Preparation of high thermal conductivity aluminium nitride ceramics with low oxygen impurity for power semiconductors

Abstract

AbstractEnergy transmission efficiency and stability place higher demands on electrical power systems. Aluminium nitride (AlN) ceramics, which possess high thermal conductivity and electrical insulation, are gradually used in heat dissipation systems for high‐power semiconductors. However, oxygen impurity has been one of the key factors limiting the thermal conductivity of AlN ceramics. The pre‐reduction treatment was used to reduce the powder oxygen content. AlN ceramics with low oxygen impurities were then obtained by hot‐pressing sintering. The decrease in the oxygen content of the powder shows a hindering effect on densification, which increases the sintering temperature to 1750°C. The pre‐reduced powders transform the grain edge phase from YAP to YAM, which is more favourable for purifying the lattice. The variations in grain size and mechanical properties are also discussed. Eventually, AlN ceramics with a thermal conductivity of 201 W m−1 K−1 and a flexural strength of 376 MPa are obtained.