During laser soldering, the soldering wire is melted with the laser in order to join two metallic components together. The advantage of soldering is its minimum heat input compared to welding processes. In the case of hot-dip galvanized sheets, this means that the zinc layer evaporates in a very limited area, and the sheets only slightly deform during processing. For this reason, the laser soldering process has become widely accepted in car body construction in order to achieve connections with high mechanical stability without impairing the corrosion protection. However, it often happens that oxides and impurities in the zinc layer of the soldered seam cause irregularities such as splashes, pores, and uneven surfaces.
To avoid this, our partner Holo/OR has now developed a diffractive optical element (DOE): It forms three beams with different diameters and power levels. Two smaller guide beams, which preheat and clean the material and thus pre-condition the zinc coating for the soldering process, are crucial for the quality of the soldered joint. The large medium beam then takes over the actual soldering process. The homogeneous energy distribution ensures that the soldering wire is melted evenly. In this way, better melting performance and cleaner edges can be achieved with a single DOE. Several lasers or complex optomechanical elements were previously required to achieve this.
The new diffractive optical element made of UV quartz glass has an efficiency of 90 percent and significantly accelerates the soldering process.
