Morton International, Inc.

Morton Thiokol Inc.

James J Briguglio

Leo Roos

Charles R Keil

Randall W Kautz

Vinai Ming Tara

Clancy P Crooks

Fredrick J Axon

Edward J Reardon, Jr

Amedeo Candore

Samuel W Shoemaker

Kirk Johnson

Frederick J Axon

Harold D Sullivan

Lawson Lightfoot

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

To apply a photoimageable composition to a substrate, such as a printed circuit board, the photoimageable composition is dissolved in a solvent system which is a mixture of propylene glycol monomethylether and ethylene glycol butylether, acetate. The liquid solution is applied to the substrate. Then the photoimageable composition is dried to remove the solvent system and thereby produce a layer of the photoimageable composition on the substrate.

Solvent system for forming films of photoimageable compositions

A dry film for forming a solder mask includes a cover sheet, a photoimageable composition layer which is curable to form a solder mask and a top coat interposed between the cover sheet and the photoimageable composition layer which is selectively adherent to the photoimageable composition layer. The dry film is applied to a surface of a printed circuit board with a minor portion of the area of the photoimageable composition layer tacked to the printed circuit board. The cover sheet is peeled away. With heat and vacuum, the photoimageable composition layer is laminated to the irregular surface of the printed circuit board, conforming the photoimageable composition layer to the contours thereof and leaving the top coat as a protective covering over the photoimageable composition layer. The photoimageable composition layer is exposed to patterned actinic radiation, developed and cured to form a hard, permanent solder mask.

Dry film photoresist for forming a conformable mask and method of

A dry film for forming a solder mask includes a cover sheet, a photoimageable composition layer which is curable to form a solder mask and a top coat interposed between the cover sheet and the photoimageable composition layer which is selectively adherent to the photoimageable composition layer. The dry film is applied to a surface of a printed circuit board. With heat, vacuum and mechanical pressure, the photoimageable composition layer is laminated to the irregular surface of the printed circuit board, partially conforming the photoimageable composition layer to the contours thereof. Within about 60 seconds and with the photoimageable composition layer still heated, the cover sheet is peeled away, leaving the top coat as a protective covering over the photoimageable composition layer. Removal of the cover sheet allows the photoimageable composition layer to fully conform to the contours of the printed circuit board. Immediately thereafter, the circuit board is cooled to about ambient temperature or below. The photoimageable composition layer is exposed to patterned actinic radiation, developed, and cured to form a hard, permanent solder mask.

Method of application of a conforming mask to a printed circuit board

Method of forming a conformable mask on a printed circuit board

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Balboa, CA, United States of America

James J Briguglio