JP2004135495A - Circuit body and junction box housing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a circuit body to be housed in a junction box. <P>SOLUTION: The circuit body is formed by using a high conductive resin, in which a metallic fiber or a metallic powder with a low melting point to be joined like a network by melting is dispersed in a thermoplastic resin, and an insulating resin. The circuit body is constituted as follows. A substrate part is formed by executing the first injection molding by a mold (first color) with the insulating resin. A conductive part is formed by executing the second injection molding by another mold (second color) with the high conductive resin to the substrate part. The substrate part and the conductive part are integrally formed in a flat plate shape with two steps. The conductive part made of the high conductive resin is embedded to the substrate part made of the insulating resin in a state that the surface of the conductive part is exposed. The conductive part is made into a required circuit shape. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a circuit body and a junction box accommodating the circuit body, and is particularly suitably used in a junction box connected to a wire harness for an automobile.

In recent years, with the rapid increase of electrical components mounted on automobiles, the number of parts required to increase the number of parts in order to form branch circuits with high density, due to the rapid increase in the number of electrical junction boxes for automobiles, especially the circuits accommodated inside junction boxes. It has become very large, and the assembling work is very time consuming.

In the junction box 1 shown in FIG. 6 among the electric connection boxes for automobiles, bus bars 5A to 5D are stacked and arranged between the upper case 2 and the lower case 3 with insulating plates A to 4E interposed therebetween. Further, an insulating plate 15 provided with wire guide grooves at both upper and lower ends is arranged, and the wires 6A and 6B are laid and housed on the insulating plate 15, and a connector housing portion provided on the upper case 2 and the lower case 3; The terminals of the relay 8, the fuse, and the connector fitted in the relay accommodating portion and the fuse accommodating portion are connected to the tab 7 projecting from the bus bar, and the electric wires 6A and 6B are press-connected to press-contact terminals (not shown). The press contact terminals are connected to terminals of a connector, a relay, and a fuse. Incidentally, although not used in the electric junction box, an FPC having a structure in which a conductor is sandwiched between resin films may be used in combination as an internal circuit.

内部 As described above, the internal circuit of the junction box is mainly of the bus bar type, but the electric wire and the electric wire and the press contact terminal connected to the electric wire may be used together. (4) In the case of the bus bar system, if the number of circuits to be taken into the junction box increases, the number of wiring circuits per layer decreases, and as a result, the number of layers increases, and the junction box becomes large and complicated. In addition, a large number of busbars are required, and they must be formed from a mold according to a change in the circuit, resulting in a very high cost. In addition, an insulating plate must be interposed between the bus bars, which causes a problem that the number of parts and the number of assembling steps increase.

圧 Although the crimping method increases the wiring efficiency and can easily cope with design changes, there is a problem in that the cost of making the insulating plate of the wiring guide is high and the equipment cost is also considerable. In addition, the bus bar method and the pressure welding method are used in combination, and the bus bar layer and the layer including the electric wire and the pressure welding terminal are arranged in layers, and each of them is connected to an external circuit. Also in this case, the above cost is required, and there is a problem that it is difficult to adopt it for a mass-produced car model aiming at low cost.

The present invention has been made in view of the above-described problems, and allows a high-density wiring of an internal circuit of a junction box while changing the bus bar and a circuit including an electric wire and a press-connecting terminal, or by using a bus bar together. It is an object of the present invention to provide a low-cost circuit body suitable for mass sales and a junction box accommodating the circuit body by reducing the problems described above.

In order to solve the above problems, the present invention is a circuit body housed inside a junction box,
A circuit body formed by using an insulating resin and a highly conductive resin in which metal fibers or a low-melting metal powder that is melted and joined in a network is dispersed in a thermoplastic resin, wherein the circuit body is formed. The first injection molding (first color) using a mold is performed with the insulating resin to form a substrate portion, and the substrate portion is subjected to a second injection molding (second color) using another mold to perform the above-described high conductivity. The conductive part is formed by conducting with a conductive resin, and the substrate part and the conductive part are integrally formed into a flat plate shape in two steps,
A circuit body is provided in which the conductive portion made of a highly conductive resin is embedded in a substrate portion made of the insulating resin in a state where the surface of the conductive portion is exposed, and the conductive portion has a required circuit shape. are doing.

That is, as the internal circuit body housed in the junction box, a new circuit body different from the bus bar, the electric wire and the press-connecting terminal, or the FPC used so far is provided. As described above, the circuit body is embedded and formed integrally with the substrate portion made of an insulating resin in a state where the surface of the conductive portion made of a highly conductive resin is exposed. It is formed into a circuit shape.

As described above, when the conductive portion forming the circuit pattern is formed of a highly conductive resin and is integrally formed with the substrate portion, the conductive portion can be efficiently arranged, and the branch circuit can be provided with high density. . In addition, when used in place of a bus bar, it is lightweight and inexpensive.

As disclosed in JP-A-10-237331 and JP-A-11-342522, the conductive resin constituting the circuit pattern contains metal fibers made of copper, nickel, iron, or the like mixed in a thermoplastic resin. And a conductive resin composition in which a low melting point alloy such as lead-free solder (low melting point solder) and Cu powder is dispersed.

As the thermoplastic resin in which conductive metal fibers are blended, propylene, polyethylene, polystyrene, acrylonitrile-butadiene-styrene resin, modified polyphenylene oxide resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyamide resin, aromatic polyamide resin, Resins such as polyphenylene sulfide resin, liquid crystal polymer, polyetherimide, polybenzimidazole, polyetheretherketone, and polyethersulfone can be used alone or in a blend. Particularly, acrylonitrile-butadiene-styrene resin, polybutylene Terephthalate resin is preferably used.

As the low melting point alloy to be mixed and dispersed in the thermoplastic resin and bonded in a network, an alloy having a melting point of 100 ° C. or higher, preferably 200 ° C. or higher and melting at the time of injection molding is used. -Ag-Pb system, Sn-Bi system, Sn-Bi-In system, Bi-Pb system, Bi-Sn system, Sn-Cu system, Sn-Cu-Ni-P system, Sn-Ag system, Sn-Bi -Pb-based and Sn-In-based ones.

As described above, in the circuit body using the highly conductive resin as the conductive portion, the first injection molding (first color) using a mold is performed using an insulating resin to form a substrate portion. The second injection molding (second color) is performed with a highly conductive resin to form a conductive portion, and in two steps, a circuit body in which the substrate portion and the conductive portion are integrated into a flat plate shape is formed. I have.

The circuit body has a substantially flat plate shape, and at least one of the two surfaces is an insulating surface composed of only an insulating resin layer.
Therefore, when the above-mentioned circuit bodies are accommodated in a stacked state inside the junction box, there is no need to interpose an insulating plate between these circuit bodies, and the conductive portion of one of the adjacently laminated circuit bodies is exposed on the surface. It is sufficient that the surface to be laminated and the insulating surface of the other circuit body are brought into contact with each other and laminated. As described above, since the insulating plate is not required, the number of parts and the number of assembling steps can be reduced, and the size of the junction box can be reduced.

た め Further, since the conductive portion is provided by injection molding, a three-dimensional circuit can be formed. Therefore, for example, the first circuit conductive part and the second circuit conductive part of the conductive part exposed on the surface are connected via the internal conductive part provided inside the insulating resin, and the internal conductive part is formed. As the jumper wire, the third circuit portion existing between the first circuit conductive portion and the second circuit conductive portion can be bypassed and connected. Therefore, a jumper wire was conventionally required, but this can be eliminated, and various circuit configurations can be realized by one circuit body.

The present invention provides a junction box that houses the above circuit. Although only the above-mentioned circuit body may be used as the internal circuit of the junction box, an internal circuit consisting of a bus bar is stacked and arranged together with the circuit body, and the bus bar is a large current circuit, while the circuit body is a medium / small current circuit. It may be a circuit.

Further, together with the above-mentioned circuit body, an internal circuit consisting of a bus bar, an internal circuit consisting of an electric wire and a press contact terminal for press-connecting to the electric wire are housed, and the bus bar has a large current circuit, an electric wire and a press contact terminal and a medium current circuit, The circuit body may be a small current circuit.

As is apparent from the above description, according to the present invention, as the internal circuit of the junction box, a circuit board in which a conductive portion made of a highly conductive resin is integrally formed with a substrate made of an insulating resin is used. High degree of freedom, high-density wiring is possible, and reduction in size and weight of the electric junction box can be achieved. In addition, by using the circuit board, the number of bus bars used can be reduced, and accordingly, the cost can be reduced.

An embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is an exploded perspective view of a junction box 10 connected to a wire harness for an automobile, 11 is an upper case, 12 is a lower case, 13 (13A and 13B) is a circuit body, 14 is a bus bar, and 15 is a unit for press-fitting. A core wire, 16 is a press contact terminal, and 17 is a conductive pin.
Although not shown, an insulating plate is interposed between the circuit body 13A and the bus bar 14 which are stacked and arranged adjacent to each other.

The bus bar 14 is used as a large current circuit connected to a power supply, the single core wire 15 is used as a medium current circuit, and the circuit body 13 is used as a small current circuit.

As described above, in the junction box 10, the internal circuit including the bus bar 14, the single core wire 15, and the press-contact terminal 16 is used together with the circuit body 13, but the internal circuit may be configured only with the circuit body 13. Although the circuit body 13 has two layers in the drawing, it is needless to say that the circuit body 13 may have a multilayer structure of two or more layers.

The circuit body 13 (13A, 13B) has a configuration shown in FIGS. 2A, 2B, and 2C, and has a conductive portion 21 made of a highly conductive resin (see FIG. (Indicated by oblique lines) is buried in a state where the surface is exposed, and is integrally formed into a flat plate shape.

表面 The surface 21a of the conductive portion 21 is exposed flush with the upper surface 20a of the substrate portion 20, and has a required circuit shape. The conductive portion 21 is not exposed on the lower surface 20b of the substrate portion 20 and is an insulating surface composed of only an insulating resin layer. The conductive portion 21 is also exposed on the side surface 20c of the substrate portion 20.

As shown in FIG. 3A, a method of manufacturing the circuit body 13 is as follows. First, as shown in FIG. I do. In this state, the conductive part 21 is not provided on the substrate part 20. Then, as shown in FIG. 3 (B), the upper mold 30A is changed to another mold 30C, joined to the lower mold 39B and clamped, and the cavity 32 is provided between the substrate portion 20 and the mold 30C. To form As shown in FIG. 3C, a highly conductive resin is injected into the cavity 32, and the conductive portion 21 is injection-molded. Thus, the circuit body 13 including the conductive portion 21 having a required circuit shape on the surface of the substrate portion 20 is integrally formed.
After forming the conductive portion 21 as a primary molded product, the circuit portion 13 may be formed by secondary forming the substrate portion 20.

(4) Alternatively, as shown in FIG. 4, the conductive portion 21 may be formed three-dimensionally and a jumper wire may be provided inside the circuit body 13. That is, the conductive portion 21-1 of the first circuit and the second conductive portion 21-2 of the conductive portion 21 exposed on the surface are connected via the internal conductive portion 22 provided inside the insulating resin portion. The internal conductive portion 22 is connected as a jumper circuit by bypassing the third circuit portion 21-3 existing between the first circuit conductive portion 21-1 and the second circuit conductive portion 21-2. I have.

(1) The circuit body 13 is housed in a case composed of an upper case 11 and a lower case 12 as shown in FIG. 1 and used as an internal circuit of a junction box. As shown in FIG. 5, the conductive portion 21 of the circuit 13 and the terminals 25 accommodated in the connector accommodating portions 11a, 12a, the fuse accommodating portions 11b, 12b, and the relay accommodating portion 12c provided in the upper case 11 and the lower case 12, respectively. , Via conductive pins 17 having tabs 17a and 17b formed at both upper and lower ends. That is, a pin press-fitting groove 26 is provided in the conductive portion 20 of the circuit body 13, and a tab 17 b at one end of the conductive pin 17 is press-fitted into the pin press-fitting groove 26 to make a surface contact therewith, while the inside of the connector inserted into the connector housing portion The female terminal 29 of the end of the electric wire and the tab 17a at the other end of the conductive pin 17 are fitted and connected. When connecting to a terminal of a fuse or a relay, a female terminal may be provided at one end of the conductive pin 17.

The connection configuration between the conductive part of the circuit body and the terminal of the electric wire, the terminal of the relay or the fuse is not limited to the above, and it goes without saying that another connection configuration may be used.

It is an exploded perspective view of the junction box of an embodiment of the present invention. 2A is a perspective view, FIG. 2B is a view taken in the direction of the arrow X in FIG. 1A, and FIG. 1C is a cross-sectional view. (A) (B) (C) is sectional drawing which shows the manufacturing process of a circuit body, (D) is sectional drawing in the orthogonal direction to (C). It is sectional drawing which shows the modification of a circuit body. (A) (B) is a drawing which shows the connection structure of a circuit board and an electric wire connection terminal. It is an exploded perspective view of the conventional junction box.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 10 Junction box 11 Upper case 12 Lower case 13 (13A, 13B) Circuit body 14 Bus bar 15 Single core wire 17 Conducting pin 20 Substrate part 21 Conductive part 22 Internal conductive part

Claims (2)

A circuit body housed inside the junction box,
A circuit body formed by using an insulating resin and a highly conductive resin in which metal fibers or a low-melting metal powder that is melted and joined in a network is dispersed in a thermoplastic resin, wherein the circuit body is formed. The first injection molding (first color) using a mold is performed with the insulating resin to form a substrate portion, and the substrate portion is subjected to a second injection molding (second color) using another mold to perform the above-described high conductivity. The conductive part is formed by conducting with a conductive resin, and the substrate part and the conductive part are integrally formed into a flat plate shape in two steps,
A circuit body, characterized in that the circuit portion is buried in a substrate portion made of the insulating resin in a state where a surface of the conductive portion made of a highly conductive resin is exposed, and the conductive portion has a required circuit shape. A junction box that houses the circuit body according to claim 1 and is connected to a wire harness for an automobile.

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