Bauschinger effect in thin metal films on compliant substrates

Flexible electronic devices such as flexible displays and solar cells draw more and more attention from the industry. In these devices, the functionality is delivered by small-scale structures consisting of thin metal lines and other materials that are integrated on a compliant (e.g. polymer) substrate to make the device flexible. A major concern is reliability, since the small-scale structures with features on the order of micrometers or below are highly fragile, however, they are subjected to large thermo-mechanical loads during manufacturing and use. Although a growing literature exists on rupture and buckling of thin metal films on polymer substrates, see for instance [1], many mechanical issues of flexible electronics have not been studied in depth. In this project, one such issue, the Bauschinger effect of thin metal films bonded to a compliant substrate, will be studied in more detail, because the Bauschinger effect appears to be a particularly important issue in flexible electronics applications where the device is subjected to multiple strain cycles.