Ultra low loss build-up film for fine pitch applications

Abstract

The new ultra-low loss build-up film has been developed by the combination of the matrix layer, which has the semi-IPN structure, and the primer layer. The matrix material was designed and prepared by the original polymer blend modification technology with co-crosslinking reaction of rigid thermosetting resin and the reactive low polar polymer. Dielectric constant and dissipation factor at 1-20 GHz of the film were <3.4 and <0.004, respectively. And the film had semi additive process compatibility and small surface roughness after desmear treatment. Wiring formation of 5 / 5μm line and space was demonstrated thereon. The peel strength to the plated Cu on the surface of the film, which had small roughness of <100 nm, was 0.6 kN/m. The coefficient of thermal expansion was 18ppm/oC.