Effect Of Bending Deformation on Damage of Ag Nanoparticle Lines Under Electrical Loading

Abstract In recent years, flexible electronic circuits, particularly flexible printed circuits (FPCs), are becoming widely used in wearable devices, flexible sensors, and liquid crystal displays. Inkjet printing technology has attracted attention for manufacturing FPCs, enabling low-cost and small-scale production of conductive lines using nanoparticle metal inks. The circuits' flexibility and durability are typically evaluated through bending and tensile tests. As electrical devices become smaller, increased current densities and Joule heating can lead to electromigration (EM) damage. EM is a phenomenon which metal atoms are transported by high-density electron wind, causing damage to electronic lines. Ag nanoparticle lines, due to their porous structure, exhibit a distinct EM damage. Therefore, understanding the damage characteristics of EM in actual situation is important for reliability evaluation of these lines. However, the EM damage characteristics of these lines under both mechanical stress such as bending and electrical stress has not been fully studied. This study investigates the effect of mechanical stress on the lifetime of Ag nanoparticle lines under electrical loading. High-density current loading tests were conducted on Ag nanoparticle lines drawn on the flexible substrates. After the tests, the line morphology was analyzed using a laser microscope to assess damage. As the results of current loading, applying tensile stress shortened the line lifetime compared to no stress, while applying compressive stress prolonged the time until voltage instability occurs. This research provides valuable insights into the reliability of flexible electronic circuits under both mechanical and electrical stresses.