Study On Electrical And Thermal Properties Of Epoxy For Electronic Packaging

As a traditional thermosetting polymer,epoxy resin(EP)is widely used in the field of electronic encapsulant due to its excellent comprehensive properties and low price.EP can enhance the integrity of the product to be sealed,improve the ability to resist external impact,while acting as insulation,moisture,water and acid and alkali corrosion resistance.However,with the development of industrial technology,the volume of power devices is getting smaller and the power density is getting larger and larger,and they are developing towards high temperature,high voltage and high frequency fields.The dielectric and thermal properties of traditional epoxy resins have been unable to meet the needs of industrial development,and become the bottleneck restricting the development of electronic devices.In this thesis,EP is organically modified by polyhedral oligomeric silsesquioxane(EP-POSS)and cyanate(CE)which have good thermal stability and chemical activity.EP/EP-POSS and EP/EP-POSS/CE composites are prepared by solution blending,vacuum defoaming and high temperature vulcanization.Firstly,the curing parameters of the composites are determined by non-isothermal DSC test and extrapolation method,and then the microstructure is characterized by XRD,SEM and FTIR.Finally,the effects of EP-POSS and CE on the electrical,thermal and mechanical properties of EP are systematically studied under various filling contents.The results show that EP-POSS can achieve molecular dispersion in EP,and there are good compatibility between them.The modification effect of EP-POSS at low filling ratio(1%,2.5%)is better than that at high filling ratio(5%,10%),and the best comprehensive performance is obtained at 1%filling ratio.At this time,the dielectric,thermal and mechanical properties of EP are improved,and the dielectric constant of EP at 50 Hz decreases from 4.83 to 4.76.The DC breakdown at 30℃increases from172.7 k V/mm to 193.1 k V/mm.At the same time,it has the lowest DC conductivity and the best space charge suppression ability.However,the thermal stability of EP is not significantly improved,and the glass transition temperature(T_g)was only increased by 9℃.The addition of CE further enhances the heat resistant and dielectric properties of EP on the basis of ensuring good compatibility,but the mechanical property is seriously deteriorated.Therefore,the best filling ratio is 1%EP-POSS and 30 wt%CE.At this time,on the basis of ensuring high insulation strength(255.1 k V/mm),the composite material has lower dielectric constant(4.31/50 Hz)and T_g up to 240℃,and its mechanical properties are basically consistent with EP,which can ensure stable operation in high temperature,high voltage and high frequency environment.It plays an active role in the development of high performance packaging materials.