PHOTOCURABLE THERMOSETTING RESIN COMPOSITION, DRY FILM AND CURED PRODUCT OF THE COMPOSITION, AND PRINTED WIRING BOARD USING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a photocurable thermosetting resin composition capable of preventing disconnection in a fine pitch circuit caused by coarse particles of an insoluble component, and to provide a dry film and a cured product of the composition, and a printed wiring board having a cured coating such as a solder resist by using the composition.SOLUTION: An alkali-developable photocurable thermosetting resin composition comprises: (A) an epoxy resin; (B) a carboxyl group-containing resin; and (C) photopolymerization initiator. The epoxy resin (A) comprises a mixture of (A-1) a bifunctional biphenyl epoxy resin and (A-2) a biphenol novolac epoxy resin having a softening point of 40 to 100°C and an epoxy equivalent of 180 to 300, or a biphenol novolac epoxy resin and a bisphenol-A novolac epoxy resin. Proportions of (A-1) and (A-2) satisfy (A-1)<(A-2). Coarse particles of the epoxy resin (A) do not exist in a dried coating film of the above composition.