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.

低介电常数、低介电损耗和高热导率的碳氢树脂基基板材料是工作在高频和高速信号传输环境中的电子设备所迫切需要的。然而，现有的基板材料是直接添加无机陶瓷填料制备的，其导热性能和综合性能不足以满足实际应用。本文报道了一种通过涂覆花状Al ₂ O ₃ (f-Al ₂ O ₃) 在 BNNs 表面构建聚合物基体中的连续导热通路。BNNs@f-Al ₂ O ₃填充的COC复合材料比BNNs和BNNs+具有相同BNNs和Al ₂含量的商业Al ₂ O ₃填充的COC复合材料显示出更高的导热性、更高的弯曲强度和更低的热膨胀系数（CTE）○ ₃。在 BNNs 负载量为 15 wt% 时，BNNs@f-Al ₂ O ₃填充的 COC 复合材料表现出 2.65 的低介电常数、10 GHz下 1.4 × 10 ^-3的低介电损耗、3.2 W 的高热导率/(mK) 和接近铜箔的 22 ppm/°C 的低 CTE。COC/BNNs@f-Al综合性能优良的₂ O ₃复合材料在高频高速基板上显示出巨大的应用潜力。