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Proceedings Paper

Reliable laser micro-spot welding of copper
Author(s): Simone Amorosi; Thomas C. Sidler; Rene Paul Salathe; Hans Peter Schwob; Joachim Hertzberg
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Paper 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.

Paper Details

Date Published: 18 November 2003
PDF: 7 pages
Proc. SPIE 5063, Fourth International Symposium on Laser Precision Microfabrication, (18 November 2003); doi: 10.1117/12.540460
Show Author Affiliations
Simone Amorosi, Ecole Polytechnique Federale de Lausanne (Switzerland)
Thomas C. Sidler, Ecole Polytechnique Federale de Lausanne (Switzerland)
Rene Paul Salathe, Ecole Polytechnique Federale de Lausanne (Switzerland)
Hans Peter Schwob, LASAG AG (Switzerland)
Joachim Hertzberg, LASAG AG (Switzerland)

Published in SPIE Proceedings Vol. 5063:
Fourth International Symposium on Laser Precision Microfabrication
Isamu Miyamoto; Andreas Ostendorf; Koji Sugioka; Henry Helvajian, Editor(s)

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