Criss‐Cross Packaging for Serpentine Interconnects to Improve Stretchability of Flexible Electronics

Abstract With the advancement of flexible electronics technology, new packaging strategies for flexible electronics are urgently needed. Packaging helps to avoid direct contact between the working environment of the electronic components and the outside environment, which is essential for improving the reliability of the flexible electronics. A typical inorganic flexible system composed of serpentine interconnects for providing stretchability, inorganic functional components, and packaging materials for protecting the device. Thus, system combining serpentine interconnects and planar flexible substrates are widely used, however, the stretchability of the structure is unsatisfactory. Herein, criss‐cross packaging is proposed to release part of serpentine interconnects from the substrate, which enable to improves the stretchability of the device significantly. Theoretical and numerical models relating to the geometric parameters of the structure are developed to study the stretchability of the structure. Roof collapse between the freestanding part of the serpentine interconnects and the substrates is considered by an analytical model. The influence of the position deviation of serpentine interconnects to the substrates is studied numerically. A LED (light‐emitting diode) system integrating the serpentine interconnects and the criss‐cross packaging is prepared, low‐cycle fatigue test confirms the stability of the criss‐cross packaging.