Numerical simulation of thermal and dielectric properties for SiO₂/polytetrafluoroethylene dielectric composite

Abstract

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 <ext-link ext-link-type="uri" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://doi.org/10.1007/s10854-020-03449-w">2020 <i>J. Mater. Sci. Mater. Electron.</i> <b>31</b> 9196</ext-link>). 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 CTE_<i>x</i> 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.