Abstract: Based on FEM and submodel technique,the electric-thermal-structural coupled analysis for flip chip ball grid array (FCBGA) package is performed to obtain the distribution of current density,temperature and stress for the key solder joint. By using atomic flux divergence (AFD) method and atomic density integral (ADI) method,the electromigration (EM) characteristics and influence factors of the key solder joint are studied. The SEM image of the key solder joint under EM demonstrates that the ADI method with the consideration of four driving mechanisms,such as electron wind force,stress gradient,temperature gradient and atomic density gradient,can effectively predict the EM failure location. The atomic density gradient (chemical potential) usually can retard EM phenomenon.