Sintering behavior and dielectric properties of La2O3-B2O3-CaO-P2O5glass/Al2O3composites for LTCC applications

The sintering behavior and dielectric properties of La2O3-B2O3-CaO-P2O5(LBCP) glass and La2O3-B2O3-CaO-P(2)O(5)glass/Al2O3(LBCP/A) composites have been investigated. The results show that the major crystalline phase of LBCP glass-ceramics sintered at 625 degrees C is low-temperature LaBO(3)phase, and it transits to high-temperature LaBO(3)phase with the sintering temperature up to 850 degrees 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 degrees 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 LaBO3, CaAl2B2O7, and Al2O3. 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 x 10(-3)in 50LBCP3/50A, which nicely meet the requirements of LTCC substrate materials.