Copper and gold are materials with high reflectance so that those are known as hard-to-weld materials. Wavelength of SHG laser is 532nm which is a half of fundamental laser (1064nm) and that makes laser absorptance to copper and gold 4.5 to 20 times higher than fundamental laser. Even copper and gold does not reflect SHG laser.SHG laser increases laser absorptancy of copper and gold Perfect solution for welding thin copper wires with PCB, welding of bus bars and more.