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SiO2/聚四氟乙烯(polytetrafluoroethylene, PTFE)复合介质材料的热膨胀系数和介电常数主要受到SiO2填充量的影响, 如何准确预测其影响至今仍是一个很大的挑战. 本文通过数值模拟系统地研究SiO2/PTFE复合介质材料的热膨胀系数和介电常数. 结果表明, 随着SiO2填充量的增加, SiO2/PTFE复合介质材料的热膨胀系数降低, 介电常数增加, 且与文献报道数据取得良好的一致性(Han K K, Zhou J, Li Q Z, Shen J, Qi Y Y, Yao X P, Chen W 2020 J. Mater. Sci. Mater. Electron. 31 9196). 研究发现, 实心SiO2球(体积分数为30%)/PTFE复合介质材料的热膨胀系数最小, 为7.5×10–5 K–1; 而空心SiO2球(体积分数为10%)/PTFE的介电常数最小, 为2.06. 由于底部的实心SiO2球充当支撑作用, 底部实心SiO2球较密集的实心SiO2/PTFE复合介质材料具有更低的热膨胀系数. SiO2填料的大长径比会降低SiO2/PTFE复合介质材料的热膨胀系数. 成型工艺对实心SiO2/PTFE复合介质材料的热膨胀系数几乎没有影响. 该工作为通过调控SiO2/PTFE复合介质材料的微观结构来控制其热膨胀系数和介电常数提供清晰的思路.Coefficient of thermal expansion (CTE) and dielectric constant for the SiO2/polytetrafluoroethylene (SiO2/PTFE) dielectric composite are mainly influenced by their filling content, and how to accurately predict the effect is still a great challenge untill now. In this work, the CTE and dielectric constant of SiO2/PTFE dielectric composite are systematically investigated by numerical simulation. The results show that with the increase of SiO2 content, CTE of SiO2/PTFE dielectric composite decreases, and the dielectric constant increases, which are in good agreement with the data reported in the literature (Han K K, Zhou J, Li Q Z, Shen J, Qi Y Y, Yao X P, Chen W 2020 J. Mater. Sci. Mater. Electron. 31 9196). The 30% (volume fraction) solid SiO2 sphere (SSS)/PTFE dielectric composite is the smallest CTE of 7.5×10–5 K–1, while 10% (volume fraction) hollow solid sphere (HSS)/PTFE possesses the smallest dielectric constant of 2.06. The CTE of SiO2/PTFE dielectric composite may decrease when the SiO2 distribution is dense at the bottom. The large aspect ratio of SiO2 filler may reduce CTEx of SiO2/PTFE dielectric composite. The molding parameters have little effect on the thermal expansion coefficient of the solid SiO2/PTFE composite dielectric material. This work provides a clear insight into the controlling of CTE and dielectric constant of SiO2/PTFE dielectric composite by adjusting its microstructure.
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中国物理学会期刊
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