Development workflow based on in situ synchrotron investigations to optimize laser processing of copper pins

Journal of Laser Applications, vol. 36

Abstract

To design future laser manufacturing processes for welding of copper materials, more and more high-end analysis methods are required. A fundamental process understanding by analyzing cause-and-effect relations of process dynamics using inline in situ diagnostics allows for an improved description of laser material interaction. Strategies for a reliable and robust welding process are derived from the findings. In this study, a four-step advanced methodical approach is presented and discussed. In the first step, a fundamental process description of the geometry of the vapor capillary and the formation of weld defects is developed. Therefore, welds on electrolytic tough pitch copper (Cu-ETP) and CuSn6 are carried out to analyze the temporal and spatial vapor capillary dynamics depending on laser power, welding speed, and focal diameter. This fundamental process understanding is transferred to the welding of copper pins in the form of I-pins. For this purpose, impurities and imperfections were applied to the pin surface to investigate the effects on the process result. As a third step, strategies by means of laser intensity distributions were adapted to compensate for imperfections in the welding process. Finally, a sensor vision system is adapted for ideal welding results. Investigations are based on in situ synchrotron analysis at Petra III, DESY in Hamburg. For the experiments, a TRUMPF TruDisk laser (100/400 μm fiber diameter), a TRUMPF TruFiber 6000P (50/100 μm fiber diameter), and a single-mode fiber laser (14 μm fiber diameter) were used. The focal diameter was adjusted with the optical system depending on the investigation.

Authors 8

1. Marc Hummel

   TRUMPF (Germany)

   Affiliation as printed

   TRUMPF Laser- und Systemtechnik SE 1 , Johann-Maus-Straße 2, Ditzingen 71254, Germany

2. Christoph Spurk Aachen Chair for Laser Technology LLT 2

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University, Chair for Laser Technology LLT 2 , Steinbachstraße 15, Aachen 52074, Germany

3. Andreas Heider

   Robert Bosch (Germany)

   Affiliation as printed

   Robert Bosch GmbH, Corporate Research 3 , Robert-Bosch-Campus 1, Renningen 71272, Germany

4. Matthias Beranek

   TRUMPF (Germany)

   Affiliation as printed

   TRUMPF Laser- und Systemtechnik SE 1 , Johann-Maus-Straße 2, Ditzingen 71254, Germany

5. André Häusler Aachen Fraunhofer-Institute for Laser Technology ILT 4

   Fraunhofer Institute for Laser Technology

   Affiliation as printed

   Fraunhofer Institute for Laser Technology ILT 4 , Steinbachstraße 15, Aachen 52074, Germany

6. Mauritz Leander Birger Möller

   TRUMPF (Germany)

   Affiliation as printed

   TRUMPF Laser- und Systemtechnik SE 1 , Johann-Maus-Straße 2, Ditzingen 71254, Germany

7. Felix Beckmann

   Helmholtz-Zentrum Hereon

   Affiliation as printed

   Helmholtz Center HEREON, Institute of Materials Physics 5 , Max-Planck-Str. 1, Geesthacht 21502, Germany

8. Julian P. Moosmann

   Helmholtz-Zentrum Hereon

   Affiliation as printed

   Helmholtz Center HEREON, Institute of Materials Physics 5 , Max-Planck-Str. 1, Geesthacht 21502, Germany