Abstract Polytetrafluoroethylene has been widely applied in advanced electronic devices due to low dielectric loss and high thermal stability. Nevertheless, its low thermal conductivity can't satisfy heat diffusion demand under the situation of high-frequency and high-speed signal transmission. The PTFE-based composites filled with hybrid fillers of Li3Mg2NbO6 ceramic particles and hexagonal boron nitride sheets modified by phenyltrimethoxysilane were fabricated. Surface modification enhanced the interface compatibility between PTFE and fillers, thus obtaining tight microstructure and better dielectric properties for the composites. The dielectric properties, thermal conductivity, coefficient of thermal expansion and flexure strength of the composites were researched systematically. When the composites were filled with 40vol% BN sheets and 10vol% Li3Mg2NbO6 particles, the high through-plane thermal conductivity of 3.3W·m−1·K-1 was obtained, which was 1220% higher than pure PTFE. Meanwhile, the low dielectric constant of 3.9, extremely low dielectric loss of 3.3 × 10−4 at 9.5 GHz and low coefficient of thermal expansion of 35 ppm/°C were also achieved. PTFE-based composites with high through-plane thermal conductivity and extremely low dielectric loss show huge potential for microwave substrates application.

中文翻译：

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表面改性的 Li3Mg2NbO6 陶瓷颗粒和六方氮化硼片填充 PTFE 复合材料，具有高穿透热导率和极低的介电损耗

摘要 聚四氟乙烯由于介电损耗低、热稳定性好，在先进电子器件中得到了广泛的应用。然而，其低热导率不能满足高频高速信号传输情况下的热扩散需求。制备了填充有 Li3Mg2NbO6 陶瓷颗粒和苯基三甲氧基硅烷改性的六方氮化硼片的混合填料的 PTFE 基复合材料。表面改性增强了 PTFE 和填料之间的界面相容性，从而获得了紧密的微观结构和更好的复合材料介电性能。系统地研究了复合材料的介电性能、导热系数、热膨胀系数和弯曲强度。当复合材料填充有 40vol% BN 片和 10vol% Li3Mg2NbO6 颗粒时，获得了 3.3W·m-1·K-1 的高穿面热导率，比纯 PTFE 高 1220%。同时，还实现了 3.9 的低介电常数、9.5 GHz 下 3.3 × 10-4 的极低介电损耗和 35 ppm/°C 的低热膨胀系数。具有高贯穿平面热导率和极低介电损耗的 PTFE 基复合材料在微波基板应用中显示出巨大的潜力。