JPS6042896A - 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 particularly to a method for manufacturing a printed wiring board having through holes.

Conventionally, printed wiring boards having through holes have been encased as described below. First, after forming a straight hole in a copper-clad printed wiring board on the surface of an insulating plate, the surface of the board is soaked in an electroless plating catalyst solution of an A-8 colloidal aqueous solution of stannous chloride and palladium chloride. and no IM on the pore wall, #kt)?
Add a catalyst for oxidation. Then no 1! After forming a non-L refill on the surface of the insulating plate and the hole wall by copper-plating, and reinforcing the electroless plate () on the hole wall by electrolytic copper plating, a printing-etching method is applied. Form the desired isoelectric circuit.

However, in the above-mentioned conventional method for manufacturing a printed wiring board having through-holes, after forming through-holes in the substrate, a mixed colloidal aqueous solution of stannous chloride and palladium chloride is used.
A phenomenon often occurs in which the pore walls of the substrate are not completely covered by the electroless plating catalyst during one process of treating the plating catalyst solution. This causes defects such as pinholes to occur in the VL-free plating film formed in the next step of electroless plating. The adsorption of a mixed colloidal aqueous solution of stannous chloride and palladium chloride (catalyst for electroless plating) onto the pore walls of the substrate is affected by the charge on the pore wall surface of the substrate, particularly by the negative charge on the pore wall surface. be done. It is thought that defects in the pore wall surface of the substrate caused by the electroless plating catalyst occur due to local accumulation of negative charges on the surface of the pore wall.

゛The method for manufacturing a printed wiring board of the present invention includes the steps of forming through holes at desired positions of a printed wiring board in which an insulating plate is coated with copper, and coating the surface of the substrate and the walls of the through holes with an electroless plating catalyst using a non-noble metal colloid aqueous solution. A step of applying a first electroless plating catalyst by immersing the substrate in an aqueous solution; a step of applying a catalyst for electroless plating, a step of sequentially forming a non-IkL deplated film and an electroplated film on the surface of the upper l-ply substrate and the wall of the through hole, and a printing-etching method on the surface of the substrate. yo)
The method is characterized in that it includes a step of forming a desired Toden N route.

The present invention is very similar to applying a first electroless plating catalyst of a gold bullion colloid to the wall surface of a through hole of a substrate, and then applying a second electroless plating catalyst of a noble metal (palladium) colloid. Yes, by applying a catalyst for the first electroless plating of the non-funded colloid, the local negative charge on the wall surface of the through hole is reduced, and the second electroless plating of the IF4 (<'radium) colloid is reduced. The coverage of the through-hole wall surface by the catalyst is improved, and the occurrence of pinhole defects in the X%-free plating film deposited in the next electroless plating process is prevented, and the electricity of the holes and holes in the completed printed wiring board is improved. The reliability of the connection is significantly improved.

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(aJ to 1e)Fi are enlarged sectional views of essential parts of a printed wiring board for detailed explanation of the present invention.

As shown in Fig. 1(a), a board 10 with copper cladding on both sides of the board
A through hole 3 was formed at a desired position using a drill.

Note that, for this substrate 10, a copper-clad epoxy glass board was used. Next, in step i, the substrate 10 is immersed in a non-t'h4 plating catalyst aqueous solution containing a copper-gold-stripe colloid, and a first anhydride is applied to the surface of the substrate 10 and the wall surface of the through hole 3.
A deplating catalyst 4 was applied to the plate (see FIG. 1).

Next, the substrate 1 was immersed in an electroless plating catalyst aqueous solution of a colloidal aqueous solution containing Km (l-tin (8nCJ, ) 61/l and palladium chloride (Pd c lt) 0.311/l.
1(C)). Naoru 1
The first and second electroless plating catalysts 4 and 5 in Figures (b) and (C) are shown further enlarged (as compared to other parts of the printed wiring board).

Next, electroless steel plating Ji16 with a thickness of about 0.5 microns is deposited on the surface of the substrate 10 and the wall surface of the through hole 3 by immersion in an electroless copper plating solution at a temperature of 25° C. for about 20 minutes. Electrolytic steel plating was performed using an acidic sulfuric acid steel plating solution at 25° C., and electrolytic copper plating a7 having a thickness of about 30 microns was deposited on the electroless copper plating gland 6.

Next, a cross-circuit 8 was formed by a printing-etching method, and a printed wiring board with M through holes was manufactured. In this example, after electroless steel plating 6 was deposited on the surface of the substrate 100 and the wall surface of the through hole 3, the state of deposition of electroless copper plating glands on the wall surface of the through hole 3 was observed using an electron microscope. No defects such as pinholes were observed during electroless copper plating. Further, after immersing the printed mounting board manufactured according to the present invention in insulating oil at a temperature of 260°C for 2.0 seconds,
1.1 at a liquid temperature of 25°C. '1-30 in tosoiroloethane
When the temperature cycle test of dipping for 1 second was repeated for 10 psi, the change in the electrical conduction resistance of the through holes was within 5% compared to the initial softening. The connection reliability was proven to be significantly improved.

[Brief explanation of the drawing]

FIGS. 1(a) to 1(e) are enlarged 1#r side views of essential parts of a printed wiring board for explaining an embodiment of the present invention. 'l
...Insulating plate, 2...Copper foil, 3...
...Through hole, 4...First IIL-free deplating catalyst, 5...Second electroless layer plating catalyst, 6.
...Electroless copper plating film, 7...'Drowsy steel plating exhibition, 8...Conductive circuit, 10...
substrate. ″:!

Claims (1)

[Claims] Completely form the shell through holes at the desired positions of the copper-plated printed wiring board, and then apply a non-negative plating catalyst aqueous solution of a non-negative gold colloid aqueous solution to the coating direction and the negative through hole wall of the board. The first electroless plating catalyst is crushed, and the through-hole walls of the separately specified base are covered with an electroless plating catalyst aqueous solution VC of a mixed colloidal aqueous solution of tin chloride and palladium chloride.
a step of applying a second non-decomposition catalyst;
Electroless plating and electroplating #t) are applied to the iron surface of the front substrate and the wall surface of the through-hole, and the desired =*( (b) A method for manufacturing a printed wiring board, comprising the step of forming a channel.