Burnout mechanism and control methods in laser soldering

The random occurrence of component burn damage is a major challenge for laser soldering, but there is no effective solution so far. In order to solve the problem, two processes of constant power mode and constant temperature mode were used for laser soldering. The corresponding change curves of power and temperature were collected. In condition, the dynamic change of laser reflectivity during the whole welding process was tested. The process can be divided into five stages. It is found that the increase of reflectivity (64%) and peak power(＞70W) in the final stage is the main cause of the burnout. Finally, the cooperation control methods of power mode and temperature mode were adopted to restrain the burnout. The results provide an effective way to dynamically adjust the wettability of laser soldering and improve the reliability of solder joints.