10 includes two semiconductor elements 30. Specifically, it includes a semiconductor element 30H that constitutes the upper arm 6H and a semiconductor element 30L that constitutes the lower arm 6L. The semiconductor elements 30H and 30L have the same configuration. The semiconductor elements 30H and 30L are arranged in the X direction. The semiconductor elements 30H and 30L are arranged at approximately the same position in the Z direction.

[0090] The heat sink 40 is a wiring component that is arranged on the back side of the semiconductor element 30 in the Z direction and is electrically connected to the collector electrode 32 via solder 80. The solder 80 connects (joins) the heat sink 40 to the collector electrode 32. The heat sink 40 serves as a backside wiring component, and the solder 80 serves as a backside joining component. The heat sink 40 has a mounting surface 40a that faces the semiconductor element 30 and a back surface 40b that is opposite to the mounting surface 40a. Solder 80 is interposed between the mounting surface 40a of the heat sink 40 and the collector electrode 32 of the semiconductor element 30, forming a solder joint.

[0091] The heat sink 40 dissipates the heat of the semiconductor element 30 to the outside. As the heat sink 40, for example, a metal plate made of Cu, Cu alloy, etc., a DBC (Direct Bonded Copper) substrate, etc. can be used. The surface may also be provided with a coating film such as Ni or Au. In this embodiment, the heat sink 40 is a metal plate made of Cu. The heat sink 40 is sometimes referred to as a heat dissipation component, a conductive component, or a lead frame. The semiconductor device 10 has two heat sinks 40. Specifically, it has a heat sink 40H constituting the upper arm 6H and a heat sink 40L constituting the lower arm 6L.

[0092] like Figure 6 As shown in FIG. 1 , the heat sinks 40H and 40L are in a generally rectangular shape. The heat sinks 40H and 40L are arranged along the X direction. Figure 3 as well as Figure 4 As shown, the heat sinks 40H and 40L have substantially the same thickness and are arranged at substantially the same position in the Z direction. Solder joints are formed between the mounting surface 40a of the heat sink 40H and the collector electrode 32 of the semiconductor element 30H, and between the mounting surface 40a of the heat sink 40L and the collector electrode 32 of the semiconductor element 30L.

[0093] The heat sinks 40H and 40L contain the corresponding semiconductor element 30 when viewed from above in the Z direction. The back surfaces 40b of the heat sinks 40H and 40L are exposed from the sealing resin body 20. The back surfaces 40b are sometimes referred to as the heat dissipation surface or the exposed surface. The back surfaces 40b are substantially flush with the back surface 20b of the sealing resin body 20. The back surfaces 40b of the heat sinks 40H and 40L are aligned in the X direction.

[0094] The heat sink 50 and the terminal 55 are wiring members arranged on the surface side of the semiconductor element 30 in the Z direction and electrically connected to the emitter electrode 31 via solder 81 and 82. The terminal 55 is sandwiched between the semiconductor element 30 and the heat sink 50 in the Z direction. The solder 81 connects (joins) the terminal 55 to the emitter electrode 31. The solder 82 connects (joins) the heat sink 50 to the terminal 55.

[0095] The terminal 55 has a first end face 55a that faces the semiconductor element 30 and a second end face 55b that faces the first end face 55a. The heat sink 50 has a mounting surface 50a that faces the second end face 55b and a back surface 50b that faces the mounting surface 50a. The mounting surface 50a is the surface of the heat sink 50 facing the semiconductor element 30. Solder 81 is interposed between the first end face 55a of the terminal 55 and the emitter electrode 31 of the semiconductor element 30, forming a solder joint. Solder 82 is interposed between the second end face 55b of the terminal 55 and the mounting surface 50a of the heat sink 50, forming a solder joint. The heat sink 50 and the terminal 55 constitute a front-side wiring component. The solder 81 constitutes a front-side joint component.

[0096] The terminal 55 is located in the middle of the conductive and thermal conductive path between the semiconductor element 30 (emitter electrode 31) and the heat sink 50. The terminal 55 contains a metal material such as Cu or a Cu alloy. A plating film may also be provided on the surface. The terminals 55H and 55L are cylindrical bodies with a planar, roughly rectangular shape that is approximately the same size as the emitter electrode 31 when viewed from above. The terminal 55 is sometimes referred to as a metal block or a relay component. The semiconductor device 10 has two terminals 55. Specifically, it has a terminal 55H constituting the upper arm 6H and a terminal 55L constituting the lower arm 6L. Solder joints are formed between the first end face 55a of the terminal 55H and the emitter electrode 31 of the semiconductor element 30H, and between the first end face 55a of the terminal 55L and the emitter electrode 31 of the semiconductor element 30L.

[0097] The heat sink 50 dissipates heat from the semiconductor element 30 to the outside. The heat sink 50 has the same structure as the heat sink 40. In this embodiment, the heat sink 50 is a metal plate made of Cu. The semiconductor device 10 includes two heat sinks 50. Specifically, the heat sink 50H constitutes the upper arm 6H, and the heat sink 50L constitutes the lower arm 6L.

[0098] like Figure 5 As shown in FIG. 1 , the heat sinks 50H and 50L are in a generally rectangular shape. The heat sinks 50H and 50L are arranged along the X direction. Figure 3 as well as Figure 4 As shown, the heat sinks 50H and 50L have substantially the same thickness and are arranged at substantially the same position in the Z direction. Solder joints are formed between the mounting surface 50a of the heat sink 50H and the second end surface 55b of the terminal 55H, and between the mounting surface 50a of the heat sink 50L and the second end surface 55b of the terminal 55L.

[0099] The heat sinks 50H and 50L contain the corresponding semiconductor elements 30 and the terminals 55 when viewed from above in the Z direction. A groove 51 for accommodating the overflowing solder 82 is formed on the mounting surface 50a of the heat sinks 50H and 50L. The groove 51 surrounds the solder joint on the mounting surface 50a. The groove 51 is formed in a ring shape, for example. The back surface 50b of the heat sinks 50H and 50L is exposed from the sealing resin body 20. The back surface 50b is sometimes referred to as the heat dissipation surface or the exposed surface. The back surface 50b is substantially flush with the surface 20a of the sealing resin body 20. The back surfaces 50b of the heat sinks 50H and 50L are arranged along the X direction.

[0100] The connectors 60 to 62 connect the elements constituting the upper and lower arm circuits 6. The connectors connect the elements constituting the semiconductor device 10. Figure 3 as well as Figure 6 As shown, the joint portion 60 is connected to the radiator 40L. The thickness of the joint portion 60 is thinner than that of the radiator 40L. The joint portion 60 is connected to the opposite surface (side surface) opposite to the radiator 40H, while being roughly flush with the mounting surface 40a of the radiator 40L. The joint portion 60 has two curved portions, thereby being roughly crank-shaped on the ZX plane. The joint portion 60 is covered by the sealing resin body 20. The joint portion 60 can be connected to the radiator 40L by being integrally provided, or can be provided as other components, or can be connected by connection. In this embodiment, the joint portion 60 is provided integrally with the radiator 40L as part of the lead frame.

[0101] like Figure 3 as well as Figure 5 As shown, the joint parts 61 and 62 are connected to the corresponding radiator 50. The joint part 61 is connected to the radiator 50H. The joint part 62 is connected to the radiator 50L. The thickness of the joint parts 61 and 62 is thinner than that of the corresponding radiator 50. The joint parts 61 and 62 are covered by the sealing resin body 20. The joint parts 61 and 62 can be connected to the radiator 50 by being set as an integral part, or can be set as other components, or can be connected by connection. In this embodiment, the joint parts 61 and 62 are set as an integral part with respect to the corresponding radiators 50H and 50L. The joint parts 61 and 62 extend from the opposite sides of the two radiators 50H and 50L along the X direction.

[0102] Heat sink 50H including joint portion 61 and heat sink 50L including joint portion 62 are common components. Heat sink 50H including joint portion 61 and heat sink 50L including joint portion 62 are arranged in a two-fold symmetric pattern about the Z axis. Solder 83 is interposed between the facing surfaces of joint portion 60 and joint portion 61, forming a solder joint.

[0103] The joint surface of the connector 61 is formed with a groove 63 to receive any excess solder 83. The groove 63 is formed in an annular shape, surrounding the solder joint. Similarly, the joint surface of the connector 62 is also formed with a groove 63 to receive any excess solder. In this embodiment, the groove 63 is formed by stamping. Therefore, the connectors 61 and 62 each have a protrusion 64 on the back side of the groove 63.

[0104] Main terminals 70 to 72 and signal terminal 75 are external connection terminals. Main terminals 70 and 71 are power supply terminals. Main terminal 70 is electrically connected to the positive terminal of smoothing capacitor 4. Main terminal 71 is electrically connected to the negative terminal of smoothing capacitor 4. Therefore, main terminal 70 is sometimes referred to as a P-terminal, and main terminal 71 is sometimes referred to as an N-terminal.

[0105] like Figure 5 as well as Figure 6 As shown, the main terminal 70 is connected to one end of the heat sink 40H in the Y direction. The main terminal 70 is thinner than the heat sink 40H. The main terminal 70 is substantially flush with the mounting surface 40a and is connected to the heat sink 40H. The main terminal 70 extends from the heat sink 40H in the Y direction and protrudes outward from the side surface 20c of the sealing resin body 20. The main terminal 70 has a curved portion midway along the portion covered by the sealing resin body 20 and protrudes from near the center in the Z direction on the side surface 20c.

[0106] like Figure 4 as well as Figure 5 As shown, the main terminal 71 is connected to the joint portion 62. Solder 84 is sandwiched between the opposing surfaces of the main terminal 71 and the joint portion 62 to form a solder joint portion. The main terminal 71 extends in the Y direction and protrudes from the same side 20c as the main terminal 70 to the outside of the sealing resin body 20. The main terminal 71 has a connection portion 71a connected to the joint portion 62 near one end in the Y direction. A portion of the main terminal 71 including the connection portion 71a is covered by the sealing resin body 20, and the remaining portion protrudes from the sealing resin body 20. The plate thickness of the connection portion 71a is thicker than the plate thickness of the portion protruding from the sealing resin body 20. The plate thickness of the connection portion 71a is, for example, approximately the same thickness as the heat sink 40. The main terminal 71 also has a curved portion like the main terminal, protruding from near the center in the Z direction on the side 20c.

[0107] The main terminal 72 is connected to the connection point between the upper arm 6H and the lower arm 6L. The main terminal 72 is electrically connected to the winding (stator coil) of the corresponding phase of the electric generator 3. The main terminal 72 is also called the output terminal, AC terminal, or O terminal. The main terminal 72 is connected to one end of the heat sink 40L in the Y direction. The thickness of the main terminal 72 is thinner than that of the heat sink 40L. The main terminal 72 is roughly flush with the mounting surface 40a and is connected to the heat sink 40L. The main terminal 72 extends from the heat sink 40L in the Y direction and protrudes from the side 20c that is the same as the main terminal 70 to the outside of the sealing resin body 20. The main terminal 72 also has a curved portion like the main terminal 71, and protrudes from near the center in the Z direction on the side 20c. The three main terminals 70 to 72 are arranged in the order of main terminal 70, main terminal 71, and main terminal 72 in the X direction.

[0108] The signal terminals 75 are electrically connected to the pads 33 of the corresponding semiconductor elements 30. In this embodiment, the electrical connection is achieved via bonding wires 87. The signal terminals 75 extend in the Y direction and protrude outward from the side surface 20d of the sealing resin body 20. The side surface 20d is the surface opposite to the side surface 20c in the Y direction. In this embodiment, five signal terminals 75 are provided for each semiconductor element 30.

[0109] in addition, Figure 2 、 Figure 5 as well as Figure 6 Reference numeral 88 denotes a suspension lead. The heat sink 40 (40H, 40L), connector 60, main terminals 70-72, and signal terminal 75 form a common lead frame. This lead frame is a shaped strip with varying thicknesses in certain areas. Before cutting, the signal terminal 75 is connected to the suspension lead 88 via tie bars. Unnecessary portions of the lead frame, such as the tie bars, are cut (removed) after the encapsulating resin body 20 is formed.

[0110] As described above, in the semiconductor device 10, the plurality of semiconductor elements 30 constituting the upper and lower arm circuits 6 of a single phase are sealed by the sealing resin body 20. The sealing resin body 20 integrally seals the plurality of semiconductor elements 30, a portion of each heat sink 40, a portion of each heat sink 50, the terminal 55, the connector portions 60-62, the main terminals 70-72, and a portion of each signal terminal 75.

[0111] In the Z direction, the semiconductor element 30 is positioned between the heat sinks 40 and 50. This allows heat from the semiconductor element 30 to be dissipated to both sides in the Z direction. The semiconductor device 10 has a double-sided heat dissipation structure. The back surface 40b of the heat sink 40 is substantially flush with the back surface 20b of the sealing resin body 20. The back surface 50b of the heat sink 50 is substantially flush with the front surface 20a of the sealing resin body 20. The exposed back surfaces 40b and 50b enhance heat dissipation.

[0112] <Thread piece>

[0113] Next, based on Figures 7 to 9 , explain the line piece. Figure 7 It is magnified Figure 6 1 is a plan view of the semiconductor element 30H and its surroundings on the upper arm 6H side. Figure 7 The positional relationship between the semiconductor element and the wiring sheet is shown. Figure 7 In FIG. 5 , for convenience, the terminal 55H, the solder 81 , the emitter electrode 31 , the pad 33 , and the bonding wire 87 are omitted from the illustration. Figure 8 It is a three-dimensional diagram showing the arrangement of the wire pieces. Figure 9 It is along Figure 7 Cross-sectional view of line IX-IX.

[0114] like Figures 7 to 9 As shown, semiconductor device 10 further includes a wire piece 90. Wire piece 90 is provided in at least one of the solder joints that electrically connect the main electrode and the wiring member. Wire piece 90 is disposed within the solder. Multiple wire pieces 90 are dispersed within a single solder. Multiple wire pieces 90 are fixed (bonded) to a first opposing surface, one of the opposing surfaces constituting the solder joint, and protrude toward a second opposing surface, the other opposing surface.

[0115] Wire piece 90 has a predetermined height to ensure a minimum solder film thickness. The height of wire piece 90 is set so that even when multiple wire pieces 90 contact the second opposing surface, the shortest distance between the first opposing surface and the second opposing surface is greater than the minimum film thickness. The minimum film thickness refers to the minimum thickness required to ensure the desired connection reliability. The height of wire piece 90 is, for example, the value obtained by adding a margin to the minimum film thickness. Wire piece 90 is a small piece of bonding wire. Wire piece 90 is sometimes referred to as a protrusion or a columnar bond.

[0116] In this embodiment, multiple wire pieces 90 are arranged in the solder 80 between the collector electrode 32 of the semiconductor element 30H and the mounting surface 40a of the heat sink 40H. All of the multiple wire pieces 90 are fixed (joined) to the mounting surface 40a of the heat sink 40H, and are not fixed to the back surface of the semiconductor element 30H, that is, the collector electrode 32. The mounting surface 40a of the heat sink 40H corresponds to the first opposing surface, and the back surface of the semiconductor element 30H corresponds to the second opposing surface. Multiple wire pieces 90 are fixed to the mounting surface 40a. The wire pieces 90 are small pieces of bonding wire made of aluminum or an aluminum alloy. All wire pieces 90 fixed to the mounting surface 40a are arranged within the solder 80.

[0117] The solder 80 has a central region 80a that overlaps with the central portion of the semiconductor element 30H when viewed from above, and a peripheral region 80b surrounding the central region 80a. The central portion of the semiconductor element 30H is the element center 30c and its surrounding area. The semiconductor element 30H has a peripheral portion surrounding the central portion. The peripheral portion is, for example, a portion of a predetermined range extending from each of the four sides of a planar rectangular shape. For example, the central portion is the active region where the element is formed, and the peripheral portion is the peripheral withstand voltage region surrounding the active region. The peripheral region 80b includes a portion that overlaps with the outer periphery of the semiconductor element 30H. Multiple wire segments 90 are disposed in each of the central region 80a and the peripheral region 80b.

[0118] A plurality of wire pieces 90 a , which are part of the wire piece 90 fixed to the mounting surface 40 a , are arranged in the central region 80 a so as to surround the device center 30 c in a plan view. Figure 7 The center line CL shown is a virtual line extending in the Z direction through the element center 30c. The wire segments 90a in the central region 80a surround this center line CL. To surround the element center 30c, three or more wire segments 90a are arranged in the central region 80a. In this embodiment, three wire segments 90a are arranged in the central region 80a. The three wire segments 90a are positioned in a three-dimensionally symmetrical relationship with respect to the element center 30c.

[0119] A plurality of wire pieces 90b, which are another portion of the wire piece 90 fixed to the mounting surface 40a, are arranged in the peripheral area 80b so as to surround the element center 30c when viewed from above. The plurality of wire pieces 90b are arranged corresponding to at least the four corners of the semiconductor element 30H, which has a planar rectangular shape. Therefore, four or more wire pieces 90b are arranged in the peripheral area 80b. In this embodiment, four wire pieces 90b are arranged in the peripheral area 80b. The wire pieces 90b are arranged in portions overlapping with the four corners of the semiconductor element 30H. In addition, the four corners do not refer to the four corners (vertices) of the planar rectangular shape, but rather to a portion within a specified range (the portion surrounding the corners) that includes the vertices.

[0120] The lower arm 6L also has the same configuration. Specifically, a plurality of wire pieces 90 are arranged on the solder 80 between the collector electrode 32 of the semiconductor element 30L and the mounting surface 40a of the heat sink 40L. The wire pieces 90 are fixed to the mounting surface 40a. Therefore, their description is omitted.

[0121] <Method for manufacturing a semiconductor device>

[0122] Next, a description will be given of a method for manufacturing the above-mentioned semiconductor device 10. In this embodiment, the semiconductor device 10 is formed using a solder die bonding method.

[0123] First, wire piece 90 is formed. An aluminum bonding wire is ultrasonically bonded to the mounting surface 40a of the heat sink 40 in the lead frame. A bonding wire typically has a first bonding portion and a second bonding portion to electrically connect two parts. Here, the wire is cut at the moment the first bonding portion is formed, resulting in wire piece 90.

[0124] Next, molten solder is applied to form a laminate. First, molten solder (solder 80) is applied to the mounting surface 40a, and the semiconductor element 30 is arranged on the molten solder in such a way that the collector electrode 32 becomes the mounting surface 40a side. Next, molten solder (solder 81) is applied to the emitter electrode 31 of the semiconductor element 30, and the terminal 55 is arranged on the molten solder in such a way that the first end face 55a becomes the semiconductor element 30 side. Furthermore, molten solder (solder 82) is applied to the second end face 55b of the terminal 55. In addition, molten solder (solder 83, 84) is also applied to the joint portion 60 and the connecting portion 71a. The molten solder can be applied using a transfer method, for example. The applied molten solder solidifies (solders), thereby obtaining a laminate of the heat sink 40, the semiconductor element 30, and the terminal 55.

[0125] All solders 80 to 84 can be solidified (cured) at once or in the order of stacking. By performing this process at once, the manufacturing process can be simplified (e.g., manufacturing time can be shortened). The connection of the bonding wire 87 can be performed in the state of the stack or before applying the solder 81 while the solder 80 is solidified. Joining in the state of the stack after all solders 80 to 84 have been applied is preferred because it can suppress defects caused by contact with the coating device, etc.

[0126] Semiconductor device 10 with a double-sided heat dissipation structure is sandwiched from both sides in the Z direction by, for example, a cooler (not shown). This requires high parallelism of the surfaces in the Z direction and high dimensional accuracy between the surfaces. Therefore, solder 82 is arranged in an amount sufficient to accommodate variations in the height of semiconductor device 10. In other words, a larger amount of solder 82 is arranged. For example, solder 82 is thicker than solders 80 and 81.

[0127] Next, the heat sink 50 is placed on a pedestal (not shown) with the mounting surface 50a facing upward. The laminate is then placed on the heat sink 50 with the solder 82 facing the mounting surface 50a of the heat sink 50, and reflow is performed. During reflow, a load (hollow arrow) is applied from the heat sink 40 side in the Z direction to bring the height of the semiconductor device 10 to a predetermined height. Specifically, the load is applied so that a spacer (not shown) contacts both the mounting surface 40a of the heat sink 40 and the mounting surface of the pedestal. This brings the height of the semiconductor device 10 to a predetermined height.

[0128] Through reflow, the terminal 55 and the heat sink 50 are connected (joined) via the solder 82. That is, the emitter electrode 31 is electrically connected to the heat sink 50. Solder 82 absorbs height variations caused by dimensional tolerances and assembly tolerances of the components constituting the semiconductor device 10. For example, if the entire amount of solder 82 is required to achieve a predetermined height for the semiconductor device 10, the entire amount of solder 82 remains in the connection area further inward from the groove 51. On the other hand, if some of the solder 82 overflows to achieve the predetermined height, the overflowing solder 82 is contained within the groove 51. The same applies to solders 83 and 84, and therefore, their description is omitted.

[0129] Next, the sealing resin body 20 is formed by transfer molding. Although not shown in the figure, in this embodiment, the sealing resin body 20 is formed in a manner that the heat sinks 40 and 50 are completely covered, and cutting is performed after forming. The sealing resin body 20 is cut together with a portion of the heat sinks 40 and 50. As a result, the back surfaces 40b and 50b are exposed. The back surface 40b and the back surface 20b are roughly flush with each other, and the back surface 50b and the surface 20a are roughly flush with each other. Alternatively, the sealing resin body 20 can be formed while the back surfaces 40b and 50b are pressed against the cavity wall of the molding die and brought into close contact. In this case, at the moment the sealing resin body 20 is formed, the back surfaces 40b and 50b are exposed from the sealing resin body 20. Therefore, cutting after forming is not required.

[0130] Next, by removing tie bars (not shown) and the like, the semiconductor device 10 can be obtained.

[0131] Furthermore, although an example is shown in which heat sink 50 is placed after forming the laminate and reflow is performed, the present invention is not limited to this. Alternatively, molten solder (solder 82) may be applied to the second end surface 55b of the terminal 55 and then heat sink 50 may be placed on the molten solder. Alternatively, all solders 80 to 84 may be solidified (cured) simultaneously to form the laminate including heat sink 50. In other words, semiconductor device 10 may be obtained without reflow.

[0132] <Summary of the First Embodiment>

[0133] Sometimes, the number of parts and costs can be reduced by using the heat sink 40 as a common component for various (multiple product numbers) semiconductor elements 30. The semiconductor element 30 has an emitter electrode 31 on the surface and a collector electrode 32 on the back, and the emitter electrode 31 and the collector electrode 32 have different areas. In this structure, warping may occur in different directions depending on the variety due to film thickness, film forming method, chip size, electrode area, etc. For example, in a certain variety, warping occurs that bulges toward the heat sink 40 side, that is, bulges downward, and in another variety, warping occurs that bulges toward the side opposite to the heat sink 40, that is, bulges upward. Even with the same element size (chip size), there are cases where the direction of warping is different due to, for example, different film forming methods (film composition). Furthermore, due to deviations in manufacturing conditions, the direction of warping sometimes differs within the same variety.

[0134] In contrast, in this embodiment, multiple wire pieces 90 are provided in the solder joint between the collector electrode 32 of the semiconductor element 30 and the heat sink 40. The wire pieces 90 are fixed to the mounting surface 40a of the heat sink 40, which serves as the first opposing surface, and protrude toward the back side of the semiconductor element 30, which serves as the second opposing surface. Three or more wire pieces 90a are arranged in the central region 80a of the solder 80, surrounding the element center 30c. Four or more wire pieces 90b are arranged in the peripheral region 80b of the solder 80, corresponding to at least the four corners of the semiconductor element 30.

[0135] Therefore, if Figure 10 As shown, when the semiconductor element 30 warps downward, the minimum film thickness of the solder 80 can be ensured by using the wire pieces 90a arranged so as to surround the center 30c of the element. For example, the semiconductor element 30 can be supported by three or more wire pieces 90a arranged so as to surround the center 30c of the element. This can suppress the tilt of the semiconductor element 30 and maintain the minimum film thickness across the entire surface.

[0136] Furthermore, if the semiconductor element 30 experiences upward warping, the minimum film thickness of the solder 80 can be ensured by the wire pieces 90b arranged at least at the four corners of the semiconductor element 30. For example, the semiconductor element 30 can be supported by the wire pieces 90b arranged at least at the four corners. This prevents tilting of the semiconductor element 30 and ensures the minimum film thickness across the entire surface. Even if the wire piece 90 contacts the collector electrode 32, the height of the wire piece 90 ensures the minimum film thickness of the solder 80.

[0137] Furthermore, the wire piece 90 is fixed to the heat sink 40. That is, it is not put into a solder melting furnace and coated with molten solder. Even if the wire piece 90 is coated with molten solder, its shape can be maintained.

[0138] According to the above, even if the semiconductor element 30 is warped in any of the downward and upward directions, the film thickness of the solder 80 can be guaranteed. Even if various semiconductor elements 30 are used, the film thickness of the solder 80 can be guaranteed. Thus, a semiconductor device 10 with higher reliability can be provided. In addition, since the solder thickness can be ensured, the detection accuracy of the ultrasonic flaw detector (SAT: Scanning Acoustic Tomograph) for gaps can also be improved. Moreover, compared with the method of using Ni balls, the cost can be reduced. In addition, in Figure 10 In the figure, the solder 80 is omitted for convenience.

[0139] While the example in which the wire piece 90 is fixed to the mounting surface 40a of the heat sink 40 is shown, this is not limiting. The wire piece 90 may also be fixed to the collector electrode 32 of the semiconductor element 30. In other words, the back surface of the semiconductor element 30 may also serve as the first opposing surface. However, a structure in which the wire piece 90 is fixed to the heat sink 40 (back-side wiring member) has less impact on bonding the wire piece 90 and is therefore preferred.

[0140] The number and arrangement of the wire pieces 90 are not limited to the above-mentioned examples. Depending on the warping of the semiconductor element 30, the wire pieces 90 may be arranged only in the central region 80a or only in the peripheral region 80b. In addition, four or more wire pieces 90a may be arranged in the central region 80a so as to surround the center 30c of the element. In addition, in the peripheral region 80b, wire pieces 90b may be arranged in portions other than the four corners along with the four corners. In other words, five or more wire pieces 90b may be arranged so as to surround the center 30c of the element. When setting the wire pieces 90, the position of the wire pieces 90 may be adjusted to match the size (dimensions) of the semiconductor element 30.

[0141] The configuration of the semiconductor device 10 is not limited to the above example. For example, the device may be configured without the terminal 55. In this case, the emitter electrode 31 may simply be connected to the mounting surface 50a of the heat sink 50. Alternatively, a protrusion may be provided on the mounting surface 50a of the heat sink 50, and a solder joint may be formed between the tip of the protrusion and the emitter electrode 31.

[0142] This configuration can also be applied without the front-side wiring components, namely, the terminal 55 and the heat sink 50. For example, a bonding wire can be connected to the emitter electrode 31 to connect the upper arm 6H to the lower arm 6L and to the main terminal. Alternatively, the wire piece 90 can be provided only on one of the solder 80 on the upper arm 6H side and the solder 80 on the lower arm 6L side.

[0143] (Second embodiment)

[0144] This embodiment is a modified example based on the previous embodiment, and the description of the previous embodiment can be cited.

[0145] As described in the previous embodiment, in the semiconductor device 10, the wire sheet 90 may be in contact with the second opposing surface or may be non-contacted. Figure 11 As shown, it is preferable that the wire piece 90 and the collector electrode 32 serving as the second opposing surface are not in contact with each other. Figure 11 1 is a cross-sectional view showing the periphery of a connection portion between a semiconductor element and a heat sink in a semiconductor device 10 according to the present embodiment. Figure 11 and Figure 9 Corresponding. Figure 11 In the figure, for convenience, electrodes on the surface side of the semiconductor element 30 are omitted. The configuration of the semiconductor device 10 is similar to that of the first embodiment, for example. Figure 11 The illustrated configuration is the same on the upper arm 6H side and the lower arm 6L side.

[0146] The wire piece 90 is fixed to the mounting surface 40a of the heat sink 40 and is arranged in the solder 80. In the joint of the solder 80, the mounting surface 40a constitutes a first opposing surface, and the surface of the collector electrode 32 constitutes a second opposing surface. Moreover, the protrusion height H1 of the wire piece 90 based on the mounting surface 40a is smaller than the thickness T1 of the solder 80. The wire piece 90 does not contact the collector electrode 32, and there is a gap between the wire piece 90 and the collector electrode 32. The protrusion height H1 is a height that can ensure the minimum film thickness as described above. The protrusion height H1 is, for example, about 50 to 100 μm. The target value of the solder 80 is, for example, about 150 μm.

[0147] <Summary of Second Embodiment>

[0148] According to this embodiment, the protrusion height H1 of the wire piece 90 is smaller than the thickness T1 of the solder 80. As a result, the wire piece 90 does not contact the second opposing surface during formation of the semiconductor device 10. This prevents the wire piece 90 from collapsing due to contact, thereby ensuring a desired solder thickness.

[0149] Furthermore, in this embodiment, the main electrode serves as the second opposing surface. That is, the wire piece 90 is fixed to the surface opposing the main electrode. Therefore, by ensuring that the protrusion height H1 is less than the thickness T1 of the solder 80, it is possible to prevent the wire piece 90 from contacting and damaging the collector electrode 32.

[0150] While the above relationship is illustrated as an example of the configuration of the first embodiment, it is not limited thereto. For example, it can also be applied to a configuration in which the number of wire pieces 90 arranged in the solder 80 is different from that of the first embodiment (for example, a total of three). Furthermore, it is preferable to arrange multiple wire pieces 90 in the solder 80, preferably three or more. More preferably, the configuration described in the first embodiment is used.

[0151] Furthermore, the present invention is not limited to the wire piece 90 within the solder 80. Any solder having the wire piece 90 can be used. This is particularly suitable for the solder joint of the main electrode. For example, if the wire piece 90 is provided within the solder 81 and fixed to the terminal 55, it is possible to ensure the specified solder thickness and suppress damage to the emitter electrode 31. Furthermore, the above relationship can be satisfied only on one side, either the upper arm 6H or the lower arm 6L.

[0152] (Third embodiment)

[0153] This embodiment is a modified example based on the previous embodiment, and the description of the previous embodiment can be cited.

[0154] In this embodiment, the line piece 90 is as follows Figure 12 As shown, it is arranged only in the outer peripheral area 80b. Figure 12 It is a plan view showing the positional relationship between the semiconductor element 30 and the wiring sheet 90 in the semiconductor device 10 according to the present embodiment. Figure 12 and Figure 7 The wire piece 90 is arranged at least at positions corresponding to the four corners of the semiconductor element 30 in the outer peripheral area 80b. Figure 12 In the embodiment, the line pieces 90 are arranged only at the four corners and are not arranged in the central area 80a. Figure 12 The illustrated configuration is the same on the upper arm 6H side and the lower arm 6L side.

[0155] Although not shown in the figure, the emitter electrode 31 of the semiconductor element 30 includes a base electrode portion formed on the surface of the semiconductor substrate using an Al-based material such as AlSi and a connecting electrode portion formed on the base electrode portion. The base electrode portion is formed, for example, by sputtering. The connecting electrode portion is formed by plating. The connecting electrode portion includes, for example, a Ni layer formed on the base electrode portion and an Au layer formed on the Ni layer. The collector electrode 32 is formed by sputtering. The collector electrode 32 includes an Al layer formed on the back surface of the semiconductor substrate using an Al-based material such as AlSi and a Ni layer formed on the Al layer. The emitter electrode 31 using the plating method is thicker than the collector electrode 32.

[0156] <Summary of the Third Embodiment>

[0157] Figure 13 It is along Figure 12 The cross-sectional view along the line XIII-XIII shows the connection structure between the semiconductor element 30 and the heat sink 40. In the above-mentioned electrode structure, Figure 13 As shown, the semiconductor element 30 will produce a downward convex warp. In this embodiment, the supply amount of the solder 80 is set to ensure the minimum film thickness of the solder 80. The solder 80 is supplied so that the junction of the semiconductor element 30 (collector electrode 32) and the heat sink 40 can be wetted and expanded to ensure a predetermined thickness greater than the minimum film thickness. Figure 13 As shown, semiconductor element 30 is supported by solder 80 and does not contact wire sheet 90. During soldering, semiconductor element 30 floats on the molten solder. Solder 80 is supplied so that the minimum film thickness is maintained between the convex tip of semiconductor element 30, in other words, the center of the element, and heat sink 40. Figure 13 The figure shows an ideal state in which the semiconductor element 30 is arranged without tilting relative to the heat sink 40 .

[0158] Figure 14 3 is a cross-sectional view of a semiconductor element 30 arranged at an angle. Figure 14 As shown, when the semiconductor element 30 that has warped downward is tilted, the semiconductor element 30 contacts a portion of the plurality of wire pieces 90. Since the wire pieces 90 support the semiconductor element 30, the minimum film thickness of the solder 80 can be ensured. The wire pieces 90 have a height that can ensure the minimum film thickness of the solder 80 when the semiconductor element 30 that has warped is tilted. Since the wire pieces 90 are arranged at at least four corners of the peripheral area 80b, the semiconductor element 30 can be supported by at least one of the wire pieces 90 regardless of the direction in which it is tilted. As described above, according to the semiconductor device 10 of this embodiment, even if a warp that protrudes downward occurs on the semiconductor element 30, the film thickness of the solder 80 can be ensured. As a result, a semiconductor device 10 with high reliability (connection reliability) can be provided.

[0159] The electrode structure in which the semiconductor element 30 is warped downward is not limited to the above-described example.

[0160] In the outer peripheral region 80b, the wire pieces 90 may be arranged in portions other than the four corners as well as the four corners. That is, five or more wire pieces 90b may be arranged so as to surround the element center 30c.

[0161] (Fourth embodiment)

[0162] This embodiment is a modified example based on the previous embodiment, and the description of the previous embodiment can be cited.

[0163] The extension direction of the line piece 90 is not particularly limited on the first opposing surface. It can be extended in any direction. Figure 15 It is preferable to extend the wire piece 90 in the specified direction shown. Figure 15 It is a plan view showing the periphery of the connection portion between the semiconductor element and the heat sink in the semiconductor device 10 according to the present embodiment. Figure 15 and Figure 7 Corresponding. Figure 15 In FIG. 1 , in order to clarify the line piece 90 , the semiconductor element 30 is indicated by a dashed line, and the line piece 90 is indicated by a solid line. The configuration of the semiconductor device 10 is similar to that of the first embodiment, for example. Figure 15 The illustrated configuration is the same on the upper arm 6H side and the lower arm 6L side.

[0164] The wire piece 90 is fixed to the mounting surface 40a of the heat sink 40. The number and arrangement of the wire pieces 90 are the same as those in the first embodiment (see Figure 7 ). In this embodiment, the wire piece 90 extends toward the element center 30c when viewed from above. That is, the extension direction (length direction) of the wire piece 90 is approximately parallel to the virtual line connecting the wire piece 90 and the element center 30c. The wire piece 90 extends along this virtual line. The three wire pieces 90a arranged in the central area 80a of the solder 80 all extend toward the element center 30c. The four wire pieces 90b arranged in the peripheral area 80b of the solder 80 all extend toward the element center 30c.

[0165] <Summary of the Fourth Embodiment>

[0166] According to this embodiment, since the wire pieces 90 extend toward the component center 30c, they are less likely to obstruct the flow of the applied molten solder as it infiltrates and spreads. This prevents the formation of gaps in the solder 80 and unfilled areas between opposing surfaces. Furthermore, by aligning at least one of the multiple wire pieces 90 with the aforementioned extension direction, various benefits are achieved. In this embodiment, all wire pieces 90 arranged in the solder 80 extend toward the component center 30c. This enhances the aforementioned benefits and, in turn, improves connection reliability.

[0167] Although the above relationship is applied to the structure of the first embodiment, it is not limited to this. For example, the number and arrangement of the wire pieces 90 arranged on the solder 80 may be applied to a structure different from the first embodiment. Figure 16 The modified example shown in FIG. 1 is applicable to the third embodiment (see FIG. Figure 12 ) structure. The wire piece 90 arranged in the peripheral area 80b of the solder 80 extends toward the center 30c of the element. As a result, the effect described in the third embodiment can be achieved and the connection reliability can be improved. In addition, by making at least one of the plurality of wire pieces 90 extend in the above-mentioned direction, many effects can be achieved. Figure 16In the embodiment, all the wire pieces 90 arranged in the outer peripheral area 80b extend toward the element center 30c. This can further improve the connection reliability.

[0168] Furthermore, the control of the extension direction is not limited to the wire piece 90 within the solder 80. Any solder having the wire piece 90 configured therein is applicable. For example, when the wire piece 90 is configured on the solder 81, the control can also be applied to the wire piece 90. When the wire piece 90 is configured on the solder 82, the control can also be applied to the wire piece 90. Furthermore, the aforementioned extension direction may be satisfied only on one of the upper arm 6H side and the lower arm 6L side.

[0169] In addition, if the solder strain is taken into consideration, it is better to set the extension length as follows. When the extension length of the wire piece 90 is less than the specified length, the solder strain becomes the largest at the end (peripheral end) of the solder 80 when viewed from above. On the other hand, if the extension length exceeds the specified length, the solder strain becomes the largest at the end of the wire piece 90. If the extension length becomes longer, the solder strain at the end of the wire piece increases. If it exceeds the specified length, the magnitude relationship between the solder strain at the end of the wire piece and the solder end is reversed. Therefore, it is preferable to set the extension length within a range in which the solder strain at the end of the wire piece 90 does not exceed the solder strain at the end of the solder 80. For example, relative to the diameter of 80μm of the aluminum bonding wire forming the wire piece 90, it is better to set the length of the wire piece 90 to be less than 350μm. Specifically, it is better to set it within the range of 200 to 350μm.

[0170] (Fifth embodiment)

[0171] This embodiment is a modified example based on the previous embodiment, and the description of the previous embodiment can be cited.

[0172] like Figures 17 to 19 As shown, the wire piece 90 can also be arranged on the solder 81 that connects the surface electrode and the surface wiring component. Figures 17 to 19 The position shown is preferably used to dispose the wire piece 90. Figure 17 The positional relationship between the wire piece 90 disposed on the solder 81 and the semiconductor element 30 in the semiconductor device 10 of the present embodiment is shown. Figure 18 The arrangement of the wire piece 90 in the terminal 55 is shown. Figure 19 It is along Figure 17 The cross-sectional view of the XIX-XIX line. Figure 19 For convenience, the gate wiring 34 is omitted from the illustration. The configuration of the semiconductor device 10 of this embodiment is similar to that of the first embodiment, for example. The configuration of the wire piece 90 disposed on the solder 81 is the same on the upper arm 6H side and the lower arm 6L side.

[0173] Multiple wire segments 90 are provided at the solder joint between the emitter electrode 31 of the semiconductor element 30 and the first end surface 55a of the terminal 55. All of the wire segments 90 are fixed (joined) to the first end surface 55a of the terminal 55, and are not fixed to the emitter electrode 31, i.e., the surface, of the semiconductor element 30. The first end surface 55a of the terminal 55 corresponds to the first opposing surface, and the surface of the semiconductor element 30 corresponds to the second opposing surface. Multiple wire segments 90 are fixed to the first end surface 55a. All of the wire segments 90 fixed to the first end surface 55a are disposed within the solder 81.

[0174] As described above, semiconductor element 30 includes gate pad 33g. Semiconductor element 30 also includes gate wiring 34 formed on the surface side and connected to gate pad 33g, and gate wiring protection portion 35, which is part of a protective film formed on the surface and protects gate wiring 34. Emitter electrode 31 is divided into two in the X direction, and gate wiring 34, made of aluminum or other materials, is formed between adjacent emitter electrodes 31.

[0175] A protective film made of polyimide or the like is formed on the surface of the semiconductor element 30, and the emitter electrode 31 and the pad 33 are exposed from the protective film. The gate wiring protection portion 35 is a portion of the protective film and covers the gate wiring 34. Figure 17 In FIG, the portion of the gate wiring protection portion 35 that overlaps with the terminal 55 when viewed from above is indicated as a dotted line area. Figure 18 In FIG. 5 , in order to indicate the positional relationship, the gate wiring protection portion 35 is indicated as a region of a single-dot chain line on the first end surface 55 a of the terminal 55 .

[0176] The wire piece 90 is arranged at a position that does not overlap with the gate wiring protection portion 35 when viewed from above. Figure 17 as well as Figure 18 As shown, a wire piece 90 is fixed near the center of the first end surface 55a, at a position that does not overlap with the gate wiring protection portion 35. Furthermore, wire pieces 90 are fixed to each of the four corners of the first end surface 55a, which is a generally rectangular shape in plan view. Thus, five wire pieces 90 are fixed to the first end surface 55a.

[0177] <Summary of the Fifth Embodiment>

[0178] In this embodiment, a plurality of wire pieces 90 are arranged in the solder 81. This ensures the minimum film thickness of the solder 81.

[0179] Furthermore, all wire pieces 90 within the solder 81 are positioned so as not to overlap with the gate wiring protection portion 35 when viewed from above. This prevents the wire pieces 90 from contacting the gate wiring protection portion 35 and damaging the protective film during fabrication of the semiconductor device 10. This also prevents the solder 81 from intruding through the damaged portion of the protective film toward the gate wiring 34 and causing a short circuit between the gate electrode and the emitter electrode 31, i.e., gate leakage.

[0180] The area of ​​the emitter electrode 31 is smaller than the area of ​​the collector electrode 32. In other words, the joint of the solder 81 is smaller than the joint of the solder 80 when viewed from above. Therefore, even if the semiconductor element 30 is warped in an upward direction, the semiconductor element 30 can be supported by a single wire piece 90 provided near the center of the first end face 55a. Thus, the minimum film thickness of the solder 81 can be ensured. In addition, even if the semiconductor element 30 is warped in a downward direction, the semiconductor element 30 can be supported by the wire pieces 90 provided at the four corners. Thus, the minimum film thickness of the solder 81 can be ensured. As described above, a semiconductor device 10 with higher reliability can be provided.

[0181] While the example of attaching the wire piece 90 to the first end surface 55a of the terminal 55 is shown, this is not limiting. The wire piece 90 may also be attached to the emitter electrode 31 of the semiconductor element 30. In other words, the surface of the semiconductor element 30 may serve as the first opposing surface. However, attaching the wire piece 90 to the terminal 55 (the front wiring member) is preferred because it minimizes the impact of bonding the wire piece 90.

[0182] The number and arrangement of the wire pieces 90 in the solder 81 are not limited to the above-described example. They can be arranged within a range that satisfies the condition of not overlapping with the gate wiring protection portion 35 when viewed from above. For example, multiple wire pieces 90 can be arranged near the center of the first end face 55a. Furthermore, wire pieces 90 can be arranged near the outer edge of the first end face 55a, as well as at the four corners, and also in portions other than the four corners. Furthermore, the above-described arrangement can be satisfied only on one of the upper arm 6H side and the lower arm 6L side.

[0183] While the above relationship is applied to the configuration of the first embodiment, the present invention is not limited thereto. The wire pieces 90 disposed on the solder 81 may be combined with at least one of the configurations of the second embodiment, the third embodiment, and the fourth embodiment. For example, the number of wire pieces 90 disposed on the solder 80 may be different from that of the first embodiment. For example, the number of wire pieces 90 disposed on the solder 80 and the number of wire pieces 90 disposed on the solder 80 and 81 may be the same.

[0184] exist Figure 20In the modified example shown, wire pieces 90 are arranged at the four corners of the peripheral area 80b in the solder 80, and wire pieces 90 are arranged at the four corners in the solder 81. That is, four wire pieces 90 are arranged in the solders 80 and 81 respectively. Even if the semiconductor element 30 is warped downward, the semiconductor element 30 can be supported by the wire pieces 90 arranged in the solder 81. In this way, the minimum film thickness of the solder 81 can be ensured. The wire pieces 90 in the solder 81 are arranged at a position that does not overlap with the gate wiring protection portion 35. The wire pieces 90 arranged in the solders 80 and 81 are aligned with the gate wiring protection portion 35. Figure 16 The structure shown is the same, extending towards the center 30c of the element. Figure 20 This is a top view of the terminal 55 as viewed from the second end face side. Figure 20 In FIG. 1 , the wire piece 90 disposed on the solder 80 is indicated by a dotted line, and the wire piece 90 disposed on the solder 81 is indicated by a dashed line.

[0185] Alternatively, instead of arranging the wire piece 90 on the solder 80, the wire piece 90 may be arranged on the solder 81 as described above. The configuration of this embodiment can also be applied to a configuration that does not include the backside wiring member, that is, the heat sink 40.

[0186] Although the semiconductor device 10 is shown as an example having the terminal 55, the present invention is not limited thereto. The present invention is also applicable to a configuration without the terminal 55. For example, the wire piece 90 may be fixed to the mounting surface 50a of the heat sink 50 at the solder joint between the emitter electrode 31 and the mounting surface 50a of the heat sink 50.

[0187] (Sixth embodiment)

[0188] This embodiment is a modified example based on the previous embodiment, and the description of the previous embodiment can be cited.

[0189] When the wire piece 90 is arranged on both sides of the solder 80 and 81, the arrangement of the wire piece 90 is not particularly limited. Figure 21 The wire piece 90 is arranged as shown. Figure 21 This is a plan view of the terminal viewed from the second end surface side in the semiconductor device 10 of the present embodiment. Figure 21 and Figure 7 The configuration of the semiconductor device 10 is, for example, the same as that of the first embodiment. Figure 21 The illustrated configuration is the same on the upper arm 6H side and the lower arm 6L side.

[0190] The semiconductor device 10 includes a plurality of wire pieces 90 disposed on the solder 80 and a plurality of wire pieces 90 disposed on the solder 81. Hereinafter, the wire pieces 90 disposed on the solder 80 may be referred to as wire pieces 900, and the wire pieces 90 disposed on the solder 81 may be referred to as wire pieces 901. Figure 21 In FIG. 1 , the line piece 900 is indicated by a dotted line, and the line piece 901 is indicated by a dashed line.

[0191] The wire piece 900 is similar to the wire piece 90 described in the first embodiment (see Figure 7 ) are arranged in the same manner. The wire pieces 900 are fixed to the mounting surface 40a of the heat sink 40, for example. Three wire pieces 900 are arranged in the central region 80a of the solder 80 so as to surround the element center 30c. Four wire pieces 900 are arranged in the peripheral region 80b, corresponding to the four corners of the semiconductor element 30, respectively.

[0192] The wire piece 901 is similar to the wire piece 90 described in the fifth embodiment (see Figure 17 ) The same configuration. The wire piece 901 is fixed to the first end face 55a of the terminal 55, for example. One wire piece 901 is arranged near the center of the first end face 55a. Wire pieces 901 are arranged at the four corners of the first end face 55a. Figure 21 As shown, the line piece 900 and the line piece 901 are arranged at positions that do not overlap each other when viewed from above.

[0193] <Summary of Sixth Embodiment>

[0194] Figure 22 Schematic diagram showing the difference between the comparative example and the present embodiment (present embodiment). In the comparative example, elements that are the same as or related to those in the present embodiment (present embodiment) are indicated by adding r at the end of the reference numerals in the present embodiment. Figure 22 In the figure, for convenience, the main electrodes of the semiconductor elements are omitted.

[0195] As mentioned above, wire pieces 900r and 901r are formed using an aluminum-based material, and their wettability with solder 80r and 81r is lower than that of the main electrode (not shown) of semiconductor element 30r, heat sink 40r, and terminal 55r. Consequently, a gap 86r is formed between wire pieces 900r and 901r and solder 80r and 81r. This gap 86r hinders heat conduction. As in the comparative example, if wire pieces 900r and 901r overlap when viewed from above, gap 86r also overlaps. Because gap 86r exists on both sides of semiconductor element 30r in the Z direction, it is difficult to dissipate heat in the Z direction from the portion of semiconductor element 30r that overlaps gap 86r (wire pieces 900r and 901r). Consequently, thermal resistance increases.

[0196] In this embodiment (this example), as in the comparative example, gaps 86 are formed between wire piece 900 and solder 80, and between wire piece 901 and solder 81. However, wire pieces 900 and 901 are positioned so as not to overlap when viewed from above. Therefore, gaps 86 in solders 80 and 81 do not overlap when viewed from above, or if they do, they only overlap minimally. This allows heat from semiconductor element 30 to be dissipated in at least one direction in the Z direction. This reduces thermal resistance and improves heat dissipation compared to the comparative example. In other embodiments, gaps 86 are omitted from the illustrations.

[0197] In this embodiment, wire piece 900 has the same configuration as the first embodiment. Therefore, in addition to the effects described in this embodiment, the effects described in the first embodiment can also be achieved. Furthermore, wire piece 901 has the same configuration as the fifth embodiment. Therefore, in addition to the effects described in this embodiment, the effects described in the fifth embodiment can also be achieved. However, the number and arrangement of wire pieces 900 and 901 can be selected within a range that satisfies the condition that wire pieces 900 and 901 do not overlap when viewed from above. In other words, the number and arrangement are not limited to the above examples.

[0198] For example, only the wire piece 900 may be configured as the same as in the first embodiment, and the wire piece 901 may be configured as different from the fifth embodiment. Alternatively, only the wire piece 901 may be configured as the same as in the fourth embodiment, and the wire piece 900 may be configured as different from the first embodiment. In addition, the number of wire pieces 900 and 901 may be the same. Figure 20 In the illustrated configuration, the number of wire pieces 90 for solder 80 and 81 is the same. Wire piece 90 on the solder 80 side, corresponding to wire piece 900 , and wire piece 90 on the solder 81 side, corresponding to wire piece 901 , are arranged so as not to overlap each other in a plan view.

[0199] Although the example in which the wire piece 900 is fixed to the heat sink 40 is shown, it can also be fixed to the back surface of the semiconductor element 30 (collector electrode 32). Although the example in which the wire piece 901 is fixed to the terminal 55 is shown, it can also be fixed to the surface of the semiconductor element 30 (emitter electrode 31). The wire piece 900 can also be fixed to the heat sink 40, and the wire piece 901 can be fixed to the semiconductor element 30. Alternatively, the wire piece 900 can be fixed to the semiconductor element 30, and the wire piece 901 can be fixed to the terminal 55. In addition, a configuration without the terminal 55 is also possible. In this case, the wire piece 901 is provided at the solder joint between the heat sink 50 and the semiconductor element 30 (emitter electrode 31).

[0200] The configuration of this embodiment may be combined with at least one of the configurations of the second embodiment, the third embodiment, and the fourth embodiment. The configuration of the second embodiment may be combined with at least one of the wire pieces 900 and 901. The configuration of the third embodiment may be combined with at least one of the wire pieces 900 and 901. The configuration of the fourth embodiment may be combined with at least one of the wire pieces 900 and 901. Furthermore, the configuration of this embodiment may be satisfied on only one of the upper arm 6H and lower arm 6L sides.

[0201] (Seventh embodiment)

[0202] This embodiment is a modified example based on the previous embodiment, and the description of the previous embodiment can be cited.

[0203] like Figure 23 As shown, the wire piece 90 can also be arranged on the solder 82. In this case, the wire piece 90 of each solder 80, 81, 82 is arranged as shown in FIG. Figure 24 The configuration shown is better. Figure 23 1 is a schematic cross-sectional view showing a stacked body between heat sinks 40 and 50 in the semiconductor device 10 according to the present embodiment. Figure 24 It is a plan view showing an example of a preferred arrangement of the wire pieces 90 in each of the solders 80 , 81 , and 82 . Figure 24 and Figure 21 Corresponding. Figure 24 In FIG, a line segment 900 is indicated by a dotted line, and a line segment 901 is indicated by a dashed line. The configuration of the semiconductor device 10 of the present embodiment is similar to that of the first embodiment, for example. Figure 23 as well as Figure 24 The illustrated configuration is substantially the same on the upper arm 6H side and the lower arm 6L side.

[0204] like Figure 23 As shown, multiple wire pieces 90 are arranged on each of solders 80, 81, and 82. Hereinafter, wire pieces 90 arranged on solder 80 may be referred to as wire pieces 900, wire pieces 90 arranged on solder 81 may be referred to as wire pieces 901, and wire pieces 90 arranged on solder 82 may be referred to as wire pieces 902. The number of wire pieces 90 varies between solders 80, 81, and 82. Wire pieces 900 are the most numerous, while wire pieces 902 are the least numerous. Wire pieces 901 are fewer than wire pieces 900, but more than wire pieces 902.

[0205] exist Figure 23 , the wire piece 900 is fixed to the heat sink 40. In addition, the wire piece 901 is fixed to the first end surface 55a of the terminal 55, and the wire piece 902 is fixed to the second end surface 55b.

[0206] like Figure 24 As shown, the wire piece 900 is the same as the wire piece 90 described in the first embodiment (see Figure 7 ) are arranged in the same manner. The wire pieces 900 are fixed to the mounting surface 40a of the heat sink 40. Three wire pieces 900 are arranged in the central region 80a of the solder 80 so as to surround the element center 30c. In the peripheral region 80b, four wire pieces 900 are arranged corresponding to the four corners of the semiconductor element 30, respectively.

[0207] The wire piece 901 is similar to the wire piece 90 described in the fifth embodiment (see Figure 17 ) are arranged in the same manner. The wire piece 901 is fixed to the first end surface 55a of the terminal 55. One wire piece 901 is arranged near the center of the first end surface 55a. Wire pieces 901 are arranged at the four corners of the first end surface 55a.

[0208] The wire piece 902 is fixed to the second end surface 55b of the terminal 55. Three wire pieces 902 are fixed to the second end surface 55b. The plurality of wire pieces 902 are arranged in a manner to surround the element center 30c. Figure 24 As shown, the wire pieces 900, 901, and 902 are arranged so as not to overlap each other when viewed from above. Furthermore, the terminal 55 corresponds to the first wiring member, and the heat sink 50 corresponds to the second wiring member. The solder 81 corresponds to the first bonding member, which is the front-side bonding member, and the solder 82 corresponds to the second bonding member.

[0209] <Summary of Seventh Embodiment>

[0210] In this embodiment, multiple wire pieces 90 are arranged on the solder 82. This ensures the minimum film thickness of the solder 82. Furthermore, multiple wire pieces 90 are arranged on each of the solders 80, 81, and 82. This ensures the minimum film thickness of all of the solders 80, 81, and 82 that form the electrical and thermal paths from the semiconductor element 30 to the heat sinks 40 and 50 on both sides in the Z direction.

[0211] In this embodiment, the number of wire segments 90 arranged varies for each solder 80, 81, and 82. The largest number of wire segments 90 (wire segments 900) is arranged on the solder 80 on the side of the collector electrode 32, which has a larger electrode area. Furthermore, on the side of the emitter electrode 31, which has a smaller electrode area than the collector electrode 32, the solder 81 on the side closer to the semiconductor element 30 has fewer wire segments 90 (wire segments 901) than the wire segments 900. Furthermore, the smallest number of wire segments 90 (wire segments 902) is arranged on the side of the solder 82 farther from the semiconductor element 30. Specifically, the semiconductor device 10 includes seven wire segments 900, five wire segments 901, and three wire segments 902 as wire segments 90.

[0212] The solders 80 and 81 are affected by the warping of the semiconductor element 30. By arranging the most wire pieces 90 on the solder 80 having the largest area when viewed from above by being connected to the collector electrode 32, the minimum film thickness of the solder 80 can be ensured. By making the arrangement of the wire pieces 900 the same as that of the first embodiment, the minimum film thickness can be ensured even for the warping of the semiconductor element 30. The solder 81 connects the emitter electrode 31, which has a smaller area than the collector electrode 32, and the terminal 55, which is a metal block. By providing a wire piece 90 near the center, the upward convex warping of the semiconductor element 30 can be dealt with. By arranging fewer wire pieces 90 than the solder 80, the minimum film thickness of the solder 81 can be ensured. By making the arrangement of the wire pieces 901 the same as that of the fifth embodiment, the minimum film thickness can be ensured even for the warping of the semiconductor element 30.

[0213] Solder 82 connects the terminal 55 to the heat sink 50. Warping does not occur on the terminal 55 and the heat sink 50 as it does on the semiconductor element 30. In addition, since the terminal 55 exists between the terminal 55 and the semiconductor element 30, it is not affected by the warping of the semiconductor element 30. As a result, the minimum film thickness of the solder 82 can be ensured with a minimum number of wire pieces 90. By making the number of wire pieces 901 and 902 less than that of the wire piece 900, the gaps 86 in the solder 81 and 82 can be reduced compared to a configuration with the same number of wire pieces 900. As a result, the minimum film thickness can be ensured and heat dissipation can be improved. Moreover, since the number of wire pieces 902 is less than that of the wire piece 901, heat dissipation can be improved compared to a configuration with the same number of wire pieces 901. In addition, the number of wire pieces 90 in the entire semiconductor device 10 can also be reduced.

[0214] Furthermore, the line pieces 900, 901, and 902 are arranged at positions where they do not overlap each other in a plan view. In the Z direction, the gaps 86 do not overlap each other, or if they do overlap, it is only a very small portion, thereby improving heat dissipation.

[0215] When the number of wire pieces 90 in solders 80, 81, and 82 differs, the number is not limited to the example above. It suffices to satisfy the following relationship: number of wire pieces 900 > number of wire pieces 901 > number of wire pieces 902. Alternatively, the number of wire pieces 900 > number of wire pieces 901 = number of wire pieces 902. Alternatively, the number of wire pieces 900 = number of wire pieces 901 > number of wire pieces 902. By making some of the wire pieces 90 in solders 80, 81, and 82 different from the remaining wire pieces 90, while the effect is reduced, it can improve heat dissipation and reduce the number of wire pieces 90.

[0216] By ensuring the minimum film thickness in each solder 80, 81, and 82, the number of wire pieces 90 can be set more freely. The number of wire pieces 90 can also be the same in each solder 80, 81, and 82. By arranging multiple, preferably three or more, wire pieces 90 in each solder, it is easier to ensure the solder thickness.

[0217] The configuration of this embodiment may be satisfied only on one of the upper arm 6H and lower arm 6L sides. Although the example in which the wire piece 90 is disposed on the solders 80 , 81 , and 82 is shown, it may also be disposed on at least one of the solders 83 and 84 .

[0218] (Eighth Embodiment)

[0219] This embodiment is a modified example based on the previous embodiment, and the description of the previous embodiment can be cited.

[0220] The shape of the terminal 55 is not particularly limited. Figure 25 In this example, the shape is better. Figure 25 This is a schematic diagram illustrating the differences between the comparative example and the present example (this embodiment) regarding the terminal connection. In the comparative example, elements identical to or related to those in the present embodiment (this embodiment) are denoted by appending an r to the end of the reference numerals in the present embodiment. Both the comparative example and the present example are side views with the top of the page being the top view, and plan views viewed from plane A. The semiconductor device 10 of this embodiment is, for example, the same as that of the first embodiment. Figure 25 The illustrated configuration is substantially the same on the upper arm 6H side and the lower arm 6L side.

[0221] The terminal is formed by punching from a metal plate using a stamping process. The wire piece is formed by photographing the terminal's end face with a camera, identifying the corners, and ultrasonically joining the wires at predetermined positions using the corners as a reference. The comparative example terminal 55r has a punched-in rounded portion 550r at one end face corner in the Z direction. Therefore, when forming a wire piece 90r on the end face facing the rounded portion 550r, there is a risk that the precision of the wire piece 90r's formation will be reduced compared to the end face without the rounded portion 550r.

[0222] In this embodiment (this example), as in the comparative example, the blanked terminal 55 has an R-shaped portion (not shown) at the corner of one end surface. However, after blanking, the R-shaped portion is chamfered, for example, in a C-shaped chamfer. A C-shaped chamfer has a chamfer angle of approximately 45 degrees. The terminal 55 has a chamfered portion 550.

[0223] <Summary of Eighth Embodiment>

[0224] As described above, the terminal 55 of this embodiment has the chamfered portion 550. Therefore, when forming the wire piece 90 on the end surface where the rounded portion is formed during punching, the corner can be accurately identified by imaging. This allows the wire piece 90 to be formed with high positional accuracy.

[0225] The configuration of this embodiment can be applied to any configuration including a terminal 55. It can be combined with the various previous embodiments. Furthermore, the connection target of the wire piece 90 is not limited to the terminal 55. It can also be applied to components formed by punching a metal sheet and having an R-shaped portion formed during punching. By chamfering the R-shaped portion after punching, the wire piece 90 can be formed with high positional accuracy on the side where the R-shaped portion is formed during punching.

[0226] (Ninth embodiment)

[0227] This embodiment is a modified example based on the previous embodiment, and the description of the previous embodiment can be cited. This embodiment has characteristics in the structure and manufacturing method of the wire sheet 90.

[0228] As described above, the wire piece 90 is formed by ultrasonically bonding aluminum wire and then cutting the wire at the time of the first bonding. Figures 26 to 29 middle.

[0229] Figure 26 The connection structure between the semiconductor element 30 and the heat sink 40 in the semiconductor device 10 of the present embodiment is shown. Figure 27 It is along Figure 26 Cross-sectional view of line XXVII-XXVII. Figure 28 Yes means applicable to Figure 26 as well as Figure 27 A three-dimensional view of the line piece 90. Figure 29 Another example of the line piece 90 is shown. Figure 26 as well as Figure 27 In the embodiment, the number of the line pieces 90 is three. Figure 26 、 Figure 27 as well as Figure 28 For the sake of convenience, the main electrodes are not shown in the figure. The semiconductor device 10 of this embodiment is similar to that of the first embodiment, for example. Figures 26 to 28 The illustrated configuration is substantially the same on the upper arm 6H side and the lower arm 6L side.

[0230] The semiconductor element 30 has a surface 30a on which an emitter electrode 31 (not shown) is formed and a back surface 30b on which a collector electrode 32 (not shown) is formed. The collector electrode 32 constitutes the back surface 30b. Figure 21 as well as Figure 22As shown, a plurality of wire pieces 90 are arranged on the solder 80. The wire pieces 90 are joined (fixed) to the mounting surface 40a of the heat sink 40. The mounting surface 40a corresponds to the fixed surface of the wiring component. The wire pieces 90 protrude from the mounting surface 40a toward the back surface 30b. The wire pieces 90 are held by the heat sink 40. Therefore, the heat sink 40 is sometimes referred to as a retaining body. The wire piece 90 has a fixed portion 91, a flat portion 92, and a non-fixed portion 93. The fixed portion 91 is a fixed portion (joint portion) fixed to the heat sink 40 on the side of the wire piece 90 opposite to the heat sink 40.

[0231] The flat portion 92 is a portion formed on the side of the wire sheet 90 that is opposite to the back surface 30b of the semiconductor element 30 and is approximately parallel to the mounting surface 40a of the heat sink. The non-fixed portion 93 is a portion of the wire sheet 90 that is connected to the fixed portion 91 on the side opposite to the heat sink 40 and is not fixed to the heat sink 40. The non-fixed portion 93 is separated from the mounting surface 40a in the Z direction. The non-fixed portion 93 floats with respect to the fixed portion 91. The wire sheet 90 is configured to be elastically deformable in the Z direction. The solder 80 enters the gap between the non-fixed portion 93 and the mounting surface 40a. The wire sheet 90 has a fixed portion 91 and a non-fixed portion 93 on the heat sink 40 side in the Z direction, and a flat portion 92 on the side opposite to the fixed portion 91 and the non-fixed portion 93.

[0232] The wire piece 90 extends along the X direction. Figure 27 as well as Figure 28 The wire piece 90 shown has flat portions 92 and non-fixed portions 93 at both ends in the extending direction. The flat portions 92 are positioned so as to overlap with the non-fixed portions 93 when viewed from above. The heights of the flat portions 92 from the mounting surface 40a to both ends are approximately equal. The wire piece 90 has a roughly U-shaped or C-shaped shape in the ZX plane. The flat portions 92 at both ends contact the back surface 30b of the semiconductor element 30.

[0233] Figure 29 Another example of a wire piece 90 is shown. This wire piece 90 has a flat portion 92 only at one end in the extension direction, not at both ends. Non-fixed portions 93 are provided at both ends in the extension direction. In wire piece 90, the height from the mounting surface 40a to the upper portion at both ends varies. Flat portion 92 is formed at the end on the side with a higher protrusion height from the mounting surface 40a. Wire piece 90 is roughly J-shaped in the ZX plane. Flat portion 92 is formed at the end farther from the element center 30c (not shown).

[0234] <Manufacturing method>

[0235] Next, a method for manufacturing the semiconductor device 10, in particular, a method for manufacturing a connection body between the semiconductor element 30 and the heat sink 40, will be described. Figure 29 An example of a wire sheet 90 is shown.

[0236] First, if Figure 30 As shown, a wire piece 90 is formed on the mounting surface 40a of the heat sink 40. The bonding wire is bonded to the heat sink 40 by ultrasonic waves from a tool not shown in the figure, forming a fixed portion 91. The fixed portion 91 is a first bonding portion. Then, after the ultrasonic wave application is completed, the bonding wire is cut in such a manner that a non-fixed portion 93 remains before and after the extension direction relative to the fixed portion 91. In this way, the bonding wire is cut without forming a second bonding portion. Since the wire piece 90 is formed using only the first bonding side, the formation time can be shortened compared to a structure having two bonding bodies, namely a first bonding portion and a second bonding portion. In addition, the size of the wire piece 90 can be miniaturized, for example, the extension length can be shortened. Therefore, it is also advantageous from the perspective of the above-mentioned solder strain.

[0237] As mentioned above, the bonding wire is made of aluminum or aluminum alloy and can be selected according to the size of the semiconductor element 30 and the thickness of the solder 80. Here, a bonding wire with a diameter of 80 μm is used to form a wire piece 90 with a protrusion height of 110 μm from the mounting surface 40a and an extension length of 350 μm.

[0238] Next, if Figure 31 as well as Figure 32 As shown, a flat portion 92 is formed on the line sheet 90. That is, a flattening process is performed. Specifically, a jig 98 having a surface (hereinafter referred to as a contact surface) parallel to the mounting surface 40a is used, as shown in FIG. Figure 31 A load is applied to the wire piece 90 as indicated by the hollow arrow in the figure. For example, a clamp 98 is installed on a punching machine, and a load is applied to the wire piece 90. The clamp 98 is pressed against the wire piece 90 while maintaining the parallel state between the contact surface and the mounting surface 40a. The clamp 98 contacts one end of the wire piece 90 which is roughly J-shaped. In addition, the wire piece 90 is elastically deformed, and at least a part of the non-fixed portion 93 contacts the mounting surface 40a. If the clamp 98 is further pressed in, the wire piece 90 is plastically deformed to form a flat portion 92. The wire piece 90 is plastically deformed according to the amount of pressing. The flat portion 92 is formed on the end side that initially contacts the clamp 98.

[0239] After the flat portion 92 is formed, the load is released and the wire piece 90 recovers from the elastic deformation state, and the portion of the non-fixed portion 93 that was in contact with the wire piece 90 leaves the mounting surface 40a. Figure 32 As shown, a line piece 90 having a flat portion 92 at a position overlapping with the non-fixed portion 93 in a plan view can be obtained. By flattening, the height of the line piece 90 is relatively Figure 30 The state becomes lower. Here, it is set to about 75μm. Through the above process, a plurality of wire pieces 90 are formed on the mounting surface 40a. In order to suppress the tilt of the semiconductor element 30, it is better to form a plurality of, more preferably three or more, wire pieces 90. It is further preferred to adopt the structure described in the previous embodiment.

[0240] Next, if Figure 33 As shown, molten solder 80S is applied. Molten solder 80S is applied to the mounting surface 40a of the heat sink 40. The wire piece 90 is covered with the applied molten solder 80S. Since the semiconductor element 30 needs to be arranged in the molten solder 80S, the heat sink 40 is heated (warmed) as needed. Here, the molten solder 80S is applied using a transfer method.

[0241] Next, if Figure 34 As shown, the semiconductor element 30 is mounted. A fixture (not shown) is used to hold the semiconductor element 30 and lower it from above the mounting surface 40a toward the molten solder 80S. As it descends, the back surface 30b of the semiconductor element 30 contacts the molten solder 80S, pressing the molten solder 80S apart. Once it descends to a predetermined position, the fixture's holding position is released. The molten solder 80S wets and spreads across the back surface 30b and the mounting surface 40a. Depending on the thickness of the heat sink 40, the thickness of the semiconductor element 30, warping, and variations in mounting accuracy, the semiconductor element 30 may be pressed against the wire piece 90.

[0242] Then, after cooling (not shown), the Figure 29 In addition, for the connection structure shown in FIG. Figure 27 as well as Figure 28 The wire piece 90 shown can also be formed by the same method. Specifically, after forming the fixing portion 91, the bonding wire is cut so that the heights of both ends are substantially equal to form the wire piece 90, and the flat portions 92 are formed at both ends using a jig 98.

[0243] <Summary of Ninth Embodiment>

[0244] If a line piece 90 without a flat portion is used, Figure 30 In the case of the wire piece 90 in the state shown, stress is concentrated on the semiconductor element 30 when the semiconductor element 30 contacts the wire piece 90. In particular, if the height deviation of the wire piece 90 is large, the possibility of the semiconductor element 30 contacting the wire piece 90 increases. In contrast, according to the wire piece 90 of this embodiment, since the semiconductor element 30 contacts the flat portion 92, stress concentration can be suppressed. In addition, by forming the flat portion 92, the height deviation of the wire piece 90 becomes smaller. As a result, the thickness of the solder 80 is stabilized, and the connection reliability can be improved. For example, the solder crack life in a temperature cycle environment can be ensured. The wire piece 90 with the flat portion 92 can be formed by wire bonding technology and simple pressing, so the cost can also be reduced.

[0245] Furthermore, the wire piece 90 includes a non-fixed portion 93. This allows the wire piece 90 to deform elastically. Consequently, even when the semiconductor element 30 contacts the wire piece 90, the elastic deformation of the wire piece 90 can suppress stress concentration on the semiconductor element 30. In particular, in this embodiment, a flat portion 92 is formed at a position overlapping the non-fixed portion 93 when viewed from above. This facilitates deformation of the flat portion 92 in contact with the semiconductor element 30 in a direction that releases stress, thereby more effectively suppressing stress concentration.

[0246] The arrangement of the wire sheet 90 is not limited to the above-mentioned example. Figures 35 to 38 middle. Figures 35 to 38 In each of the examples shown, two wire pieces 90 are arranged on a single cross section including the Z direction.

[0247] exist Figures 35 to 37 In the example shown, two wire sheets 90 are connected to Figure 29 The wire pieces 90 shown are identical and each has only one flat portion 92. The flat portion 92 is formed at the outer end portion of each of the two wire pieces 90 in the arrangement direction (X direction). Figure 35 As shown, when the semiconductor element 30 does not warp, the flat portion 92 of any wire piece 90 is in contact with the semiconductor element 30. This can suppress stress concentration on the semiconductor element.

[0248] like Figure 36 As shown in FIG. 1 , when the semiconductor element 30 is warped upward, the flat portions 92 of the wire pieces 90 also contact the semiconductor element 30. This can suppress stress concentration on the semiconductor element. Figure 37 As shown, when the semiconductor element 30 is warped downward, as indicated by the solid arrow in the figure, the inner end of the wire piece 90 contacts the semiconductor element 30. Depending on the amount of warpage, there is a risk that the semiconductor element 30 may contact the end on the side where the flat portion 92 is not formed.

[0249] Alternatively, the flat portion 92 may be formed at the end of the wire sheet 90. Figure 37 The warping shown can also suppress stress concentration because the flat portion 92 provided at the inner end contacts the semiconductor element 30. However, if there are both upwardly protruding semiconductor elements 30 and downwardly protruding semiconductor elements 30 in the same assembly batch, for example, if the flat portion 92 is positioned to align with the upwardly protruding semiconductor element 30, there is a risk that stress will concentrate on the downwardly protruding semiconductor element 30.

[0250] In contrast, in Figure 38 In the example shown, two wire sheets 90 are connected to Figure 27 as well as Figure 28 The wire piece 90 shown has flat portions 92 at both ends. Therefore, if the semiconductor element 30 warps downward, the inner flat portion 92 contacts the semiconductor element 30. Although not shown, if the semiconductor element 30 warps upward, the outer flat portion 92 contacts the semiconductor element 30. Consequently, stress concentration can be suppressed regardless of the direction of warping of the semiconductor element 30.

[0251] The structure of the wire piece 90 of this embodiment is not limited to the wire piece 90 arranged on the solder 80. As long as it is a wire piece 90 provided at the solder joint portion between the main electrode and the wiring member, it can be applied. Figure 39 In the example shown, a wire piece 90 is arranged on the solder 81 between the emitter electrode 31 and the terminal 55 (not shown), and a flat portion 92 is also formed on the wire piece 90. Figure 39 In the embodiment, the flat portion 92 is formed only at one end of the wire sheet 90 , but the flat portion 92 may be formed at both ends.

[0252] The present invention can also be applied to a configuration in which the solder joint is formed between the heat sink 50 and the emitter electrode 31 without the terminal 55. In this case, the wire piece 90 bonded to the mounting surface 50a only needs to have the flat portion 92. Furthermore, the present invention can also be applied to a configuration in which only one of the front-side wiring member and the back-side wiring member is provided.

[0253] The structure of the wire piece 90 described in this embodiment can be combined with the wire piece 90 of the previous embodiment. In addition, the manufacturing method of the wire piece 90 described in this embodiment can be applied to the formation of the wire piece 90 described in the previous embodiment. Although an example of the wire piece 90 having a non-fixed portion 93 is shown, it is not limited to this. It is sufficient to have at least a flat portion 92. In addition, the flat portion 92 can also be provided at a position that does not overlap with the non-fixed portion 93 when viewed from above. This embodiment can be applied to a wire piece arranged at the junction of the main electrode of a semiconductor element and a wiring component. The configuration of the wire piece is not limited to the configuration shown in the previous embodiment.

[0254] (Tenth embodiment)

[0255] This embodiment is a modified example based on the previous embodiment, and the description of the previous embodiment can be cited. In this embodiment, a preferred embodiment of the wire sheet 90 is also shown.

[0256] <Thread size>

[0257] First, based on Figures 40 to 43 The preferred size of the wire piece 90 will be described. The wire piece 90 is arranged on the solder that connects the main electrode of the semiconductor element 30 and the wiring member. The solder here is, for example, solder 80 and 81.

[0258] Figure 40 The simulation results show the relationship between the volume of the wire piece 90 and the solder strain. The horizontal axis represents the volume of the wire piece 90 (×10 7 μm 3 ), the vertical axis represents solder strain (arbitrary unit) and the horizontal axis is a logarithmic axis. Figure 41 : is a diagram showing the wire sheet 90 of this embodiment. Figure 41 In the figure, the top of the paper is the side view and the bottom of the paper is the top view. Figure 42 This is a cross-sectional view for explaining the maximum height of the wire piece 90 arranged on the solder 80 . Figure 43 This is a cross-sectional view for explaining the maximum height of the wire piece 90 arranged on the solder 81 .

[0259] according to Figure 40 The simulation results show that if the volume of the wire piece 90 is large, the thermal stress caused by the difference in linear expansion coefficient between the wire piece 90 and the solder, in other words, the solder strain, increases. If the volume exceeds the specified value, cracks or other component damage will occur. Figure 40 If the value is greater than the dotted line, the device will be damaged. Therefore, in order to suppress the damage to the device, it is preferable to set the volume of the wire piece 90 to 1.0×10 7 μm 3 In the semiconductor device 10 of this embodiment, the volume of each wire piece 90 is set to 1.0×10 7 μm 3 the following.

[0260] Next, a configuration that satisfies the aforementioned volume relationship and can suppress height variations of the wire piece 90 without performing a flattening process will be described.

[0261] like Figure 41 As shown, the wire sheet 90 is divided into three parts in the extension direction. The wire sheet 90 has a joint portion 94, a feed portion 95 and a tail portion 96. The joint portion 94 is located between the feed portion 95 and the tail portion 96 in the extension direction of the wire sheet 90. The joint portion 94 is a portion joined to the radiator 40. The joint portion 94 has a fixing portion 91 on the side opposite to the radiator 40. The joint portion 94 is a portion that includes the fixing portion 91 and overlaps with the fixing portion 91 when viewed from above. That is, the joint portion 94 is the fixing portion 91 and the portion directly above the fixing portion 91. The joint portion 94 is equivalent to the joint portion. The joint portion 94 is crushed by the load from the tool during ultrasonic joining. Therefore, the width of the joint portion 94 is wider than the width of the feed portion 95 and the tail portion 96.

[0262] The feed portion 95 is connected to the bonding portion 94 at the front end of the wire sheet 90. The feed portion 95 is the portion not bonded to the heat sink 40. The feed portion 95 has a non-fixed portion 93 on the side facing the heat sink 40. The feed portion 95 includes the non-fixed portion 93 on the front end and overlaps with the non-fixed portion 93 when viewed from above. In other words, the feed portion 95 includes the non-fixed portion 93 on the front end and the portion directly above the non-fixed portion 93. The feed portion 95 does not have a flat portion 92 on the side facing the semiconductor element 30 (not shown).

[0263] Tail portion 96 is connected to bonding portion 94 on the rear end of wire sheet 90. Like feed portion 95, tail portion 96 is not bonded to heat sink 40. Tail portion 96 has a non-fixed portion 93 on the side facing heat sink 40. Tail portion 96 includes non-fixed portion 93 on the rear end and overlaps with non-fixed portion 93 when viewed from above. Specifically, tail portion 96 includes non-fixed portion 93 on the rear end and the portion directly above non-fixed portion 93. Tail portion 96 does not have flat portion 92 on the side facing semiconductor element 30 (not shown).

[0264] The feed portion 95 and the tail portion 96 correspond to the non-joined portion. The front end refers to the side with the end (cut end) before ultrasonic joining. The rear end refers to the end formed by severing the bond line after ultrasonic joining. Although not shown, the heat sink 40 has a cut mark directly below the rear end of the wire sheet 90, resulting from severing the bond line.

[0265] In the following, the length of the joint 94 in the extension direction is sometimes expressed as LB, the length of the feed portion 95 in the extension direction is sometimes expressed as LF, and the length of the tail 96 in the extension direction is sometimes expressed as LT. The length of the wire sheet 90 in the extension direction (full length) is sometimes expressed as LW, and the width of the joint 94 is sometimes expressed as WB. The width WB is the length in the direction perpendicular to the extension direction in the joint 94. In addition, the height of the joint 94 is sometimes expressed as HB, the height of the feed portion 95 is sometimes expressed as HF, and the height of the tail 96 is sometimes expressed as HT. In addition, the length LF of the feed portion 95 and the length LT of the tail 96 are as shown in Figure 41 The length shown is the length of the side (upper surface) facing the semiconductor element 30, not the side (lower surface) facing the heat sink 40. The height refers to the height of the portion farthest from the first opposing surface as the bonding surface in the Z direction.

[0266] When the wire piece 90 is formed using a bonding wire with a diameter of 80 μm, the length LB of the bonding portion 94 is substantially the same in the configuration with the flat portion 92 as in the present embodiment. For example, the length LB is 260 μm ± 100 μm. In order to make the volume of the wire piece 90 1.0×10 7 μm 3Hereinafter, it is preferable that the total length LW of the wire piece 90 be set to 400 μm or more and 450 μm or less, and the lengths LF and LT of the feed portion 95 and the tail portion 96 be set to 100 μm or less.

[0267] In the configuration in which the flat portion 92 is provided, it is necessary to ensure the length of the flat portion 92 in the extension direction. If the flat portion 92 is provided on both end sides, the total length of the wire piece 90 exceeds 450 μm, for example, becomes about 500 μm. In this embodiment, since the flat portion 92 is not provided, the lengths LF and LT of the feed portion 95 and the tail portion 96, which are non-joining portions, can be shortened to less than 100 μm, respectively. Therefore, even if there is a deviation in the length LB, the total length LW of the wire piece 90 can be made less than 450 μm. That is, the wire piece 90 can be miniaturized. Therefore, it is easy to make the volume of the wire piece 90 1.0×10 7 μm 3 Furthermore, since the lengths LF and LT are short, variations in the heights HF and HT can be suppressed.

[0268] The height HF of the feed portion 95 and the height HT of the tail portion 96 are preferably set to 80 μm or more and 100 μm or less. A height of 80 μm is equivalent to the wire diameter. In this case, the feed portion 95 and the tail portion 96 are in contact with the mounting surface 40 a of the heat sink 40 but are not bonded.

[0269] In the case where the semiconductor element 30 may be warped downward, such as Figure 42 As shown, the volume of the opposing space between the semiconductor element 30 and the heat sink 40 is maximized when no warping occurs. When the volume of the opposing space is maximized, the largest amount of solder 80 is required to ensure that the solder wets and spreads over substantially the entire surface of the collector electrode 32. This required solder volume is minimized when the semiconductor element 30 is supported by the wire piece 90. The minimum required solder volume is the value obtained by subtracting the recessed portion of the solder 80 from the volume of the portion overlapping the semiconductor element 30 (collector electrode 32) when viewed from above, when the thickness and heights HF and HT of the solder 80 are equal.

[0270] If the heights HF and HT are set to 110 μm or greater, there is a risk that the specified supply amount of solder 80 will fall below the minimum required solder volume. This is evident from simulation results. In this case, there is a risk that the solder 80 will only wet and spread over a portion of the collector electrode 32. If the solder heights HF and HT are set to 100 μm or less, the specified supply amount of solder 80 will exceed the minimum required solder volume. This ensures that the solder 80 wets and spreads over substantially the entire surface of the collector electrode 32, ensuring connection reliability.

[0271] The same applies to the solder 81 on the emitter electrode 31 side. Figure 43 As shown, when the warpage is maximum (e.g., 0.1 μm), the volume of the space between the semiconductor element 30 and the terminal 55 becomes maximum. When the volume of the space is maximum, the largest amount of solder 81 is required to ensure that the solder wets and spreads over the substantially entire surface of the emitter electrode 31. This required solder volume is minimum when the semiconductor element 30 is supported by the wire piece 90.

[0272] If the heights HF and HT are set to 110 μm or greater, there is a risk that the specified supply amount of solder 81 will fall below the minimum required solder volume. This is evident from simulation results. In this case, there is a risk that solder 81 will only wet and spread over a portion of emitter electrode 31. If the solder heights HF and HT are set to 100 μm or less, the specified supply amount of solder 81 will exceed the minimum required solder volume. This ensures that solder 81 wets and spreads over substantially the entire surface of emitter electrode 31, ensuring connection reliability.

[0273] In addition, as in the previous embodiment (refer to Figure 14 ) As shown in FIG, even when the semiconductor element 30 protruding downward is arranged at an angle, as long as the heights HF and HT are 70 μm or more, the wire pieces 90 arranged at least at the four corners (see FIG. Figure 12 as well as Figure 20 ) ensures a minimum film thickness for solders 80 and 81. The minimum film thickness required to ensure connection reliability is, for example, 43 μm. In this embodiment, the wire diameter is 80 μm, and the minimum heights HF and HT are 80 μm. This ensures connection reliability even when the downwardly protruding semiconductor element 30 is arranged at an angle.

[0274] If the lengths LF and LT are shortened as described above, the ratios of the lengths LF and LT of the feed portion 95 or the tail portion 96 to the length LB of the joint portion 94 (LF / LB, LT / LB) are smaller than those in the configuration in which the flat portion 92 is provided. 7 μm 3 Hereinafter, LF / LB and LT / LB are preferably set to 0.1 or more and 0.65 or less. By satisfying this relationship, the length of the feed portion 95 and the tail portion 96 can be reduced relative to the joint portion 94, and the wire piece 90 can be miniaturized. In addition, the variation in the heights HF and HT can be suppressed.

[0275] Furthermore, it is preferable to set the ratio of the width WB of the joint 94 to the length LB of the joint 94 (WB / LB) to be between 0.2 and 0.7. In other words, it is preferable to narrow the width WB. This can reduce the volume of the wire sheet 90 and also suppress variations in the heights HF and HT.

[0276] More specifically, the wire piece 90 is preferably formed to meet the following dimensions: The overall length LW of the wire piece 90 is preferably 420 μm ± 20 μm, the length LF of the feed portion 95 is preferably 85 μm ± 15 μm, and the length LT of the tail portion 96 is preferably 70 ± 30 μm. The length LB of the joint 94 is preferably 260 μm ± 100 μm, the height HB of the joint is preferably 70 μm ± 5 μm, and the width WB of the joint 94 is preferably 90 μm + 15 μm - 5 μm. The height HF of the feed portion 95 is preferably 85 μm + 15 μm - 5 μm, and the height HT of the tail portion 96 is preferably 85 μm ± 5 μm.

[0277] <Method for producing thread sheets>

[0278] Next, based on Figures 44 to 48 The following describes a method for manufacturing the wire piece 90 that satisfies the aforementioned volume and dimensions. Hereinafter, an example is shown in which the wire piece 90 is provided on the heat sink 40 , but the same applies to the terminal 55 .

[0279] like Figure 44 As shown, the ultrasonic bonding apparatus includes a wire guide 100, a tool 101, and a cutter 102. First, the bonding wire 99 drawn from the wire guide 100 is positioned at a predetermined position on the mounting surface 40a of the heat sink 40. At this time, the bonding wire 99 is positioned so as to ensure the predetermined length of the feed portion 95 described above, with the bonding portion of the tool 101 as a reference.

[0280] Then, if Figure 45 As shown, ultrasonic bonding is performed using tool 101. Ultrasonic bonding forms joint 94. Bond line 99 is significantly compressed by the power of ultrasonic bonding and the load applied by tool 101. This increases the width of joint 94. In this embodiment, the power and load are adjusted so that width WB of joint 94 does not increase excessively, but rather falls within the range of 90 μm + 15 μm - 5 μm, or in other words, 85 μm to 105 μm.

[0281] By ultrasonic bonding, e.g. Figure 45 As indicated by the middle arrow, compressive stress acts on the upper surface of the feed portion 95. Meanwhile, tensile stress acts on the lower surface of the feed portion 95, in other words, on the heat sink 40 side. This causes the feed portion 95 to spring upward relative to the mounting surface 40a of the heat sink 40. The portion of the non-fixed portion 93 that was in contact with the mounting surface 40a moves away from the mounting surface 40a.

[0282] After the ultrasonic bonding is completed, Figure 46 As shown, the tool 101 (ultrasonic bonding device) is retreated. Figure 46The amount of retreat of the tool 101 indicated by the hollow arrow is determined by the cutting position of the cutter 102, that is, the length of the tail 96. Specifically, the amount of retreat is determined so that the length LT of the tail 96 and the total length of the wire piece 90 are respectively predetermined lengths.

[0283] Then, if Figure 47 As shown, wire cutting is performed. When the tool 101 is in the state of pressing the bonding wire 99 in the above-mentioned retreat position, the bonding wire 99 is cut by the cutter 102. By wire cutting, the wire sheet 90 is formed. After the wire cutting, as shown in FIG. Figure 48 As shown, the ultrasonic bonding device including tool 101 is retracted. By releasing the load through cutting, the tail portion 96 of the wire piece 90 recovers from its elastic deformation and springs up relative to the mounting surface 40a of the heat sink 40. The portion of the non-fixed portion 93 that was in contact with the mounting surface 40a is removed from the mounting surface 40a.

[0284] By wire cutting, such as Figure 48 As shown, a cut 41 is formed in the heat sink 40. The cut 41 is formed just below the tail portion 96 at both ends of the wire piece 90 in the extending direction.

[0285] <Summary of the Tenth Embodiment>

[0286] In this embodiment, the volume of the wire sheet 90 is set to 1.0×10 7 μm 3 As a result, thermal stress can be reduced, and element damage can be suppressed. In other words, the reliability of the semiconductor device 10 can be improved.

[0287] In addition, in the previous embodiment (refer to Figure 28 ) can also satisfy the aforementioned volume relationship. However, providing flat portions 92 at both ends increases the overall length LW of the wire piece 90. Furthermore, without leveling, the wire heights, in other words, the heights HF and HT, vary significantly. The need for leveling increases the number of steps and, consequently, the manufacturing cost.

[0288] In this embodiment, to meet the aforementioned volume requirements, the overall length LW of the wire piece 90 is set to 400 μm to 450 μm, and the lengths LF and LT of the feed portion 95 and tail portion 96 are set to 100 μm or less. Since the flat portion 92 is not provided, the lengths LF and LT of the feed portion 95 and tail portion 96, as well as the overall length LW of the wire piece 90, can be shortened. Furthermore, flattening is not required, which can reduce manufacturing costs, for example.

[0289] In particular, the lengths LF and LT of the feed portion 95 and the tail portion 96 are shortened relative to the length LB of the joint portion 94. Specifically, LF / LB and LT / LB are set to be between 0.1 and 0.65. This can suppress variations in the heights HF and HT.

[0290] In the present embodiment, the height HF of the feed portion 95 and the height HT of the tail portion 96 are set to be not less than 80 μm and not more than 100 μm. This ensures connection reliability.

[0291] In this embodiment, the ratio of the width WB of the joint 94 to its length LB (WB / LB) is set to 0.2 or more and 0.7 or less. Narrowing the width WB reduces the volume of the wire sheet 90. Furthermore, narrowing the width WB allows the power and load during ultrasonic bonding to be suppressed while maintaining bonding strength. This reduces the amount of crushing and, in turn, suppresses variations in the heights HF and HT.

[0292] The wire piece 90 without the flat portion 92 shown in this embodiment can be combined with the first to eighth embodiments. Figure 12 、 Figure 20 The configuration shown is that the wire pieces 90 are arranged only at the four corners. This embodiment can be applied to wire pieces arranged at the junction between the main electrodes of semiconductor elements and wiring members. The arrangement of the wire pieces is not limited to that shown in the previous embodiment.

[0293] (Other embodiments)

[0294] The disclosure in this specification and the drawings is not limited to the illustrated embodiments. The disclosure includes the illustrated embodiments and variations made by those skilled in the art based on them. For example, the disclosure is not limited to the combination of parts and / or elements shown in the embodiments. The disclosure can be implemented through a variety of combinations. The disclosure may have additional parts that can be added to the embodiments. The disclosure includes the case where parts and / or elements of the embodiments are omitted. The disclosure includes the replacement or combination of parts and / or elements between one embodiment and other embodiments. The technical scope of the disclosure is not limited to the description of the embodiments. The several technical scopes disclosed are indicated by the description of the claims and should be understood to include all changes within the meaning and scope equivalent to the description of the claims.

[0295] The disclosures in the specification, drawings, and other aspects are not limited by the claims. They encompass the technical concepts described in the claims and encompass a wider range of technical concepts than those described in the claims. Therefore, a wide variety of technical concepts can be extracted from the disclosures in the specification, drawings, and other aspects, without being constrained by the claims.

[0296] Although the semiconductor device 10 is applied to the inverter 5 as an example, the present invention is not limited thereto. For example, the semiconductor device 10 may be applied to a converter. Furthermore, the semiconductor device 10 may be applied to both the inverter 5 and the converter.

[0297] Although the semiconductor element 30 is shown as an example having an IGBT 6i and a FWD 6d forming a single arm, this is not limiting. The IGBT 6i and FWD 6d may also be separate chips (separate components). Although the IGBT 6i is shown as an example of a switching element, this is not limiting. For example, a MOSFET may also be used. Furthermore, a diode may be used as a vertically structured element having main electrodes on both sides.

[0298] A plurality of semiconductor elements 30H may be provided, and the plurality of semiconductor elements 30H may be connected in parallel to form one of the upper arms 6H. A plurality of semiconductor elements 30L may be provided, and the plurality of semiconductor elements 30L may be connected in parallel to form one of the lower arms 6L.

[0299] Although the example in which the back surfaces 40 b and 50 b of the heat sinks 40 and 50 are exposed from the sealing resin body 20 is shown, the present invention is not limited to this. Alternatively, at least one of the back surfaces 40 b and 50 b may be covered by the sealing resin body 20. Alternatively, at least one of the back surfaces 40 b and 50 b may be covered by an insulating member (not shown) other than the sealing resin body 20. Although the example in which the semiconductor device 10 includes the sealing resin body 20 is shown, the present invention is not limited to this. Alternatively, the semiconductor device 10 may not include the sealing resin body 20.

[0300] While the semiconductor device 10 is shown as including multiple semiconductor elements 30 that constitute the upper and lower arm circuits 6 of a single phase, this is not limiting. Alternatively, the semiconductor device 10 may include only semiconductor elements that constitute a single arm. For example, the semiconductor device 10 may include a semiconductor element 30 that constitutes a single arm and a pair of heat sinks 40 and 50 that are arranged to sandwich the semiconductor element 30. Alternatively, the semiconductor elements that constitute the upper and lower arm circuits 6 of three phases may be included as a single package.

[0301] Although the example in which the signal terminal 75 is connected to the pad 33 via the bonding wire 87 is shown, the present invention is not limited thereto. For example, the signal terminal 75 may be connected to the pad 33 via solder. Since space for the bonding wire 87 is not required, a configuration without the terminal 55 may be employed.

[0302] Although an example is shown in which the groove 51 is provided in the heat sink 50 and the groove 63 is provided in the joints 61 and 62, the present invention is not limited to this. A configuration may also be made in which at least one of the grooves 51 and 63 is excluded. Although an example is shown in which the connection structure of the two joints 60 and 61 is used to realize the connection portion connecting the upper arm 6H and the lower arm 6L, the present invention is not limited to this. A configuration may also be made in which the joint connected to one of the heat sinks 40L and 50H is connected to the other. In addition, although an example is shown in which the joint 62 is provided, the present invention is not limited to this. A configuration may also be made in which the main terminal 71 is connected to the heat sink 50L without passing through the joint 62.

Claims

1. A semiconductor device, characterized in that: have: A semiconductor element having a surface electrode and a back electrode as main electrodes, wherein the surface electrode is formed on the surface, and the back electrode is formed on the back surface opposite to the surface in the plate thickness direction and has an area larger than that of the surface electrode; a joining member sandwiched between the first opposing surface and the second opposing surface to form a joining portion; a wiring member electrically connected to the main electrode via the bonding member; as well as A plurality of wire pieces are arranged in the joining member, fixed to the first opposing surface and protruding from the first opposing surface, The wiring member includes a back-side wiring member disposed on the back side and connected to the back electrode. The bonding member includes a back-side bonding member that forms a bonding portion between the back electrode and the back-side wiring member and is provided with a plurality of the wiring pieces. The back-side bonding member has a central region that overlaps with a central portion of the semiconductor element including the element center when viewed in plan along the plate thickness direction; and a peripheral region including a portion overlapping with the peripheral portion of the semiconductor element surrounding the central portion and surrounding the central region, In the outer peripheral region, at least four or more wire pieces are arranged corresponding to at least four corners of the semiconductor element. At least one of the line pieces extends toward the center of the element when viewed from above, The wire piece is fixed to the wiring member at a junction between the main electrode and the wiring member. The wiring piece has a flat portion on a side facing the main electrode in the plate thickness direction and parallel to the fixing surface of the wiring member. The wire piece includes: a fixed portion fixed to the wiring member on a side opposite to the wiring member in the plate thickness direction; and a non-fixed portion connected to the fixed portion and not fixed to the wiring member. The non-fixed portion is provided on both sides of the fixed portion in the extending direction of the line piece. The flat portion is provided at at least one end portion of the wire piece in the extending direction, is provided at a position overlapping with the non-fixed portion in the plan view, and is in contact with the semiconductor element.

2. A semiconductor device, characterized in that have: A semiconductor element having a surface electrode and a back electrode as main electrodes, wherein the surface electrode is formed on the surface, and the back electrode is formed on the back surface opposite to the surface in the plate thickness direction and has an area larger than that of the surface electrode; a joining member sandwiched between the first opposing surface and the second opposing surface to form a joining portion; a wiring member electrically connected to the main electrode via the bonding member; and A plurality of wire pieces are arranged in the joining member, fixed to the first opposing surface and protruding from the first opposing surface, The wiring member includes a back-side wiring member disposed on the back side and connected to the back electrode. The bonding member includes a back-side bonding member that forms a bonding portion between the back electrode and the back-side wiring member and is provided with a plurality of the wiring pieces. The back-side bonding member has a central region that overlaps with a central portion of the semiconductor element including the element center when viewed in plan along the plate thickness direction; and a peripheral region including a portion overlapping with the peripheral portion of the semiconductor element surrounding the central portion and surrounding the central region, In the outer peripheral region, at least four or more wire pieces are arranged corresponding to at least four corners of the semiconductor element. At least one of the line pieces extends toward the center of the element when viewed from above, The wire piece is fixed to the wiring member at a junction between the main electrode and the wiring member. The volume of each of the wire sheets is 1.0×10 7 μm 3 the following, The wire piece includes a joining portion joined to the wiring member and non-joining portions connected to the joining portion and provided at both ends of the wire piece in its extending direction and not joined to the wiring member.

3. The semiconductor device according to claim 2, wherein In the extending direction, the length of the line piece is 400 μm or more and 450 μm or less, and the length of each of the non-joined portions is 100 μm or less.

4. The semiconductor device according to claim 3, wherein A height of the non-joining portion from the joining surface of the wiring member is not less than 80 μm and not more than 100 μm.

5. The semiconductor device according to any one of claims 2 to 4, wherein: In the extending direction, a ratio of a length of the non-joining portion to a length of the joining portion is greater than or equal to 0.1 and less than or equal to 0.

65.

6. The semiconductor device according to any one of claims 2 to 4, wherein: A ratio of a width of the bonding portion to a length of the bonding portion in the extending direction is greater than or equal to 0.2 and less than or equal to 0.

7.

7. The semiconductor device according to claim 1 or 2, wherein: In the central region, three or more wire pieces are arranged to surround the center of the element.

8. The semiconductor device according to claim 1 or 2, wherein: The wiring member includes a surface wiring member disposed on the surface side and electrically connected to the surface electrode. The bonding member includes a front-side bonding member that forms a bonding portion between the front-side electrode and the front-side wiring member and includes a plurality of the wiring pieces.

9. The semiconductor device according to claim 8, wherein The semiconductor element comprises: a gate pad formed on the surface; a gate wiring formed on the surface side and connected to the gate pad; and a gate wiring protection portion which is a portion of a protective film formed on the surface and protects the gate wiring. In the front-side bonding member, the wire piece is arranged at a position not overlapping with the gate wiring protection portion.

10. The semiconductor device according to claim 8, wherein The thread piece in the front-side joining member is arranged at a position not to overlap with the thread piece in the back-side joining member.

11. The semiconductor device according to claim 8, wherein The front-side wiring member includes a first wiring member and a second wiring member connected to the front-side electrode via the first wiring member. The bonding member includes a first bonding member and a second bonding member as a bonding member arranged on the surface side, the first bonding member serving as the surface side bonding member, the second bonding member forming a bonding portion between the second wiring member and the first wiring member, and a plurality of the wire pieces being arranged. The number of the line pieces is different among the back-side bonding member, the first bonding member, and the second bonding member, with the back-side bonding member having the largest number and the second bonding member having the smallest number.

12. The semiconductor device according to claim 1 or 2, wherein: The height of the line piece with respect to the first opposing surface is smaller than the thickness of the joining member forming a joining portion between the first opposing surface and the second opposing surface.

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