JPS61170091A - Manufacture of printed wiring board - 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 [Industrial Application Field] The present invention relates to a method for manufacturing a printed wiring board, and more particularly to an improved method for manufacturing a printed wiring board by a transfer method.

[Prior art] Generally, printed wiring boards are made by bonding copper foil to an insulating substrate.
It is manufactured by an etching method in which a resist pattern is formed on a copper foil, and then the portions of the copper foil where the resist is not applied are removed by etching to form a conductor pattern.

The etching method has the disadvantage that there is a large loss of expensive copper foil and that a precise resist pattern must be formed for each sheet.

In contrast, the transfer method has the advantage that there is no loss of copper foil, and as long as the resist can withstand the plating and transfer steps, printed wiring boards can be mass-produced by simply repeating the plating and transfer steps. However, typical resists for metals or alloys tend to stick or stick to adhesives or uncured substrates during the transfer process, causing the resist to peel off or leaving adhesives or uncured substrates on the resist.
Difficult to use repeatedly. Another major problem with the transfer method is that the plating gets into the unevenness of the cross section of the Renost without any gaps, making it difficult to remove, and when the transfer restoration plate is separated from the substrate, there is a gap between the adhesive and the substrate or the uncured substrate. The plating tends to peel off internally and remain on the original plate. This phenomenon can be greatly improved by making the plated surface of the base plate convex and peeling the base plate while imparting curvature to the base plate, but this is not sufficient.

On the other hand, there are two methods for forming a resist pattern: resist printing and photoresist. However, since there is a limit to printing precision in lenost printing, fine circuits with a wiring width of 150 μm and a width between wires of 100 μm or less can be formed. cannot be obtained, and with the method using photoresist,
Since strong adhesion cannot be obtained and the strength of the resist is therefore insufficient, it cannot be used repeatedly.

[Object of the Invention] One object of the present invention is to provide a method for manufacturing a printed wiring board having a fine circuit by a transfer method.

Another object of the present invention is to provide a method for manufacturing a printed wiring board suitable for mass production, which can obtain a base board that can be used repeatedly.

[Structure of the Invention] The method for manufacturing a printed wiring board of the present invention includes forming grooves on the surface of a metal or alloy plate, leaving a portion corresponding to a conductor pattern;
The surface of the plate is covered with resin so that the resin is embedded in the grooves, the resin surface is ground to expose the remaining metal surface, the exposed metal or alloy surface is plated, and then adhesive is applied onto it. The plating layer is transferred to the substrate by stacking substrates coated on the surface or uncured substrates having adhesive properties and applying pressure.

As the material of the base plate, conventionally used metals or alloys can be used, but stainless steel is most preferable.

Further, an alloy such as brass can also be used, and in this case, chrome plating is applied only to the plated portion.

The grooves can be formed by laser machining or wire electrical discharge machining. According to such a processing method, a fine pattern with a wiring width of 15 to 50 μm and an inter-wiring width of 10 to 50 μm can be drawn. A cross-sectional view of the base plate at this stage is shown in FIG. 1 is the original plate, and 2 indicates the formed grooves.

Next, as shown in FIG. 2, the surface of the original plate is coated with resin 3 so as to fill the grooves. The resin coating is performed by immersing the base plate in uncured resin, evacuating it to float away the gas in the grooves, and then curing it. The type of resin is not limited, but epoxy resins and silicone resins are preferred.

Grinding of the resin can be performed by various methods, for example, by grinding using a surface grinder.

After grinding, the portion corresponding to the conductor pattern is exposed, as shown in FIG.

Next, the exposed portion of the base plate is plated using a conventionally known method. The original plate in this state is shown in FIG. 4 is metsuki.

Transfer can be performed in a conventional manner.

Substrates for printed wiring boards that can be used in the present invention include ordinary substrates such as phenolic resin boards, glass-epoxy laminates, paper-phenol laminates, polyimide films, polyester films, etc., as well as aluminum or the like as a core material and epoxy resin on the surface. It can also be applied to a substrate provided with an insulating layer such as.

If the substrate is flexible, it is easy to apply the adhesive in advance using a roll coater or the like, and if the substrate is rigid, it is easy to use a film adhesive.

Further, if the substrate is a rigid body, it is preferable to use a foil as the base plate, press the base plate and the base plate, and then pull up the base plate and peel it off.

After plating, the original plate is pressed onto the substrate mainly using a press or a roll. If foil is used as the base plate, it is difficult to handle as the plating peels off partially when bent, so it is better to perform plating and crimping in succession. With roll transfer, it is difficult to apply sufficient heat to thermally cure the adhesive on the substrate and firmly adhere the plating, so the plating is bonded with a strong adhesive. On the other hand, since press allows sufficient holding time, it is possible to use adhesives that adhere firmly through heat curing. The temperature and pressure of the roll and press are determined by the adhesive, or for the roll, use the adhesive with the strongest possible adhesive force at room temperature to 100°C and a pressure of 5 to 70 K97cm, and for the press to harden the adhesive. Near temperature, 5-50
It is best to use a pressure of K9/cx". In either case, it is preferable to use cardboard, rubber, etc. as a material to equalize the pressure. In crimping using a roll, generally the crimping using a press, the substrate and the plating Therefore, pressure bonding using a roll is suitable for foil-like base plates, which can give curvature to the base plate to facilitate peeling of the plating.

[Effects of the Invention] According to the method of the present invention, the grooves are formed by laser machining or wire electric discharge machining, so very fine wiring can be printed. Furthermore, since the groove width can be made deeper than the wiring width, the resin firmly adheres to the groove, making the life of the base plate semi-permanent. Furthermore, even if the surface of the original plate is scratched, the same original plate can be used again by re-grinding the surface by the depth of the scratch.

[Example] Next, the present invention will be specifically explained with reference to Examples.

A groove shown in FIG. 5 was created by laser machining or wire electric discharge machining on a smooth 5US304 plate having a thickness of I+nm.

That is, only the outer periphery of the eyelet hole 11 and the eyelet portion 12 was laser processed, and the straight line 113 was formed into a through groove by wire electric discharge machining. By using a 20μ molybdenum wire, a pattern with a groove width of 50μ and an inter-groove width of 30μ could be produced.

This was filled with lincone resin, surface ground, and used as a base plate.

After plating was carried out for 15 minutes at a current density of 3 A/da'' in a copper sulfate plating bath, it was transferred onto a polyimide film having a urethane adhesive layer.

It was possible to manufacture a fine printed wiring board with a wiring width of 50 μm and a width between wires of 30 μm.

[Brief explanation of drawings]

Figure 1 is a sectional view of the original plate with grooves provided, Figure 2 is a sectional view of the original plate with resin embedded in the grooves, Figure 3 is a sectional view of the original plate with the resin surface ground, and Figure 4 is a sectional view of the original plate with the resin surface ground. The figure is a sectional view of the plated base plate, and FIG. 5 is a plan view of the base plate manufactured in the ζ embodiment. l... Original plate, 2... Groove, 3... Resin, 4... Plating, 11... Eyelet hole, 12... Eyelet part,! 3
···groove. Patent applicant: Sumitomo Electric Industries, Ltd. Representative: Patent attorney: Mr. Maeda and 2 others Figure 1
2nd TI! J Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1. A groove is provided on the surface of a metal or alloy plate leaving a portion corresponding to the conductor pattern, the plate surface is covered with resin so that the resin is embedded in the groove, and the resin surface is ground. The remaining metal surface portion is exposed, the exposed metal or alloy surface is plated, and then a substrate coated with an adhesive or an uncured substrate with adhesive properties is placed on top of it and pressure is applied to form a plating layer. 1. A method for manufacturing a printed wiring board, comprising transferring the above onto a substrate. 2. The manufacturing method according to claim 1, wherein the grooves are provided by laser processing. 3. The manufacturing method according to claim 1, wherein the grooves are provided by wire electrical discharge machining.