Study And Preparation On Silver Conductive Adhesive

The preparation and performance of the silver conductive adhesive were studied in thispaper. The silver conductive adhesive components and its selection principle were describedat first. Through theoretical analysis and experiments, the components of thermosetting silverconductive adhesive were confirmed: epoxy resin, acid anhydride curing agent, modifiedimidazole compounds used as curing accelerator,5μm flake silver powder used as conductivefiller. The thermoplastic silver conductive adhesive was also discussed. And it was made up of:ethyl cellulose, terpineol or two ethylene glycol monobutyl ether, and silver powder.The components and curing properties of thermosetting silver conductive adhesivematrix were discussed, and its conductivity, adhesion strength and electromagnetic shieldingperformance were tested. The conductivity of silver conductive adhesive was tested by smallcurrent resistance tester, when the mass fraction of silver powder is more than75%, theresistivity can reach10-4cm; the adhesion strength of silver conductive adhesive was testedby digital electronic universal testing machine, and when the content of silver powder is60%,the tensile shear strength is15.75MPa; the electromagnetic shielding performance of silverconductive adhesive was tested by electromagnetic shielding room, and the shieldingeffectiveness can reach51dB. The relationship among the components of resin matrix andcuring speed and applicable term of silver conductive adhesive was studied. The resultsshowed that: the amount of curing accelerator is the main influence factor of resin matrixapplicable term and curing time. When the amount of accelerant is large, the applicationperiod is shorten, at the same time curing time will be shortened; with less accelerant, thesilver conductive adhesive is suitable for longer periods, at the same time, its curing time willbe longer. The influence of powder morphology and filling volume of silver on silverconductive adhesive properties was studied. The results show: the flake silver particles havelarge contact area, the conductive adhesive has lowest resistivity; with large silver content, thesilver conductive adhesive has low volume resistivity after cured, but at the same timeadhesion strength decreased; the shielding effectiveness increased with the silver contentincreased. Shielding effectiveness was also influenced by coating thickness.The components, preparation and performance of the thermoplastic silver conductiveadhesive were studied. Based on the thermal plastic resin research, ethyl cellulose was chosenas thermoplastic conductive polymer resin; terpineol and two ethylene glycol monobutyl etherwere chosen as solvents. The optimal quantization ratio of solvent and polymer resin was4:1.The printing performance of thermoplastic silver conductive adhesive was studied.Non-contact printing method was chosen. The screen was stainless steel screen, and printingmaterials was polymeric membrane. When the ratio of solvent and ethyl cellulose mass was4:1, the silver conductive adhesive was dispersed easily and easy to grind, and easy to printthrough the mesh to form a smooth line. The effect of diluent on silver conductive adhesiveshowed that: in the process of coating can be improved by diluent, but the resistance value ofthe effect was uncertainty. The process of silver conductive adhesive with of three roller millwas explored, and the results show that the mixing effect of three roller mill is better than themanual preparation. In this paper, thermosetting and thermoplastic silver conductive adhesive were studied. Andtheoretical and experimental basis were founded.