Patent ID: 7080447

Claim:
A solder mask manufacturing method of a printed circuit board adapted to apply a solder mask on a surface of a substrate of the printed circuit board, wherein the surface of the substrate is provided with a conductor pattern having an unsheltered portion and a sheltered portion being covered by said solder mask, the manufacturing method comprising the following steps: (a) coating a layer of semi-solid solder mask material, which is pre-coated on one side of a metal foil, on the surface of the substrate such that the sheltered and unsheltered portions of said conductor pattern are covered by said solder mask material layer, said solder mask material having a thermal expansion coefficient substantially identical to that of the substrate of said printed circuit board; (b) pressing said metal foil and curing said semi-solid solder mask material layer into solid form such that said solder mask material layer firmly covers the surface of the substrate; (c) covering a photo-resist layer on the other side of the metal foil; (d) photoimaging positions of the photo-resist layer; (e) removing the photo-resist layer and the metal foil corresponding in location above the unsheltered portion of said conductor pattern for exposing the solder mask material layer above the unsheltered portion of said conductor pattern to outside; (f) removing the residual photo-resist layer and then removing the solder mask material layer above the unsheltered portion of said conductor pattern such that said unsheltered portion can be exposed outside; and (g) removing the residual metal foil.