Thermal conductivity of AlN-cordierite composite for microelectronic packaging

Abstract

The ongoing pursuit of improving the performance of microelectronics constantly increases the demands for better heat dissipation capability of the packagings which house these electronic devices. Besides heat dissipation, other factors such as the dielectric constant, processing temperature and coefficient of thermal expansion also need to be considered where selecting an effective packaging material. A composite consisting of Aluminium Nitride and Cordierite could in theory meet all of the above requirements. This project involved the characterization of the microstructure and thermal conductivity of a set of samples consisting of varying amounts of Aluminium Nitride and Cordierite. Increasing amounts of Aluminium Nitride generally increased the thermal conductivity of the composite for Aluminium Nitride content lesser than 60%. At 60% Aluminium Nitride content, there is a drop in thermal conductivity. This is followed by a subsequent increase in thermal conductivity in the last sample containing 70% Aluminium Nitride. It was observed that these changes in thermal conductivity with Aluminium Nitride and Cordierite content were linked to the microstructure and thermal conduction pathways within the composite. A transition in the continuous phase of the composite from Cordierite to Aluminium Nitride was linked to the drop in thermal conductivity at 60% Aluminium Nitride content. The completion of this transition at higher Aluminium Nitride content led to a subsequent increase in thermal conductivity of the composite.