Metal particle filled, thermally conductive polymer composites for electronic packaging applications

Abstract

Conductive polymer composites were prepared by mixing high density polyethylene (HDPE) with aluminum powder at various volumetric concentrations, then the mixed sample is placed in a die and melted at 185°C under 4 MPa pressure. The filler content varies from the pure HDPE to 50% by volume of aluminum particles. After cooling and solidification under pressure the samples are taken out of the die, for thermal diffusivity measurements, samples are rectangular in form with 20mm length, 10mm width, and 1mm thickness. The matrix material is commercial high density polyethylene in powder form, density 0.968 g/cm3 melt index 5.8 g/10min. The metallic filler is aluminum in the form of fine powder with particle size in the range of 10–20 microns, the solid density of Al is 2.7 g/cm3 and its solid thermal conductivity 204 W/mK. A microscopic study shows that aluminum particles are uniformly distributed in HDPE matrix, with no voids in the composite structure. Thermal diffusivity measurements were performed using photothermal method with step heating. Thermal diffusivity varied from 2.45×10−7 m2/s for pure HDPE to 11.30×10−7 m2/s for 50% by volume of aluminum particles. Heat capacities were also measured using a differential scanning calorimeter (DSC).