High Thermal Conductivity Aluminum Nitride Substrates Prepared by Aqueous Tape Casting

High thermal conductivity aluminum nitride (AlN) substrates were prepared by aqueous tape casting. The characteristics of surface-treated AlN powder were studied in aqueous ball-milling media. The oxygen content of AlN powder with the dispersant was lower than that of AlN powder without the dispersant at the same ball-milling time. The isoelectric points of the surface-treated AlN with and without a dispersant were, respectively, at pH～3.35 and pH～3.90. The atmosphere had considerable effects on organic additive burnout of aqueous AlN green sheets. The composition of grain boundaries changed with increasing holding time at 1850°C. A translucent AlN substrate with a uniform microstructure and a thermal conductivity of 263 W·(m·K)^?1 was obtained by pressureless sintering at 1850°C for 6 h in a nitrogen atmosphere.