Development of a Next Generation Stretchable Substrate for Micro-LED Application

Stretchable-and-flexible-substrate-based systems have been focused as one of the next-generation applications of smart devices. The pre-stretched substrate implemented by buckled/wrinkled layers is widely used to enhance the stretchability and reliability of the system. At the same time, many different materials are tested to deal with large deformation for the substrate. However, most of the pre-stretched substrates can be stretched in uniaxial due to its nature of the wavy structure. Moreover, embedded rigid subcomponents on the substrate are severely affected and finally delaminated because of the excessive strain of the substrate. This study introduces a new concept of a hybrid stretchable substrate by combining two different regions into a single layer; rigid and soft regions. The soft region enables to stretch of the substrate in biaxial, while the rigid region offers a safe space for subcomponents to protect from the strain of the substrate. Two types of substrates of 40 mm x 40 mm and 150 mm x 120 mm were successfully fabricated. The hybrid substrate showed >20% uniaxial stretchability and >40% areal stretchability without failure. This hybrid substrate can be laminated with a pre-stretched substrate and/or used as a substrate for stretchable-and-flexible applications.