Research On The Preparation And Thermal Conductivity Of EP Encapsulating Adhesive For High-power LED

In this paper, pure ZnO was successfully coated on the surface of BN,which acted as thethermal conductivity inorganic filler of epoxy resins(EP) encapsulating adhesive via the sol-gelmethod. The high-blooded interfacial properties of ZnO was a great help to improve the thermalconductivity of the sealant by better the dispersion of BN in epoxy matrix.The BN@ZnO fillerswere eventually synthesized after sintering, moreover, the influence of precursor solution pH value,the sintering temperature and the coating concentration were empirically discussed. In addition, thecomposite filler (BN+AlN) were synthesized via the hot pressed sintering in order to to improve theloading of fillers into EP. The compatibility between surface modified and matrix was enhancedwith silane coupling，and so the viscosity was reduced. To optimize the process parameters for thepreparation of the fillers, the thermal conductivity of encapsulating was texted under differentprocess conditions.The phase composition and morphology of samples were analysised by X-raydiffraction (XRD) and scanning electron microscopy (SEM). Solidworks thermal simulation wasused to forecast heat transmission capacity of the encapsulating adhesive when the LED lamp A70worked.The different heat dissipation performance of two kinds of encapsulating adhesive werealso tested and evaluated.The results show:1) ZnO layer was successfully coated on the surface of BN, which couldimprove the compatibility between BN and EP matrix, and ameliorate the particle dispersion intoEP;2) The correlation between crystal structure of BN@ZnO and heat-conducting property wasinvestigated systematically. When the pH value of precursor solution is6, the coating concentrationof BN and ZnO is5:1,and the sintering temperature is850℃, the coating effect is the best.Whilethe volume filling content is15%, the thermal conductivity of BN@ZnO/EP sealant was1.09W/(m·K);3) Pure BN filling into EP with high viscosity, while adding BN/AlN ccould reduce theviscosity of the system;4) Under the protection of nitrogen hot pressed sintering, the compositefiller (BN+AlN) could come into being.When the volume is35%,(BN+AlN)/EP sealant got thehighest conductivities,1.18W/(m·K).After that, silane coupling agent was used to do surfacetreatment of the composite filler, the thermal conductivity could be further improved;5) With theloading increasing, two potting glues’ viscosity, tensile strength and thermal conductivity changed;6) Thermal simulation based on LED A70showed that both of encapsulating adhesive worked out. The dissipation effect of (BN+AlN)/EP sealant was superior to that of BN@ZnO/EP sealant,respectively, the lamp’s temperature of the link layer was decreased by2.17℃and1.8℃.