JPS6064495A - Method of producing printed circuit 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 The present invention relates to a method for manufacturing a printed wiring board, and more particularly to a method for manufacturing a printed wiring board in which conductive circuits are selectively formed on an insulating plate by electroless plating.

Conventionally, as a manufacturing method for printed wiring boards in which conductive circuits are selectively formed on an insulating plate by electroless plating, the r
After forming through holes at the desired positions, the insulating plate was chemically treated with a mixed aqueous solution of chromium tonne and sulfuric acid, and then treated with chloride mud.
Mixed colloidal water of tin and palladium chloride
Electrolytic plating: After immersing the insulating plate in a hot water bath, then coating one circuit part of the surface of the insulating plate with a resist film for electroless plating.
A conductive circuit was formed by applying a thick electroless m-plating film to the circuit part on the surface of the insulating plate, which had not been exposed to air, and one hole in the shell.

However, printed wiring boards manufactured using such conventional techniques have the disadvantage that palladium metal, which is a catalyst for electroless plating, remains under the resist film, which significantly reduces the electrical insulation between conductive circuits. was.

The following technology has been disclosed as a method for manufacturing a printed wiring board that improves the drawbacks of the conventional technology (i.e., after forming through holes at desired positions on the insulating board, the non-circuit portions on the surface of the insulating board are After coating with a resist film containing an oxidizing agent for electroless plating, and then chemically treating the insulating plate with a mixed aqueous solution of chromic acid and sulfuric acid, a colloidal water H solution of stannous chloride and palladium chloride was applied. After being immersed in an electrolytic plating catalyst aqueous solution, it is coated with a resist film by electroless plating, and a non-Xi-free plating film is formed on the surface of the insulating plate and the walls of the through holes. A single conductive circuit was formed. However, this prior art also had the following drawbacks:

That is, the resist film for non-W and M-plating contains an oxidizing agent, and when an insulating plate coated with a resist film for electroless plating is immersed in an electroless plating catalyst aqueous solution, the resist film in the resist film is immersed. The oxidizing agent oxidizes stannous chloride and has the effect of suppressing adsorption of palladium chloride onto the resist film. However, when an insulating plate is immersed in an electroless plating solution, the oxidizing agent in the resist film dissolves in the electroless plating solution, resulting in contamination of the electroless plating solution.

An object of the present invention is to provide a method for manufacturing a printed wiring board that eliminates the drawbacks of the prior art.

The method for manufacturing a printed wiring board of the present invention includes the steps of forming through holes at M desired positions on an insulating plate, and covering only the non-circuit portions on the surface of the insulating plate with a resist film for electroless plating. and the process of chemically creating curved holes in the convex portions of the surface of the loquat plate, and the walls of the through-holes.

A process of immersing an insulating plate in a non-precious metal colloid water bath solution and applying a catalyst for non-ms plating to the surface of the insulating plate and the walls of the through holes, and The process of removing the plating catalyst and the electroless plating process on the circuit part of the surface of the insulating plate and the wall of the through hole allows the electroless plating @ membrane to be removed and a conductive circuit is formed. It is characterized by a process of forming.

According to the present invention, after forming a resist film for electroless plating (hereinafter referred to as plating resist film) on the re-coating of an insulating plate, in the step of immersing it in an electroless plating catalyst aqueous solution of a non-negative metal colloid aqueous solution. The electrolytic plating catalyst also adsorbs on the plated resist film, but the adsorption power of the non-noble metal colloidal electroless plating catalyst with the plating resist film is the same as that of the electroless plating catalyst of the mixed colloid of radicum and stannous chloride. It is significantly smaller than the adsorption force with the plating resist film, and can be easily removed from the plating resist film by mechanical polishing, allowing electroless plating on the circuit portion of the insulating board without adding an oxidizing agent to the plating resist. Films can be selectively deposited to form conductive circuits. In addition, since there is no electroless plating catalyst under the plating resist film between the conductive circuits, the electrical insulation between the conductive circuits is
This can be significantly improved over printed wiring boards according to the prior art. Embodiments of the method for manufacturing a printed wiring board of the present invention will be described below with reference to the drawings.

FIGS. 1(a) to 1(e) are enlarged sectional views of main parts of a printed wiring board for explaining the present invention in detail. A printed wiring board (hereinafter referred to as a board) 10 with an adhesive layer 2 adhered to the surface of an insulating plate 1 is prepared, and holes are punched or drilled at desired positions on the board 10 by a punching method or a laser drilling method. A through hole 3 is formed (FIG. 1(a)). Next, only the non-circuit portions of the surface of the substrate 10 are covered with a thermosetting epoxy resin resist film 4 (FIG. 1(b)). Note that as the resist film, an ultraviolet curable resist film or a photosensitive organic film may be used. Next, the adhesive layer 2 on the surface of the substrate IO is roughened with a chromic acid-sulfuric acid mixed aqueous solution, and then immersed in a copper metal colloid aqueous solution to apply an electroless plating catalyst 5 on the surface of the substrate IO and the through holes 3. (Figure 1 (C)
). Next, the surface of the substrate 10 is water-polished using a sponge or the like to selectively remove the electroless plating catalyst on the resist film 4 (FIG. 1(d)).

Next, it is immersed in an electroless copper plating solution with a liquid temperature of 70C to a thickness of about 3.
An electroless copper plating film of 0 micron was deposited on the circuit portion of the surface of the substrate 10 and the wall of the through hole 3 to form a conductive circuit 6 (FIG. 1(e)), and a printed wiring board was manufactured. In this way, a printed wiring board was manufactured. It was found that the electrical insulation resistance between the conductive circuits 6 of the obtained printed wiring board was 1014 (Ω) or more, which was extremely excellent. Also, there was no contamination due to the resist film of the electroless copper plating solution, which is one aspect of the present invention. The practicality of this has been proven.

[Brief explanation of drawings]

FIGS. 1(a) to 1(e) are enlarged sectional views of main parts of a printed wiring board for explaining one embodiment of the present invention. 1... Insulating plate 12... Adhesive layer, 3...
...Through hole, 4...Resist film, 5.
... Catalyst for electroless plating, 6 ... Conductive circuit, 10 ... (printed wiring) substrate. Agent Patent Attorney: Kil, Sound Diagram 1

Claims (1)

[Claims] A process of forming a through hole at a desired position of the insulating plate, a process of covering only the non-circuit part on the surface of the insulating plate with a resist film for electroless plating, and a process of forming a through hole on the surface of the insulating plate and the wall of the through hole. The process of chemically roughening the surface of The process of removing the #1C11L deplating catalyst on the resist film for electroless plating by surface polishing, and the process of electroless plating on the circuit part and through hole wall of the insulating plate surface by non-1i deplating process. A method for manufacturing a printed wiring board, the method comprising the step of depositing a conductive circuit to form a conductive circuit.