PHOTO-SOLDER-RESIST INK COMPOSED OF VARIO US OLIGO(ACRYLATE)S

Photochemical properties of various polyfunctional acrylates were eval uated using UV-FTIR method. These measurements were carried out by rap id scanning FTIR in situ with continuous UV irradiation during the cur ing procedure. Dipentaerythritol hexaacrylate (DPET-6A) showed the hig hest photochemical reactivity among the oligo-(acrylate)s used. Photo- curable solder resist ink was prepared by mixing DPET-6A and resins ca rrying acrylate or epoxide side chains besides carboxylic residues. Th e resist films thus obtained were employed for the irradiation experim ents. The consumptions of vinyl, epoxide, and carboxylic groups were d etermined by FTIR spectroscopy and potentiometric titration analysis. The comparison with the degree of photoreaction of each functional gro up. Showed that the electric resistivity of cured film was much influe nced by the space density of crosslinking.