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Proceedings Paper

Process spread reduction of laser microspot welding of thin copper parts using real-time control
Author(s): Antoon Blom; Par Dunias; Piet van Engen; Willem Hoving; Janneke de Kramer
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Paper Abstract

In present-day industry, particularly in the area of microelectronics packaging and assembly, there is a strong demand for highly reliable, miniature joints of thin copper parts. Laser welding could be the perfect solution for making such joints if this process were not highly sensitive to various parameters, such as the reflectivity of the copper workpiece, the gap between the product parts to be welded, and laser-power density. The robustness of the process is further limited because two important product properties (reflectivity and heat conductivity) change strongly during welding. An investigation has been performed to increase the robustness by means of real-time feedback control, based on several parameters that are monitored simultaneously during the process. It is shown how this drastically decreases the influence of the above-mentioned variations with "heat conduction" welds. The control algorithm was based on an approximate model of the (non-linear) welding process. In addition, it is shown how adaptive feedforward control is required to cope with the limited response time of the system. Finally, some remarks are made on experiences iterative learning control. This investigation was part of the European co-operation project SLAPS, performed within the framework of the IMS/Brite-Euram III program. The support from the European Commission and the IMS regional offices is gratefully acknowledged.

Paper Details

Date Published: 17 October 2003
PDF: 15 pages
Proc. SPIE 4977, Photon Processing in Microelectronics and Photonics II, (17 October 2003); doi: 10.1117/12.478612
Show Author Affiliations
Antoon Blom, Philips Ctr. for Industrial Technology (Netherlands)
Par Dunias, Philips Ctr. for Industrial Technology (Netherlands)
Piet van Engen, Philips Ctr. for Industrial Technology (Netherlands)
Willem Hoving, Philips Ctr. for Industrial Technology (Netherlands)
Janneke de Kramer, Technische Univ. Eindhoven (Netherlands)

Published in SPIE Proceedings Vol. 4977:
Photon Processing in Microelectronics and Photonics II
Alberto Piqué; David B. Geohegan; Friedrich G. Bachmann; Koji Sugioka; Frank Träger; Jan J. Dubowski; Peter R. Herman; Willem Hoving; Kouichi Murakami; Kunihiko Washio; Jim Fieret, Editor(s)

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