Reliable laser micro-spot welding of copper

Simone Amorosi; Thomas C. Sidler; Rene Paul Salathe; Hans Peter Schwob; Joachim Hertzberg

doi:10.1117/12.540460

18 November 2003 Reliable laser micro-spot welding of copper

Simone Amorosi, Thomas C. Sidler, Rene Paul Salathe, Hans Peter Schwob, Joachim Hertzberg

Proceedings Volume 5063, Fourth International Symposium on Laser Precision Microfabrication; (2003) https://doi.org/10.1117/12.540460
Event: Fourth International Symposium on Laser Precision Microfabrication, 2003, Munich, Germany

Abstract

Nd:YAG laser welding of high reflectivity metals is difficult because of the highly non-linear light-material interaction yielding a narrow process window and poor reliability. However, achieving high reliability is mandatory for applying this technique in industrial production lines. The welding control can be improved by real-time monitoring of the process evolution with sensors. Such sensor signals are particularly useful for weld classification and for laser power control in off-line or in closed-loop feedback configurations. The latter possibility is difficult to implement in pulsed lasers and requires a careful sensor choice. Here, we report on laser lap micro-spot welding of thin copper sheets using a pulsed Nd:YAG laser. The welding was performed under atmospheric conditions on pure, 50 μm thick, slightly oxidized copper sheets with pulse durations and energies of less than 8 ms and 8 J, respectively. The process was experimentally analyzed by detecting normal laser reflection, heat emission, and instantaneous laser power with high time resolution. The meaningful signal parameters have then been selected for a closed loop feedback control. The variance of top and bottom weld spot diameters could be reduced by more than a factor of 8 in the case of closed loop control.

Citation Download Citation

Simone Amorosi, Thomas C. Sidler, Rene Paul Salathe, Hans Peter Schwob, and Joachim Hertzberg "Reliable laser micro-spot welding of copper", Proc. SPIE 5063, Fourth International Symposium on Laser Precision Microfabrication, (18 November 2003); https://doi.org/10.1117/12.540460

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