Evaluation and suppression of PET damage in the UV nanosecond laser ablation of an SS304 circuit on a metal/resin composite film

Flexible heating elements consisting of metal circuits and resin layers are widely used in semiconductor, medical, and food service equipment. Laser fabrication of the metal circuit on the resin layer is more efficient and environmentally friendly than traditional chemical etching processes. This study assessed thermal damage on a polyethylene terephthalate (PET) layer while ablating a stainless steel 304 (SS304) circuit on SS304/PET composite films using a nanosecond pulsed laser. The effects of the laser power, scan speed, and scan pass on the damaged width and depth of the PET film were explored. The results showed that the pulsed laser radiation on the upper SS304 foil has a low risk of causing thermal damage to the PET film. The PET thermal damage occurred mainly owing to direct laser radiation after the upper SS304 material was removed. The damage depth developed significantly faster than did the damage width, as the tapered SS304 cutting slit obstructed the periphery of the laser beam. In addition, adding a 35 μm-thick polyethylene vinyl acetated adhesion layer between the SS304 and PET can reduce approximately 80% of the damaged depth. This research provides a reference for the laser cutting of metal circuits/resin films for heating elements.