A multilevel epoxy substrate for flip-chip hybrid multichip module applications

A multilevel substrate consisting of two portions of a multiple multilayer is discussed. One portion is thicker than the other, reinforced by organic fiber in each layer; the other is an unreinforced thick film which forms low dielectric-constant layers. A sophisticated epoxy-resin two-dimensional support, but its adhesion strength between the epoxy layers, stabilizes the elongation, shrink and warp by one-order smaller compared to the substrate of FR-4 with inorganic reinforcement. The resin of an aromatic-amine adducted type may lower the dielectric constant making it suitable for high-frequency circuits and it is an excellent acceptor of both copper-foil and copper-plated electrodes. This two-portion substrate enables ideal flip-chip bonding on thick-film hybrid circuits, gives the necessary impedance of semiconductor-circuit, and leaves a compatible zone for wire bonding and a reflow soldering