Glass fiber/polytetrafluoroethylene composite with low dielectric constant and thermal stability for high-frequency application

Dielectric composites with low dielectric constants (ε), low dielectric loss (tan δ), and excellent thermal-mechanical stability are highly desired for high signal transmission speed and high device integration. Polytetrafluoroethylene (PTFE) based composites exhibit tremendous potential due to the outstanding dielectric properties and high-frequency stability of PTFE. However, achieving PTFE-based dielectric composites with thermal-mechanical stability and low dielectric constant is challenging. Herein, we develop a glass fiber/polytetrafluoroethylene (GF/PTFE) composite for high-frequency communication applications with a designed skeleton structure. By the paper-making process, the glass fiber can be dispersed in random directions to set up a skeleton with the PTFE matrix entering the space in the fiber network. The modification of GF was also carried out to low down the dielectric loss of the composite. Benefiting from the supporting effect of the skeleton structure and surface modification, the thermal-mechanical stable dielectric composite was achieved with a low dielectric constant, and dielectric loss remained (m-GF content = 15 wt%, ε = 2.326 and tan δ = 5.24 × 10−3 at 30 GHz, xy-CTE = 29 ppm/°C and z-CTE = 47 ppm/°C). Moreover, the composites also have good dielectric constant frequency stability and thermal conductivity. Thus, this work provided an effective way to tailor the structure of functional composites with disordered fiber fillers.