Effect of electromigration induced joule heating and strain on microstructural recrystallization in eutectic SnPb flip chip solder joints

► A refinement of the lamellar microstructure was observed after electromigration. ► The strain induced by electromigration under a high current density is estimated. ► A possible mechanism on the formation of nano-scale lamellae is proposed. ► Electromigration induced two extreme microstructure changes is compared.