THERMAL-CONDUCTIVITY OF EPOXY-RESIN FILLED WITH PARTICULATE ALUMINUM NITRIDE POWDER

The thermal conductivity of an AlN- and an alumina-particulate-filled epoxy resin was investigated as a function of their volume content rat ios. AIN composite exhibited thermal conductivity of 7.15 W/m . K at 6 8.5 vol% filler content but that of alumina composite was lower than 2 .68 W/m . K even if the filler content was as much as 63.8 vol%. The t hermal conductivity of the composites is strongly dependnt on that of the filler. In the AlN filler properties, the particle size of the fil ler used affected the thermal conductivity of composites, and composit es with higher thermal conductivity could be obtained by using filler with large particle size. The thermal conductivity of composites is go verned by the number of resin layers on the surface of an ALN particle . The composite thermal conductivities decreased with increasing the o xygen content of the filler. The thermal conductivity of an AlN partic le depends on the oxygen content of the particle itself and the decrea se of the composite thermal conductivity with the increase of the oxyg en content of the filler is due to the increase of the aluminum oxide layer thickness produced on the surface of particles. In the thermal c onductivity model, the measured thermal conductivity of AlN-ground-pow der-filled composites disagreed with the ones calculated using Bruggem an's expression. However the measured values of alumina-spherical-powd er-filled composites agreed with the calculated ones. It is considered that the results depended on the sphericity of the used powder.