Product Code: ICA13_M604

Extension of the Process Boundaries for the Soldering of Elongated Interconnectors with a Simultaneous Energy Deposition
Authors:
Simon W. Britten, Fraunhofer Institute for Laser Technology Ilt; Aachen Germany
Wolfgang Fiedler, Fraunhofer Institute for Laser Technology Ilt; Aachen Germany
Alexander Olowinsky, Fraunhofer Institute for Laser Technology Ilt; Aachen Germany
Arnold Gillner, Fraunhofer Institute for Laser Technology Ilt; Aachen Germany
Presented at ICALEO 2013

Soldering processes are used to bond elongated interconnectors to metallized silicon wafers e.g. solar cells. The minimal process time is expected to be limited due to the maximal thermoshock resistance of the substrate, the required time for the energy deposition and the wetting process of the solder. The simultaneous energy deposition realized with a diode laser and a line optic lowers the process time for interconnectors of 140mm length below 1 s. The selective energy deposition on the interconnector reduces the temperature-induced stress in the substrate. The wetting process of the solder is evaluated with high-speed cameras and compared to the characteristic temperature profile measured with a pyrometer. Different process times and the effect of short-term overheating to reach process times below 0,5s are investigated. The minimum process time is assessed regarding the physical wetting process of the solder and the effect on the solder quality.