Method of making printed circuit board

Claim 1

A method of making a printed circuit board having on at least one side thereof an electric circuit comprising pad portions, through-hole portions and conductors, which comprises the following steps (A), (B), (C), (D) and (E): (A) providing an insulating laminate having copper-clad conductor portions and pad portions on at least one surface thereof; (B) subsequent to step (A) and prior to step (E), forming through-holes in said insulating laminate having inner walls corresponding to the through-hole portions of said electric circuit; (C) applying a photopolymerizable resin composition onto said at least one surface of said laminate, the photopolymerizable resin composition: (1) comprising (A) a photopolymerizable unsaturated compound having at least two terminal ethylene groups, (B) an initiator capable of initiating polymerization of the above unsaturated compound upon irradiation with actinic rays, (C) a compound having at least two epoxy groups and (D) a compound selected from the group consisting of dicyandiamide, p,p'-diaminodiphenyl compounds, polycarboxylic acids having at least two carboxyl groups, polycarboxylic anhydrides and mixtures of the polycarboxylic acids and the polycarboxylic anhydrides and (2) being adapted to be, upon irradiation with actinic rays, insoluble in an organic solvent but capable of being laminated on and firmly attached to a metal or resin plate by heating while pressing at a temperature of 100° C. or more and adapted to be completely curable by heating, following irradiation with actinic rays, at a temperature of 40° to 180° C., whereby a coat of the resin composition is formed on said at least one surface of said laminate; (D) irradiating the coat of the photopolymerizable resin composition on the laminate with actinic rays through a pattern mask to expose said coat to the actinic rays except at those portions corresponding to the pad portions and through-hole portions of said electric circuit whereby at least 10% by weight of said photopolymerizable resin composition of the exposed portions gels; trating the irradiated laminate with an organic solvent to dissolve away the photopolymerizable resin composition from the unexposed portions corresponding to the position of the pad portions and through-hole portions to effect development of a predetermined image; and (E) applying an electroless copper plating only onto the pad portions and through-hole portions, said pad portions and through-hole portions having a sensitivity to electroless plating.

Claim 2

A method of making a printed circuit board having on at least one side thereof an electric circuit comprising pad portions, through-hole portions and conductors, which comprises the following steps (A), (B), (C), (D) and (E): (A) providing an insulating laminate having copper-clad conductor portions and pad portions on at least one surface thereof; (B) subsequent to step (A) and prior to step (E), forming through-holes in said insulating laminate having inner walls corresponding to the through-hole portions of said electric circuit; (C) applying a photopolymerizable resin composition onto said at least one surface of said laminate, the photopolymerizable resin composition: (1) comprising (A) a photopolymerizable unsaturated compound having at least two terminal ethylene groups, (B) an initiator capable of initiating polymerization of the above unsaturated compound upon irradiation with actinic rays, (C) a compound having at least two epoxy groups and (D) a compound selected from the group consisting of dicyandiamide, p,p'-diaminodiphenyl compounds, polycarboxylic acids having at least two carboxyl groups, polycarboxylic anhydrides and mixtures of the polycarboxylic acids and the polycarboxylic anhydrides and (2) being adapted to be, upon irradiation with actinic rays, insoluble in an organic solvent but capable of being laminated on and firmly attached to a metal or resin plate by heating while pressing at a temperature of 100° C. or more and adapted to be completely curable by heating, following irradiation with actinic rays, at a temperature of 40° to 180° C., whereby a coat of the resin composition is formed on said at least one surface of said laminate; (D) irradiating the coat of the photopolymerizable resin composition on the laminate with actinic rays through a pattern mask to expose said coat to the actinic rays except at those portions corresponding to the pad portions and through-hole portions of said electric circuit whereby at least 10% by weight of said photopolymerizable resin composition of the exposed portions gels; trating the irradiated laminate with an organic solvent to dissolve away the photopolymerizable resin composition from the unexposed portions corresponding to the position of the pad portions and through-hole portions to effect development of a predetermined image; and (E) applying an electroless copper plating only onto the pad portions and through-hole portions, said pad portions and through-hole portions having a sensitivity to electroless plating.