| abstract |
There is disclosed a photo-imaging resist ink containing (A) an unsaturated group-having polycarboxylic acid resin which is a reaction product of (c) succinic anhydride with an additive reaction product of (a) an epoxy resin with (b) an unsaturated group-having monocarboxylic acid, wherein (a) the epoxy resin is represented by the following formula (1):n n wherein M stands forn n n is at least 1 non the average; and m is 1 to n on the average. n In forming a solder resist pattern by exposing a coating film of a resist ink through a patterned film to ultraviolet light and developing the coating film to dissolve away the unexposed portions thereof, the foregoing resist ink is excellent in developability and photosensitivity, while the cure product thereof is excellent in flex resistance and folding resistance, and well satisfactory in adhesion, pencil hardness, solvent resistance, acid resistance, heat resistance, etc. Accordingly, the resist ink is especially suitable as a liquid solder resist ink for flexible printed circuit boards and thin pliable rigid circuit boards. |