JP2005045998A - Circuit configuration - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circuit configuration which constructs an electric circuit of a simple and thin structure which includes semiconductor switching elements and improves heat dissipation of the element. <P>SOLUTION: The circuit configuration has a plurality of bus bars 11, 12 and 14 composing an electric circuit and adhered on the surface of a control circuit substrate 20, and semiconductor switching elements mounted on them. The control circuit substrate 20 has a part 22, which exposes the bus bars 11, 12 and 14 on the opposite side of the surface where these bus bars are adhered, and a current-carrying terminal of the semiconductor switching element is mounted on the bus bar through this part 22. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a circuit structure including both a bus bar constituting a power circuit and a control circuit board for controlling driving of a semiconductor switching element provided in the power circuit.

  Conventionally, as a means for distributing power from a common in-vehicle power source to each electronic unit, a distribution circuit is configured by stacking a plurality of bus bar boards, and an electric junction box incorporating a fuse or relay switch is generally known. It has been.

  Further, in recent years, in order to realize the miniaturization of such an electric junction box and high-speed switching control, a device in which a semiconductor switching element such as an FET is interposed between the input terminal and the output terminal instead of the relay has been developed. Has reached.

For example, Patent Literature 1 below includes a bus bar substrate that forms a current circuit, an FET as a semiconductor switching element incorporated in the current circuit, and a control circuit substrate that controls the operation of the FET. And the control circuit board are arranged in two upper and lower stages while being spaced apart from each other, an FET is provided between them, and the drain terminal and the source terminal of the FET are connected to the bus bar board, while the gate terminal of the FET is connected to the control circuit board An electrical junction box is disclosed that is adapted to be connected to a cable.
JP-A-10-35375

  The electrical junction box shown in the above publication requires at least two substrates, a bus bar substrate and a control circuit substrate, and these substrates are spaced apart from each other and arranged three-dimensionally, and an FET is placed between the two substrates. There must be enough space for placement. Therefore, the introduction of the FET can reduce the size of the conventional relay-type electrical junction box, but the overall configuration is complicated and the size cannot be reduced sufficiently. In particular, the reduction of the height dimension is a major issue.

  Further, in the electrical junction box, since the FET is disposed between the bus bar substrate and the control circuit substrate, the heat generated by the FET is likely to be trapped between both substrates, and it is necessary to take a complicated structure for the heat dissipation. .

  Further, in the electrical junction box, the drain terminal and the source terminal of the FET are connected to the lower bus bar substrate, while the gate terminal must be connected to the upper control circuit substrate. It is complicated and difficult to automate, and improvements are also desired.

  In view of such circumstances, the present invention provides a circuit structure that can construct a power circuit including a semiconductor switching element such as an FET with a simple and thin structure and is excellent in heat dissipation of the semiconductor switching element. Objective.

  As means for solving the problems, the present invention provides a plurality of bus bars constituting a power circuit, a semiconductor switching element provided in the power circuit, and a control circuit board for controlling driving of the semiconductor switching element. The bus bar is bonded to the surface of the control circuit board in a state where the bus bars are arranged on substantially the same plane, and the semiconductor switching element is disposed on the surface of the control circuit board opposite to the surface to which the bus bar is bonded. The control circuit board has a portion that exposes the bus bar on the side opposite to the side to which the bus bar is bonded, through which the energizing terminal of the semiconductor switching element is connected. It is connected to the bus bar.

  In this configuration, a plurality of bus bars constituting the power circuit are bonded to the surface of the control circuit board in a state where they are arranged on substantially the same plane, and a semiconductor switching element is mounted on both the bus bar and the control circuit board. Therefore, the height dimension (thickness dimension) of the entire circuit structure is very small, and the bus bar substrate (the bus bar is held by an insulating substrate) and the semiconductor switching element that are required in the conventional electrical junction box A wiring material for connection to each substrate is basically unnecessary (however, the present invention does not prevent the wiring material from being partially used). Therefore, as compared with an electrical junction box in which the bus bar board and the control circuit board are spaced apart from each other and the semiconductor switching element is connected to both boards as in the prior art, the overall configuration is greatly reduced in thickness and simplified. The

  Further, the semiconductor switching element can be connected to the control circuit board while maintaining a thin structure with a simple configuration in which a portion exposing the bus bar is provided on a side opposite to the surface to which the bus bar is bonded at an appropriate position of the control circuit board. It can be mounted on both bus bars.

  In this case, the semiconductor switching element has the energization terminal on the back surface of the main body, and the control circuit board has the semiconductor switching element as a portion that exposes the bus bar on the side opposite to the side to which the bus bar is bonded. The main body of the semiconductor switching element is mounted on the bus bar in a state where the energization terminal on the back surface of the main body of the semiconductor switching element is in contact with the bus bar. Is more preferable. According to this configuration, since the semiconductor switching element is mounted so that the energization terminal provided on the back surface of the semiconductor switching element directly contacts the bus bar, the number of terminals protruding from the semiconductor switching element main body is reduced, and the configuration is simpler. And the mounting process of the semiconductor switching element is simplified.

  In the present invention, the specific arrangement of each bus bar is not particularly limited. However, if a plurality of bus bars protrude from the control circuit board to the side to constitute a terminal connected to an external circuit, Connection between the power circuit formed by the bus bar and the external circuit is facilitated.

  Furthermore, if the bus bars constituting the terminals are bent in the same direction and substantially perpendicular to the control circuit board, the occupied area of the entire circuit structure is reduced by the amount of the bent. The external wiring material can be connected to each terminal from the same direction, reducing the wiring space and facilitating the wiring connection work.

  Further, if a connector is formed by providing a housing made of an insulating material around the terminal, the terminal and the external wiring material can be more easily connected using the connector. become.

  The housing may be a single one, but made of an insulating material and provided with a case for housing the bus bar and the control circuit board, by forming at least a part of the housing integrally with the case, The number of parts is further reduced.

  With respect to this case, a waterproof wall surrounding the region including the semiconductor switching element is erected on the case, and the inside of the waterproof wall is sealed with a potting agent in a state where the opening of the waterproof wall is closed with a cover. It is more preferable to have a configuration. With this configuration, each semiconductor switching element can be reliably waterproofed with a simple structure.

  As the power circuit formed by the bus bar, for example, a power distribution circuit that distributes power from a common power source to a plurality of electrical loads is preferable. In this case, the terminal includes an input terminal connected to the power source and an electrical load. And the plurality of bus bars may constitute a power distribution circuit that outputs the power supplied to the input terminal from the output terminal to each of the electrical loads. .

  In addition, the terminal can include a signal input terminal to which a command signal is input from the outside. In this case, a control circuit in which a bus bar constituting the signal input terminal is provided on the control circuit board. A predetermined command signal can be input to the control circuit board with a simple configuration that is simply electrically connected to the control circuit board.

  In the circuit structure according to the present invention, a heat radiating member is provided on the opposite side of the control circuit board across the bus bar, and the bus bar is connected to the heat radiating member via an insulating layer. Thus, it is possible to further improve the heat dissipation.

  Moreover, this invention is a semiconductor switching element used for the above circuit structure, Comprising: It has an electricity supply terminal mounted in the said bus-bar, and a control terminal mounted in the said control circuit board, These electricity supply terminals and control A step substantially equal to the thickness of the control circuit board is provided between the terminals.

  According to this configuration, regardless of the thickness of the control circuit board, each terminal can be directly mounted on the bus bar and the control circuit board without causing excessive deformation of the energization terminal and the control terminal, The stress of each terminal after mounting is reduced.

  As described above, the present invention is such that a plurality of bus bars constituting a power circuit are bonded to the surface of a control circuit board, and semiconductor switching elements are mounted on both the bus bar and the control circuit board. There is an effect that it is possible to construct a power circuit including a semiconductor switching element with a simple and thin structure and to provide a circuit structure having excellent heat dissipation of the semiconductor switching element.

  A preferred embodiment of the present invention will be described with reference to the drawings. In addition, although the manufacturing method of the circuit structure body which comprises the power distribution circuit which distributes the electric power supplied from the common power supply mounted in a vehicle etc. to several electric load here is shown, the circuit structure body concerning this invention The use of is not limited to this, and can be widely applied when the on / off switching of energization in the power circuit is performed by a semiconductor switching element.

1) Bus Bar Formation Step First, when manufacturing the circuit component, a bus bar component plate 10 as shown in FIG. 1 is formed.

  The illustrated bus bar constituting plate 10 has a rectangular outer frame 16, and in its inner region, a plurality of input terminal bus bars 11 constituting input terminals and a plurality of output terminal bus bars constituting output terminals. 12 and a plurality of signal input terminal bus bars 14 are arranged in a predetermined pattern, and an appropriate bus bar is connected to the outer frame 16 by a narrow connecting portion 18, and specific bus bars are connected to each other. Are interconnected by a small connecting portion 18.

  In the illustrated example, the end portion 11a of the input terminal bus bar 11 and the outer end portion 14a of the signal input terminal bus bar 14 are all arranged on the left side of the bus bar constituting plate 10, and the end portions 12a of the output terminal bus bar 12 are all bus bar constituting plates. The bus bar end portions 11 a, 12 a, and 14 a are free end portions that are not connected to the outer frame 16.

  The bus bar constituting plate 10 can be easily formed, for example, by punching a single metal plate by press working.

  The outer frame 16 is not necessarily included. However, the inclusion of the outer frame 16 increases the rigidity of the bus bar component board 10 as a whole, which facilitates adhesion to the control circuit board 20 and damages the bus bar body by gripping the outer frame 16. It can be handled easily without any problems. In addition, an appropriate power circuit can be easily constructed by separating the outer frame from the bus bar component after bonding.

2) Bonding Step The control circuit board 20 is bonded to one side (the upper surface in FIG. 1) of the bus bar constituting plate 10 to obtain the state shown in FIG.

  The control circuit board 20 includes a control circuit for controlling the switching operation of an FET (semiconductor switching element) 30 described later. For example, a normal printed circuit board (a conductor constituting the control circuit is printed on an insulating board) It is possible to constitute by a thing). In the illustrated example, a sheet-like control circuit board 20 having a very small thickness (for example, 0.3 mm) is used in order to further promote overall thinning and waterproofing improvement. A plurality of through holes 22 are provided. The through-hole 22 is used for mounting the FET 30 on the bus bar by exposing the bus bar to the side opposite to the surface to which the bus bar is bonded, the details of which will be described later.

  The outer shape of the control circuit board 20 is made smaller than the outer shape of the bus bar component plate 10, and in particular, the width of the substrate in the lateral direction is made sufficiently smaller than that of the bus bar component plate 10. Specifically, the control circuit board 20 is bonded to the central portion of the bus bar constituting plate 10 as shown in the figure, so that the end portion 11a of the input terminal bus bar 11 and the signal input terminal are provided on the left outer side from the bus bar constituting plate 20. The end 14a of the bus bar 14 projects, the end 12a of the output terminal bus bar 12 projects to the right outside, and all the connecting portions 18 are exposed to the outside of the control circuit board 20 (FIG. 2).

  Various methods can be used to bond the control circuit board 20 to the bus bar component board 10. An example is shown below.

  a) Conductor patterns are provided on both front and back surfaces of the control circuit board 20, and an adhesive is applied to the back side (upper side in FIG. 1) pattern or the bus bar constituting plate 10 to adhere the back side pattern to the upper surface of the bus bar. In this case, only the pattern having the same potential as the bus bar bonded to the back side of the control circuit board 20 is routed.

  b) An insulating adhesive is applied to the back surface of the control circuit board 20 or the upper surface of the bus bar constituting plate, and an insulating layer is formed between the control circuit board 20 and each bus bar by this adhesive. When the control circuit board 20 includes a through hole, the insulating adhesive is prevented from adhering to the through hole (details will be described later).

  c) Adhesive is applied only to the rear edge of the control circuit board 20 and adhered to the upper surface of the bus bar. In this case, the adhesion region is only the edge portion, and the control circuit board 20 and the bus bar are free from each other in the inner region, so that the stress is reduced accordingly.

  In any of the above a), b) and c), the adhesive can be applied by printing, which can promote the efficiency and automation of the manufacturing process.

3) Mounting Step Using the through hole 22 provided in the control circuit board 20, the FET 30 is mounted as a semiconductor switching element on both the control circuit board 20 and the bus bar component board 10.

  As shown in FIG. 4, the FET 30 used here includes a substantially rectangular parallelepiped main body 32 and at least three terminals (a drain terminal, a source terminal 34, and a gate terminal 36, not shown). Among the terminals, the drain terminal is provided on the back surface of the main body 32, and the source terminal 34 and the gate terminal 36 protrude from the side surface of the main body 32 and extend downward.

  Corresponding to the FET 30, each through hole 22 of the control circuit board 20 has a rectangular portion 22a through which the body 32 of the FET 30 can be inserted, and a source terminal of the FET 30 extending in a predetermined direction from the rectangular portion 22a. 34 includes an extending portion 22b having a shape that can be inserted. The FET main body 32 is mounted on the bus bar 11 by bringing the drain terminal on the back surface of the FET main body 32 directly into contact with the upper surface of the bus bar 11 for input terminals of the bus bar constituting plate 10 through the rectangular portion 22a, and the extending portion. The source terminal 34 of the FET 30 is connected to the output terminal bus bar 12 through 22 b, and the gate terminal 36 of the FET 30 is connected to an appropriate conductor pattern on the control circuit board 20.

  That is, in this mounting process, all the FETs 30 can be simultaneously mounted on both the control circuit board 20 and each bus bar from the upper side, and both the FETs 30 are positioned at a position between the bus bar board and the control circuit board as in the prior art. The assembly work efficiency is dramatically improved as compared with the method of separately connecting to the substrate via the wiring members.

  This mounting process can be performed simply by, for example, applying molten solder in each through-hole 22 by printing or the like and placing the FET 30 thereon.

  In performing this mounting process, it is more preferable to provide a step t substantially equal to the thickness of the control circuit board 20 between the source terminal 34 and the gate terminal 36 in advance as shown in FIG. . In this way, regardless of the thickness of the control circuit board 20, the terminals 34 and 36 are directly connected to the output terminal bus bar 12, the control circuit board 20, and the like without causing excessive deformation of the terminals 34 and 36. The stress of each terminal after mounting can be greatly reduced.

  Further, when there is a bus bar to be directly connected to the control circuit of the control circuit board 20 in the bus bar included in the bus bar constituting plate 10, for example, an appropriate protrusion is formed from the bus bar as shown in part A of FIG. The protrusion may be made to be soldered to the control circuit board 20 side.

4) Bending process Bus bar end portions (including at least the end portions 11a, 12a, and 14a of the bus bars 11, 12, and 14 in the drawing) protruding from the control circuit board 20 to the left and right sides are bent upward as shown in FIG. Thus, a terminal connected to an external circuit is formed. By performing such a bending process, it becomes possible to connect the external wiring material to each terminal from one direction, and the connection work is simplified.

5) Housing mounting process (connector formation process 1)
As shown in FIG. 7, a housing 40 made of an insulating material such as a synthetic resin is provided around a plurality of signal input terminals (in the figure, the end portions 14a of the signal input terminal bus bars 14 are arranged in a horizontal row). Secure to form the connector. A protrusion 42 for engaging with a case 50 described later is formed on the side surface of the housing 40.

6) Separation process The bus bars in the bus bar constituting plate 10 are separated by a press or the like to complete the power circuit. Specifically, the connecting portion 18 exposed to the outside of the control circuit board 20 may be cut and removed. The removal of the connecting portion 18 inevitably removes the outer frame 16 from the circuit structure. In the state after the separation step, the overall height dimension (thickness dimension) is very small, and the occupied area is suppressed to be almost equal to the area of the control circuit board 20. This circuit component can be used alone, but by adding a case 50 and a heat radiating member 60 to be described later, it becomes possible to further improve waterproofness and heat radiating properties, such as a vehicle power distributor. A circuit body suitable for the above can be obtained.

  In addition, you may perform this isolation | separation process before the said process 3) -5). However, when the bus bar end portions 11a, 12a, and 14a constituting the terminal are connected to the outer frame 16 or another bus bar, it is necessary to perform the disconnecting step first.

7) Case mounting process (connector formation process 2)
A case 50 (FIG. 9) made of an insulating material such as a synthetic resin is placed on the circuit structure obtained in the separating step 6) from the upper side. The case 50 has a shape that opens downward and covers the entire control circuit board 20 from above. An opening that opens the FET 30 upward is provided at the center, and the case 50 faces upward from the periphery of the opening. A waterproof wall 52 is erected. That is, the waterproof wall 52 surrounds the region including the FET 30.

  A cylindrical housing 54 and a housing mounting portion 56 that are open vertically are formed integrally with the case 50 at both left and right edge portions of the case 50 (the left and right outer portions of the waterproof wall 52). The housing 54 is formed at a plurality of locations, and individually surrounds the end portion 11a (input terminal) of the input terminal bus bar 11 and the end portion 12a (output terminal) of the output terminal bus bar 12, and a connector is connected with these terminals. Constitute. The housing mounting portion 56 is formed at a position corresponding to the housing 40 (housing surrounding the signal input terminal). The housing 40 is inserted into the housing mounting portion 56 from below, and the projection 42 on the side wall of the housing 40 is formed. By engaging the upper end of the housing mounting portion 56, the bus bar and the control circuit board 20 are locked to the case 50.

  In this structure, for example, by connecting a connector provided at a terminal of a wire harness routed to a vehicle to a connector constituted by the terminals and the housings 40 and 54, the terminal and an external circuit are connected. It can be easily connected.

  Note that a plurality of fin covers 58 arranged side by side protrude downward from both front and rear ends of the case 50.

8) Heat radiating member connection process The upper surface 64 of the heat radiating member 60 as shown in FIG.

  The heat dissipating member 60 is entirely formed of a material having excellent thermal conductivity such as an aluminum-based metal, has a flat upper surface 64, and a plurality of fins 62 arranged side by side project downward from the lower surface. The positions of the fins 62 correspond to the positions of the fin covers 58 in the case 50, and the longitudinal ends of the fins 62 are covered with the fin covers 58 by mounting the heat radiating members 60.

  The adhesion between the heat radiation member 60 and the bus bar is preferably performed by the following procedure, for example.

  8-1) An insulating adhesive made of an epoxy resin is applied to the upper surface 64 of the heat radiating member 60 and dried to form a thin insulating layer.

  8-2) Applying an adhesive that is softer and higher in thermal conductivity than the material constituting the insulating layer (for example, a grease-like material such as a silicone-based adhesive) over the insulating layer, or The adhesive is applied to the bus bar side, and the bus bar is bonded with the adhesive.

  Here, although the insulating layer of 8-1) is not necessarily required, the amount of the expensive adhesive of 8-2) (soft adhesive having excellent thermal conductivity) is minimized by forming the insulating layer. Thus, it is possible to ensure reliable electrical insulation while keeping the pressure on the surface. Further, the insulating layer 8-2) can be formed, for example, by sticking an insulating sheet on the upper surface 64 of the heat dissipation member 60.

  When the bus bar includes a thing to be grounded, the heat radiating member 60 may be screwed to the bus bar and fixed, and the heat radiating member 60 may be connected to the ground.

  In addition to the adhesion between the bus bar and the heat radiating member 60, it is preferable that the case 50 and the heat radiating member 60 are provided with engaging portions that engage with each other, for example, and the heat radiating member 60 is fixed to the case 50. Further, by interposing a sealing material made of silicon rubber or the like between the case 50 and the heat radiating member 60, the waterproofness of the circuit structure is further enhanced.

9) Potting process The inside of the waterproof wall 52 is sealed by covering the upper end of the waterproof wall 52 with a cover 70 as shown in FIG. 11 and joining them together (for example, vibration welding). Further, as shown in FIG. 12, the inside of the waterproof wall 52 is sealed by injecting an appropriate potting agent from a potting agent injection port 72 provided in the cover 70. Thereby, the waterproof effect of a circuit structure will be further improved.

  In the circuit structure manufactured as described above, a power source is connected to the input terminal (end portion 11a of the input terminal bus bar 11), and an electric load is connected to the output terminal (end portion 12a of the output terminal bus bar 12). As a result, a power distribution circuit that distributes power from the power source to an appropriate electrical load is constructed, and the operation of the FET 14 provided in the middle of the power distribution circuit is controlled by a control circuit incorporated in the control circuit board 20. Thus, on / off control of energization of the power distribution circuit is executed.

  In the bonding step, when an insulating adhesive is applied to the back surface of the control circuit board 20 or the top surface of the bus bar component plate, the insulating adhesive may be applied only to one of these surfaces, As shown in FIG. 13, the control circuit board 20 and the portion overlapping the control circuit board 20 on the upper surface of the bus bar (only the input terminal bus bar 11 is shown as an example in the figure, but the same applies to other bus bars). If the adhesive 80 is applied to both of the lower surfaces of the end portions, more reliable bonding can be achieved.

  Further, when the control circuit board 20 has a through-hole connecting portion 24 as shown in FIG. 14, an electrical connection is made by arranging an adhesive 80 avoiding the through-hole connecting portion 24 as shown in FIG. The control circuit board 20 and the bus bar 11 can be bonded together while ensuring reliability.

  This also applies to the case where the bus bar 11 and the control circuit board 20 are electrically connected by soldering using the through-hole connecting portion 24. For example, as shown in FIG. 15A, when the difference between the width of the through-hole connecting portion 24 and the width D of the bus bar 11 is small (the bus bar width D is relatively small), before and after the through-hole connecting portion 24 The adhesive 80 may be provided only when the bus bar width D is sufficiently large as shown in FIG. 5B, and the adhesive 80 may be provided so as to surround the through-hole connecting portion 24.

  Also, as shown in FIG. 16, when the side surface of the bus bar 11 and the lower surface of the control circuit board 20 are electrically connected by soldering 26, the adhesive 80 is disposed so as to avoid the soldering 26 region. It is preferable to do this.

  The circuit structure according to the present invention is not limited to the one manufactured by the above method, and at least has a structure in which a semiconductor switching element is mounted on the bus bar with the bus bar adhered to the surface of the control circuit board. Thus, the effects of simplification and thinning of the overall configuration can be enjoyed.

  In addition, the semiconductor switching element used in the present invention is not limited to the FET, but may include an energization terminal connected to the power circuit side formed by a bus bar and a control terminal connected to the control circuit board 20 side. Widely applicable.

It is a perspective view which shows the bus-bar structure board and control circuit board which are used for manufacturing the circuit structure concerning embodiment of this invention. It is a perspective view which shows the state which adhere | attached the said bus-bar structural board and the control circuit board. It is a perspective view which shows the state which mounted FET on the said bus-bar structure board and a control circuit board. It is an expanded sectional perspective view which shows the mounting state of the said FET. It is a perspective view which shows the direct connection location of the said bus-bar structure board and a control circuit board. It is a perspective view which shows the state which bent the edge part of the predetermined | prescribed bus bar in the said bus-bar structural board upwards. It is a perspective view which shows the state which provided the housing around the edge part of the bent bus bar for signal input terminals, and formed the connector. It is a perspective view which shows the state which removed the outer frame from the said bus-bar structural board, and cut | disconnected bus bars. It is a perspective view which shows the state which mounted | wore the said control circuit board and the bus bar. It is a perspective view which shows the circuit structure body with which the said case was mounted | worn, and the heat radiating member with which this is mounted | worn. It is a perspective view which shows the circuit structure body with which the said heat radiating member was mounted | worn, and the cover with which the waterproof wall of the case is mounted | worn. It is a perspective view which shows the process of inject | pouring a potting agent from the potting injection hole of the attached cover. It is sectional drawing which shows the example of the adhesive agent application area | region in the said adhesion process. (A) is a bottom view showing an example of an adhesive application region when a through-hole connection portion is present on the control circuit board in the bonding step, and (b) is a cross-sectional view taken along line AA in (a). (A) and (b) are bottom views which show the example which applies an adhesive agent avoiding a through-hole connection part. It is a bottom view which shows the example which applies an adhesive agent avoiding a soldering connection part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Bus-bar component board 11 Bus bar for input terminals 12 Bus bar for output terminals 14 Bus bar for signal input terminals 16 Outer frame 18 Connecting part 20 Control circuit board 22 Through-hole 30 FET (semiconductor switching element)
32 FET body 34 Source terminal (energization terminal)
36 Gate terminal (control terminal)
40 Housing 50 Case 52 Waterproof Wall 54 Housing Formed in Case 60 Heat Dissipation Member 70 Cover 72 Potting Agent Injection Port

Claims (11)

  A plurality of bus bars constituting a power circuit, a semiconductor switching element provided in the power circuit, and a control circuit board for controlling driving of the semiconductor switching element, wherein the bus bars are arranged on substantially the same plane And a part of the terminals of the semiconductor switching element are connected to the surface of the control circuit board opposite to the surface to which the bus bar is adhered. The substrate has a portion that exposes the bus bar on the side opposite to the side to which the bus bar is bonded, and a circuit configuration in which the energization terminal of the semiconductor switching element is connected to the bus bar through this portion. body.   2. The circuit structure according to claim 1, wherein the semiconductor switching element has the energization terminal on a back surface of the main body, and the control circuit board exposes the bus bar on a side opposite to the side to which the bus bar is bonded. The portion of the semiconductor switching element has a size that can be inserted as a portion to be inserted, and the main body of the semiconductor switching element is in contact with the bus bar through the portion with the energization terminal on the back surface of the semiconductor switching element in contact with the bus bar. A circuit structure characterized by being mounted on top.   3. The circuit structure according to claim 1, wherein a plurality of bus bars protrude from the control circuit board to a side to constitute a terminal connected to an external circuit. 4.   4. The circuit structure according to claim 3, wherein the bus bars constituting the terminals are bent in the same direction and substantially perpendicular to the control circuit board.   5. The circuit structure according to claim 4, wherein a connector is formed by providing a housing made of an insulating material around the terminal.   6. The circuit structure according to claim 5, comprising a case made of an insulating material and housing the bus bar and the control circuit board, and at least a part of the housing is formed integrally with the case. Construct.   7. The circuit structure according to claim 6, wherein a waterproof wall surrounding the region including the semiconductor switching element is erected on the case, and the inside of the waterproof wall is potted in a state where the opening of the waterproof wall is closed with a cover. A circuit structure which is sealed with an agent.   8. The circuit structure according to claim 3, wherein the terminal includes an input terminal connected to a power source and a plurality of output terminals connected to an electrical load, and the plurality of bus bars are the input. A circuit structure comprising a power distribution circuit that outputs power supplied to a terminal from the output terminal to the electrical loads.   9. The circuit structure according to claim 3, wherein the terminal includes a signal input terminal to which a command signal is input from the outside, and a bus bar configuring the signal input terminal is provided on the control circuit board. A circuit structure characterized by being electrically connected to a control circuit.   The circuit structure according to any one of claims 1 to 9, wherein a heat radiating member is provided on a side opposite to the control circuit board across the bus bar, and the bus bar is connected to the heat radiating member via an insulating layer. A circuit structure characterized by that.   It is a semiconductor switching element used for the circuit composition object according to any one of claims 1 to 10, and has an energization terminal mounted in the bus bar, and a control terminal mounted in the control circuit board. A semiconductor switching element, wherein a step substantially equal to the thickness of the control circuit board is provided between the energization terminal and the control terminal.

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