Femtosecond laser polishing of pure copper surfaces with perpendicular incidence

Over the past few years, femtosecond (fs) laser processing has drawn a growing interest in a wide range of applications as it offers the possibility to process the surface morphologies of metals and semiconductors. In contrast to other polishing techniques, laser polishing offers a flexible and non-contact solution, thereby avoiding potential external contamination, while enabling a precise selection of processing areas. We investigated the influence of fs laser parameters on surface roughness of pure copper and ablation thickness, focusing on highlighting the importance of fluence and scanning overlap. With a two-step processing strategy, composed of coarse and fine polishing steps, surfaces with Sa < 400 nm were achieved, representing a 98% reduction from the high roughness of 15 μm on initial surfaces. This research demonstrated the possibility of directly polishing rough parts using a fs laser with a perpendicular incidence. • Fs laser polishing reduces copper roughness using perpendicular incidence. • The research emphasizes optimizing laser parameters for optimal polishing results. • Laser polishing reduced surface roughness from 15 μm to <400 nm, a 98% improvement. • The laser polishing method can apply to other materials with complex structures.