Research On Materials System And Molding Technology Of Epoxy Molding Compounds With High Thermal Conductivity

A type of epoxy molding compounds using SiO₂,Al₂O₃,Si₃N₄ as fillers was obtained by orthogonal layout and thermal press method. This paper tested thermal conductivity,coefficient of thermal expansion(CTE) and dielectric constant by scanning electron microscope(SEM),PCY-â…¢instrument for CTE and tester for dielectric property respectively. The influence of the content,species,distributing,shape of the fillers and different technical conditions on its thermal conductivity,dielectric and molding property were investigated respectively. Experimental results show: i) The micrograph of ceramic/epoxy molding compounds prepared by a ball-mill mixer show that the distribution of fillers in resin matrix is not so uniform, a few of conglobe particles were existed still. The more fills content, the more air holes. At the same fills content, the distribution of fillers by crumbing is better than ball-milling, there is no visible conglobe particles; ii) thermal conductivity of EMC improves obviously with the filler content increasing. The composites show a highest thermal conductivity of 2.3W/m?K when the volume fraction of fillers reaches 60%. Results of binary mixture of a Si₃N₄-filled(60vol%) EMC indicate that the effects of filler particle size overrides filler size distribution in the thermal conductivity of EMC. Calculated with theory thermal models and compared to experimental data , the result show that the improvement of thermal conductivity of ceramic/polymer composites related to the formation of thermal network of fillers; iii) With filler content increasing, the CTE descends dramatically. At the same volume fraction, the CTE of EMC filled with alumina and silicon nitride is lower than that's of EMC filled with silicon dioxide and silicon nitride. At 65% volume fraction, the CTE reaches 1.493×10-5/℃and 1.643×10-5/℃respectively;â…³) The dielectric constant also increases with the filler content increasing, but it remains at a relative low level. In the experiment of fillers size distribution, a small value of dielectric constant was obtained when the small size filler content at 20vol%. And it remarks that filler particle size effects dielectric constant mostly.