Morton International, Inc.

Vinai Ming Tara

Kathy M Flynn

Thomas A Koes

Vincent J Nizzo

James Rath

William Luong-Gia Tran

Charles R Keil

Randall W Kautz

James J Briguglio

Edward J Reardon, Jr

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.

In a method of providing a resist pattern on a substrate surface, a layer of photoimageable composition is applied to a substrate, which photoimageable composition provides a tack-free surface. The photoimageable composition comprises: A) between about 25 and about 75 wt % of a binder polymer, B) between about 20 and about 60 wt % of a photopolymerizeable material which is a multifunctional photopolymerizeable monomer or short chain oligomer, and C) between about 2 and about 20 wt % of a photoinitiator chemical system (the weight percentages are based on the total weight of components A)-C)). The binder polymer A) comprises a backbone formed of between about 45 and about 65 mole percent of monomers which are selected from the group i) consisting of styrene, C.sub.1 14 C.sub.6 -substituted styrene and mixtures thereof and between about 35 and about 55 mole percent of monomers which are selected from the group ii) consisting of maleic anhydride, alkyl-substituted maleic anhydride, aromatic-substituted maleic anhydride and mixtures thereof. Monomers of group ii) provide anhydride groups to the backbone of the polymer. The anhydride groups are mono-esterified to between about 50 and about 65 mole percent with an alkyl, aryl, cycloalkyl, alkylaryl, or arylalkyl first alcohol a) having a molecular weight of at least 100 or mixture of first alcohols a); and the anhydride groups are mono-esterified to between about 15 and about 50 mole percent of a C.sub.1 -C.sub.3 -alkyl second alcohol b) or mixture of second alcohols b). Polymer A) is mono-esterified to at least about 80 mole percent total of its anhydride groups. The polymer has a weight average molecular weight of between about 80,000 and about 200,000, and an acid number of between about 170 and about 220. The photoimageable composition layer is directly contacted with patterned artwork, exposed through the artwork, and developed in alkaline aqueous solution to remove non-exposed portions thereof.

Method of producing a resist pattern by contact imaging a photoimageable

A photoimageable composition, useful as a photoresist for forming a printed circuit board, is both alkaline aqueous developable but, subsequent to exposure and development, is processable in highly alkaline environments, such as additive plating baths and ammoniacal etchants. The photoimageable composition is tack-free and is resistance to polymerization inhibition by oxygen, and is therefore particularly suitable for contact printing. The photoimageable composition comprises A) between about 25 and about 75 wt % of a binder polymer, B) between about 20 and about 60 wt % of a photopolymerizeable material which is a multifunctional photopolymerizeable monomer or short chain oligomer, and C) between about 2 and about 20 wt % of a photoimageable chemical system, the weight percentages being based on the total weight of components A)-C). The improvement is the use in the photoimageable composition of a binder polymer A) which is a styrene/maleic anhydride copolymer in which the incorporated maleic anhydride units are mono-esterified to between about 50 and about 65 mole percent of an alkyl, aryl, cycloalkyl, alkaryl, or arylalkyl alcohol having a molecular weight greater than 100, to between about 15 and about 50 mole percent of a C.sub.1 -C.sub.3 -alkyl alcohol, and to at least about 80 mole percent total. The polymer has between about 45 and about 65 mole percent incorporated styrene units and between about 35 and about 55 mole percent incorporated maleic anhydride units, a weight average molecular weight of between about 80,000 and about 200,000, and an acid number of between about 170 and about 220.

Photoimageable composition having improved alkaline process resistance

In a dry film laminate useful in the printed circuit industry comprising a support sheet, a photoimageable composition layer and a protective sheet, a dual intermediate layer is interposed between the photoimageable composition layer and the support sheet. The intermediate layer consists of a water-soluble tie coat in contact with the photoimageable composition layer and a top coat in contact with the support sheet, the top coat being insoluble in neutral or acidic aqueous solution but soluble in dilute alkaline aqueous solution.

Photosensitive laminate having dual intermediate layers

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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Anaheim, CA, United States of America

Vinai Ming Tara