Microwave dielectric properties of mixtures of glass-forming oxides Zn–B–Si and dielectric ceramics MgTiO3–CaTiO3 for LTCC applications

Low dielectric constant, low temperature co-fired ceramics (LTCC) using glass-forming oxides (ZnO, B2O3 and SiO2) with/without MgTiO3–CaTiO3 have been prepared by conventional solid-state route. The crystalline phases were studied by the X-ray diffraction and microstructures by the SEM techniques. The materials of different compositional ratio were characterized at microwave frequencies. The microwave dielectric properties of the specimens were found strongly depended on the Zn–B–Si ratios. A short-sintering-time formulation containing Zn–B–Si in a ratio of 35:25:40 and 15 wt% CaTiO3 can possess promising microwave dielectric properties (ɛr = 7.05, Q × f = 3500 GHz at 16 GHz, and τf = 5.93 ppm/°C) at 900 °C for 0.5 h. It shows not only better properties in comparison with commercial ones but also leaves out the prior glass preparation.