Ultralow‐k hollow glass microsphere filled perfluoroalkoxy composites

Abstract

Perfluoroalkoxy (PFA) composites filled with different volume fractions of hollow glass microsphere (HGM) and HGM/PFA-HGM/HBO 3 -HGM/PFA sandwich layered composites were prepared by simple dry mixing and hot-pressing process. The dielectric frequency and temperature response characteristics, thermal expansion coefficient, and mechanical strength were investigated as a function of the loading fraction of HGM fillers. The obtained .6V f HGM/.4V f PFA composite demonstrates ultralow-k (ε r ∼ 1,63@1 MHz; 1.57@10 GHz) with lowdielectric loss (∼7.2 × 10 −4 @1 MHz; ∼1.73 × 10 −3 @10 GHz), water absorption of ∼1.21%, in-plane thermal expansion coefficient of 42 ppm/ • C, and temperature coefficient of dielectric permittivity (τ εr ) of ∼−92 ppm/ • C. The temperature stabilities of dimension and dielectric permittivity for the .6V f HGB/.4V f PFA composite could be substantially improved by forming .6V f HGM/.4V f PFA-.6V f HGM/.4V f HBO 3 -.6V f HGM/.4V f PFA sandwich-layered composite, which still maintained reasonable dielectric properties and mechanical rigidity with flexural strength of ∼8.1 MPa.