DEVELOPMENT OF TEMPERATURE-STABLE THICK-FILM DIELECTRICS .3. ROLE OF GLASS ON THE MICROSTRUCTURE EVOLUTION OF A THICK-FILM DIELECTRIC

Abstract

Glass phase plays an important role in the characteristics of thick-film microelectronics. A dielectric system in BaTiO3 and SrTiO3 containing PbO, B2O3, SiO2, and Al2O3 glass constituents is investigated. Microstructure evolution and phase distribution after thermal aging are studied with the aid of electron microscope and X-ray diffractometer. It is observed that the phases in 40 vol% BaTiO3-25 vol% SrTiO3-35 vol% glass thick-film dielectric are not altered after 500-degrees-C aging for 480 h. The variation in surface morphology after long time aging is attributed to the precipitation of heavy metal component from the glass which acts as a diffusion species and then dissolves the crystalline phase during firing. The presence of glass in the dielectric enhances the formation of solid solution (Ba(x)Sr1-x)TiO3 and results in the broadening of the Curie peak.