The effects of debinding condition on the thermal conductivity of AlN pressureless sintered at 1850 oC for 5 h in a N2 atmosphere were investigated. Spray dried AlN powder compacts incorporating 3 ~ 5 wt% Y2O3 sintering additive and 0.5 wt% PVB binder were calcined in air or a N2 atmosphere for binder burn-out. The debinding condition affected the second phase, the second phase distribution, and the thermal conductivity of the sintered AlN samples. All sintered AlN samples were densified to higher than 98% theoretical density. The sample debinded in a N2 atmosphere showed higher thermal conductivity (170W/mk) than that of the sample debinded in an air atmosphere (< 140 W/mk). In the sample debinded in the air atmosphere, a YAG phase, Y3Al5O12, was observed as the secondary, intergranular phase showing a wide distribution. On the other hand, when the debinding process was conducted in a N2 atmosphere, Y4Al2O9, YAlO3 and Y2O3 phases were observed at the triple point, and the sample color was different at the sample surface and interior due to the residual carbon. In this study, a commercial, spray dried AlN powder was also sintered and examined to confirm the obtained results.

Keywords: AlN, Debinding, Thermal conductivity, YAG, Firing atmosphere.