Fabrication of bi-level circuits

摘要

Disclosed is a method of fabricating bi-level circuits which include metallization of via holes (14 and 15) in insulating subustrates (10). A thick film metal paste (13) is prepared which according to one embodiment comprises copper, glass frit and an organic vehicle including a low molecular weight ethyl cellulose binder and solvents of butyl carbitol acetate and alpha terpineol. The paste is deposited onto the substrate and through the holes. The structure is baked with the printed surface (12) down in order to establish a solvent concentration gradient in the paste which results in solid material accumulating away from the printed surface to form the contact pad (16). The material is then fired to establish the desired conductivity.