Experimental and Numerical Investigation of Electromigration Behavior of Printed Silver Wire Under High Current Density

Abstract

The electromigration (EM) damage is becoming a severe problem in the printed flexible electronics as the printed circuits are fabricated thinner and thinner due to the development of printing technology. In this work, the EM behavior of printed silver wires was investigated by EM experiments and numerical simulations. The EM tests showed that voids are generated in the cathode area and hillocks are formed in the anode area for a wire with a small length. However, with the increase of wire length, hillocks tend to occur on the two sides of the silver wire middle part. The results of numerical simulations based on the atomic flux divergence (AFD) method revealed that the formation of the hillocks on the printed wire is caused by not only the mechanism of electron wind but also the strong temperature gradient along the wire length and width direction. Also, it can be concluded that the temperature gradient induced by Joule heating plays a more important role than electron wind in the atomic migration of the printed silver wire subjected to a high current density. The influence of the printed silver wire size on the EM behavior was also analyzed by numerical simulation, and the results demonstrated that the printed silver wires with a larger length and a smaller width-to-thickness ratio are more likely to develop hillocks on the two sides of silver wire middle part while subjected to a high current density.