Preparation of a CaO-Al2O3-B2O3-SiO2 glass/Al2O3 LTCC substrate material with high flexural strength for microwave application

A CaO-Al2O3-B2O3-SiO2 (CABS) glass/Al2O3 LTCC substrate material with high flexural strength for microwave application has been successfully prepared through the avenue of investigating the effects of B2O3 in CABS glass and different glass/ceramic mass ratios on sintering shrinkage behavior, phase composition, microstructure, mechanical properties, and microwave dielectric properties of CABS glass/Al2O3 composites. The results show that adding an appropriate amount of B2O3 can lower the softening temperature of CABS glass and control the interfacial reaction between CABS glass and Al2O3, which is beneficial to the densification of CABS glass/Al2O3 and improves the microwave dielectric and mechanical properties. When the content of B2O3 is 22 wt% (in the CABS glass), the CABS glass/50 wt% Al2O3 sample sintered at 875 degrees C for 2 h exhibits the best comprehensive properties with the dielectric constant (epsilon(r)) of 6.95, dielectric loss (tan delta) of 4.56 x 10(-3) (similar to 10 GHz) and flexural strength of 223 MPa.