A High Density Thick Film Multilayer Process for LSI Circuits

An advanced thick film multilayering technology using new materials and processes has been developed for the fabrication of hybrid LSl circuits. Not only does this technology offer reduced fabrication time, compared to converttional thick film processing, but it also makes possible 4 mil linewidths and spacings on both conductive layers, and matching 4 mil vias in the dielectric. The resulting interconnection structures are very ordered and hence amenable to high density designs. New technological developments include pattern etching of all layers, use of the new fritless thick film golds, and thermocompression bonding of copper or nickel leads to these fritless conductors. The fabrication of a typical 1.15 inch X 2.4 inch digital hybrid circuit is traced, starting with the blank substrate and concluding with the finished unit furnished with leads, active devices, and hermetic seal. The pertinent materials, equipment and processes are described.