Influence of ball milling contamination on properties of sintered AlN substrates

Abstract

The AlN substrate was fabricated by the tape casting process, and its thermal conductivity and electrical conductivity were investigated for various ball milling times and types of milling media. The oxygen content was measured after ball milling, de-binding process, and sintering. The oxygen content after the de-binding process was 1.2-2.3 wt%, similar to that after milling. After the de-binding process, the specimens were sintered at 1850 degrees C for 3 h in nitrogen atmosphere. The thermal conductivity of the sintered specimens decreased from 158 W m(-1) K-1 to 100 W m(-1) K-1 with increasing milling time. Simultaneously, the electrical conductivity decreased from approximately 10(-7) Omega(-1) cm(-1) to 10(-9) Omega(-1) cm(-1 )at 500 degrees C when Al2O3 or ZrO2 balls were used, whereas the electrical conductivity did not decrease when Si3N4 balls were used.