The effects of encapsulation on fatigue lifetime of stretchable interconnects under uniaxial cyclic tensile loading by finite element methods

This work investigates the effects of encapsulation on deformation behavior and fatigue lifetime of horseshoe-patterned stretchable interconnects, under uniaxial cyclic tensile loading. The finite element software ABAQUS is applied to analyze the deformational behavior of stretchable interconnects under different cyclic stretching conditions (10%, 15% and 20% elongation). Then according to the finite element analysis of various models, the empirical Coffin-Manson model is employed to evaluate the fatigue lifetime of stretchable interconnects. The simulation results show that, during cyclic stretching, the encapsulation layer on top of the stretchable interconnects not only suppresses the out-of plane deformation but also influences the value of plastic strain gradient in the thickness direction of copper. Moreover, based on the Coffin-Manson law, it can be found that the fatigue lifetime of stretchable interconnects decreases with the increase of encapsulation thickness (varied from 0.0 to 0.5mm).