Epoxy adhesive sheet with copper foil for multiple IVH build-up technology

Abstract

The interstitial via hole (IVH) structure, in which the interconnections of signal layers are designed with nonthrough holes, is strongly focused to meet the need for small and high-performance electronic equipment with thinner and high wiring density multilayer boards (MLBs). A new epoxy adhesive sheet with copper foil was developed for multiple IVH build-up technology. Since no glass cloth is used for reinforcement, the adhesive sheet allows IVH structure fabrication by CO/sub 2/ laser ablation. It has superior resin flow properties for filling both inner-pattern and inner-layer IVH structures. The surface flatness of the build-up layer with this new sheet allows very fine wiring patterns on to be fabricated. This sheet, which does not concave during the wire-bonding process since its surface is hard at high temperature, is suitable for MLBs with semiconductor chips. This material is effective for manufacture of thin MLBs with IVH structure and high wiring densities.