JPS5937879B2 - Manufacturing method of printed wiring board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a flash type printed wiring board (a flat type in which the surface of a conductor pattern is different from the surface of other parts).

This flash type printed wiring board is used for printed wiring boards that are inconvenient when there is a step in the conductor pattern, such as a printed wiring board that constitutes a rotary switch. Manufactured by either.

The push-in type is made by applying an adhesive such as phenol or epoxy to prepreg (a mat made of paper or glass fiber impregnated with phenol or epoxy, which is not completely cured). , the conductor pattern is pushed into the adhesive layer by heating, pressing, etc. while the adhesive layer is not cured, and the surface is flattened. The mold type is a method in which a normal type (conductor pattern protrudes above the board) printed wiring board is manufactured, and the parts other than the conductor pattern are molded with an insulator to make the surface flat. be. In addition, the polished type is
This involves scraping off the protrusions (conductor pattern parts) on the surface of the reprinted wiring board using a polishing machine or the like. Conventionally, among these, the first-mentioned push-in type has been widely used.

By the way, in the case of this push-in type, a conductor pattern must be formed on the semi-cured adhesive layer, but this is done by an etching method. However, when using the etching method, the adhesive layer is semi-cured, so the adhesive may deteriorate due to etching liquid, resist, etc., or the conductor pattern may be easily deformed because the adhesive layer is semi-cured. There are some very difficult aspects of the above. An object of the present invention is to provide a method for manufacturing a flash type printed wiring board that is advantageous in terms of manufacturing cost by applying a die stamping method.

An embodiment of the present invention will be described below with reference to the drawings.

First, as shown in FIG. 1, an adhesive is applied to one surface of a substrate 1 to form an adhesive layer 2. For example, phenol resin can be used as the adhesive, and the thickness of this adhesive layer 2 is as follows:
10 to 15 times thicker than the thickness of the conductor pattern that will be pushed in later.
It is assumed to be about μm thick. On the adhesive layer 2 side, a conductor foil 3 having a thickness of about 35 μm is die-stamped with a blade 4 that follows the shape of the conductor pattern. The temperature of this blade mold 4 is set to such a level that the adhesive flows (suddenly softens).
The temperature shall be 0 to 150°C. In this way, a conductor pattern 31 is formed on the adhesive layer 2 as shown in FIG. This conductor pattern 31 is pressed into the adhesive layer 2 to some extent. Next, as shown in FIG. 3, the adhesive layer 2 side is pressed by a hardening stainless steel plate 5 with a flat surface to push the conductive pattern 31 into the adhesive layer 2 and harden the adhesive layer 2. . The pressure of the stainless steel plate 5 is set to 0.1 t0n/d or more, and a separator 6 made of polypropylene or Teflon film with a thickness of about 30 μm or less is arranged between the stainless steel plate 5 and the adhesive layer 2 side. Then, as shown in FIG. 4, the conductor pattern 31 is pushed into the cured adhesive layer 2, and a printed wiring board with a flat surface is obtained.

According to the prototype experiment, it was found that it is possible to manufacture a flat-tube printed wiring board in which the level difference between the surface of the conductor pattern 31 and the adhesive layer 2 is 5 μm or less. There is no molding or molding process, and the conductor pattern is pressed in at the same time as the process of curing the adhesive layer, which simplifies the manufacturing process and, as a result, reduces manufacturing costs. Further, since the conductor pattern is formed by the die stamping method, the problems caused by the conventional etching method are solved, and problems such as deformation of the conductor pattern do not occur.

[Brief explanation of drawings]

1, 2, 3} and 4 are sectional views showing each process for explaining a method of manufacturing a flash type printed wiring board according to an embodiment of the present invention. 1...Substrate, 2...Adhesive layer, 3...
...Conductor foil, 31...Conductor pattern, 4.
...Blade type, 5...Stainless steel maple for hardening
6...Separator.

Claims (1)

[Claims] 1 After forming an adhesive layer on the substrate, die-stamping the conductor foil with a predetermined blade type to form a conductor pattern on the adhesive layer side, and then pressing the adhesive layer side with a flat surface curing press plate. The print is characterized in that the conductor pattern is pressed into the adhesive layer to make the surface of the conductor pattern flat against the surface of the adhesive layer, and the adhesive layer is cured. Method of manufacturing wiring boards.