By Philipp von Witzendorff, Lorenz Gehrmann, Martin Bielenin, Jean-Pierre Bergmann, Stefan Kaierle and Ludger Overmeyer

Pulsed laser welding is applied for welding of thin aluminum sheets when the heat affected zone has to be minimized. The pulsed laser process enables a low and precise heat input because the heat dissipates away in between the laser pulses. Applications are hermetic sealing of electronics or opto-electronics which are not persistent enough to resist high temperatures. Aluminum has a low absorptivity (~ 5 %) for the laser radiation of industrial established YAG laser sources which restricts the process efficiency. In addition, several aluminum alloys have a high tendency to generate hot cracks during welding which is even more severe in pulsed laser welding because the pulsed mode leads to rapid cooling. Continue reading →