多层电路板存在散热性能较差的问题，限制其在高频电路中的应用。实验以Al₂O₃为填料，制备了聚四氟乙烯（PTFE）/SiO₂高导热复合薄膜材料，用于增强多层电路板的导热性能。将不同添加量的Al₂O₃加入PTFE中，采用浸渍工艺结合高温烧结制备PTFE/SiO₂复合薄膜，研究Al₂O₃含量对PTFE/SiO₂复合薄膜的微观形貌、密度、导热性能、力学性能的影响。结果表明：随着Al₂O₃含量的提高，复合薄膜的导热系数呈现上升趋势，密度和力学强度均呈现先升高后下降的趋势。当Al₂O₃含量为4%时，PTFE/SiO₂复合薄膜（样品3）的微观缺陷最少，具有最高的密度和力学强度，同时具有较为合理的导热系数和电绝缘性。样品3的密度为2.119 g/cm³，力学强度为17.3 MPa，导热系数为0.98 W/（m·K），体积电阻率为380.9 GΩ·m。

Multi-layer circuit board has the problem of poor heat dissipation performance, which limits its application in high frequency circuit. In this experiment, polytetrafluoroethylene (PTFE)/SiO₂ high thermal conductivity composite film materials were prepared with Al₂O₃ as filler to enhance the thermal conductivity of multi-layer circuit boards. PTFE/SiO₂ composite films were prepared by impregnation process combined with high temperature sintering by adding different amounts of Al₂O₃ into PTFE. The effects of Al₂O₃ content on the microstructure, density, thermal conductivity and mechanical properties of PTFE/SiO₂ composite films were studied. The results show that with the increase of Al₂O₃ content, the thermal conductivity of the composite film shows an upward trend, and the density and mechanical strength show a trend of increasing first and then decreasing. When the Al₂O₃ content is 4%, the PTFE/SiO₂ composite film (sample 3) has the least micro-defects, the highest density and mechanical strength, and has a reasonable thermal conductivity and electrical insulation. The density of sample 3 is 2.119 g/cm³, the mechanical strength is 17.3 MPa, the thermal conductivity is 0.98 W/(m·K), and the volume resistivity is 380.9 GΩ·m.