Influence of laser parameters and material properties on micro drilling with femtosecond laser pulses

We report experimental results of drilling micro holes in Al, Mo, Ti, Cu, Ag, Au, and brass thin metal foils in air using 60-femtosecond Ti:sapphire laser pulses. The influence of laser parameters and material properties on drilling processes at the sub-10-micron scale has been examined. Comparison of hole drilling using 60-fs pulses with that using 50-ps and 10-ns pulses at an energy fluence of ∼15 J/cm2 indicates that a significant amount of melting is present in both ps and ns regimes, whereas with fs pulses, fewer and much smaller droplets from the molten phase are observed.