Computational damage mechanics of electromigration and thermomigration

Articles you may be interested in Thermomigration and electromigration in Sn58Bi solder joints Electromigration in flip chip solder joints having a thick Cu column bump and a shallow solder interconnect Effect of entropy production on microstructure change in eutectic SnPb flip chip solder joints by thermomigration Appl. Reliability of solder joints under Electromigration (EM) and Thermomigration (TM) has drawn increasing attention in recent years, however current understanding regarding degradation physics of solder alloys under time varying current loading is still quite limited. As most integrated circuit (IC) connectors carry Pulse Direct Current/AC signals under normal operating condition instead of DC, investigation of EM/TM failure under time varying current becomes essential. In this paper, detailed formulation is presented to characterize material damage due to electromigration and thermomigration. Entropy based damage model is adopted to characterize the material degradation physics. Thermal gradient is observed to reach 1000 K/cm in current crowding regions, which is high enough to induce TM damage. Most of the time solder joint failure is due to combined action of EM and TM effects, therefore failure under pulsed current loadings due to combined action is investigated. Vacancy accumulation during current on period, and healing during current off period is modeled. In order to simulate EM/TM degradation of solder joints under pulsed current, ABAQUS user defined subroutines (UEL and UMAT) are used. V C 2013 AIP Publishing LLC.