A solder mask manufacturing method adapted to apply a solder mask on a surface of a substrate of a circuit board, said surface is provided with a conductor pattern having an unsheltered portion and a sheltered portion which is covered by said solder mask. The method comprises the steps of: a) disposing a layer of semi-solid solder mask material having an expansion coefficient substantially the same as that of the substrate on the surface of said substrate to cover said copper conductor pattern, and a metal foil covering the material layer; b) applying pressure to the metal foil and applying baking treatment to cure the solder mask material in to solid; c) utilizing chemical solution and plasma etching to remove the metal foil and the solid solder mask material above the unsheltered portion of said copper conductor pattern respectively such that the unsheltered portion can be exposed; and d) using chemical solution to remove the residual metal foil.

A printed circuit board having a permanent solder mask includes a substrate made of a glassfiber reinforced epoxy resin material. The top and bottom surfaces of the substrate are disposed thereon a conductive pattern respectively. An epoxy resin solder mask is coated on each surface of the substrate in such a way that the conductive pattern is divided into a sheltered portion covered by the solder mask and an unsheltered portion exposed outside. The solder mask also has an even and smooth outer surface with a micro-roughness ranging between 0.5 .mu.m.about.10 .mu.m and an optimum thickness ranging between 2 .mu.m.about.200 .mu.m.

A PC board micro hole processing method using plasma technique to etch the substrate of the PC board, and then using chemical etching technique to remove residual material such as glass fibers.