SOLDER MASK FOR MANUFACTURE OF PRINTED CIRCUIT BOARDS

摘要

A permanent solder maskis applied to the surface of aprinted circuit board using a cop-per foil carrier. The solder maskpreferably is one or two lay-ers of a thermosetting resin e.g.epoxy resin. Selected circuitfeatures are exposed by etch-ing away portions of the copperfoil and removing the underly-ing thermosetting resin. Then,the remaining copper foil is re-moved, leaving the solder maskon the surface of the printed cir-cuit board.