Sensitization of Sulfonium Salt Photoinitiators in Epoxy Films
Original Publication Date: 1986-Dec-01
Included in the Prior Art Database: 2005-Mar-09
Epoxy resins have good electrical properties and high Tg's which makes them desirable for packaging applications in the electronics industry. Epoxy resin resist consists of a formula which contains polyfunctional epoxide monomers and an onium salt photoinitiator. Sulfonium salts are widely used due to their thermal stability and photoactivity. The two major drawbacks in these systems are the poor photospeeds (ca. 500 mJ) at accessible wavelengths (>350nm) for production tools and the relatively large amounts of initiator required (up to 10%) for satisfactory processing. Sensitization of sulfonium salts presents a solution to both of these problems.