Electromigration　(EM)　has　become　one　of　the　reliability　concerns　to　the　fine　pitch　solder　joint　due　to　its　increasing　capacity　to　bear　the　high　current　density　The　EM　effects　on　microstructure　evolution　of　Sn-3.0Ag-0.5Cu+XNi　(X=0,　0.05,　0.45,　2.0wt.　%)　solder　joint　was　investigated.　Findings　of　this　study　indicated　that　an　appropriate　addition　of　Ni　element　and　moderate　ambient　temperature　can　alleviate　EM　damages　in　solder　joint.　The　intermetallic　compound　layer　which　held　a　planar　type　and　appropriate　thickness　improved　the　resistance　of　EM　effects　by　suppressing　the　polarity　effect.　Ag3Sn　and　the　bulk　IMCs　also　retard　the　effects　from　current　stressing　for　the　solder　joint.　©　2011　IEEE.