Low‐Loss Sr2Ti9O20‐Filled Butyl Rubber Composites for Miniaturized Flexible Microwave Substrate Applications

Abstract

Low‐loss Sr2Ti9O20 (STO)/butyl rubber (BR) composites have been prepared by mixing and hot pressing. X‐ray diffraction and energy‐dispersive spectroscopy are employed to investigate the phases contained in the STO filler, and the microstructural characteristics of the composites are discovered using scanning electron microscopy. The STO/BR composites demonstrate a high relative permittivity of 10.98 and a low loss of 0.003 at 10 GHz, corresponding to an optimum filler volume fraction of 45%. In addition, a low coefficient of thermal expansion of 50.72 ppm °C−1 and a high thermal conductivity of 0.9603 W m−1 K−1 have been found for the optimum composition, with an acceptable moisture absorption of 0.071%. The obtained composites can be employed for miniaturized, flexible radio‐frequency substrate applications.