Low temperature sintering and performance of aluminum nitride/borosilicate glass

Aluminum nitride (AlN)/borosilicate glass composites were prepared by the tape casting process and hot-press sintered at 950 °C with AlN and SiO2-B2O3-ZnO-Al2O3-Li2O glass as starting materials. We characterized and analyzed the variation of the microstructure, bulk density, porosity, dielectric constant, thermal conductivity and thermal expansion coefficient (TEC) of the ceramic samples as a function of AlN content. Results show that AlN and SiO2-B2O3-ZnO-Al2O3-Li2O glass can be sintered at 950 °C, and ZnAl2O4 and Zn2SiO4 phase precipitated to form glass-ceramic. The performance of the ceramic samples was determined by the composition and bulk density of the composites. Lower AlN content was found redounding to liquid phase sintering, and higher bulk density of composites can be accordingly obtained. With the increase of porosity, corresponding decreases were located in the dielectric constant, thermal conductivity and TEC of the ceramic samples. When the mass fraction of AlN was 40%, the ceramic samples possessed a low dielectric constant (4.5∼5.0), high thermal conductivity (11.6 W/(m·K)) and a proper TEC (3.0×10−6 K−1, which matched that of silicon). The excellent performance makes this kind of low temperature co-fired ceramic a promising candidate for application in the micro-electronics packaging industry.