| abstract |
A negative-acting photoimageable composition useful as a primary imaging resist in the manufacture of printed circuit boards comprises an acid-functional binder polymer, a photopolymerizable component, and a photoinitiator chemical system, in which all or a portion of the photopolymerizable component comprises a (meth)acrylate functional urethane oligomer, wherein the (meth)acrylate functionality is separated from the urethane linkage by at least two alkylene oxide groups and at least one ring-opened lactone group for improved flexibility, tenting strength, fine line adhesion, developer scumming, coupled with unexpectedly improved resistance to processing chemicals, such as alkaline developing solutions, acid etching solutions, and acid plating baths, and stripping ability in strong alkaline aqueous stripping solutions. The acid-functional binder polymer has a low molecular weight and does not contain styrene, contributing to stripping ability and improved resolution. |