Effect of surface modification on laser direct joining of cyclic olefin polymer and stainless steel

As for the surface pretreatment of COP, the generation of bubbles in ultraviolet (UV)-ozone processing due to thermal degradation of the COP was more noticeable than with plasma pretreatment. Excessive surface modification of the COP, causing a decrease in joint strength was found to correlate with the surface energies of COP and SUS304.