Precise patterning of carbon films on polyethylene terephthalate polymer substrates using femtosecond lasers

A carbon film on a polyethylene terephthalate (PET) substrate is a novel type of flexible laminated material with unique mechanical and electrical properties, making it suitable for the fabrication of various flexible electronic components. However, due to its micron-level thickness, conventional mechanical processing methods are incapable of precisely removing the carbon film without damaging the substrate. Femtosecond laser processing is an advanced technique for achieving precise etching of thin-film materials due to its non-contact, high-precision, and minimal thermal effects. Therefore, we use femtosecond lasers to achieve precision etching of carbon resistive films on PET substrates to minimize substrate damage. In this study, a series of orthogonal and single-factor experiments were conducted to optimize the laser processing parameters. Various measurement and characterization methods, including X-ray photoelectron spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, Raman spectroscopy, ultraviolet–visible spectroscopy, and confocal microscopy, were employed to analyze the removal of the carbon layer, changes in light transmittance, surface quality, and chemical composition of the processed substrate. Furthermore, the mechanisms of carbon film removal and PET substrate damage are explained.