A novel approach for Al2O3/epoxy composites with high strength and thermal conductivity

Insulating materials for electronic packaging should ideally have high strength and thermal conductivity. Ceramic/polymer composite is one of the candidates for such materials. In this work, Al2O3/epoxy composites with very high flexural strength and thermal conductivity were prepared using a new processing technique consisting of the gelcasting, sintering and vacuum infiltration methods. Al2O3 green bodies were first formed by gelcasting. After being degreased at 600 °C, the green bodies were sintered at different temperatures from 1200 °C to 1500 °C, and porous Al2O3 ceramic skeletons with different porosity were resulted. The porosity was readily controlled by the sintering temperature. Higher sintering temperature resulted in lower porosity and larger average grain size in the Al2O3 ceramic skeletons. Epoxy was vacuum infiltrated into the sintered porous Al2O3 ceramic skeletons to form Al2O3/epoxy composites by curing. High Al2O3 loadings up to 70 vol.% in the composites were achieved. The flexural strength and thermal conductivity of the Al2O3/epoxy composites were found to reach 305 MPa and 13.46 W m−1 K−1, respectively. These results are remarkably higher than those previously reported in the literature. This work provides an effective approach for fabricating high performance ceramic/polymer composites for electronic packaging.