Ceramic Substrates for Microcircuitry

Ceramic substrates for housing microelectronic circuits must be extremely stable electrically and mechanically. They should also exhibit good thermal and mechanical shock resistance in order to withstand not only process steps encountered in fabricating microcircuits on their surfaces, but also subsequent environmental applications. Chemical activity requirements have also been imposed on the substrate by current developments in metal-glaze resistors and protective coatings, and to avoid migration of circuit metallizing. Both alumina and bery!lia under proper treatment, are particularly suited for this application. When moderately large values of capacitances are required, high dielectric constant substrates, such as barium titanate, may be employed.