Effects on the thermal expansion coefficient and dielectric properties of CLST/PTFE filled with modified glass fiber as microwave material

Ceramic and polytetrafluoroethylene composites as dielectric materials have a low dielectric loss at high frequency and play an important role in the modern communication field. However, room temperature phase transformation of PTFE resins, which is accompanied by a large volume change (> 400 ppm/℃), seriously affects the dimensional stability and performance stability of materials. The LD125 modified glass fiber (GF) was introduced to the CaO-Li₂O-Sm₂O₃-TiO₂ (CLST)/PTFE composite, to reduce the thermal expansion coefficient (CTE) of the composites. The tri-phase composites (CLST/PTFE/GF) show the low dielectric loss and excellent machine-ability. The effect of GF content on the dielectric properties and CTE was also investigated. The CLST/PTFE filled with 5% GF exhibits the best overall performance, which is a promising microwave dielectric material for microwave communication.