High-temperature resistant marking patterns prepared on polyimide film using femtosecond laser

This study investigates the preparation and recognition of marking patterns on high-temperature-resistant polyimide (PI) film surfaces using femtosecond laser. By optimizing laser processing parameters, PI surfaces with anti-reflective micro/nano structures and diffractive laser-induced periodic surface structures (LIPSSs) were obtained. Moreover, the traditional two-dimensional code and color code were fabricated based on the optimal laser processing parameters. Subsequently, after laser processing, Raman spectroscopy indicated carbonization on the PI surface. An analysis of the atomic ratios and group content on the PI surface revealed that the alteration of chemical groups was dependent on the generation and removal processes. High-temperature testing demonstrated that the marking patterns on the PI surface remained stable in environments up to 300 ℃, with no significant changes observed in the traditional two-dimensional code after exposure to high temperatures. The color code comprised four colors: the inherent brown-yellow of the PI substrate, black from ablation, and two additional colors induced during processing. Furthermore, the color code was recognized by separately extracting the black, yellow, and purple parts. Therefore, this research further achieved the marking patterns with easy identification, high capacity, and high-temperature resistance on PI film.