Electromigration effects upon interfacial reactions

At the joints in microelectronic products, electric currents pass through interfaces of dissimilar materials. At these joints, atomic fluxes are driven by both the compositional gradients and electromigration effects. Although interfacial reactions at these joints appear to be affected by both of the driving forces, most often only compositional gradients are investigated when interfacial reactions are concerned. This study examines the effects of electromigration upon interfacial reactions together with the effects of compositional gradients, primarily in lead-free solder joints. It is found that electromigration significantly affects intermetallic compound growth in various systems. Growth rates of the intermetallic compounds are either enhanced or retarded depending upon the diffusion directions of the primary moving species and those of the applied electric currents. This study demonstrates that electromigration effect is an important factor in the interfacial reactions at the joints with the passage of electric currents. For more information, contact Sinn-wen Chen, National Tsing Hua University, Department of Chemical Engineering, Hsin-Chu, Taiwan 300, ROC;+886-3-572-1734; fax +886-3-571-5408; e-mail swchen@che.nthu.edu.tw.