Investigation of TiO2 and SiO2 Filled Polybutadiene Composite Substrates and Their Dielectric Properties

Polybutadiene-based (PB) composite substrates filled with TiO2 and SiO2 ceramics were fabricated in this work. The total content of ceramic components modified by vinyltrimethoxysilane (A171) was fixed at 80 wt.% with TiO2 amount varying from zero to 8 wt.%. The differences of characteristics of ceramic fillers before and after surface modification were analyzed comprehensively and the treated ceramic fillers were uniformly distributed in the polymer matrix. The effects of TiO2 filler addition on the performances of SiO2/PB composite substrates, such as microstructure, moisture absorption, dielectric and thermal properties were also systematically studied. The composite filled with 4 wt.% TiO2 and 76 wt.% SiO2 exhibited excellent dielectric properties with proper dielectric constant (epsilon(r)=3.2), ultra-low dielectric loss (tan delta=0.0017) at 10 GHz and a near-zero tau(epsilon) (0.5 ppm/degrees C) was obtained at filler content of 8 wt.% TiO2 and 72 wt.% SiO2.