Effects of TiO_2 on microstructures and properties of Li_2O-Al_2O_3-SiO_2 glass-ceramics for LTCC substrates

摘要

In order to increase the flexural strength and to adjust the coefficient of thermal expansion (CTE), TiO_2 was introduced into Li_2O-Al_2O_3-SiO_2 (LAS) glass-ceramics to satisfy LTCC applications. The effects of TiO_2 addition on the microstructure, thermal, mechanical and electrical properties were studied. The results showed that the crystal phases were composed of Li_2OAl_2O_37.5SiO_2 (major), as well as TiO_2 and CaMgSi_2O_6 (minor). The crystal phase TiO_2 having higher CTE value could appropriately increase the CTE value of LAS to fit the silicon and remarkably improve the flexural strength of LAS glass-ceramic with low CTE. The dielectric and insulating properties also strongly depended on the amount of TiO_2. LAS glass-ceramic sintered at 800 ℃ with high performances was achieved in the case of 1 wt% TiO_2: α = 2.56 × 10~(-6)/℃, σ = 151 MPa, ε = 6.8, tanδ = 1.731 × 10~(-3), ρ = 8.29 × 10~(10) Ω cm.