Abstract:
Copper through-hole printed wiring boards are produced by forming an etching resist layer on the copper plating of a double sided copper clad laminate. The etching resist layer is formed after a negative resist pattern is applied to both sides of the laminate, and then dipped in a solution containing at least one salt of 2-alkylbenzimidazoles, 2-alkylalkyl-benzimidazoles, 2-phenyl-benzimidazoles and 2-phenyl-alkylbenzimidazoles. After the negative resist pattern is selectively removed with an alkaline aqueous solution, in accordane with the predetermined pattern of the wiring, the exposed copper plating is etched off with an alkali etchant.
Abstract:
The method comprises applying to the surface of a metal a preflux containing as an active component a benzimidazole compound represented by the following general formula (1):
(wherein R₁ stands for H or an alkyl group of three to 17 carbon atoms, R₂ for H or an alkyl group of one to six carbon atoms, and n for an integer in the range between 0 and 3) or the following general formula (2):
(wherein R₃ for H or an alkyl group of one to six carbon atoms, R₄ for H or an alkyl group of one to six carbon atoms, R₅ for an alkyl group of zero to seven carbon atoms, and n for an integer in the range between 0 and 3) and then performing an oxidizing treatment thereon. A printed wiring board according to this invention has a film of benzimidazole copper complex formed by this method on the metallic surface for mounting of electronic parts.