Effect of electromigration and isothermal aging on interfacial microstructure and tensile fracture behavior of SAC305/Cu solder joint

The Cu/Sn-3.OAg-0.5Cu/Cu butting solder joints were fabricated to investigate the evolution of the interfacial intermetallic compound（IMC） and the degradation of the tensile strength of solder joints under the effect of electromigration（EM） and aging processes.Scanning electron microscopy（SEM） results indicated that the Cu₆Sn₅ interfacial IMC presented obvious asymmetrical growth with the increase of EM time under current density of 1.78×10⁴ A/cm² at 100℃,and the growth of anodic IMC presented a parabolic relationship with time while the cathodic IMC got thinner gradually.However,as for aging samples at 100℃ without current stressing,the Cu₆Sn₅ IMC presented a symmetrical growth with a slower rate than the anodic IMC of EM samples.The tensile results indicated that the tensile strength of the solder joints under current stress declined more drastic with time than the aging samples,and the fracture mode transformed from ductile fracture to brittle fracture quickly while the fracture mode of aging samples transformed from cup-cone shaped fracture to microporous gathering fracture in a slow way.