Characteristics of mechanical behavior and environmental reliability of ultra-stretchable Ecoflex substrates

The selection of suitable stretchable substrates is important for successful development of stretchable electronics. Stretchable substrates should possess a higher stretchability, proper stiffness and reliability. In this study, we investigated the elastic mechanical behaviors of the Ecoflex substrate. The variations of the elastic modulus were evaluated using a tensile tester as a function of the base/curing agent mixing ratio, curing temperature and strain rate. Changes of the mechanical behavior of the Ecoflex after high temperature and high humidity storage tests were also investigated. Ecoflex showed the maximum true elastic modulus of 83.4 kPa at the base/curing agent mixing ratio of 4:1, on the other hand, the minimum elastic modulus at the mixing ratio of 8:1. The curing temperature also influenced the elastic modulus of the Ecoflex. The Ecoflex cured at 60 °C exhibited the maximum elastic modulus, on the while the Ecoflex cured at 90 °C showed the minimum elastic modulus. The results of the high temperature and high humidity storage tests showed that the change of the elastic modulus was relatively small, indicating the good mechanical stability of the Ecoflex on the environmental conditions. Ecoflex exhibited a very low hysteresis characteristics.