Improved coefficient thermal expansion and mechanical properties of PTFE composites for high-frequency communication

With the combined advantages of polymers and ceramic fillers, Polymer-ceramic dielectric composites are widely used in microwave substrates due to their excellent dielectric properties, good mechanical properties, and easy formability. To optimize the properties of polymer composites, it is necessary to enhance the compatibility between polymer matrix and ceramic filler. In this study, to realize polytetrafluoroethylene (PTFE) composites with low dielectric constant, low dielectric loss, good mechanical properties and appropriate coefficient of thermal expansion, PTFE/SiO₂ composites were prepared by demulsification treated PTFE and modifying SiO₂ with silane treatment. Compared with PTFE composites, the mechanical properties of PTFE/SiO₂ composites prepared by the demulsification treatment were improved at a low SiO₂ content. Compared with the untreated PTFE composites, treated PTFE composites exhibit better properties such as lower dielectric loss, good mechanical properties and lower CTE. Furthermore, the composites show low dielectric constant and loss even at frequencies up to 10 GHz.