Research And Preparation Of High-performance Silver Electrically Conductive Adhesive

Isotropic electrically conductive adhesive(ICAs),a new type of environmental friendly materials as a substitute of traditional Sn/Pb solder,has been widely used in microelectronic packaging due to their numerous advantages,such as lower curing temperature,simpler operation process,and fine pitch capability.However,compared to the mature soldering technology,there are also many challenges for ICAs,for example,relatively high volume resistivity,low thermal conductivity,weak bonding strength,short shelf life,low glass transition temperature and so on.In present thesis,the formula and curing conditions of ICAs was optimized,including the systematically analyse of resin matrix,curing agent,and conductive fillers.IPNs formed from a model triallyl isocyanurate(TAIC)and dicyandiamide-cured epoxy resin(E-51)has been introduced into conductive adhesive formula.The viscosity of ICAs based on the IPNs decrease sharply.Furthermore,ICAs based on IPN have a lower volume resistivity,higher thermal conductivity,higher glass transition temperature(T_g)and higher shear strength due to entanglement of polymer chain and formation of interpenetrating networks.In order to improve the electrical properties of ICAs,silver nano-particles(Ag-NPs)have been introduced into conductive adhesive formula by spin steaming instrument.This simple method prevented the agglomerates of Ag-NPs.Only a small amount of Ag-NPs,much lower than literature reported previously,can dramatically improve the electrical conductivity of the ICAs based on Ag-MFs.The method makes that ICAs with less silver fillers have a lower volume resistivity and reduces the cost for application in electronic packaging.To further improve the electrical properties of electrically conductive adhesives(ICAs),silver halides has been introduced into a typical isotropic conductive adhesive formula.ICAs with a small amount of silver iodide have lower percolation threshold(P_c),lower volume resistivity,higher thermal conductivity and higher glass transition temperature(T_g).The reliability of the micro-Ag-flake filled epoxy adhesives is evaluated by the 85°C/85%relative humidity moisture exposure for1000 hr.The micro-Ag-flake filled epoxy adhesives with the excellent performance can be considered to be an ideal ICAs candidate for electronic packaging applications.