Method for manufacturing a power conversion device

Abstract

The present invention provides a method for manufacturing a power conversion device, wherein the power conversion device is formed by interconnecting an embedded wiring member of a base component, a semiconductor chip, and a connecting wire. The method for manufacturing the power conversion device comprises: an installation step, in which a positional relationship between the base component, the semiconductor chip, and the connecting wire is specified by using a first clamp, and a first bonding member is arranged between the base component and the semiconductor chip and between the semiconductor chip and the connecting wire, a second bonding member connecting the semiconductor chip and the connecting wire is maintained by using a second clamp, and a third bonding member connecting the connecting wire and the embedded wiring member is arranged on the connecting wire; and a reflow step, in which the assembly of the installation step is heated to melt the bonding sheet, the first bonding sheet, and the second bonding sheet.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a power conversion device.

[0002] This application claims priority based on Japanese Patent Application No. 2019-190116 filed in Japan on October 17, 2019, the contents of which are incorporated herein by reference. Background Art

[0003] Japanese Patent Application Laid-Open No. 2014-187817 discloses a method for manufacturing a power converter and a jig used therefor. Background to this is a technique in which solder balls are placed on a bend formed in a connecting conductor of the power converter and facing a power supply busbar. The solder balls are then heated and melted in a reflow process, thereby connecting the connecting conductor to the busbar. Summary of the Invention

[0004] Problems to be solved by the invention

[0005] However, although not explicitly described in Japanese Patent Application Laid-Open No. 2014-187817, in the background art, a reflow process for connecting the semiconductor chip to the circuit board and a reflow process for connecting the connecting wire to the semiconductor chip are required as a pre-process for the reflow process for connecting the connecting wire to the bus bar.

[0006] That is, the above-mentioned background art manufactures a power conversion device by connecting a semiconductor chip, a circuit board, and connecting wires to each other through a plurality of reflow processes.

[0007] Therefore, the above-mentioned background technology requires multiple reflow processes, which increases manufacturing time and cost. In order to manufacture the power conversion device in a shorter time and at a lower cost, it is necessary to reduce the number of reflow processes.

[0008] The present invention has been developed in view of the above-mentioned circumstances, and an object of the present invention is to provide a method for manufacturing a power conversion device capable of manufacturing the power conversion device with fewer reflow steps than in the conventional art.

[0009] Technical solutions to solve problems

[0010] In order to achieve the above-mentioned object, the present invention adopts the following means.

[0011] (1) One aspect of the present invention provides a method for manufacturing a power conversion device, wherein the power conversion device is formed by interconnecting an embedded wiring member of a base component, a semiconductor chip, and a connecting wire, the method comprising: an installation step, wherein a positional relationship among the base component, the semiconductor chip, and the connecting wire is defined by using a first jig, and a first bonding member is arranged between the base component and the semiconductor chip and between the semiconductor chip and the connecting wire, a second bonding member connecting the semiconductor chip and the connecting wire is held by using a second jig, and a third bonding member connecting the connecting wire and the embedded wiring member is arranged on the connecting wire; and a reflow step, wherein the assembly obtained in the installation step is heated to melt the first bonding member, the second bonding member, and the third bonding member.

[0012] (2) Based on the aspect of (1) above, the following scheme may also be adopted: as for the first clamp, when the first bonding member is inserted between the base member and the semiconductor chip, the positional relationship of the semiconductor chip relative to the base member is specified, and when the fourth bonding member is inserted between the semiconductor chip and the connecting wire, the positional relationship between the semiconductor chip, the connecting wire and the embedded wiring member is specified.

[0013] (3) Based on the above aspects (1) or (2), the following solution may also be adopted: in the first or second solution, the power conversion device includes an insulating heat dissipation circuit substrate for dissipating heat generated by the semiconductor chip in an insulated state, and the first clamp includes a substrate position limiting portion for positioning the insulating heat dissipation circuit substrate relative to the semiconductor chip.

[0014] (4) In addition to the aspects described in any one of (1) to (3) above, the first jig may include an inclined surface for positioning the semiconductor chip by contacting the respective sides thereof.

[0015] (5) In addition to the aspects described in any one of (1) to (4) above, the second clamp may include a through hole extending in the vertical direction on the connecting wire and accommodating the second connecting member.

[0016] (6) In addition to the aspects described in any one of (1) to (5) above, the semiconductor chip may include a wire bonding pad, and the second jig may include a pad protection portion for protecting the wire bonding pad.

[0017] Effects of the Invention

[0018] According to the above-described aspects of the present invention, a power conversion device can be manufactured with fewer reflow steps than in the conventional art. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a front view showing the mechanical structure of a power conversion device according to one embodiment of the present invention.

[0020] Figure 2 This is a circuit diagram showing the electrical structure of the power conversion device.

[0021] Figure 3 This is a flowchart showing a method for manufacturing the power conversion device.

[0022] Figure 4 This is a first perspective view for explaining the method for manufacturing the power conversion device.

[0023] Figure 5A This is a front view for explaining a method for manufacturing the power conversion device.

[0024] Figure 5B It is a rear view for explaining the manufacturing method of the power conversion device.

[0025] Figure 5C It is a longitudinal sectional view for explaining the manufacturing method of the power conversion device.

[0026] Figure 6A This is a second perspective view for explaining the method for manufacturing the power conversion device.

[0027] Figure 6B This is a second side view for explaining the method of manufacturing the power conversion device.

[0028] Description of Reference Numerals

[0029] A. Power conversion device

[0030] B Base component B

[0031] C, C1~C14 semiconductor chips

[0032] D Insulation heat dissipation circuit board

[0033] E1 step-up and step-down circuit

[0034] E2 first inverter circuit

[0035] E3 Second inverter circuit

[0036] H1 First solder sheet (first bonding member)

[0037] H2 Second solder sheet (fourth bonding member)

[0038] H3 First solder sheet (second joint)

[0039] H4 Second solder sheet (third joint)

[0040] H5 Third solder sheet

[0041] J First clamp

[0042] j1 Storage area

[0043] j2 First wire storage portion

[0044] j3 Second wire storage part

[0045] j4 Board position restriction section

[0046] j5 chip position restriction unit

[0047] j6 Wire position restriction section

[0048] K Second clamp

[0049] K1 through hole

[0050] K2 pad protection

[0051] L1 first connecting wire

[0052] L2 Second connecting wire

[0053] P1 first connection pad

[0054] P2 Second connection pad (pad for wire bonding)

[0055] R1~R3 installation area

[0056] U, U1, U2 busbars

[0057] 1 to 14 power transistors DETAILED DESCRIPTION

[0058] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

[0059] First, refer to Figure 1 and Figure 2 The power converter A of this embodiment is described. The power converter A is a PCU (power control unit) mounted on a hybrid vehicle or electric vehicle, and includes a step-up / step-down circuit E1 and two inverter circuits (a first inverter circuit E2 and a second inverter circuit E3). Figure 1 In FIG. 1 , region R1 is the packaging area of ​​the step-up / step-down circuit E1 , region R2 is the packaging area of ​​the first inverter circuit E2 , and region R3 is the packaging area of ​​the second inverter circuit E3 .

[0060] like Figure 2 As described above, the step-up / step-down circuit E1 includes two power transistors 1 and 2 as electronic components. The first inverter circuit E2 includes six power transistors 3 to 8 as electronic components. The second inverter circuit E3 includes six power transistors 9 to 14 as electronic components. Figure 1 As shown, these 14 power transistors 1 to 14 are packaged on a base member B as semiconductor chips C1 to C14.

[0061] Here, the two power transistors 1 and 2 that comprise the step-up / step-down circuit E1 have significantly greater current capacity than the power transistors 3-14 that comprise the first inverter circuit E2 and the second inverter circuit E3. Based on this current capacity relationship, power transistor 1 secures the desired current capacity by connecting two semiconductor chips C1 in parallel. Similarly, power transistor 2 secures the desired current capacity by connecting two semiconductor chips C2 in parallel.

[0062] It should be noted that, hereinafter, when any one of the semiconductor chips C1 to C14 is not specified and the entirety is collectively referred to as the semiconductor chip C. Figure 1 and Figure 4 As shown in FIG. 1 and FIG. 2 , the semiconductor chip C is a rectangular plate-shaped component and includes a plurality of connection pads (first connection pads P1 and second connection pads P2 ) on its upper surface.

[0063] The first connection pads P1 are connected to first connection wires L1 described later and have a relatively large area, while the second connection pads P2 are wire bonding pads to which bonding wires described later are connected and have a relatively small area.

[0064] It should be noted that if Figure 2 As shown in FIG. 1 , the step-up / step-down circuit E1 includes power transistors 1 and 2 as well as a reactor and two capacitors as electronic components. Figure 1 It is not shown in the (front view) and is packaged on the back side of the base member B.

[0065] The base member B is a resin molded component in which wiring members such as bus bars are embedded as embedded wiring members. That is, the base member B is a resin molded component formed by insert molding and has a plurality of chip storage portions b for storing semiconductor chips C.

[0066] Base component B is a housing (IPM (Intelligent Power Module) housing) that mechanically (physically) houses the power converter A, which serves as an electrical circuit. It is secured to the vehicle. A heat dissipation component (e.g., a radiator) is mounted on the back of base component B to dissipate heat generated by power converter A.

[0067] Typical materials for the embedded wiring member of the base member B are Figure 1 The busbars U1 and U2 are a pair of busbars shown. One busbar U1 is a buried wiring member constituting a high-potential output line of the step-up / step-down circuit E1, and the other busbar U2 is a buried wiring member constituting a low-potential output line of the step-up / step-down circuit E1.

[0068] The main parts of the pair of busbars U1 and U2 are buried in a parallel and opposing state, with a portion exposed as the connection portion of the first connecting conductor L1 and the second connecting conductor L2. It should be noted that in the following, when no specific busbar U1 or U2 is specified, the entire pair is referred to as busbar U.

[0069] The first connecting wire L1 and the second connecting wire L2 are individual wiring components that are separate from the base component B and are provided for each semiconductor chip C. They also mediate the connection between the semiconductor chip C and the busbar U, and the connection between the insulating heat dissipation circuit substrate D, which will be described later, and the busbar U. Specifically, one end of the first connecting wire L1 and the second connecting wire L2 is connected to the first connection pad P1 of the semiconductor chip C, and the other end is connected to the busbar U. One end of the second connecting wire L2 is connected to the insulating heat dissipation circuit substrate D, and the other end is connected to the busbar U. It should be noted that, in addition to the first connecting wire L1 and the second connecting wire L2, the individual wiring components also include bonding wires, which will be described later.

[0070] Such electronic components, embedded wiring members, and individual wiring members are connected to each other by using bonding members such as bonding sheets and bonding pieces. It should be noted that the bonding sheets are the first solder sheet and the second solder sheet described later. In addition, the bonding pieces are the first solder sheet and the second solder sheet described later. The power conversion device A in this embodiment connects the electronic components, embedded wiring members, and individual wiring members to each other through such bonding members, thereby serving as Figure 2 The circuit shown works.

[0071] Next, a method for manufacturing the power conversion device A of this embodiment, that is, a method for connecting the joint member using the above-mentioned electronic components, embedded wiring members, and individual wiring members, is described. Figure 3 The flowchart shown is explained in detail.

[0072] like Figure 3 As shown, the method for manufacturing the power conversion device A includes a collective mounting step (mounting step) S1 , a collective reflow step (reflow step) S2 , a wire bonding step S3 , and an inspection step S4 .

[0073] The collective installation step S1 is the most characteristic manufacturing step in this manufacturing method. Figures 4 to 6B As shown, the simultaneous installation process S1 is a manufacturing process in which the positional relationship between the base component B (embedded wiring component), the semiconductor chip C, the first connecting wire L1 and the second connecting wire L2 is specified by using the first clamp J, and the first solder sheet H1 (first bonding member), the second solder sheet H2 (fourth bonding member), the first solder sheet H3 (second bonding member) and the second solder sheet H4 (third bonding member) are arranged at specified positions.

[0074] The power conversion device A of this embodiment includes an insulating heat dissipation circuit board D as an additional component that dissipates heat generated by the semiconductor chips C in an insulated state. The insulating heat dissipation circuit board D is a rectangular plate-shaped component provided for each semiconductor chip C. It is an electronic component that electrically insulates and transfers heat from the semiconductor chips C to a heat sink or other heat dissipation component.

[0075] like Figure 4 As shown in FIG, the insulating heat dissipation circuit substrate D is interposed between each semiconductor chip C and the base member B, and is bonded to the base member B via the third solder sheet H5. Figure 4 As shown, the insulating heat dissipating circuit substrate D is connected to the second connecting wire L2 via the second solder sheet H2.

[0076] The first jig J is described in detail. The first jig J is a metal formed part shaped so as to fit into the chip receiving portion b of the base member B. Figure 4 and Figures 5A to 5C As shown, the first jig J includes a receiving portion j1, a first wire receiving portion j2, a second wire receiving portion j3, a substrate position restriction portion j4, a chip position restriction portion j5, and a wire position restriction portion j6.

[0077] The receiving portion j1 ​​is a recessed portion provided on the front side of the first fixture J. Figure 4 and Figure 5A As shown, the semiconductor chip C, the first solder sheet H1, a portion of the first connecting wire L1 (lower end side), the insulating heat dissipation circuit board D, and the third solder sheet H5 are stacked and stored. The first wire storage portion j2 is a recessed portion adjacent to the storage portion j1 ​​across the wire position limiting portion j6. Figure 5A As shown, a portion (upper end side) of the first connecting wire L1 is accommodated.

[0078] The second wire receiving portion j3 is a recessed portion adjacent to the receiving portion j1 ​​and the first wire receiving portion j2. Figure 5A As shown, the second connecting wire L2 is received. Figure 5BAs shown, the substrate position limiting portion j4 is a plurality of protrusions arranged on the back side of the first clamp J in a positional relationship that conforms to the outer shape of the insulating heat dissipation circuit substrate D, that is, in a manner that surrounds the outer periphery of the insulating heat dissipation circuit substrate D, so as to position the insulating heat dissipation circuit substrate D relative to the base component B.

[0079] The chip position limiting portion j5 is a portion for positioning each semiconductor chip C relative to the insulating heat dissipation circuit substrate D. Figure 5C As shown, the chip position restriction portion j5 is an inclined surface that abuts against the outer periphery of the semiconductor chip C stacked on the insulating heat dissipating circuit substrate D from above via the first solder sheet H1.

[0080] Specifically, the chip position restricting portion j5 comprises four inclined surfaces that face the four sides of the outer periphery of the semiconductor chip C (rectangular shape) and are inclined outwardly. These chip position restricting portions j5 define the position of the semiconductor chip C relative to the insulating heat dissipating circuit board D by pressing the semiconductor chip C from above with the inclined surfaces.

[0081] The wire position regulating portion j6 is a portion for positioning the first connection wire L1 relative to each semiconductor chip C. Figure 4 and Figure 5A As shown, the wire position restricting portions j6 are a pair of protrusions that engage with the recesses formed in the first connection wire L1. These wire position restricting portions j6 restrict the position of each semiconductor chip C to a predetermined position by engaging with the recesses of the first connection wire L1.

[0082] That is, in the collective installation step S1, the first jig J is as follows Figure 4 As shown, in a state where each third solder sheet H5 is inserted between each insulating heat dissipation circuit substrate D and the base component B (embedded wiring component), the positional relationship of each insulating heat dissipation circuit substrate D relative to the base component B (embedded wiring component) is specified. In a state where the first solder sheet H1 is inserted between each insulating heat dissipation circuit substrate D and each semiconductor chip C, the positional relationship of each semiconductor chip C relative to each insulating heat dissipation circuit substrate D is specified. In addition, in a state where the second solder sheet H2 is inserted between each semiconductor chip C and the second connecting wire L2, the positional relationship of each semiconductor chip C and the second connecting wire L2 is specified.

[0083] Furthermore, in this collective mounting step S1, a second jig K placed on the first and second connecting wires L1 and L2 is used to hold the first solder sheet H3 connecting each semiconductor chip C to the first connecting wire L1. The second jig K is a metal molded component that is placed in a predetermined position relative to each semiconductor chip C and includes a through-hole K1 for receiving the first solder sheet H3. The through-hole K1 extends vertically above the first connecting wire L1.

[0084] In addition to the through hole K1, the second jig K further includes a pad protection portion K2. The pad protection portion K2 protects the second connection pad P2 (wire bonding pad) provided on the upper surface of the semiconductor chip C. Figure 6A and Figure 6B As shown, the pad protection portion K2 is a metal piece supported vertically and movably by the main body of the second jig K. The pad protection portion K2 protects the second connection pads P2 (wire bonding pads) by having its lower surface (flat surface) abut against the second connection pads P2 (wire bonding pads).

[0085] Furthermore, in the collective installation process S1, two second solder sheets H4 connecting the first connecting wire L1 and the second connecting wire L2 to the busbar U (embedded wiring member) are respectively arranged on the first connecting wire L1 and the second connecting wire L2. The second solder sheets H4 are arranged at the final stage of the collective installation process S1. Figure 6B As shown, the second solder sheet H4 is set in the following manner, that is, after the second clamp K is placed on the first connecting conductor L1 and the second connecting conductor L2, it is installed between the portion (connection portion) in the first connecting conductor L1 and the second connecting conductor L2 that is inclined in a manner where the front end is lowered, and the connection portion of the busbar U in a vertical posture.

[0086] The collective reflow step S2 is a manufacturing process in which the assembled components from the collective mounting step S1 are temporarily heated, i.e., the components being reflowed, in a state where the electronic components, embedded wiring members, individual wiring members, and bonding members are positioned in a predetermined relationship using the first jig J and the second jig K, to melt and solidify the bonding members. This collective reflow step S2 connects the electronic components, embedded wiring members, and individual wiring members to one another.

[0087] Specifically, the melting and solidification of the third solder sheet H5 among the first solder sheet H1, the second solder sheet H2, the first solder sheet H3, the second solder sheet H4, and the third solder sheet H5 bond the insulating heat dissipation circuit board D to the embedded wiring member of the base member B. The melting and solidification of the first solder sheet H1 bond the semiconductor chip C to the insulating heat dissipation circuit board D. Furthermore, the melting and solidification of the second solder sheet H2 bond the second connecting wire L2 to the second connecting pad P2 of the semiconductor chip C.

[0088] Furthermore, the first solder sheet H3 melts and solidifies, thereby bonding the first connecting wire L1 to the first connecting pad P1 of the semiconductor chip C. Furthermore, one of the two second solder sheets H4 melts and solidifies, thereby bonding the second connecting wire L2 to the busbar U, while the other melts and solidifies, thereby bonding the insulating heat dissipating circuit board D to the busbar U.

[0089] The wire bonding step S3 is a manufacturing step in which the first jig J and the second jig K are removed from the assembly of the combined reflow step S2, and a dedicated bonding device is used to connect the second connection pads P2 (wire bonding pads) of the semiconductor chip C to the embedded wiring member of the base member B. Through this wire bonding step S3, the Figure 2 The power conversion device A is shown in the wiring state.

[0090] Inspection step S4 is a manufacturing step for confirming whether the power conversion device A exhibits the expected performance. In this inspection step S4, not only the electrical performance of the power conversion device A is confirmed, but also its mechanical performance. Specifically, in inspection step S4 of this embodiment, the power conversion device A is mounted on a vehicle for use, and therefore, it is confirmed whether it exhibits sufficient electrical and mechanical performance under this mounting environment.

[0091] In this embodiment, a collective mounting step S1 is employed, in which the electronic components, embedded wiring members, individual wiring members, and bonding members that mechanically (physically) constitute the power conversion device A are positioned in a predetermined relationship using a first jig J and a second jig K. Consequently, the power conversion device A can be manufactured using fewer reflow steps than in conventional techniques, i.e., a single reflow step.

[0092] It should be noted that the present invention is not limited to the above-mentioned embodiment, and for example, the following modified examples (1) to (3) can also be adopted.

[0093] (1) In the above embodiment, the first solder sheet H1, the second solder sheet H2, the first solder piece H3, the second solder piece H4, and the third solder sheet H5 are used as the bonding members. However, the present invention is not limited to these. In other words, the bonding sheets and bonding pieces of the present invention are not limited to solder as the brazing material.

[0094] (2) In the above embodiment, the power converter A is described as including the insulating heat dissipating circuit board D. However, the present invention is not limited thereto. That is, the present invention can also be applied to the manufacturing process of a power converter that does not include the insulating heat dissipating circuit board D.

[0095] (3) In the above embodiment, the Figures 4 to 6BAlthough the first jig J and the second jig K are shaped as shown, the present invention is not limited thereto. As long as they can perform the same functions as the first jig J and the second jig K, jigs of other shapes may be used.

[0096] Industrial applicability

[0097] According to the method for manufacturing a power conversion device of the present invention, a power conversion device can be manufactured with fewer reflow steps than in the conventional art, thus having greater production applicability.

Claims

1. A method for manufacturing a power conversion device, wherein the power conversion device is formed by interconnecting an embedded wiring member of a base member, a semiconductor chip, and a connecting wire, the method comprising: The mounting step comprises: using a first jig to define a positional relationship among the base member, the semiconductor chip, and the connecting wire, and arranging a first bonding member between the base member and the semiconductor chip, and arranging a fourth bonding member between the semiconductor chip and the connecting wire. a second jig is used to hold a second bonding material connecting the semiconductor chip and the connecting wire, and a third bonding material connecting the connecting wire and the embedded wiring member is arranged on the connecting wire; The reflow step heats the assembly obtained in the mounting step to melt the first bonding material, the second bonding material, the third bonding material, and the fourth bonding material.

2. The method for manufacturing a power conversion device according to claim 1, wherein: As for the first clamp, In a state where the first bonding material is inserted between the base member and the semiconductor chip, a positional relationship of the semiconductor chip with respect to the base member is defined. In a state where the fourth bonding material is inserted between the semiconductor chip and the connecting wire, a positional relationship among the semiconductor chip, the connecting wire, and the embedded wiring member is defined.

3. The method for manufacturing a power conversion device according to claim 1, wherein: The power conversion device includes an insulating heat dissipation circuit substrate for dissipating heat generated by the semiconductor chip in an insulated state. The first jig includes a substrate position regulating portion for positioning the insulating and heat dissipating circuit substrate relative to the semiconductor chip.

4. The method for manufacturing a power conversion device according to claim 1, wherein: The first jig includes inclined surfaces that perform positioning by coming into contact with respective sides of the semiconductor chip.

5. The method for manufacturing a power conversion device according to claim 1, wherein: The second clamp includes a through hole extending in the vertical direction on the connecting wire and accommodating the second connecting member.

6. The method for manufacturing a power conversion device according to any one of claims 1 to 5, wherein: The semiconductor chip includes a pad for wire bonding, The second jig includes a pad protection portion that protects the wire bonding pad.

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