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

A CaO-Al 2 O 3 -B 2 O 3 -SiO 2 (CABS) glass/Al 2 O 3 LTCC substrate material with high flexural strength for microwave application has been successfully prepared through the avenue of investigating the effects of B 2 O 3 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/Al 2 O 3 composites. The results show that adding an appropriate amount of B 2 O 3 can lower the softening temperature of CABS glass and control the interfacial reaction between CABS glass and Al 2 O 3 , which is beneficial to the densification of CABS glass/Al 2 O 3 and improves the microwave dielectric and mechanical properties. When the content of B 2 O 3 is 22 wt% (in the CABS glass), the CABS glass/50 wt% Al 2 O 3 sample sintered at 875 °C for 2 h exhibits the best comprehensive properties with the dielectric constant ( ε r ) of 6.95, dielectric loss (tan δ ) of 4.56 × 10 –3 (~ 10 GHz) and flexural strength of 223 MPa.