EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Electrically conducting metal layers play a crucial role in flexible and form adjusting electronic devices and components. Conductive metal coatings on polymer substrates are often combined with thin metal interlayers to improve adhesion to the substrate. These adhesion promoting interlayers are mostly brittle in nature, greatly affecting a device’s susceptibility to damage under mechanical load. Studies are needed to understand such an interlayer’s effect on fatigue properties, damage mechanisms, and lifetimes of devices. We looked at the influence a 30 nm chromium interlayer has on a conducting gold film on a polyimide (PI) substrate. The focus of the analysis is on the role the hard interface (Au-Cr) has on fatigue properties of the system in comparison to a soft interface (Au-PI) without an adhesion promoting interlayer. With cyclic uniaxial straining, using a combination of in-situ electrical resistance measurements and surface imaging methods, a large amount of data was generated to model micro-damage mechanics. Finite element simulations were used to further improve our understanding of the failure mechanisms of thin film material systems.