High thermal conductive composite with low dielectric constant and dielectric loss accomplished through flower-like Al2O3 coated BNNs for advanced circuit substrate applications

Abstract Hydrocarbon resin-based substrate materials with low dielectric constant, low dielectric loss and high thermal conductivity are eagerly demanded by electronic equipment operating at high-frequency and high-speed signal transmission situation. Nevertheless, existing substrate materials were fabricated by directly adding inorganic ceramic fillers, whose thermal conductive properties and comprehensive properties were not enough to meet practical applications. Herein a facile and effective method to obtain the cyclic olefin copolymer (COC)-based substrate materials with high thermal conductivity was reported by coating flower-like Al2O3 (f-Al2O3) on the surface of BNNs to construct the continuous thermal conductive pathways in polymer matrix. BNNs@f-Al2O3 filled COC composites show higher thermal conductivity, higher flexure strength and lower coefficient of thermal expansion (CTE) than BNNs and BNNs + commercial Al2O3 filled COC composites with the same content of BNNs and Al2O3. At the BNNs loading of 15 wt%, the BNNs@f-Al2O3 filled COC composites exhibit a low dielectric constant of 2.65, a low dielectric loss of 1.4 × 10−3 at 10 GHz, a high thermal conductivity of 3.2 W/(mK) and a low CTE of 22 ppm/°C near to copper foil. The COC/BNNs@f-Al2O3 composites with fine comprehensive properties show huge application potentiality in high-frequency and high-speed substrates.