The mechanism study of laser peeling of ultra-thin polyimide film from the transparent substrate

Laser peeling of ultra-thin polyimide (PI) film from transparent substrate is a critical technology in the flexible electronics industry. This paper studies the laser ablation and interface separation of the PI film to reveal the mechanism of laser peeling. In the laser ablation process, the supercritical environment is formed, and gas bubbles appear. Then the gas bubbles fuse together and become cavitation holes. These cavitation holes fuse together and produce sparse nanopillar structures that can be seen as a blister. In the interface separation process, the blister absorbs thermal energy and expands under laser irradiation. This paper proposes a discrete quasi-static method to analyze the separation of the PI film from the transparent substrate during the blister expansion. The cohesive zone model is also introduced to predict the peeling behaviors of the PI film. The results show that the blister profile is related to the laser influence, and the blister profile obtained by the theoretical model can fit well with the experiment. When the laser fluence is larger, the blister profile is steeper, and the pressure inside the blister is larger. This paper provides a new perspective for understanding the laser peeling mechanism of ultra-thin PI film from a transparent substrate.