Improved flexural strength and dielectric loss in Al2O3-based LTCC with La2O3–CaO–B2O3–SiO2 glass

Abstract A novel low temperature cofired ceramic (LTCC) material composed of new La2O3–CaO–B2O3–SiO2 (LCBS) glass + Al2O3 composites was synthesized through a solid-state reaction. The thermal properties, mechanical properties, microwave dielectric properties, and the internal mechanism of the material were discussed. DSC and FT-IR results revealed that adding an appropriate content of SiO2 was beneficial to LCBS glass crystallization, while the glass network did not change with SiO2 addition. The synergistic effect of relative contents of LaAl2.03(B4O10)O0.54 and Al2O3 phase is assumed to be the main factor for better dielectric performance and high flexural strength of the composites. Dense samples of 40LCBS3/60Al2O3 composites sintered at 850 °C for 30 min showed excellent comprehensive performance: a moderate dielectric constant 6.87, a low dielectric loss 2.2 × 10-3, τf = −55.7 ppm/°C, CTE = 6.13 × 10-6/°C, and a high flexural strength 241 MPa. This composite demonstrated good chemical compatibility with the Ag electrode, indicating that the proposed 40LCBS3/60Al2O3 material was promising for LTCC substrates.