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Proceedings Paper

Use of pre-pulse in laser spot welding of materials with high optical reflection
Author(s): Ihor Mys; Manfred Geiger
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Paper Abstract

Laser micro welding has become a standard manufacturing technique, particularly in industry sectors, such as automotive and aerospace electronics or medical devices, where the requirements for strength, miniaturization and temperature resistance are constantly rising. So far the use of laser micro welding is limited due to the fluctuation of the quality of the welded joints, because the welding results for material with high optical reflection and thermal conductivity, such as copper and copper alloys, depend very strongly on the condition of the material surface. This paper presents investigations on the use of a laser pre-pulse in spot welding of electronic materials with Nd:YAG laser. In order to achieve reproducible joining results two strategies are followed-up. The first one utilizes a reflection-based process control for measuring the reflection during the short pre-pulse. The intensity of the reflected light is used to calculate an appropriated welding pulse power, which corresponds to the measured relative absorption. Adjustment of laser parameters according to the condition of the surface is done in real time before laser main pulse. A second possibility for the stabilization of copper welding is the employment of a short and powerful laser pre-pulse before laser main pulse. This pre-pulse affects the workpiece surface and creates more reproducible absorption conditions for the main pulse, independent from the initial situation on material surface.

Paper Details

Date Published: 18 November 2003
PDF: 5 pages
Proc. SPIE 5063, Fourth International Symposium on Laser Precision Microfabrication, (18 November 2003); doi: 10.1117/12.540602
Show Author Affiliations
Ihor Mys, Univ. Erlangen-Nuremberg (Germany)
Manfred Geiger, Univ. Erlangen-Nuremberg (Germany)

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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