Sintering and dielectric properties of CaO-B2O3-SiO2 low temperature co-fired ceramics

The CaO-B2O3-SiO2 (CBS) green tape was prepared by tape-casting a crystallizable glass selected from CBS ternary glass system. After binder bun-out process, the LTCC material can be successfully sintered at the temperatures ranging from 775 degrees C to 950 degrees C. The densification and crystallization behaviors of the CBS green tape were investigated. The effects of sintering temperature on densification and crystallization were studied. The results show that the major crystalline phase of the LTCC was always beta-CaSiO3 and a little CaB2O4 existed at the temperature ranging from 850 degrees C to 900 degrees C. The densification process was prior to the crystallization process, which favored the densification. Bulk crystallization may dominate the crystallization process. The bulk densities decreased with the increase of firing temperature. Increasing sintering temperature could promote the crystallization. The dielectric constant decreased with increasing the sintering temperature because the crystals have lower dielectric constant than CBS glass.