Product Code: ICAL09_906

Laser Pulse Influence on Spreading of AlSI12-Solder During Flux-less Laser Brazing of Aluminum
Authors:
Dmitri Donst, Fraunhofer IPT; Aachen Germany
Andreas Janssen, Fraunhofer I P T; Aachen Germany
Markus Niessen, Fraunhofer I L T; Aachen Germany
Fritz Klocke, Fraunhofer I P T; Aachen Germany
Presented at ICALEO 2009

Market and technology driven developments on aluminum light weight constructions require suitable joining techniques. Laser brazing of aluminum alloys is an appropriate technique that offers economical and technological advantage. However, the natural oxide layer on the surface of the aluminum alloys inhibits the wetting and so constrains the laser brazing process. Currently the industry applies chemical aggressive and hazardous fluxes which are cost-intensive and laborious in use. Therefore Fraunhofer IPT developed a novel two-beam-method for flux-less laser brazing of aluminum. The new technique uses simultaneously a continuous (cw) laser for heating and a pulse (pw) laser to improve the wetting behaviour of AlSi12-solder. Thus the ultra short pulses substitutes fluxes. The high-intensity laser pulses ablate the oxide layer and cause a recoil pressure on the melted solder. The pressure influence results in spreading of melted solder on the aluminum material. The aim of actual investigations is to advance the basic process know-how on the basis of computer simulations and experimental work. The middle-term goal of investigations is to enable an industrial implementation of the novel laser brazing technique. The research paper discusses recently gained results.