High thermal conductivity of polyimide/silicon nitride composite films

This research aim was to investigate study the preparation of high thermal conductivity of polyimide composite films that using silicon nitride (Si3N4) as filler. The effect of the difference types of coupling agents and the amount of Si3N4 on the thermal and mechanical properties were studied. Three types of silane coupling agents were used for the investigation of the effects of Si3N4 surface modification on composite films. There were 3-minopropyltrimethoxysilane (APTS), 3-(2-aminoethylamino)propyltrimethoxymethylsilane (AEPDS) and 3-[2-(2-aminoethyl amino) ethylamino]propyltrimethoxysilane (AEEPTS). Three different sizes of Si3N4 particles are micron, submicron and nano sized. The PI filled modified Si3N4 fillers using silane coupling agent have better mechanical properties than that of untreated Si3N4 fillers. The PI composite films with APTS treated Si3N4 fillers showed higher thermal conductivity higher than that of AEPTS, untreated and AEEPTS, respectively. The composite films filled with nano sized Si3N4 shows higher thermal conductivity than other sizes at the same weight fraction that were more than two times of micron sized particle and about two times of submicron sized particle. The incorporation of hybrid micron-submicron and submicron-nano sized Si3N4 at the maximum packing density into polyimide matrix can give thermal conductivity higher than mono sizes of Si3N4 fillers regardless of the same weight ratio of Si3N4. In addition, Agari and Uno model can well predict the experimental thermal conductivity better than any other theoretical models.