Study on mechanical reliability of flexible display structure considering multiple neutral planes

Abstract

Recently, multiple-neutral-planes approach was suggested to demonstrate highly flexible electronics which has low elastic modulus adhesive, but the works have been limited to its application only. To adopt the multiple-neutral-planes approach for structural design of flexible electronics, fundamental analysis and practical validation focused on the multiple-neutral-planes configuration are significant. In addition, although flexible OLED display contains soft adhesive layers during transfer process, the multiple-neutral-planes concept has not been considered yet. Here, the multiple-neutral-planes in the structure was verified experimentally with low elastic modulus adhesive and Indium-tin-Oxide (ITO) thin films. Based on the experimental validation, protection of dual ITOs under dual bending directions was demonstrated. Furthermore, Parameter study was conducted to analyze the generation of multiple-neutral-planes with respect to configuration of the structure. Through this, design guidelines were suggested based on a threshold modulus which captures the transition in generation of multiple-neutral-planes. Based on the fundamental study of multiple-neutral-planes, flexible OLED display structure was analyzed considering large deformation of soft adhesive by FEA.