Sintering behavior and dielectric properties of La_2O_3-B_2O_3-CaO-P_2O_5 glass/Al_2O_3 composites for LTCC applications

摘要

The sintering behavior and dielectric properties of La_2O_3-B_2O_3-CaO-P_2O_5 (LBCP) glass and La_2O_3-B_2O_3-CaO-P_2O_5 glass/Al_2O_3 (LBCP/A) composites have been investigated. The results show that the major crystalline phase of LBCP glass-ceramics sintered at 625 °C is low-temperature LaBO_3 phase, and it transits to high-temperature LaBO_3 phase with the sintering temperature up to 850 °C. With the increase of La/B ratio in LBCP glass, the crystallization tendency of LaBO_3 phase increases. LBCP/A composites could be well sintered at 850 °C for 2 h. The bulk density of LBCP/A composites increases with the glass content rising and then decreases owing to foaming. The main crystalline phases of LBCP/A composites are LaBO_3, CaAl_2B_2O_7, and Al_2O_3. Dielectric properties are related to the glass composition and content, which determines the density of the composites. The optimized dielectric properties of LBCP/A composites are dielectric constant of 7.108 and dielectric loss of 1.024 × 10~(-3) in 50LBCP3/ 50A, which nicely meet the requirements of LTCC substrate materials.