SrTiO ₃ ‐Filled PTFE Composite Laminates for Microwave Substrate Applications

Abstract

Strontium titanate (SrTiO 3 ) filled polytetrafluroethylene (PTFE) substrates were fabricated through sigma mixing (SM), extrusion (E), calendering (C) followed by hotpressing (H) (SMECH) process. The filler dispersion in the polymer matrix and the surface morphology were studied using scanning electron microscopic (SEM) technique. The permittivity (ɛ′ r ) and loss tangent (tan δ) of the composites were measured using precision impedance and vector network analyzers. The experimental permittivity of filled composites was compared with theoretically predicted values. Dimensionally stable substrate having a permittivity of 13.1 and a loss tangent of 0.0055 at X‐band was prepared in the PTFE/SrTiO 3 composite system.