JPH02224289A - Formation of three-dimensional molded circuit - Google Patents

Abstract

PURPOSE:To simplify a process by bonding a conductive metal foil to a flexible unhardened resin plate, and molding into a desired shape by bending and squeezing the unhardened resin plate after a circuit pattern is formed. CONSTITUTION:A conductive metal foil 11 is pasted onto a flexible unhardened resin plate 10, and a desired circuit pattern 12 is formed by etching. Next, the unhardened resin plate 10 is bent and squeezed by a pair of press molds and molded into a desired shape such as a box-shaped case 13. The resin 10 is hardened at the same time as for the processing, thus a three-dimensional molded circuit is formed. As a result, even a complex pattern can be formed easily, and the process is shortened and simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for forming a three-dimensional molded circuit using the wall surface of a case of an electrical device such as an electrical connection box or an instrument panel.

[Prior Art] A busbar wiring board or a printed wiring board is usually used for the internal circuit of an electrical junction box of a vehicle. However, as the number of on-vehicle electrical components increases, the mounting space for connection devices and control devices such as electrical connection boxes tends to decrease more and more, and there is a demand for their miniaturization.

Therefore, attempts have been made to save space by forming a three-dimensional molded circuit using the inner and outer walls of the case instead of the conventional printed wiring board.

FIG. 2 awd shows a conventional circuit forming method.

First, as shown in a, the case 1 is injection molded using a catalyst-containing compound 2 for electroless plating.

At that time, the portion corresponding to the circuit section 3 is made to protrude in advance.

Next, a compound 2' that does not contain a catalyst is injection molded thereon (b), the circuit part 3 is left as is, and the catalyst is attached only to the circuit part 3 on the surface of the molded product (case) 1. There is.

Furthermore, as shown in C, the surface of the circuit section 3 is roughened 3' with a treatment liquid such as chromic acid to improve the adhesion of the plating.

Finally, electroless plating is applied to the circuit portion 3' whose surface has been roughened to form a circuit 4.

[Problem to be solved by the invention]

In the conventional method, two sets of molds are required for two injection moldings, making the process complicated, and expensive catalysts for electroless plating are partially unused (see Figure 2a). ), had the disadvantage of high cost.

An object of the present invention is to provide a method for forming a three-dimensional molded circuit without such drawbacks.

[Means to solve the problem]

In order to achieve the above object, in the present invention, a conductive metal foil is bonded to a flexible uncured resin plate, and a circuit is formed on the conductive metal foil by etching. After the pattern was formed, the uncured resin plate was subjected to bending, drawing, etc. to be formed into a desired shape.

The above-mentioned object is also achieved by carrying out the method according to claim 2.

The above configuration will be specifically described below with reference to drawings showing examples.

〔Example〕

1a to 1d show the process of forming a three-dimensional molded circuit according to the present invention.

In FIG. 1a, numeral 10 denotes an uncured resin plate, which is formed and cut into a plate shape according to the dimensions of a product to be molded, such as a case for an electrical connection box. Uncured resin is a resin in the stage before being hardened by crystallization, such as crystalline polyester, and has flexibility and is easy to draw and bend.

Next, as shown in FIG. 1, a conductive metal foil 11 such as copper foil is pasted onto the uncured resin plate 1O using an adhesive, double-sided adhesive tape, or the like.

Subsequently, as shown in FIG. 1C, a desired circuit pattern 12 is formed by etching. Etching is metal foil 1.1
A conductive circuit mask (
(not shown), and then the metal foil 11 in non-mask areas is dissolved and removed using an etching solution using a known method.

Finally, as shown in FIG. 1d, the uncured resin plate 10 is bent and drawn using a pair of press dies (not shown) to form a desired shape such as a box-shaped case 13. Simultaneously with processing, the resin is heated, for example, at 160 to 180°C for several seconds to crystallize and harden. As a result, a three-dimensional molded circuit 12' is formed.

Instead of the method using the conductive metal foil 11 described above, a catalyst for electroless plating is printed on the uncured resin plate 10 by a known method such as screen printing along a predetermined circuit pattern, and After bending and drawing in the same manner as in FIG. 1d, the catalyst may be subjected to electroless plating to form a three-dimensional molded circuit.

Electroless plating is a chemical plating method that utilizes reduction by contact action (catalyst) on the surface of the material, and since the film is generally thin, electrolytic plating is further applied to adjust the thickness of the circuit conductor to the desired current value. It is desirable to form layers in a corresponding manner.

[For production]

As shown in FIG. 1C, since the circuit pattern 12 is first provided on the flat uncured resin plate 10, even complex patterns can be easily formed.

Three-dimensional molding of the circuit pattern 12 is performed simultaneously with a molding process including a hardening process by crystallizing the uncured resin plate 10, as shown in FIG. 1d.

Therefore, the process of the present invention is shorter and simpler than conventional forming methods, and only one molding die is required.

When the circuit pattern 12 is a conductive metal foil such as copper foil, a three-dimensional molded circuit with a large current capacity can be obtained as is.

In addition, when the circuit pattern 12 is formed by a combination of electroless plating and electrolytic plating, the followability during molding of the uncured resin plate 10 is good, and by keeping the pattern width constant and changing the plating thickness, various It is possible to form a circuit conductor according to the current capacity of the circuit.

(Effects of the Invention) As described above, according to the present invention, it is possible to form a three-dimensional molded circuit using the wall surface of the case at low cost through fewer steps.

[Brief explanation of the drawing]

1A to 1D are explanatory diagrams of the formation process of a three-dimensional molded circuit according to an embodiment of the present invention, and FIGS. 2A to 2D are explanatory diagrams of a conventional example, respectively. 10... Uncured resin plate, 11... Conductive metal foil, 1
2...Circuit pattern, 13...Case.

Claims (2)

[Claims] (1) A conductive metal foil is bonded to a flexible uncured resin plate, a circuit pattern is formed on the conductive metal foil by etching, and then the uncured resin plate is bent, drawn, etc. as desired. A method for forming a three-dimensional molded circuit, characterized by molding it into a shape. (2) After printing an electroless plating catalyst along a predetermined circuit pattern on a flexible uncured resin plate, bending the uncured resin plate, drawing, etc., and forming it into the desired shape,
A three-dimensional molded circuit characterized in that a circuit is formed by subjecting the catalyst to electroless plating, and the circuit is electrolytically plated as necessary to form a circuit conductor to a thickness corresponding to a desired current value. Formation method.