Ba(Mg1/3Ta2/3)O3 filled PTFE composites for microwave substrate applications

Phase pure Ba(Mg1/3Ta2/3)O3 (BMT) ceramic filler has been prepared through solid-state ceramic route and characterized using XRD. Planar BMT filled PTFE composites were fabricated through SMECH process comprising of Sigma Mixing, Extrusion, Calendering followed by Hot pressing. Morphology and filler distribution of the composites were studied using Scanning Electron Microscopic technique. The microwave dielectric properties of the composites at X-band were measured using waveguide cavity perturbation technique. BMT filled PTFE composite exhibits a dielectric constant of 6.7 with loss tangent 0.003 at optimum filler loading. Dielectric constant of the composites shows better matching with the theoretically predicted values using Litchnecker model. The moisture absorption characteristics of the samples were ascertained as per IPC-TM-650 2.6.2.1. The loss tangent of the PTFE/BMT composites was improved to 0.0018 while incorporating long range ordered BMT fillers.