| 摘要 |
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 comprises A) between 20 and 75 wt% of a binder polymer, B) between 20 and 60 wt% of a photopolymerizable material which is a multifunctional photopolymerizable monomer or short chain oligomer, and C) between 2 and 20 wt% of a photoinitiator chemical system, the weight percentages being based on the total weight of components A)-C). The binder polymer A) is a styrene/maleic anhydride copolymer in which the maleic anhydride residues are mono-esterified to between 50 and 65 mole percent of an alkyl, aryl, cycloalkyl, alkaryl, or arylalkyl alcohol having a molecular weight greater than 100, to between 15 and 50 mole percent of a C1-C3-alkyl alcohol, and to at least 80 mole percent total. The polymer has between 45 and 65 mole percent styrene residues and between 35 and 55 mole percent maleic anhydride residues, a weight average molecular weight of between 80,000 and 200,000, and an acid number of between 170 and 220. A photoimageable composition containing an epoxy resin and the novel polymer of the present invention is hardenable to form a solder mask. The novel polymer of the present invention provides tack-free photoimageable compositions, permitting contact imaging. |
