Thermal properties of low loss PTFE‐CeO₂ dielectric ceramic composites for microwave substrate applications

Abstract

Polytetrafluroethylene (PTFE) composites filled with CeO 2 were prepared by powder processing technique. The PTFE is used as the matrix and the loading fraction of CeO 2 in the composite varied up to 0.6 volume fraction. The thermal conductivity and coefficient of thermal expansion were studied in relation to filler concentration. The thermal conductivity increased and coefficient of thermal expansion decreased with increase in CeO 2 content. For 0.6 volume fraction loading of the ceramic, the composite has a thermal conductivity of 3.1 W/m C and coefficient of thermal expansion 19.6 ppm/ C. Different theoretical approaches have been employed to predict the effective thermal conductivity and coefficient of thermal expansion of composite systems and the results were compared with the experimental data.

Dependence of Dielectric Properties on Zn-Based Ceramic Fillers of the Polystyrene-Matrix Composites

“…Although the all predicted K were fitted well with the experimental results at lower ceramic content (up to 0.1 V f ), the difference between experimental and predicted K was increased with the ceramic content. These results are due to the imperfect dispersion of ceramic particles at higher ceramic content and also to the air enclosed in the composites [12]. Generally, all theoretical predictions are valid for low filler content.…”

“…In general, the dielectric properties of the composites not only affected by the dielectric properties of individual components but also by several factors such as size and shape of the ceramic particle, porosity, interface between components, and homogeneity of distribution [12]. Figure 5 shows the K, tan δ and TCF of PS/Zn-based ceramic composites with volume fraction of ceramics at 12 GHz.…”

Flexible 0–3 Ceramic‐Polymer Composites of Barium Titanate and Epoxidized Natural Rubber

“…The effective medium theory (EMT) model has been used to calculate the permittivity of composites: where n is a shape factor of the ceramic particles. A small value of n corresponds to near‐spherical shape, while a high value of n is used for elongated particle shapes.…”

Material Characterization and Microwave Substrate Applications of Alumina‐Filled Butyl Rubber Composites

“…also reported the effect of alumina particle size on the mechanical and physical properties of silicone rubber composites. Many studies have been conducted to improve the dielectric properties of polymers by adding ceramic fillers . Butyl rubber is a synthetic rubber with excellent dielectric properties due to its nonpolar paraffinic character, good weathering resistance, aging resistance, flexibility, etc .…”