The operating ambient of flexible electronics interconnects is a complex environment that includes mechanical deformation, electric current, and temperature. It is a potential threat to the long‐term service reliability of flexible electronic devices. This paper aims to develop a multiphysics fatigue model for flexible metal films. The effect of multiphysics fields is considered in the Coffin–Manson relationship based on reasonable simplification. The fatigue behavior of copper films of various thicknesses on a flexible substrate was investigated when electrical current and mechanical displacement loads were applied simultaneously. The developed model is validated to compare with experimental results. The numerical results show that it can analyze the effect of multiphysics fields and predict the fatigue life of copper films. Therefore, it could be a means to assess the fatigue performance of metal films on flexible substrates in multiphysics fields.

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.

Wire breakage has always attracted much attention in drawing. Mastering the mechanism of drawing fracture can effectively improve the quality of steel wire. In this study, the morphology of the fracture samples is analyzed. There are obvious V-shaped microcracks in the materials by observing the microstructure. Base on the above results, the wire models with V-shaped microcrack of different inclinations are established via the finite element method (FEM). Besides, the multi-pass drawing under different back tension is simulated, and the process from crack propagation caused by damage to fracture is realized. The results show that microcrack has a great influence on the drawing fracture, and inclination is a key factor. With the increase of angle, the propagation rate of crack increases accordingly. Meanwhile, back tension will increase the accumulation of damage. The larger the back tension is, the larger the crack path is, which eventually leads to the formation of pen-tip shaped fracture.