| In order to solve the questions of curing temperatures are high, time is long forconductive adhesive curing only by heating, and incomplete curing only by pure UVlight, in this paper, epoxy acrylate resin is prepared and UV-thermal dual curingtechnology is be used. The conductive adhesive is prepared by epoxy acrylate resin andthe optimum amount of each component, optimum curing conditions are studied, at last,curing mechanism of the conductive adhesive is studied.The epoxy acrylate resin with1/4,1/3,1/2,5/8,3/4,7/8,1/1esterification ratiosare synthesized by E51and α-methacrylic acid. The reaction times and conversion ratiosof the epoxy acrylate resin are determined and characterized by testing epoxy value andFTIR. The adhesives are prepared by these epoxy acrylate resin and the mechanical andheat resistance properties of the curing film after cured the adhesives by UV-thermalmethod and the5/8esterification resin is determined the suitable for preparingconductive adhesive.The conductive adhesive is prepared with5/8esterification resin throughUV-thermal dual curing technology and the optimum amount of the diluents,photoinitiators, thermal initiators, curing agents and the conductive filler of theconductive adhesive are20%,3.5%,1.5%,10%,60%. The most suitable curingtemperature is140℃, curing time is120300s. The tensile拉伸剪切强度of the curedfilm reaches5.71MPa, the peeling strength is2.10kN m-1,硬度is6H, the resistivity isreduced to to5.30×10-2Ω m. The test results variable temperature resistance test and theTG show that the conductive adhesive has good thermal stability. And whentemperature reaches300℃, the conductive adhesive still has good electricalconductivity reliability. The SEM pictures of the Cured film surface and cross-sectionshow that the conductive particles are distributed uniformly and no settling phenomenonoccurring.The curing mechanism of the UV-thermal curing conductive adhesive is studied byusing non-isothermal DSC method and infrared absorption. Through the DSC curveswith different temperature rising, the average apparent activation energy to bedetermined is40.53kJ mol-1according to Kissinger and Ozawa equation. The curingreaction order of0.95is determined by Crane equation and the kinetics of the curing reaction equation is-da|dt=k（1-a）0.95. Through analysis of the conversion ratio ofactive groups in the curing reaction system, the curing process of the UV-thermal curingconductive adhesive probably are divided into three stages: the first is the rapid growthstage, in this stage the induced effect and oxygen inhibition effect are the mainlyhindrances. The second is tardiness rising stage, in this stage the cage wall effect is themainly hindrance. The third is stationary stage, in this stage the number of free radicalswill rapidly decrease due to the joint action of the induced effect and the cage walleffect and the curing degree of the conductive adhesive reaches a steady state. |
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