PURPOSE: To obtain a solder mask which can be developed with a noncombustible developer and has high resolution, high heat resistance and high workability in blanking by using a photosensitive resin compsn. contg. a photopolymerizable unsatd. compd. obtd. by a reaction between an epoxy resin having polysulfide skeletons and an unsatd. carboxylic acid, then allowing a univalent isocyanate to react with said photopolymerizable unsatd. compd.
CONSTITUTION: A photosensitive resin compsn. consisting of (a) a photopolymerizable unsatd. compd., (b) a sensitizing agent and/or a sensitizing system which generates free radicals by the effect of active rays, and (c) a heat-curing agent, is useable as a solder mask for the production of a print-circuit board or a resist for chemical plating. The photopolymerizable unsatd. compd. (a) is obtd. by producing an unsatd. compd. by an addition reaction of an epoxy resin having polysulfide skeletons and being expressed by the formula I with an unsatd. carboxylic acid in 0.1-0.98 ratio of acid equivalent/epoxy equivalent, then allowing a univalent isocyanate to react with secondary OH groups of the unsatd. compd. in 0.1-1.2 ratio of isocyanate equivalent/OH equivalent. Thus, a thick film solder mask which can be developed with a noncombustible developing soln, can be produced by a photographic process.
TSUCHIYA KATSUNORI
TSUKADA KATSUSHIGE
