Photoresist composition and printed circuit boards and packages made therewith

A printed circuit board comprising a fully cured epoxy-resin-containing substrate, a pattern of conductive material disposed on said substrate, and an imagewise pattern of a fully cured photocurable composition disposed on said substrate;

• said fully cured photocurable composition resulting from a reaction between a photocurable composition and a cationic photoinitiator;
• said photocurable composition comprising the product of:
• (a) a polyepoxyfunctional novolak resin which is curable through the action of said cationic photoinitiator;
• and
• (b) a diluent soluble in developing solvents for photoresists and reactive with the epoxy functional groups of said epoxy novolak resin by the action of said cationic photoinitiator to form said fully cured composition insoluble in said developing solvents;
• wherein said epoxy novolak resin comprises at least approximately 65 weight percent of the resin solids of said photocurable composition, said diluent comprises from approximately 10 to approximately 35 weight percent of said resin solids, and said cationic photoinitiator comprises from approximately 2 to approximately 6 weight percent of said resin solids;
• said fully curved photocurable composition being at least approximately 0.0015 inch in cross sectional height;
• and
• said fully cured photocurable composition being substantially resistant to delamination from said substrate when temperature cycled.