Development of Photosensitve Polyimide B-stage Sheet Having High Cu Migration Resistance

Abstract

Fan-out type wafer level packaging (FO-WLP) technology is one of promising next generation semiconductor package. The FO-WLP technology requires fine pattern pitch re-distribution layer (RDL) with good electrical insulation. In order to meet those requirements, we examined Cu migration resistance of two types of polyimides and photosensitive system under high temperature, high humidity, and high electronic field in order to meet the requirement electrical insulation of fine pattern pitch. We found that there is no large difference between negative photosensitivity and positive photosensitivity. Polyimide structure significantly affects Cu migration under bias HAST condition. From these results, we will describe highly reliable PSPI dry film and coatings. From those results, we developed a reliable positive tone photosensitive polyimide B-stage dry film.