PHOTOSENSITIVE COMPOSITIONS CONTAINING COMB POLYMER BINDERS

摘要

A novel class of comb polymer compositions are disclosed which are particularly useful in photosensitive formulations such as photoresists solder masks and the like. These compositions comprise a branched polymer product containing hydrophilic groups, i.e., comb polymer, comprising one or more branch polymer segment(s) chemically linked along a linear polymer backbone segment. The linear polymer backbone segment has a weight average molecular weight (Mw) between about 10,000 and about 500,000 and the branch polymer segments have a weight average molecular weight (Mw) of about 40,000 or less, wherein the weight ratio of the backbone segment to the branch segments ranges between 200/1 to 1/4, and wherein the branch segments contain 35 % to 100 % of the hydrophilic groups. The comb polymers of this invention are particularly useful as binders in photosensitive compositions containing crosslinking monomers such as solder masks. Upon exposure to actinic radiation, solder mask coatings of such photosensitive compositions form permanent protective solder masks having superior toughness and flexibility.