Microwave dielectric properties of a novel Li2O-Al2O3-B2O3 glass-ceramic for ULTCC application

The 50 Li2O - x Al2O3 - (50 - x) B2O3 (x = 3-7 mol%) glass-ceramics were prepared by solid-state reaction method. Homogeneous glasses were obtained by water quenching, and the glass-ceramics with the LiBO2 and Li3AlB2O6 as main crystalline phases were prepared after the subsequent sintering process. The appropriate content of Al2O3 can significantly improve the densification and crystallization of Li2O - Al2O3 - B2O3 (LAB) glasses. The fully densified glass-ceramics with 4 mol% Al2O3 exhibit uniform and fine microstructure and large volume density. This glass-ceramic sintered at 650 degrees C for 7 h displays excellent microwave dielectric properties with epsilon r = 5.47, Q x f = 21814 GHz (at 13.6 GHz), and zf = - 61.3 ppm/degrees C. Additionally, the LAB glass-ceramics are chemically compatible with aluminum (Al) and silver (Ag) electrodes at their sintering temperatures, which shows significant potential in ultralow temperature co-fired ceramic (ULTCC) for packaging substrate applications based on their good microwave dielectric performance and good chemical compatibility.