Preparation, characterization and properties of Sm2Si2O7 loaded polymer composites for microelectronic applications

The dielectric and thermo-mechanical properties of Sm2Si2O7 filled polyethylene and polystyrene composites for microwave packaging applications are reported in this paper. The composites were synthesized by melt mixing and hot pressing methods. The effect of different volume fractions of the ceramic (vf = 0-0.5) on the dielectric properties of the composites was investigated at 1 MHz and at 8 GHz. The dielectric properties (relative permittivity and dielectric loss) were found to increase with the ceramic filler content. It was observed that the addition of 0.5 vf of Sm2Si2O7 filler to polyethylene, increased the relative permittivity and the dielectric loss to 5.3 and 0.009 respectively whereas the corresponding values for the polystyrene-Sm2Si2O7 composite are 4.6 and 0.01 respectively at 8 GHz. The variation of relative permittivity with temperature in the range -25 deg. C to 60 deg. C was investigated for both the composites. The relative permittivities obtained experimentally were compared with that of the theoretical predictions and Effective Medium Theory was found to agree well for both the composites. The thermal conductivity, thermal expansion coefficient and Vickers microhardness of the composites were also investigated.