Gadolinium Zinc Borate Glass-Based Low Temperature Co-fired Ceramics

New microwave materials based on a gadolinium zinc borate (20ZnO-20Gd2O3-60B2O3) glass with typical Al2O3 filler have been investigated as a dielectric candidate for low temperature co-fired ceramic (LTCC) applications. The experimental parameters, such as filler contents and firing temperature, were found to affect seriously densification, crystallization and microwave dielectric properties. The presence of ZnAl2O4 and GdBO3 phases with an unexpected GdAl3(BO3)4 phase were assumed to influence the final performance of the materials. In particular, the GdAl3(BO3)4 phase is the consequence of chemical reactions between the glass and Al2O3 filler during firing. As a promising dielectric composition, the sample consisting of 20ZnO-20Gd2O3-60B2O3 and 40 wt.% Al2O3 filler exhibited k (dielectric constant) ~8.1 and Q (quality factor) ~ 312 at 18.6 GHz when fired at 850℃.