Morton International, Inc.

Edward J Reardon, Jr

Charles R Keil

Randall W Kautz

James J Briguglio

Vinai Ming Tara

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.

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Laguna Niguel, CA, United States of America

Edward J Reardon, Jr