Enhanced Thermal Conductivity of Epoxy Composites Filled with Al2O3/Boron Nitride Hybrids for Underfill Encapsulation Materials

Abstract

In this study, a thermal conductivity of 0.22 W·m^-1·K^-1 was obtained for pristine epoxy (EP), and the impact of a hybrid filler composed of two-dimensional (2D) flake-like boron nitride (BN) and zero-dimensional (0D) spherical micro-sized aluminum oxide (Al₂O₃) on the thermal conductivity of epoxy resin was investigated. With 80 wt.% hybrid Al₂O₃-BN filler contents, the thermal conductivity of the EP composite reached 1.72 W·m^-1·K^-1, increasing approximately 7.8-fold with respect to the pure epoxy matrix. Furthermore, different important properties for the application were analyzed, such as Fourier-transform infrared (FTIR) spectra, viscosity, morphology, coefficient of thermal expansion (CTE), glass transition temperature (T_g), decomposition temperature (T_d), dielectric properties, and thermal infrared images. The obtained thermal performance is suitable for specific electronic applications such as flip-chip underfill packaging.