Electromigration　(EM)　is　considered　to　be　one　of　the　most　important　reliability　issues　for　current　and　future　ICs　in　10nm　technology　and　below.　In　this　paper　we　focus　on　the　EM　stress　evaluation　for　one-dimensional　multi-segment　interconnect　wires　in　which　all　the　segments　have　the　same　direction,　which　is　a　common　routing　structure　for　power　grid　networks.　The　proposed　method,　which　is　based　on　integral　transform　technique,　could　efficiently　calculate　the　hydrostatic　stress　evolution　for　multi-segment　metal　wires　stressed　with　different　current　densities.　The　new　method　can　also　naturally　consider　the　pre-existing　residual　stresses　coming　from　thermal　or　other　stress　sources.　Based　on　this　new　transient　EM　assessment　method,　a　full-chip　assessment　algorithm　for　power　grid　networks　is　then　proposed.　The　new　algorithm　is　also　based　on　the　IR-drop　metrics　for　failure　assessment　of　the　power　grid　networks.　However,　it　finds　the　precise　location　and　time　of　EM-induced　void　nucleation　by　directly　checking　the　time-changing　hydrostatic　stresses　of　all　the　wires.　The　resulting　EM　assessment　method　can　ensure　sufficient　accuracy　of　the　EM　verification　for　large　scale　power　grid　networks　without　sacrificing　the　efficiency.　The　accuracy　of　the　proposed　transient　analysis　approach　is　validated　against　the　numerical　analysis.　Also　the　resulting　EM-aware　full-chip　power　grid　reliability　analysis　has　been　demonstrated　and　compared　with　existing　methods.