Glycine-Modified Boron Nitride/Epoxy Composites with High Thermal Conductivity and Low Coefficient of Thermal Expansion

As electronic devices are being developed towards higher integration density and higher frequency, significant amount of heat will be generated during operation. The accumulated heat will impact the performance and the lifespan of electronic devices, which must be dissipated effectively and timely. Boosting the thermal conductivity of their constituents is one of the most efficient approaches to dissipate the accumulated heat. Boron nitride (BN) represents an attractive filler for enhancing the thermal conductivity of composite materials because of its excellent properties in terms of insulation capability, thermal conductivity, and coefficient of thermal expansion (CTE). However, its chemical inertness and poor dispersion capability in polymer matrix limit its practical application. This paper presents a simple method to modify hexagonal BN (hBN) with glycine via ball milling to prepare g-hBN, which is then filled into epoxy matrix to form composites. Compared to unmodified hBN, g-hBN fillers endow the composite films with higher thermal conductivity (up to by 19%) and lower CTE due to better dispersion. Besides, the composites film can also maintain excellent dielectric and mechanical properties.