Stretchable metal interconnects. The video shows microscopic view of stretching of a newly design meander-shaped metal tracks. The newly presented meander design is optimized to distribute and lower the peak stress value and torque in the locations where premature failure commonly occurred. The presented design uses a variation of the well established “horse shoe shaped conductors”. Our meander shaped metal ribbons varied the widths and radius of curvature. The weakest points in the reference structure are the upper and lower turning points of the meander, which are inline with the direction of elongation. These locations are exposed to high levels of torque and stress. Torque propagates to these points due to the build up of higher and lower levels of stress at the outer and inner edges of the relatively wide and uniform meander. It eventually leads to premature rupture of the metal track in this region. A combination of two measures was used to improve this section. Specifically, we reduced the width of the meander and added a small connecting loop in the section leading to this turning point to minimize the twist. Moreover, reinforcement bars are introduced to offer stress relief in the contact pad region connecting the devices where defects occurred.
Tags: Stretchable metal interconnects, horse shoe shaped conductors, meander, metal tracks, stretchable interconnects, stretchable electronics, metamorphic electronics, reinforcement bar