Circuit device

Abstract

The purpose of the present invention is to provide technical features that enable an increase in productivity related to a connection body for connecting a circuit board and a jumper bus bar. This circuit device comprises a circuit board, a jumper bus bar, and a conductive piece. The circuit board has a first surface provided with a land, a second surface opposite the first surface, and a through hole penetrating through the first surface and the second surface in a portion where the land is provided. The jumper bus bar includes a body plate part disposed outside the second surface, and a protrusion part protruding from the body plate part and inserted into the through hole. The conductive piece is mounted on the first surface so as to span the end surface of the protrusion part and the land, and is welded to each of the end surface of the protrusion and the land.

Description

circuit device

[0001] The present disclosure relates to a circuit device.

[0002] Patent Document 1 discloses a jumper bus bar that is connected to a printed circuit board. The jumper bus bar and the printed circuit board are connected by inserting connection terminals of the jumper bus bar into through holes in the printed circuit board and mounting the jumper bus bar by flow soldering.

[0003] JP 2010-62249 A

[0004] Generally, as the current flow through a jumper bus bar increases, the thickness and width of the jumper bus bar also increase, and the thermal capacity of the jumper bus bar also increases. If a jumper bus bar with such a large thermal capacity is mounted by flow soldering, the heat dissipation during soldering increases, which can affect productivity due to factors such as poor solder wicking.

[0005] Therefore, an object of the present invention is to provide a technique that can improve the productivity of connections between circuit boards and jumper bus bars.

[0006] The circuit device of the present disclosure comprises a circuit board, a jumper bus bar, and a conductive piece, wherein the circuit board includes a first surface on which a land is provided, a second surface opposite the first surface, and a through hole penetrating the first surface and the second surface at the portion where the land is provided, the jumper bus bar includes a main plate portion arranged on the outside of the second surface, and a convex portion protruding from the main plate portion and inserted into the through hole, and the conductive piece is mounted on the first surface so as to straddle an end face of the convex portion and the land, and is welded to each of the end face of the convex portion and the land.

[0007] According to the present disclosure, the productivity of a connection between a circuit board and a jumper bus bar can be improved.

[0008] FIG. 1 is a schematic perspective view showing a circuit device according to an embodiment. FIG. 2 is a schematic perspective view showing the circuit device with the upper case removed. FIG. 3 is a schematic plan view showing the circuit device with the upper case removed. FIG. 4 is a schematic exploded perspective view showing the circuit device. FIG. 5 is a schematic exploded perspective view showing some components of the circuit device. FIG. 6 is a schematic block diagram showing the main configuration of a power supply system using the circuit device. FIG. 7 is a schematic cross-sectional view taken along line VII-VII in FIG. 3. FIG. 8 is a schematic cross-sectional view taken along line VIII-VIII in FIG. 3. FIG. 9 is a schematic cross-sectional view taken along line IX-IX in FIG. 3. FIG. 10 is a schematic cross-sectional view taken along line X-X in FIG. 3. FIG. 11 is a schematic cross-sectional view taken along line XI-XI in FIG. 3. FIG. 12 is a schematic cross-sectional view taken along line XII-XII in FIG. 3. FIG. 13 is a schematic perspective view illustrating an example of a method for manufacturing the circuit device. FIG. 14 is a schematic perspective view illustrating an example of a method for manufacturing the circuit device. FIG. 15 is a schematic plan view illustrating an example of a method for manufacturing the circuit device. FIG. 16 is a schematic bottom view illustrating an example of a method for manufacturing the circuit device. Fig. 17 is a schematic perspective view for explaining an example of a method for manufacturing a circuit device. Fig. 18 is a schematic perspective view for explaining an example of a method for manufacturing a circuit device. Fig. 19 is a schematic perspective view for explaining an example of a method for manufacturing a circuit device. Fig. 20 is a schematic perspective view for explaining an example of a method for manufacturing a circuit device. Fig. 21 is a schematic plan view for explaining an example of a method for manufacturing a circuit device. Fig. 22 is a schematic cross-sectional view taken along line XXII-XXII in Fig. 21. Fig. 23 is a schematic perspective view for explaining an example of a method for manufacturing a circuit device. Fig. 24 is a schematic perspective view for explaining an example of a method for manufacturing a circuit device.

[0009] [Description of Embodiments of the Present Disclosure] First, embodiments of the present disclosure will be listed and described.

[0010] The circuit device of the present disclosure is as follows.

[0011] (1) A circuit device comprising: a circuit board; a jumper bus bar; and a conductive piece; the circuit board including a first surface on which a land is provided, a second surface opposite the first surface, and a through hole penetrating the first surface and the second surface at the portion where the land is provided; the jumper bus bar including a main plate portion arranged on the outside of the second surface and a convex portion protruding from the main plate portion and inserted into the through hole; the conductive piece mounted on the first surface so as to straddle an end face of the convex portion and the land, and welded to each of the end face of the convex portion and the land.

[0012] According to the circuit device of (1), the jumper bus bar and the circuit board are connected via conductive pieces welded to each other. Here, a welded connection allows high energy to be applied intensively to a relatively small area of ​​the material, including the connection point, which reduces the impact of the material's heat capacity on productivity compared to a flow soldering connection. Therefore, even if the jumper bus bar has a large heat capacity, the jumper bus bar and the circuit board can be connected via the conductive pieces in a relatively short time, improving the productivity of the connection between the jumper bus bar and the circuit board.

[0013] (2) In the circuit device of (1), the main body plate may have a main surface parallel to the second surface, and the protrusion may protrude from the main surface of the main body plate. This allows the circuit device to be made thinner in the direction perpendicular to the second surface, compared to when the main surface of the main body plate is perpendicular to the second surface.

[0014] (3) In the circuit device of (1) or (2), the jumper bus bar may be made of a metal primarily composed of aluminum, which allows the jumper bus bar to be lighter than when the jumper bus bar is made of a metal primarily composed of copper.

[0015] (4) In the circuit device of (3), the land and the conductive piece may each be made of a metal primarily composed of copper. In this case, the first weld between the conductive piece and the jumper bus bar is a dissimilar metal joint between aluminum and copper, and the second weld between the conductive piece and the land is a homogeneous metal joint between copper and aluminum. Even in this case, if the connection is welded, it is easy to set the welding conditions for the first weld and the second weld separately, making it easier to obtain a good welded state at each of the first weld and the second connection.

[0016] (5) In any one of the circuit devices (1) to (4), a heat sink may be provided that is thermally connected to the jumper bus bar. This allows heat generated when a current is applied to the jumper bus bar to be transferred to the heat sink, thereby preventing a large increase in the temperature of the jumper bus bar even when a large current flows through the jumper bus bar.

[0017] (6) The circuit device according to any one of (1) to (5), further comprising: an external connection bus bar provided with a connection portion for connecting to an external conductive member; and a molded resin portion insert-molded with the external connection bus bar as an insert component, wherein the molded resin portion supports a connection between the circuit board and the jumper bus bar. This allows the connection between the circuit board and the jumper bus bar and the external connection bus bar to be integrated via the molded resin portion.

[0018] (7) The circuit device according to (2) may further include an external connection bus bar having a connection portion with an external conductive member, a molded resin portion insert-molded with the external connection bus bar as an insert component, an electronic component provided across the external connection bus bar and the circuit board, and a heat sink thermally connected to the jumper bus bar and the external connection bus bar, wherein the molded resin portion supports a connection between the circuit board and the jumper bus bar so that the external connection bus bar and the circuit board are adjacent to each other, the electronic component includes a first terminal connected to the external connection bus bar and a second terminal connected to the land, and the heat sink may include a portion laminated with the jumper bus bar and a portion laminated with the external connection bus bar, thereby integrating the connection between the circuit board and the jumper bus bar and the external connection bus bar via the molded resin portion. Furthermore, a high-current circuit is formed by connecting the external connection busbar and the jumper busbar via electronic components, a circuit board, and conductive pieces. By thermally connecting the external connection busbar and the jumper busbar to a heat sink, heat generated when current flows through the high-current circuit is efficiently transferred to the heat sink. This prevents the temperature of the high-current circuit from rising significantly even when a large current flows through it.

[0019] [Details of the embodiment of the present disclosure] Specific examples of the circuit device of the present disclosure will be described below with reference to the drawings. Note that the present disclosure is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0020] <General Description of Circuit Device> Fig. 1 is a schematic perspective view showing a circuit device 1 according to an embodiment. Fig. 2 is a schematic perspective view showing the circuit device 1 with an upper case 81 removed. Fig. 3 is a schematic plan view showing the circuit device 1 with the upper case 81 removed. Fig. 4 is a schematic exploded perspective view showing the circuit device 1. Fig. 5 is a schematic exploded perspective view showing some of the components of the circuit device 1. Hereinafter, for convenience of explanation, the side shown in Fig. 3 will be referred to as the upper surface or upper side of the circuit device 1, and the opposite side will be referred to as the lower surface or lower side of the circuit device 1.

[0021] The circuit device 1 includes a circuit board 2, a jumper bus bar 3, and a plurality of conductive pieces 4. The circuit device 1 also includes a pair of external connection bus bars 5, a molded resin portion 6, a plurality of mounted components 7, a case 8, and a plurality of intervening members 9.

[0022] The circuit board 2 is, for example, a rectangular plate-like member. The circuit board 2 includes, for example, an insulating substrate 22 and a conductive layer 23 provided on the insulating substrate 22. The insulating substrate 22 may be, for example, a ceramic substrate or a substrate containing resin. In the latter case, the insulating substrate 22 may be a glass epoxy substrate or another substrate containing resin. The conductive layer 23 may be made of copper or another metal. The conductive layer 23 is provided, for example, on the upper surface of the insulating substrate 22. The circuit board 2 may be a single-layer substrate or a multi-layer substrate. The circuit board 2 may have the conductive layer 23 not only on the upper surface but also on the lower surface, or may have the conductive layer 23 as an inner layer. In this example, the circuit board 2 is a rigid substrate, but it may also be a sheet-like flexible substrate or a composite substrate in which a rigid substrate and a flexible substrate are integrated.

[0023] The circuit board 2 includes a first surface 20 and a second surface 21. A resist is provided on the first surface 20, covering a portion of the conductive layer 23. The portion of the conductive layer 23 that is not covered by the resist is exposed as a land 24. A plurality of lands 24 are provided on the circuit board 2. A plurality of through holes 25 are formed in the circuit board 2, penetrating from the first surface 20 to the second surface 21. The through holes 25 are formed in some of the lands 24.

[0024] The lands 24 include lands 24a, 24b, and 24c for connecting the conductive pieces 4 and lands 24d for mounting the components 7. The lands 24a, 24b, and 24c include lands 24a aligned along one of the four sides of the circuit board 2, lands 24b aligned along the other side, and lands 24c aligned along the other side. The patterns of the lands 24a, 24b, and 24c are connected together in the portions covered with resist to form the main power supply circuit 23A (see FIG. 6 , described below). A through-hole 25 is formed in each of the lands 24a, 24b, and 24c. The patterns of some of the lands 24d are also connected to the pattern forming the main power supply circuit 23A.

[0025] The jumper bus bar 3 is a metal member. The jumper bus bar 3 includes a flat main body plate portion 30 and a plurality of protrusions 36 protruding from the main body plate portion 30. The main body plate portion 30 has a first extension portion 33, a second extension portion 34, and a third extension portion 35. The first extension portion 33 and the second extension portion 34 extend parallel to each other and spaced apart from each other. The third extension portion 35 connects one end of the first extension portion 33 to one end of the second extension portion 34. A portion of the main body plate portion 30 surrounded by the first extension portion 33, the second extension portion 34, and the third extension portion 35 forms a recess. The plurality of protrusions 36 are aligned at a distance from each other along the extension direction of the main body plate portion 30. The plurality of protrusions 36 includes a plurality of protrusions 36 provided on the first extension portion 33, a plurality of protrusions 36 provided on the second extension portion 34, and a plurality of protrusions 36 provided on the third extension portion 35. The main body plate portion 30 is located outside the second surface 21 with respect to the circuit board 2. The plurality of protrusions 36 protrude from the main body plate portion 30 toward the circuit board 2 and are inserted into the plurality of through holes 25.

[0026] As shown in Figure 5, the circuit board 2 and the main plate portion 30 of the jumper bus bar are arranged parallel to each other. The main plate portion 30 has a first main surface 31 and a second main surface 32 opposite to the first main surface 31. For example, of the multiple surfaces of the main plate portion 30, the pair of surfaces with the largest areas are the first main surface 31 and the second main surface 32 of the main plate portion 30. The first main surface 31 faces the second surface 21 of the circuit board 2. A plurality of protrusions 36 protrude from the first main surface 31 of the main plate portion 30. The circuit board 2 is provided on the first main surface 31 of the jumper bus bar 3.

[0027] The plurality of conductive pieces 4 are provided at positions corresponding to the plurality of protrusions 36. The conductive pieces 4 are metal members larger than the through holes 25. The conductive pieces 4 are arranged across the periphery of the through holes 25 of the lands 24 and the end faces of the protrusions 36 inserted into the through holes 25. For example, the conductive pieces 4 are arranged across the tip faces of the protrusions 36 and the lands 24. The conductive pieces 4 are welded to the lands 24 and the end faces of the protrusions 36, respectively, and are fixed to and electrically connected to the lands 24 and the protrusions 36. The lands 24 and the jumper bus bar 3 are electrically connected via the conductive pieces 4.

[0028] Each external connection bus bar 5 is a metal member. Each external connection bus bar 5 is, for example, a rectangular plate-like member. One end of each external connection bus bar 5 is housed within the case 8. The other end of each external connection bus bar 5 is exposed to the outside of the case 8. An external conductive member 103 is connected to the other end of each external connection bus bar 5. Here, a bolt B is provided in advance at the other end of each external connection bus bar 5. The external connection bus bar 5 and the external conductive member 103 are connected using the bolt B. In other words, the bolt B is an example of a connection portion of the external connection bus bar 5 with the external conductive member 103.

[0029] The molded resin portion 6 electrically insulates the bus bars 3, 5 from each other while holding the bus bars 3, 5 and the circuit board 2 in a fixed position. The molded resin portion 6 is molded integrally with the bus bars 5, for example, by insert molding, with the bus bars 5 as insert components. The circuit board 2 and bus bars 3 are not inserted components, but are supported by the molded resin portion 6 after molding. Hereinafter, the circuit board 2 and bus bars integrated by the molded resin portion 6 may be referred to as a board module.

[0030] The plurality of mounted components 7 include a plurality of electronic components 70, a plurality of electronic components 71, and a connector 72. Each of the electronic components 70, 71 is, for example, a switching element. However, the electronic components 70, 71 may be an electronic component other than a switching element.

[0031] The electronic component 70 is, for example, a metal-oxide-semiconductor field-effect transistor (MOSFET). A MOSFET is a type of semiconductor switching element. Hereinafter, the electronic component 70 may be referred to as a MOSFET 70. The electronic component 70 may be a switching element other than the MOSFET 70. The MOSFET 70 is disposed so as to straddle the circuit board 2 and the external connection bus bar 5, and is surface-mounted by reflow soldering. The MOSFET 70 includes, for example, a drain terminal, a source terminal, and a gate terminal. Furthermore, the drain terminal is connected to the external connection bus bar 5, and the source terminal is connected to the circuit board 2.

[0032] The electronic component 71 is, for example, an IPD (Intelligent Power Device). The IPD is a chip formed from a switching element such as a MOSFET or an IGBT (Insulated Gate Bipolar Transistor) and a control circuit that controls the switching element. Hereinafter, the electronic component 71 may be referred to as the IPD 71. The electronic component 71 may also be a switching element other than the IPD 71. The IPD 71 is, for example, disposed on the circuit board 2 and surface-mounted by reflow soldering.

[0033] In this example, the circuit device 1 includes 10 MOSFETs 70 and 16 IPDs 71, but the numbers of MOSFETs 70 and IPDs 71 included in the circuit device 1 are not limited to this.

[0034] The connector 72 includes a housing 720 and a plurality of connector terminals 721. For example, the housing 720 is made of insulating resin, and the connector terminals 721 are made of metal. The housing 720 is provided on the first surface 20 of the circuit board 2. One ends of the plurality of connector terminals 721 are held by the housing 720 in a state connectable with connector terminals of the mating connector 105. Here, the housing 720 has an opening for receiving the mating connector 105, and one ends of the plurality of connector terminals 721 are exposed within the opening. The other ends of the plurality of connector terminals 721 are inserted into through-holes in the circuit board 2 and are through-hole mounted by flow soldering. When the connector 72 and the mating connector 105 are connected, the housing 720 is fitted into the housing of the mating connector 105, and one ends of the plurality of connector terminals 721 are connected to the connector terminals of the mating connector 105.

[0035] The case 8 covers the board module except for the connection portion with the outside, thereby protecting the inside of the circuit device 1. The case 8 includes a lower case 80 and an upper case 81. The lower case 80 is formed in a box shape with an open top. The board module is housed inside the lower case 80. The upper case 81 is formed in a lid shape that closes the top opening of the lower case 80. The openings for the bolt B and the connector 72 are exposed and not covered by the case 8.

[0036] In this embodiment, the lower case 80 serves as the heat sink 80. The heat sink 80 is, for example, a metal member. The heat sink 80 is provided on the underside of the board module. The heat sink 80 is thermally connected to the jumper bus bar 3 and the external connection bus bar 5. The heat sink 80 dissipates heat generated by the bus bars 3 and 5, and heat generated by the MOSFET 70 and the IPD 71 that is transmitted through the bus bars 3 and 5, to the outside. The circuit device 1 including the case 8 can be considered an electrical junction box.

[0037] The interposing member 9 includes thermally conductive members 90 and 91. The thermally conductive member 90 is interposed between the heat sink 80 and the jumper bus bar 3, and thermally connects the heat sink 80 and the jumper bus bar 3. The thermally conductive member 90 may be an insulating member and insulates the heat sink 80 from the jumper bus bar 3. The thermally conductive member 91 is interposed between the heat sink 80 and the external connection bus bar 5, and thermally connects the heat sink 80 and the external connection bus bar 5. The thermally conductive member 91 may be an insulating member and insulates the heat sink 80 from the jumper bus bar 3.

[0038] The interposing member 9 includes a joining member 92 (see FIG. 8 , etc., described later). The joining member 92 is interposed between the circuit board 2 and the jumper bus bar 3 to join the circuit board 2 and the jumper bus bar 3. The joining member 92 is interposed between the second surface 21 of the circuit board 2 and the first main surface 31 of the main plate portion 30 to join the two. The joining member 92 is also interposed between the jumper bus bar 3 and the molded resin portion 6 to join the jumper bus bar 3 and the molded resin portion 6.

[0039] <Detailed Description of Circuit Device> Fig. 6 is a schematic block diagram showing the configuration of a main part of a power supply system 100 using the circuit device 1. Fig. 7 is a schematic cross-sectional view taken along line VII-VII in Fig. 3. Fig. 8 is a schematic cross-sectional view taken along line VIII-VIII in Fig. 3. Fig. 9 is a schematic cross-sectional view taken along line IX-IX in Fig. 3. Fig. 10 is a schematic cross-sectional view taken along line X-X in Fig. 3. Fig. 11 is a schematic cross-sectional view taken along line XI-XI in Fig. 3. Fig. 12 is a schematic cross-sectional view taken along line XII-XII in Fig. 3.

[0040] 6, the circuit device 1 is provided, for example, in an automobile power supply system 100, so as to form part of a power supply path between a battery 101 and various loads 102. The use of the circuit device 1 is not limited to this.

[0041] The conductive layer 23 of the circuit board 2 has one main power supply circuit 23A, multiple load-side power supply circuits 23B, and a signal circuit (not shown). In the circuit device 1, the external connection bus bar 5 and the main power supply circuit 23A are connected via multiple MOSFETs 70. A pair of external connection bus bars 5a, 5b are electrically connected to the main power supply circuit 23A via MOSFETs 70a, 70b. Drain terminals 700 of the multiple MOSFETs 70a are electrically connected to each other. Drain terminals 700 of the multiple MOSFETs 70a are electrically connected to the external connection bus bar 5a. Drain terminals 700 of the multiple MOSFETs 70b are electrically connected to each other. Drain terminals 700 of the multiple MOSFETs 70b are electrically connected to the external connection bus bar 5b. Source terminals 701 of the multiple MOSFETs 70a, 70b are electrically connected to each other. The source terminals 701 of the multiple MOSFETs 70a, 70b are connected to the main power supply circuit 23A.

[0042] The input terminals of the multiple IPDs 71 are also electrically connected to the main power supply circuit 23A. The input terminals of the multiple IPDs 71 are electrically connected to one another. The output terminals of the multiple IPDs 71 are not electrically connected to one another. The output terminals of the multiple IPDs 71 are connected to corresponding circuits among the multiple load-side power supply circuits 23B. The output terminals of the IPDs 71 are electrically connected to connector terminals 721 through the load-side power supply circuit 23B.

[0043] A gate terminal of each MOSFET 70 is electrically connected to a signal circuit on the circuit board 2. A control terminal of each IPD 71 is electrically connected to the signal circuit on the circuit board 2. The MOSFETs 70 and the IPDs 71 are connected to a drive circuit via the signal circuit. Such a drive circuit may be provided on the circuit board 2, or may be provided in an ECU (electronic control unit) or the like external to the circuit device 1. The gate terminal of the MOSFET 70 and the control terminal of the IPD 71 may also be electrically connected to a connector terminal 721 via the signal circuit on the circuit board 2. The switching of the MOSFET 70 or the IPD 71 may be controlled externally via the connector 72.

[0044] The external connection bus bar 5 is electrically connected to an external conductive member 103. The external conductive member 103 electrically connects, for example, the battery 101 and the circuit device 1. The connector 72 is electrically connected to a mating connector 105. The mating connector 105 is provided, for example, on a wire harness 104. The wire harness 104 electrically connects, for example, each load 102 and the circuit device 1.

[0045] Therefore, the output voltage of the battery 101 is supplied to each load 102 through the external conductive member 103, the external connection bus bar 5, the MOSFET 70, the main power supply circuit 23A, the IPD 71, the load-side power supply circuit 23B, the connectors 72 and 105, and the wire harness 104. The circuit device 1 is configured to be capable of switching-controlling the main power supply circuit 23A through the MOSFET 70. Therefore, the circuit device 1 is configured to be capable of collectively switching-controlling the multiple loads 102 through the MOSFET 70. The circuit device 1 is also configured to be capable of individually switching-controlling the multiple load-side power supply circuits 23B through the multiple IPDs 71. Therefore, the circuit device 1 is configured to be capable of individually switching-controlling the multiple loads 102 through the multiple IPDs 71.

[0046] Currents for multiple loads 102 can flow through the main power supply circuit 23A at one time. As the number of loads 102 increases, the current through the main power supply circuit 23A increases. A jumper bus bar 3 is provided as an auxiliary circuit for the main power supply circuit 23A. The jumper bus bar 3 is connected to the main power supply circuit 23A at positions both upstream and downstream. Here, the upstream position of the main power supply circuit 23A corresponds to the MOSFET 70, and the downstream position of the main power supply circuit 23A corresponds to the IPD 71. Therefore, the jumper bus bar 3 is connected to the main power supply circuit 23A at the positions corresponding to the MOSFET 70 and the IPD 71.

[0047] The jumper bus bar 3 and the main power supply circuit 23A are connected via conductive pieces 4. The multiple conductive pieces 4 include multiple conductive pieces 4a, multiple conductive pieces 4b, and multiple conductive pieces 4c. The multiple conductive pieces 4a correspond to the multiple MOSFETs 70a, respectively. The multiple conductive pieces 4b correspond to the multiple MOSFETs 70b, respectively. Each of the conductive pieces 4a, 4b electrically connects the circuit board 2 and the jumper bus bar 3 near the corresponding MOSFET 70a, 70b. Furthermore, the multiple conductive pieces 4c correspond to the multiple IPDs 71, respectively. Each of the conductive pieces 4c electrically connects the conductive layer 23 of the circuit board 2 and the jumper bus bar 3 near the corresponding IPD 71. For example, the number of conductive pieces 4a is the same as the number of MOSFETs 70a. For example, the number of conductive pieces 4b is the same as the number of MOSFETs 70b. For example, the number of conductive pieces 4c is half the number of IPDs.

[0048] <Details of each part of the circuit device 1> The through holes 25 and the protrusions 36 have elongated shapes that are long in one direction in a plan view. The long direction of the protrusions 36 is along the extension direction of the main plate portion 30. The conductive pieces 4 are plate-shaped and thinner than the circuit board 2 and the main plate portion 30. The conductive pieces 4 are thicker than the lands 24 of the circuit board 2. The end faces of the protrusions 36 are flat and are flush with the lands 24 on the periphery of the through holes 25. The conductive pieces 4 have a rectangular shape. The conductive pieces 4 are welded to the protrusions 36 and are welded to the lands 24 on both sides along the short direction of the protrusions 36.

[0049] The welded portion between the conductive piece 4 and the protrusion 36 of the jumper bus bar 3 is referred to as a first welded portion W1, and the welded portion between the conductive piece 4 and the land 24 is referred to as a second welded portion W2. One conductive piece 4 has one first welded portion W1 and two second welded portions W2. A second welded portion W2 is provided on each side of one first welded portion W1.

[0050] For example, the first welded portion W1 and the second welded portion W2 are each laser welded by a laser welding machine. In this case, for example, laser light is irradiated from the laser welding machine toward the conductive piece 4. The first welded portion W1 and the second welded portion W2 may be welded by welding other than laser welding. It is preferable that the first welded portion W1 and the second welded portion W2 be welded by directly joining the welding materials together without using a filler metal.

[0051] The jumper bus bar 3 is made of a metal primarily composed of aluminum. The lands 24 and the conductive pieces 4 are each made of a metal primarily composed of copper. Therefore, the first weld W1 is a dissimilar metal joint between the conductive piece 4, which is made of a metal primarily composed of copper, and the protrusion 36, which is made of a metal primarily composed of aluminum. Furthermore, the second weld W2 is a homogeneous metal joint between the conductive piece 4, which is made of a metal primarily composed of copper, and the land 24, which is also made of a metal primarily composed of copper. In this way, one conductive piece 4 is provided with the first weld W1, which is a dissimilar metal joint, and the second weld W2, which is a homogeneous metal joint. Furthermore, the first weld W1 joins the thin conductive piece 4 to the land 24, which is a thicker plate than the conductive piece 4, and the second weld W2 joins the thin conductive piece 4 to the land 24, which is a thinner plate than the conductive piece 4. Even in this case, when welding, it is easy to set the welding conditions for the first welded portion W1 and the welding conditions for the second welded portion W2 individually, making it easy to set welding conditions suitable for each of the first welded portion W1 and the second welded portion W2.

[0052] For example, the penetration depth of the second weld W2 is shallower than the penetration depth of the first weld W1. The penetration depth of each weld can be adjusted by adjusting the welding conditions (e.g., the output of the welding equipment) when welding each weld. Because the land 24 is provided on the first surface 20 of the circuit board 2, it is thinner than the protrusion 36 that penetrates the circuit board 2. Because both the conductive piece 4 and the land 24 are primarily composed of copper, they can be well connected even with a shallow penetration depth. By reducing the penetration depth, the thermal impact on the circuit board 2 during welding of the second weld W2 can be reduced. Because the protrusion 36 is thicker than the land 24, it is easy to increase the penetration depth. By increasing the penetration depth of the first weld W1, the interior of the aluminum protrusion 36 can be firmly welded. The penetration depth of the first weld W1 may be deeper than the sum of the thicknesses of the land 24 and the conductive piece 4.

[0053] Weld marks WM may remain on the surface of the conductive piece 4. The weld marks WM are portions that indicate the traces of welding a portion of the conductive piece 4. The portions of the conductive piece 4 where the weld marks WM are formed have a different appearance from the portions of the conductive piece 4 that are not welded. The weld marks WM may be formed on the surface of the conductive piece 4 when the material of the conductive piece 4 and the material of the mating member (the protrusion 36 or the land 24) are heated to a high temperature during welding and melted together. The weld marks WM may be formed in an elongated shape along the longitudinal direction of the protrusion 36. Furthermore, three weld marks WM may be formed on one conductive piece 4 to correspond to one first weld W1 and two second welds W2.

[0054] Of the multiple lands 24d, the pattern of the land 24d connected to the source terminal 701 of the MOSFET 70 and the pattern of the land 24d connected to the input terminal of the IPD 71 are also connected to the patterns of the lands 24a, 24b, and 24c that form the main power supply circuit 23A. Note that the land 24d connected to the source terminal 701 of the MOSFET 70a and the land 24a may not be separate and may form a single land 24. The land 24d connected to the source terminal 701 of the MOSFET 70b and the land 24b may not be separate and may form a single land 24. The land 24d connected to the input terminal of the IPD 71 and the land 24c may not be separate and may form a single land 24. The lands 24a, 24b, and 24c have protruding portions that extend outward beyond the outer edges of the conductive pieces 4a, 4b, and 4c, and the source terminal 701 of the MOSFET 70 or the input terminal of the IPD 71 may be connected to the protruding portions.

[0055] The rectangular circuit board 2 has a pair of first sides and a pair of second sides connecting the pair of first sides. A first extension portion 33 extends along one of the first sides of the circuit board 2, a second extension portion 34 extends along the other first side, and a third extension portion 35 extends along one of the second sides. Here, the circuit board 2 is formed in a rectangular shape and has a pair of short sides and a pair of long sides. The first extension portion 33 extends along one of the short sides of the circuit board 2, the second extension portion 34 extends along the other short side, and the third extension portion 35 extends along one of the long sides. The protrusions 36 are provided spaced apart from one another along the extension directions of the extension portions 33, 34, and 35.

[0056] The molded resin part 6 supports the connection between the circuit board 2 and the jumper bus bar 3. The molded resin part 6 includes a frame part 60 that covers the periphery of the circuit board 2. An opening 61 is formed in the center of the frame part 60, and the circuit board 2 fits into the opening 61. The opening 61 is formed in a rectangular shape that is the same size as the circuit board 2. The molded resin part 6 supports the connection between the circuit board 2 and the jumper bus bar 3 so that the external connection bus bar 5 and the circuit board 2 are adjacent to each other.

[0057] The molded resin portion 6 has support portions 63 and 64 that protrude from the inner surface of the frame portion 60 toward the opening 61. The support portions 63 and 64 are provided below the circuit board 2 so as to cover part of the opening 61. One support portion 63 extends along the long side of the rectangular opening 61 so as to connect two corners. The two support portions 64 are formed in a rectangular shape smaller than the support portion 63 and are provided at the remaining two corners of the rectangular opening 61, respectively. The jumper bus bar 3 is supported on the upper surfaces of the support portions 63 and 64, and the circuit board 2 is supported on the upper surface of the jumper bus bar 3. The support portions 63 and 64 and the upper surface (first surface 20) of the circuit board 2 supported by the body plate portion 30 of the jumper bus bar 3 are flush with the upper surface of the frame portion 60. The thickness of the frame portion 60 is approximately the same as the sum of the thickness of the support portion 63 or the support portion 64 , the thickness of the jumper bus bar 3 , and the thickness of the circuit board 2 .

[0058] The external connection busbar 5 is integrated with the frame portion 60. The upper surface of the frame portion 60 is flush with the upper surface of the external connection busbar 5. The upper surface of the external connection busbar 5 is exposed from the frame portion 60 without being covered by it. The circuit board 2 is supported by the molded resin portion 6 so that the first surface 20 of the circuit board 2 and the upper surface of the external connection busbar 5 are flush with each other. The molded resin portion 6 has a wall portion 65 that is provided on the upper surface of the frame portion 60 and that partitions the portion of the external connection busbar 5 where the bolt B is provided. A portion of the wall portion 65 also serves as a wall that covers the side wall of the upper case 81.

[0059] A portion of the side surface of the external connection bus bar 5 may be exposed from the frame portion 60 and face the opening 61 without being covered by the frame portion 60. As shown in Fig. 8 , a portion of the side surface of the circuit board 2 may be in contact with the external connection bus bar 5. Another portion of the side surface of the circuit board 2 may be in contact with the molded resin portion 6.

[0060] A portion of the lower surface of the external connection busbar 5 may be exposed from the frame portion 60 without being covered by the frame portion 60. An opening 62 that exposes a portion of the lower surface of the external connection busbar 5 may be formed in the lower surface of the frame portion 60. As shown in Fig. 8 , a wall that is part of the frame portion 60 and separates the opening 61 and the opening 62 may be provided on the lower surface of the external connection busbar 5.

[0061] As shown in FIG. 8 , the outer edge of the circuit board 2 may protrude outward beyond the outer edge of the jumper bus bar 3. The side surface of the jumper bus bar 3 may be spaced apart from the peripheral edge of the opening 61 of the frame 60. The side surface of the jumper bus bar 3 may be joined to the inner surface of the frame 60 via a joining member 92. The side surfaces of the first extending portion 33 and the second extending portion 34 of the jumper bus bar 3 may be joined to the inner surface of the frame 60 via a joining member 92. When the external connection bus bar 5 is thicker than the circuit board 2, the bottom surface of the external connection bus bar 5 protrudes below the bottom surface of the circuit board 2. Even in this case, a joining member 92 is interposed between the jumper bus bar 3 and the external connection bus bar 5. The joining member 92 is an insulating member that insulates the jumper bus bar 3 from the external connection bus bar 5. The side surface of the third extending portion 35 of the jumper bus bar 3 is in contact with the frame portion 60, and the joining member 92 does not necessarily have to be provided.

[0062] The lower case 80, which also serves as a heat sink 80, has a bottom plate 801, side plate 802, connecting protrusions 803 and 804, and fins 805. The side plate 802 and connecting protrusions 803 and 804 protrude from one side of the bottom plate 801, and the fins 805 protrude from the other side of the bottom plate 801. The side plate 802 extends along the outer edge of the bottom plate 801. The bottom plate 801 and the side plate 802 form a box portion that is open at the top and that houses the board module. The bottom plate 801 supports the underside of the frame 60 of the board module.

[0063] The connection protrusions 803, 804 are provided inside the outer edge of the bottom plate portion 801. The connection protrusion 803 is provided in a portion where the opening 61 of the molded resin portion 6 is located, and the connection protrusion 804 is provided in a portion where the opening 62 of the molded resin portion 6 is located. The connection protrusion 803 is provided in a portion of the first extension portion 33, the second extension portion 34, and the third extension portion 35 that corresponds to a portion that is not supported by the support portions 63, 64. The connection protrusion 803 is inserted into the opening 61. The upper surface of the connection protrusion 803 is thermally connected to the lower surfaces of the first extension portion 33, the second extension portion 34, and the third extension portion 35 via the heat conduction member 90. The connection protrusion 804 is provided in a portion that corresponds to the external connection bus bar 5. The connection protrusion 804 is inserted into the opening 62. The upper surface of the connection protrusion 804 is thermally connected to the lower surface of the external connection bus bar 5 via the heat conduction member 91. The heat sink 80 includes a connection protrusion 803 as a portion to be laminated with the jumper bus bar 3 and a connection protrusion 804 as a portion to be laminated with the external connection bus bar 5 .

[0064] 8 , the connector terminal 721 is located in the center of the circuit board 2, surrounded by the main plate portion 30. In a plan view, the jumper bus bar 3 and the connection protrusions 803 and 804 are not provided at the position of the connector terminal 721. The tip of the connector terminal 721 is separated from the bottom plate portion 801. This prevents the connector terminal 721 from being electrically connected to the jumper bus bar 3 and the heat sink 80.

[0065] <Example of Manufacturing Method of Circuit Device 1> First, as shown in Fig. 13, a stud bolt B made of a material is press-fitted into a hole provided in an external connection bus bar 5 formed into a predetermined shape and fixed. The external connection bus bar 5 is made of, for example, oxygen-free copper (C1020) or a copper alloy, and its surface may be nickel-plated. The external connection bus bar 5 may have a thickness of, for example, approximately 1.5 mm. The stud bolt B may be made of, for example, cold-headed carbon steel.

[0066] Next, the pair of external connection bus bars 5 are placed in an insert molding die, and a resin material is injected into the die using an injection molding machine. The resin material may be a thermoplastic resin with excellent heat resistance, such as PPS resin. This results in the molded resin portion 6 being integrally molded with the external connection bus bars 5, producing the bus bar insert circuit board shown in FIGS. 14 to 16.

[0067] Next, as shown in FIG. 5 , the busbar insert substrate, circuit board 2, and jumper busbar 3 are integrated. First, the protrusions 36 of the jumper busbar 3 are fitted into the through holes 25 formed in the lands 24 of the circuit board 2, and the circuit board 2 and the jumper busbar 3 are joined with a joining member 92. This forms a connection body in which the jumper busbar 3 is attached to the circuit board 2. At this time, the circuit board 2 and the jumper busbar 3 are positioned so that the surfaces of the protrusions 36 are flush with the lands 24. Then, the connection body between the jumper busbar 3 and the circuit board 2 is joined to the busbar insert substrate with the joining member 92. This completes the substrate module shown in FIG. 17 . The joining member 92 between the circuit board 2 and the jumper busbar 3 and the joining member 92 between the connection body and the busbar insert substrate may be, for example, a silicone structural adhesive.

[0068] The circuit board 2 may be a copper-clad laminate in which copper foil is attached to the surface of an insulating substrate 22 made of glass epoxy resin. The thickness of the circuit board 2 may be, for example, 1.2 mm to 1.6 mm. The thickness of the copper foil may be, for example, 70 μm.

[0069] The jumper bus bar 3 may be made of pure aluminum (A1050), for example. The main body plate portion 30 of the jumper bus bar 3 is formed by molding a base material into a predetermined shape. The thickness of the main body plate portion 30 may be, for example, approximately 2 mm. The protrusion dimension of the protrusion 36 from the main body plate portion 30 is the same as or slightly larger than the thickness dimension of the circuit board. The protrusion 36 of the jumper bus bar 3 may be formed by bending and deforming a portion of the main body plate portion 30 using a doweling process or the like. In this case, a recess corresponding to the protrusion 36 is formed in a portion of the second main surface 32 of the main body plate portion 30 located behind the protrusion 36. The protrusion 36 may be formed by removing a portion of the main body plate portion 30 using an etching process, a cutting process, or the like. In this case, no recess corresponding to the protrusion 36 is formed in a portion of the second main surface 32 of the main body plate portion 30 located behind the protrusion 36, and the entire second main surface 32 can be flat.

[0070] Next, as shown in Figures 18 and 19, the conductive piece 4 is placed so as to straddle the protrusion 36 and the land 24 adjacent to the protrusion 36. The material of the conductive piece 4 is, for example, pure copper or a copper alloy. The thickness of the conductive piece 4 is, for example, 0.2 mm to 0.5 mm. The shape of the conductive piece 4 is, for example, a flat plate.

[0071] 20 and 21 , the conductive piece 4 and the protrusion 36 are welded to form a first weld W1, and the conductive piece 4 and the land 24 are welded to form a second weld W2. A laser welder may be used as the welder for this process. The welding conditions of the welder may be optimized when welding the first weld W1 and the second weld W2.

[0072] For example, the first welded portion W1 is a dissimilar metal joint between a metal primarily composed of copper and a metal primarily composed of aluminum, and the second welded portion W2 is a homogeneous metal joint between two metals primarily composed of copper. Furthermore, the land 24 and the protrusion 36 have different thicknesses. As shown in Fig. 22 , the welding conditions of the welding machine may be set so that the penetration depth of the first welded portion W1 is deeper than the penetration depth of the second welded portion W2. For example, the output of the laser welder when welding the first welded portion W1 may be set higher than the output of the laser welder when welding the second welded portion W2.

[0073] Next, solder paste (not shown) is applied to predetermined positions on the board module. Then, as shown in Fig. 23, the MOSFET 70 and the IPD 71 are mounted and reflow soldered. At this time, other electronic components (not shown) may also be reflow soldered.

[0074] Next, as shown in FIG. 24, the connector terminals 721 of the connector 72 are attached to the through holes of the circuit board 2 and flow soldered.

[0075] Next, as shown in FIG. 4 , the circuit module is mounted on the lower case 80 equipped with the heat sink 81. This completes the manufacturing of the circuit device 1 shown in FIG. 2 with the upper case 81 removed. The lower case 80 and the circuit module may be fixed together with, for example, screws (not shown). The lower case 80 is made of, for example, die-cast aluminum. The external connection bus bar 5 and the jumper bus bar 3 exposed on the back surface of the circuit module are thermally coupled to the lower case 80 via thermally conductive members 90 and 91. The thermally conductive members 90 and 91 may be, for example, a heat dissipation sheet or thermal grease. The thermally conductive members 90 and 91 thermally couple the lower case 80 and the external connection bus bar 5 while insulating them from each other. The thermally conductive members 90 and 91 thermally couple the lower case 80 and the jumper bus bar 3 while insulating them from each other.

[0076] Finally, the upper case 81 is attached, thereby completing the manufacture of the circuit device 1 shown in FIG.

[0077] <Effects, etc.> In the circuit device 1 configured as described above, the jumper bus bar 3 and the circuit board 2 are connected via the conductive pieces 4 welded to each other. Here, a welded connection allows high energy to be applied intensively to a relatively small area of ​​the material that includes the connection point, which reduces the impact of the material's heat capacity on productivity compared to a flow soldering connection. Therefore, even if the jumper bus bar 3 has a large heat capacity, the jumper bus bar 3 and the circuit board 2 can be connected via the conductive pieces 4 in a relatively short time, thereby improving the productivity of the connection between the jumper bus bar 3 and the circuit board 2.

[0078] Furthermore, main body plate 30 has first main surface 31 parallel to second surface 21, and protrusion 36 protrudes from first main surface 31 of main body plate 30. This allows circuit device 1 to be made thinner in the direction perpendicular to second surface 21, compared to when first main surface 31 of main body plate 30 is perpendicular to second surface 21.

[0079] The jumper bus bar 3 is made of a metal containing aluminum as its main component, which allows the jumper bus bar 3 to be lighter in weight than if it were made of a metal containing copper as its main component.

[0080] Furthermore, the land 24 and the conductive piece 4 are each made of a metal primarily composed of copper. In this case, the first weld W1 between the conductive piece 4 and the jumper bus bar 3 is a dissimilar metal joint between aluminum and copper, and the second weld W2 between the conductive piece 4 and the land 24 is a homogeneous metal joint between copper and aluminum. Even in this case, if the connection is welded, it is easy to set the welding conditions for the first weld W1 and the second weld W2 individually, making it easier to obtain a good welded state at each of the first weld W1 and the second connection.

[0081] The circuit device 1 also includes a heat sink 80 thermally connected to the jumper bus bar 3. This allows heat generated when current flows through the jumper bus bar 3 to be transferred to the heat sink 80, thereby preventing the temperature of the jumper bus bar 3 from rising significantly even when a large current flows through the jumper bus bar 3.

[0082] The circuit device 1 also includes an external connection bus bar 5 provided with a connection portion with the external conductive member 103, and a molded resin part 6 insert-molded with the external connection bus bar 5 as an insert part, and the molded resin part 6 supports the connection body between the circuit board 2 and the jumper bus bar 3. This allows the connection body between the circuit board 2 and the jumper bus bar 3 and the external connection bus bar 5 to be integrated via the molded resin part 6.

[0083] Furthermore, a large current circuit is formed by electrically connecting the external connection bus bar 5 and the jumper bus bar 3 via the electronic components 70, 71, the circuit board 2, and the conductive pieces 4. By thermally connecting the external connection bus bar 5 and the jumper bus bar 3 to the heat sink 80, heat generated when current is passed through the large current circuit is efficiently transferred to the heat sink 80. This makes it possible to prevent the temperature of the large current circuit from rising significantly even when a large current flows through the large current circuit.

[0084] [Additional Note] In the examples described above, the power supply system 100 has redundancy because the multiple loads 102 are connected to the two batteries 101. In other words, even if the power supply from one battery 101 to the load 102 is interrupted, the other battery 101 can still supply power to the load 102. However, the multiple loads 102 may be configured to be connected to only one battery 101. In this case, one of the two sets of external connection bus bars 5a, 5b and MOSFETs 70a, 70b may be omitted from the circuit device 1. In this case, the jumper bus bar 3 may be formed in an L-shape or the like, with the connection portion between the one set of external connection bus bars 5 and MOSFET 70 omitted.

[0085] Although the first main surface 31 of the main body plate portion 30 has been described as being parallel to the second surface 21 of the circuit board 2, this is not a required configuration. The first main surface 31 of the main body plate portion 30 may be perpendicular to the second surface 21. In this case, the protrusion 36 may protrude from the side surface of the main body plate portion 30, rather than from the first main surface 31 of the main body plate portion 30.

[0086] Although the jumper bus bar 3 has been described as being made of a metal whose main component is aluminum, this is not a necessary configuration. The jumper bus bar 3 may also be made of a metal whose main component is copper.

[0087] Although the circuit device 1 has been described as including the molded resin portion 6, this is not a required configuration. For example, instead of the molded resin portion 6, the circuit device 1 may include a resin frame that is molded separately from the external connection bus bars 5 and that supports the circuit board 2, the jumper bus bars 3, and the external connection bus bars 5.

[0088] The configurations described in the above embodiments and modifications can be combined as appropriate as long as they are not mutually contradictory.

[0089] REFERENCE SIGNS LIST 1 Circuit device 2 Circuit board 20 First surface 21 Second surface 22 Insulating substrate 23 Conductive layer 23A Main power supply circuit 23B Load side power supply circuit 24, 24a, 24b, 24c, 24d Land 25, 53 Through hole 3 Jumper bus bar 30 Main body plate portion 31, 51 First main surface 32, 52 Second main surface 33 First extension portion 34 Second extension portion 35 Third extension portion 36 Convex portion 4, 4a, 4b, 4c Conductive piece 5 External connection bus bar 6 Molded resin portion 60 Frame portion 61, 62 Opening 63, 64 Support portion 65 Wall portion 7 Mounted component 70, 70a, 70b MOSFET (electronic component) 700 Drain terminal (first terminal portion) 701 DESCRIPTION OF SYMBOLS Source terminal (second terminal portion) 71 IPD (electronic component) 72 Connector 720 Housing 721 Connector terminal 8 Case 80 Lower case (heat sink) 801 Bottom plate portion 802 Side plate portion 803, 804 Connection protrusion 805 Fin 81 Upper case 9 Interposition member 90, 91 Heat conduction member 92 Joint member 100 Power supply system 101 Battery 102 Load 103 External conductive member 104 Wire harness 105 Mating connector B Bolt W1 First welded portion W2 Second welded portion WM Weld mark

Claims

1. A circuit device comprising: a circuit board; a jumper bus bar; and a conductive piece; wherein the circuit board includes a first surface on which lands are provided, a second surface opposite the first surface, and a through hole penetrating the first surface and the second surface at the portion where the lands are provided; the jumper bus bar includes a main plate portion arranged on the outside of the second surface, and a convex portion protruding from the main plate portion and inserted into the through hole; and the conductive piece is mounted on the first surface so as to straddle an end face of the convex portion and the land, and is welded to each of the end face of the convex portion and the land.

2. A circuit device according to claim 1, wherein the main plate portion has a main surface parallel to the second surface, and the protrusion protrudes from the main surface of the main plate portion.

3. A circuit device according to claim 1 or 2, wherein the jumper bus bar is made of a metal whose main component is aluminum.

4. A circuit device according to claim 3, wherein each of said lands and said conductive pieces is made of a metal whose main component is copper.

5. A circuit device according to claim 1 or 2, comprising a heat sink thermally connected to the jumper bus bar.

6. A circuit device as claimed in claim 1 or 2, comprising: an external connection bus bar provided with a connection portion with an external conductive member; and a molded resin part insert-molded with the external connection bus bar as an insert part, wherein the molded resin part supports a connection between the circuit board and the jumper bus bar.

7. A circuit device as claimed in claim 2, comprising: an external connection bus bar having a connection portion with an external conductive member; a molded resin portion insert-molded using the external connection bus bar as an insert part; electronic components arranged across the external connection bus bar and the circuit board; and a heat sink thermally connected to each of the jumper bus bar and the external connection bus bar, wherein the molded resin portion supports a connection between the circuit board and the jumper bus bar so that the external connection bus bar and the circuit board are adjacent to each other, the electronic components include a first terminal portion connected to the external connection bus bar and a second terminal portion connected to the land, and the heat sink includes a portion laminated with the jumper bus bar and a portion laminated with the external connection bus bar.