International Business Machines Corporation

John R Mertz

David John Russell

Donald Herman Glatzel

Richard Allen Day

Robert David Allen

Gregory Michael Wallraff

William Dinan Hinsberg

Jeffrey Donald Gelorme

William D Hinsberg, Iii

Logan L Simpson

Joel L Roth

An improved photoimagable cationically polymerizable epoxy based coating material is provided, that is suitable for use on a variety of substrates including epoxy-glass laminate boards cured with dicyandiamide. The material includes an epoxy resin system consisting essentially of between about 10% and about 80% by weight of a polyol resin which is a condensation product of epichlorohydrin and bisphenol A having a molecular weight of between about 40,000 and 130,000; and between about 35% and 72% by weight of an epoxidized glycidyl ether of a brominated bisphenol A having a softening point of between about 60&deg; C. and about 110&deg; C. and a molecular weight of between about 600 and 2,500. Optionally, a third resin may be added to the resin system. To this resin system is added about 0.1 to about 15 parts by weight per 100 parts of resin of a cationic photoinitiator capable of initiating polymerization of said epoxidized resin system upon exposure to actinic radiation; the system being further characterized by having an absorbance of light in the 330 to 700 nm region of less than 0.1 for a 2.0 mil thick film. Optionally a photosensitizer such as perylene and its derivatives or anthracene and its derivatives may be added.

Composition for photoimaging

An improved photoimagable cationically polymerizable epoxy based coating material is provided, that is suitable for use on a variety of substrates including epoxy-glass laminate boards cured with dicyandiamide. The material includes an epoxy resin system consisting essentially of between about 10% and about 80% by weight of a polyol resin which is a condensation product of epichlorohydrin and bisphenol A having a molecular weight of between about 40,000 and 130,000; and between about 35% and 72% by weight of an epoxidized glycidyl ether of a brominated bisphenol A having a softening point of between about 60.degree. C. and about 110.degree. C. and a molecular weight of between about 600 and 2,500. Optionally, a third resin may be added to the resin system. To this resin system is added about 0.1 to about 15 parts by weight per 100 parts of resin of a cationic photoinitiator capable of initiating polymerization of said epoxidized resin system upon exposure to actinic radiation; the system being further characterized by having an absorbance of light in the 330 to 700 nm region of less than 0.1 for a 2.0 mil thick film. Optionally a photosensitizer such as perylene and its derivatives or anthracene and its derivatives may be added.

The present invention provides a photoimageable soldermask that may be applied using aqueous solvents, thereby reducing the emission of organic solvents. The soldermask contains an epoxy based resin system comprised of at least one epoxy resin, a coating agent, and preferably a cationic photoinitiator and a dye.

Aqueous soldermask

According to the present invention, good image resolution of a cationically polymerized epoxy based coating, such as a solder mask or dielectric or etch resist, is provided by combining a cationically polymerized epoxy based coating with conventional epoxy glass substrates cured with a curing agent that does not produce basic reaction products. Preferably, the coating is photoimagable. The method for making the same is also provided. The coating material includes an epoxy resin system comprising between from about 10% to about 90%, preferably about 28% to about 57% by weight of a polyol epoxy resin, and from about 10% to about 90%, preferably about 43% to 72% by weight, of a brominated epoxy resin. Optionally, a polyepoxy resin or an epoxy creosol novolak resin is added to the resin system. The polyepoxy resin may be added from an effective amount up to less than 90% of the resin system; the epoxy creosol novolak may be added from an effective amount up to about 80 pph.

Composition for photo imaging

An improved photoimagable cationically polymerizable epoxy based coating material is provided, that is suitable for use on a variety of substrates. The material includes an epoxy resin system consisting essentially of between about 10% and about 80% by weight of a polyol resin which preferably is a condensation product of epichlorohydrin and bisphenol A having a molecular weight of between about 40,000 and 130,000; and between about 35% and 72% by weight of an epoxidized glycidyl ether of a brominated bisphenol A having a softening point of between about 60.degree. C. and about 110.degree. C. and a molecular weight of between about 600 and 2,500. A third resin, either an epoxy cresol novolak or a polyepoxy resin, is also added to the resin system. To this resin system is added about 0.1 to about 15 parts by weight per 100 parts of resin of a cationic photoinitiator capable of initiating polymerization of said epoxidized resin system upon exposure to actinic radiation; the system being further characterized by having an absorbance of light in the 330 to 700 nm region of less than 0.1 for a 2.0 mil thick film. Optionally a photosensitizer such as perylene and its derivatives or anthracene and its derivatives may be added.

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Endicott, NY, United States of America

John R Mertz