Rutile filled PTFE composites for flexible microwave substrate applications

Rutile filled PTFE composite substrates were fabricated for microwave circuit applications. Morphology of the composites and dispersion of filler in the polymer matrix were studied using Scanning Electron Microscopic technique. Microwave dielectric properties of filled composites were measured by waveguide cavity perturbation technique using Vector Network Analyzer. Different theoretical modeling approaches were used to predict the dielectric constant of PTFE composites with respect to filler loading. The temperature coefficient of dielectric constant ( τ ε ′ r ) was measured in the 0–100 °C temperature range. Moisture absorption properties were measured as per IPC-TM-650 2.6.2 standards. Universal testing machine was used to evaluate the tensile properties. Flexible laminates having dielectric constant 10.2 with loss tangent 0.0022 was realized in the PTFE/rutile composites at X-band frequency region.