Thermal and Electrical Conductivity of AlN Ceramics with Low Temperature Sintering

Abstract

The Aluminum nitride (AlN) is the most promising material for ceramic substrate due to its outstanding thermal conductivity, electrical resistivity and mechanical stability. Because of its strong covalent bonding and its low self-diffusion coefficient, AlN has been typically densified at high temperature (>1800 oC). However, the high sintering temperature not only increases the production cost of AlN ceramics but also causes significant grain growth, which results in a reduction of mechanical strength. In this regard, the research in AlN ceramics is mainly focused on attaining full densification at low sintering temperature by using various sintering additives. A further investigation on the optimization of sintering conditions and appropriate sintering additives are necessary for low temperature sintering of the AlN ceramics. In this study, effects of multiple additives on the low temperature sintering of AlN were examined. Low temperature sintering mechanism was investigated by TGA, dilatometery and SEM. In addition, thermal conductivity was characterized by laser flash method. Electrical resistivity was also characterized by AC impedance spectroscopy at high temperature.