Micromachining of copper using Nd:YAG laser radiation at 1064, 532, and 355 nm wavelengths

The interaction phenomena of nanosecond time period Q-switched diode-pumped Nd:YAG laser pulses using 1064, 532 and 355 nm with 0.25 mm thick pure-copper foil was investigated at an incident laser intensity range of 0.5– 57.9 GW/ cm 2 . For each sample, etch rate and surface structure were determined. Analysis of the results of the tests included scanning electron microscopy (SEM). A maximum etch rate of 13.3 μm per pulse was obtained for the etch rate tests carried out at 532 nm . The maximum etch rate obtainable for 1064 nm was 2.21 μm per pulse, and for 355 nm , 6.68 μm per pulse. The dramatic decrease in etch rate observed when processing at 1064 nm is thought to occur due the highly reflective nature of copper as the interaction wavelength is increased, plus the nature of the plasma formed above the material during the high-intensity laser–material interaction. This plasma then imparts energy to the surface of the processed area leading to surface melting of the area surrounding the hole as can be seen by the SEM photographs.