Multi‐scale analyses on mechano‐electric degradation of film interconnects in flexible electronics

In flexible electronics, the fatigue reliability of film interconnects will directly affect the stability of the entire device. Since the thickness of the film material is usually much smaller than its length and width, the fatigue of film interconnects exhibits significant size effects. To evaluate the reliability of film interconnects, based on the theory of continuum damage mechanics, a multi‐scale damage model considering length‐scale effect is established. For the convenience of the model application in damage prediction of film interconnects, a multi‐scale mechano‐electric degradation model is further proposed. Validation with experimental data shows that the model can predict the fatigue life and resistance changes of not pre‐stretched films well. For pre‐stretched films, the proposed model is also applicable to thicker films without debonding or damage localization. The proposed model is expected to provide a facile approach for fatigue life prediction of flexible electronic devices with coplanar mesh structures. Highlights A multi‐scale mechano‐electric degradation model for film interconnect is developed. The combined effect of thickness and grain size is reflected in the proposed model. Damage and electrical degradation of film interconnect can be effectively predicted. Films less affected by pre‐stretching are also suitable for the proposed model.