Influence of Nanosecond Pulse Bursts at High Repetition Rates on Ablation Process

Nanosecond laser pulsed ablation is a common technique for micromachining of microelectronics. Recent laser technologies use temporal shaping of single pulses to create 'pulse bursts' of several short consecutive pulses at several times the laser repetition rate with a reduced peak power, achieving significantly higher average powers. In this study we tested the effects of pulse bursts on ablation of multilayer PCB. We show that by implementing temporal beam shaping, we were able to increase the throughput by a factor of 40%. To gain a deeper insight of the laser mater interactions of ablation with pulse bursts, we studied the plasma emissions and monitor the process with a time resolution of several nanoseconds. These results demonstrate the importance of temporal pulse shapes for laser micromachining in the microelectronics industry. Keywords: nanosecond ablation, plasma dynamics, temporal pulse shaping, microelectronics, pump-probe microscopy