Low temperature sintering and properties of CaO-B2O3-SiO2 system glass ceramics for LTCC applications

The P2O5 + ZnO, ZrO2 + TiO2, B2O3 and a low-melting-point CaO-B2O3-SiO2 glass (LG) are selected as the sintering additives, and the effect of their additions on the microwave dielectric properties, mechanical properties and microstructures of CaO-B2O3-SiO2 system glass ceramics is investigated. It is found that the sintering temperature of pure CBS glass is higher than 950 °C and the sintering range is about 10 °C. With the above additions, the glass ceramics can be sintered between 820 °C and 900 °C. The dielectric properties of the samples are dependent on the additions, densification and microstructures of sintered bodies. The major phases of this material are CaSiO3, CaB2O4 and SiO2. With 10 wt% B2O3 and LG glass additions, the CBS glass ceramics have better mechanical properties, but worse dielectric properties. The ɛr values of 6.51 and 7.07, the tan δ values of 0.0029 and 0.0019 at 10 GHz, are obtained for the CBS glass ceramics sintered at 860 °C with 2 wt% P2O5 + 2 wt% ZnO and 2 wt% ZrO2 + 2 wt% TiO2 additions, respectively. This material is suitable to be used as the LTCC material for the application in wireless communications.