Morton International, Inc.

Kathy M Flynn

Vinai Ming Tara

Thomas A Koes

Vincent J Nizzo

William Luong-Gia Tran

James Rath

Kathleen L Nelson

In a process for fabricating a multilayer printed circuit board with permanent innerlayers of photoresist, the photo-imageable 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.

Method of forming a multilayer printed circuit board and product thereof

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.

A photoimageable composition for forming a solder mask has a photopolymerizable acrylate chemical system which renders exposed portions insolvable to alkaline aqueous developers and an epoxy chemical system which hardens the composition after exposure and development. The acrylate chemical system comprises acrylate monomers, epoxy-acrylate oligomers and a photoinitiator. The epoxy chemical system comprises an epoxy resin and a curative therefore. The composition further comprises a cross-linking agent which is reactive with hydroxyl groups of the acrylate and epoxy chemical systems.

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Santa Clarita, CA, United States of America

Kathy M Flynn