Heat-cycle endurance and in-plane thermal expansion of Al2O 3/Al substrates formed by aerosol deposition method

Abstract

A new heat radiation substrate for high power modules has been proposed by utilizing Al2O3 thick films formed by the aerosol deposition method (ADM) on Al substrates. Dense Al2O3 thick films (AD-Al2O3) could be obtained by the ADM at room temperature. A heat-cycle endurance test between -80°C and 180°C revealed that the AD-Al2O3/Al substrates were superior to the conventional direct brazed aluminum (DBA) substrates using AlN ceramics bounded to Al substrates. No lamination was observed between the AD-Al 2O3 films and Al substrates after heat-cycle test in spite of the difference of thermal expansion coefficient between Al2O 3 and Al. The inplane thermal expansion coefficient of AD-Al 2O3 films was almost the same as that of Al substrates, indicating that plastic deformation was induced in the AD-Al2O 3 films consisting of nano-sized grains to relax the stress caused by the difference of thermal expansion coefficient. ©2008 The Ceramic Society of Japan. All rights reserved.