Evaluation of Onium Salt Cationic Photoinitiators as Novel Dissolution Inhibitor for Novolac Resin

Triarylsulfonium and diaryliodonium salts are a new class of dissolution inhibitors for novolac resins. These radiochemical acid generators are soluble in common casting solvents and are thermally very stable. Simple triphenylsulfonium and diphenyliodonium salts sensitive to deep UV inhibit the dissolution of novolac resins in aqueous base very efficiently and render the exposed areas more soluble in aqueous base, providing full development at 25 mJ/cm2of 254 nm radiation. © 1988, The Electrochemical Society, Inc. All rights reserved.