Method of forming a multilayer printed circuit board and product thereof.

摘要

In a process for fabricating a multilayer printed circuit board (20) with permanent innerlayers (22) of photoresist, the photoimageable composition used to form the hard permanent layer comprises a polymerizable acrylate monomer; an oligomer form by the reaction of an epoxy resin and an acrylic or methacrylic acid; a photosensitive, free radical generating initiator for polymerization of the acrylic monomer and oligomer; a curable epoxy resin; a curing agent for the epoxy resin; and, optionally, a cross-linking agent reactive with hyroxyl groups. After exposure and development of a layer of the photoimageable composition and etching of the underlying metal layer on a board, the resultant photoresist is left on the circuitry traces (14). The innerlayers of photoresist are stacked in a press where it initially conforms under heat and pressure to fill voids between the innerlayers and then cures to permanence. <IMAGE>