Improvement of thermal conductivity of epoxy composites using the synergistic effect of boron nitride nanosheets and boron nitride whiskers

Using epoxy resin (EP) composites with high thermal conductivity as electronic packaging materials is an effective means to solve the heat dissipation problem of electronic components. In this study, BNWKs-Bnnss/EP composites were prepared by mixing two-dimensional BNNSs and one-dimensional boron nitride whiskers (BNWKs) with different mass ratios at a fixed filling content of 30wt%, in order to achieve the effect of "1+1>2". The experimental results show that adding a small amount of BNWKs can effectively improve the thermal conductivity of the composite, but when the content exceeds a certain level, the thermal conductivity of the composite will decrease significantly. The thermal conductivity of 3.75wt% BNWKs-26.25wt% BNNSs/EP composite is the highest, which can reach 1.497 W/(m·K), which is 1.20 times that of 30wt% BNNSs/EP. At the same time, at room temperature, its volume resistivity and breakdown field strength are still as high as 1.15×10¹⁴ Ω•m and 70.98 kV/mm, which has relatively excellent electrical insulation performance and meets the application requirements of packaging materials. This study provides an effective method for preparing epoxy resin matrix composites with high thermal conductivity.