PHOTOSENSITIVE POLYIMIDE FOR MCM-D/L

摘要

The use of thin film redistribution on a laminate substrate, MCM-D/L, offers a favorable cost/performance ratio for many applications including portable electronics. No commercial thin film dielectric materials have been developed specifically for this application. Epoxy-based soldermasks have been employed but these materials tend to suffer from thickness, resolution, and adhesion limitations. Compatibility with conventional laminate fabrication processes requires good adhesion to plated copper, a low cure temperature, and low shrinkage. Polyimides, while widely used in MCM-D constructions, are generally not suitable for this application because of the cure temperature and thickness requirements. Moreover, most polyimide coatings are not compatible with copper. One class of polyimide coatings, however, is well suited to MCM-D/L. Auto-photosensitive, preimidized polyimide solutions do not require a conventional cure and are easily processed in thick coats with a resolution of up to 1:1. Adhesion to copper has been measured at over 6 lb/in. This paper discusses the use of this type of polyimide coating for thin film redistribution on FR-4 and similar low temperature substrates.