Densification, flexural strength and dielectric properties of CaO-MgO-ZnO-SiO2/Al2O3 glass ceramics for LTCC applications

Abstract Novel glass ceramics for LTCC applications with high flexural strength can be achieved by CaO-MgO-ZnO-SiO2(CMSZ) glass cofiring with Al2O3. The sintering shrinkage behavior, crystalline phases, mechanical and dielectric properties, and thermal expansion of the CMZS/Al2O3 glass ceramic were determined. The X-ray diffraction results revealed that multiphases (CaMgSi2O6, Al2Ca(SiO4)2 and ZnAl2O4) formed in the sintering process of the CMZS/Al2O3 glass ceramic. The flexural strength of CMZS/Al2O3 glass ceramics first increases and then decreases with increasing Al2O3 content. The CMZS/Al2O3 glass ceramic with 50 wt % Al2O3 sintered at 890 °C for 2 h achieved the best performance, with a maximum flexural strength of 256 MPa, dielectric constant (er) of 7.89, dielectric loss (tan δ) of 3.41 × 10−3 (12 GHz), temperature coefficient of resonance frequency (τf) of −29 ppm/°C, and the CTE value of 7.93 × 10−6/°C.