JPS6290999A - Manufacture of molded product including printed circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention [Industrial Application Field] The present invention relates to a method for manufacturing a molded article having a three-dimensional printed circuit on its surface.

[Prior Art 1] There are cases where it is desired to form an electric or electronic circuit (hereinafter simply referred to as a "circuit") on the surface of a synthetic resin molded product.

As a method for forming circuits, a so-called printed circuit board manufacturing method is widely practiced in which copper foil pasted on a board is etched, leaving only the necessary portions. This is a wet process that is time consuming and difficult to apply to bulky molded products.

Instead of etching, there is a method of forming a circuit by printing a conductive paste by a method such as screen printing, and this method is used for In such as membrane switches. Although this technique can certainly be applied to molded products, it cannot be printed on unless it is a flat surface, and it is difficult to implement depending on the shape.

Another drawback is that it requires a drying process after printing.

By using a method of transferring circuits to molded products using a transfer sheet that is printed on a base film in advance, it can be applied to three-dimensional objects such as boxes, and it can also be applied to curved surfaces. It's not impossible either. However, this method requires a two-step process, molding the molded product and transferring the circuit, and requires a press die for transfer in addition to the mold, especially when transferring to a curved surface. It is.

[Problems to be Solved by the Invention] The object of the present invention is to solve the problem of the surface of a three-dimensional synthetic resin molded product, regardless of whether it is formed by intersecting planes or a curved surface. Another object of the present invention is to provide a method by which a circuit having a desired three-dimensional shape can be formed using simple equipment and processes.

Structure of the Invention (Means for Solving the Problems) As shown in FIG. A transfer sheet having the following properties is preformed as shown in FIG. 2, and this transfer sheet preform is
As shown in FIG. 3, the molded product 3 is placed in injection molding molds 2A and 2B, and molten synthetic resin is injected into the molds.
1d and at the same time, a three-dimensional printed circuit 12 is formed on the surface to obtain a product as illustrated in FIG.

The basic structure of the transfer sheet is that it is sufficient to have a printed circuit on a base film, but if necessary, a release layer is provided between the base film and the circuit, and an adhesive layer is provided on the printed circuit.

The material of the base film is polyvinyl chloride, polyamide,
Polyvinylidene chloride, polypropylene, polyurethane,
A single film or a laminate of a plastic film having relatively good heat resistance and moldability, such as polycarbonate, polystyrene, polysulfone, polyarylate, or polyethersulfone, is preferable. If the shape has less aperture,
Polyester can also be used.

The material for the release layer is preferably a thermoplastic resin such as polyvinyl chloride, acrylic, polyamide, nitrocellulose, polyurethane, or polyvinyl acetate, or a thermosetting resin such as melamine, phenol, or polyurethane. To form the release layer, roll coating, gravure printing, silk screen printing, or any other method may be used.

There are two types of release layers: one that remains on the base film side after transfer, and the other that moves to the printed circuit side, and is selected depending on the intended use of the molded product. If it is transferred to the printed circuit side, it can also be used as circuit protection ff1W. If necessary, do not print a release layer on the parts where the terminal or parts will be attached.

The printed circuit is formed by printing conductive ink on the base film or on the release layer using a method such as screen printing, gravure printing, or offset printing. The printed resistor and the melon protective layer may be formed simultaneously with the formation of the printed circuit.

Conductive ink is AU, Pd, Act, Ni, CLI
A metal powder such as or C powder is kneaded with a binder to prepare the mixture. The binder is mainly composed of synthetic resins, such as thermosetting resins such as epoxy and phenol, polyolefins, polyurethanes, polyesters, etc.
An appropriate thermoplastic resin such as polyamide is selected and used. If the transfer film has a large elongation due to preforming, it is better to use a thermoplastic resin binder. This is because the thermosetting resin binder cannot follow a large elongation, and even if it appears to be elongating uniformly, the conductivity of the conductive ink often decreases.

If it is desired to ensure the adhesion between the printed circuit and the molded product, an adhesive layer may be provided on the printed circuit.

This increases the degree of freedom in combinations of conductive ink and molding resin.

As the material of the molded article, any thermoplastic resin or thermosetting resin that can be injection molded can be used.

Preforming of the transfer sheet is performed by a molding method selected from vacuum forming, pressure forming, vacuum pressure forming, and mated die molding. If an injection mold is used as the mold for vacuum and/or pressure molding, the equipment will be simplified.

The process of placing a preformed body of a transfer sheet in an injection mold and performing injection molding itself is known as so-called [Function molding J], and the present invention may also be carried out according to that technique.

[Function] According to the manufacturing method of the present invention, molding of a synthetic resin molded product and printing of a circuit can be performed in one step, and a molded product of any three-dimensional shape can have a three-dimensional circuit on any surface thereof. product is obtained.

There is also a method of placing the transfer film in an injection mold without preforming it and creating a three-dimensional shape using the heat and pressure of the injected resin, but this method has the following limitations.

* Since the transfer film is stretched without applying sufficient heat, it is difficult to maintain the conductivity and stability of the printed circuit.

* Because uniform heat cannot be applied, the Furukawa characteristic of the pattern is low, making it unsuitable for producing complex shapes.

Therefore, preforming of a transfer film is essential for forming a printed circuit with high performance and reliability as an electric circuit on the surface of a molded product having a complex three-dimensional shape.

[Example] A conductive ink prepared by kneading AQ powder with a binder mainly composed of acrylic resin was silk screen printed on a 100μ thick polycarbonate film having a release layer formed by coating with nitrocellulose resin. A transfer sheet was prepared by printing a desired circuit pattern using a method.

This transfer sheet was heated with a hot platen at a temperature of 170'C, preformed by vacuum-pressure molding, placed in an injection mold, and ABS resin was injection-molded at a resin temperature of 220'C.
This was taken out from the mold and the base film was peeled off to obtain a molded product having a three-dimensional shape and a printed circuit on its surface.

A three-dimensional circuit was firmly formed in a predetermined position on the surface of the molded product.

Effects of the Invention According to the method of the present invention, a molded article having a printed circuit can be manufactured in a simplified and easily automated process.
There are no restrictions on the shape of the molded product or the shape of the surface on which the printed circuit is provided. When forming a printed circuit in a three-dimensional shape that includes a curved surface, there is no need for a stamping die for transfer, so the product cost is low. Further, this method itself is a dry process, and the wet process is only carried out in the manufacturing process for the transfer sheet 1, so it is easy to maintain a good working environment.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing the basic structure of a transfer sheet used in the manufacturing method of the present invention. Figures 2 and 3 are cross-sectional views for explaining the manufacturing process of the present invention, with Figure 2 showing the transfer sheet preformed, and Figure 3 showing the transfer sheet preformed body being injection molded. Each is shown where it is placed in the mold. FIG. 4 is a cross-sectional view of a molded article having a printed circuit manufactured by the method of FIGS. 2 and 3. FIG. 1...Transfer sheet 11...Base film 12...Printed circuit 2A, 2B...Injection mold 3...Patent applicant for molded product having printed circuit Patent attorney for Dainippon Printing Co., Ltd. Souo Suga Figure 1 Figure 2 Figure 3

Claims (2)

[Claims] (1) Preform a transfer sheet with a printed circuit formed with conductive ink on a base film, place this transfer sheet preform in an injection mold, and pour molten synthetic resin into the mold. A method for manufacturing a molded article having a printed circuit, characterized by forming a three-dimensional printed circuit on the surface of the molded article at the same time as the molded article is obtained by injection. (2) Preforming the transfer sheet by vacuum forming, pressure forming,
The manufacturing method according to claim 1, which is carried out by a molding method selected from vacuum-pressure molding and mated die molding.