PURPOSE:To enable sufficient plating hindrance and to prevent film defects by incorporating an org. compd. having a thio or dithio group in a specified UV- hardenable type resin compsn. CONSTITUTION:An intended resin compsn. consists of the first unsatd. compd. having =2 terminal double bonds for forming the skeleton of this compsn. upon being hardened, such as a novolak type epoxy acrylate represented by formula I ; the second unsatd. compd. having a terminal double bond, such as a bisphenol A type epoxy (meth)acrylate represented by formula II, R being H or methyl; a photopolymn. initiator; and an org. compd. having a thio or dithio group, such as mercaptan or thioester. The resin compsn. to be partially soldered is coated with said compsn. on the parts to be masked, resulting in inhibiting an undercoating material from attaching to the parts to be masked and hindering plating. Since this compsn. is freed from solvent, and pinholes are prevented, good partial plating can be executed.
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