METHOD OF FORMING A MULTILAYER PRINTED CIRCUIT BOARD AND PRODUCT THEREOF

摘要

In a process for fabricating a multilayer printed circuit board with permanent innerlayers of photoresist, the photoimageable composition used to form the hard permanent layer comprises a polymerizable acrylate monomer; an oligomer formed 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 crosslinking agent reactive with hydroxyl 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. 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.