Design for reliability of multi-layer thin film stretchable interconnects

Abstract

To date, nearly all electronic systems have been rigid and inflexible. However, there are many areas such as in biomedical devices in which these rigid electronics are less than ideal and which require new conformable electronic systems. In order to create effective, compact, and complex systems, stretchable interconnects must be designed to overlap one another in multiple layers. The circular strain relief structure described in this paper effectively redistributes the strain to the crest of the horseshoes of the interconnects themselves. Numerical analysis and simulations of the strain relief structures described in this paper indicate that the structures will function indefinitely when stretched up to a 20% elongation. In-situ electromechanical measurements show that the structures are able to withstand elongations of 285% or more before failing. Precise failure mechanisms including straightening of the interconnects and micro-crack formation are documented with images taken during the electromechanical tests.