Effects of ZrO2 on phase evolution, microstructure and properties of ZBS/SiO2 composites for LTCC applications

A series of novel glass–ceramic/ceramic composites, composed of a low softening ZnO–B 2 O 3 –SiO 2 (ZBS) glass–ceramic and SiO 2 /ZrO 2 ceramics, were fabricated for low temperature co-fired ceramic (LTCC) applications. The effects of the ZrO 2 /SiO 2 mass ratio on sintering behavior, microstructure, crystallization behavior and resultant properties of the ZBS/SiO 2 /ZrO 2 (ZSZ) composites were systematically investigated. The results indicate that the major crystalline phase Zn 2 SiO 4 remained stable with increasing ZrO 2 /SiO 2 mass ratio, while a minor ZrSiO 4 phase precipitated. Variations in the Zn 2 SiO 4 /ZrSiO 4 phase content resulted in an increase in the coefficient of thermal expansion (CTE) value from 2.75 × 10 –6 /K to 3.81 × 10 –6 /K, alongside a rise in flexural strength from 120.8 MPa to 152.3 MPa. The optimal properties were achieved in the ZSZ composite with a ZrO 2 /SiO 2 mass ratio = 4:5, sintered at 900 °C for 30 min: \({\varepsilon }_{r}\) = 5.52, tan δ  = 6.92 × 10 –4 , CTE = 3.81 × 10 –6 /K, flexural strength (152.3 MPa) and excellent compatibility with Ag electrodes.