The Preparation And Properties Of Al₂O₃/ZnO-filled Thermal Conductivity Epoxy Potting

An epoxy potting adhesive with high thermal conductivity, low viscosity and good application performance was prepared using E-51epoxy resin as a matrix, and CYH-277as a diluent, RX-381as a curing agent. The surface treatment of fillers, the thermal conductive filler single filling, the Al2O3/ZnO composite filling on the encapsulant performances were investigated.The types of epoxy resin matrix were investigated. The experiment choose type E-51epoxy resin with a smaller viscosity as the matrix resin so as for the epoxy potting compound can smoothly potting in electronic devices after the comparison of E-44, E-51’parameters.The types of curing agents and curing condition on the epoxy potting compound performances were investigated. The results showed that the epoxy potting compound performed best when the curing agent and curing condition were the RX-381cured4hours under90℃.The types and dosages of reactive diluents on the epoxy potting compound performances were investigated. The results showed that the epoxy potting compound performed best when the reactive diluent was the CYH-277.The viscosity and heat resistance were both gradually decline with the increasing dosage of CYH-277and the best dosage was30wt%.The dosages and types of coupling agents on the performances of the epoxy potting compound were investigated. The results showed that the epoxy potting compound performed best when the coupling agent was the silane coupling agent KH-560and its dosage was1.25wt%.The activation grade of the modified thermal conducting fillers reached0.99.The filling fractions, and different particle size mixtures of Al2O3and ZnO on the performances of epoxy potting compound were investigated. The results showed that Heat resistance, the viscosity and the thermal conductivity of the epoxy potting compound were all rise with the increasing content of the thermal conductive fillers. At the same filler content, the thermal conductive fillers with smaller particle size was beneficial to a higher thermal conductivity and a higher viscosity than the thermal conductive fillers with bigger particle size. Compared with single Al2O3filled composite, it is found that hybrid Al2O3filled composite has higher thermal conductivity.The Al2O3particle sizes, hybrid ZnO/Al2O3mixed ratios on the performances of the epoxy potting compound were investigated. The results showed that the epoxy potting compound performed best when the filling contend of ZnO was20wt%, the different particle size ratio of Al2O3(6μm:20μm) was controlled at2:3. When the filling fraction of hybrid thermal conductive fillers was86wt%, the thermal conductivity reach to2.23W/(m-K) and the viscosity is30100mPa·s,the volume resistivity is4.7×1015Ω·cm, the rockwell hardness (HRR) is106, the tensile strength is14.89MPa, the thixotropic index is1.79, the sedimentation rate is3.59%, which showed high thermal conductivity and good flow properties.