Numerical and experimental study on laser soldering process of SnAgCu lead-free solder

Abstract

Laser soldering has been widely used in the connection of the electronic components and printed circuit boards. Normally, the temperature and thermal stress of solder joints significantly influence the soldering performance and the reliability of solder joints. However, it is difficult to be accurately measured by the experiment during laser soldering process. In order to reveal the effect of laser process parameters on the temperature and thermal stress of SnAgCu solder joints, a novel 3D transient thermo-mechanical coupling numerical model is proposed using finite element method. The numerical simulation results reveal that the temperature and the thermal stress as well as the deformation of the as-soldered samples are proportional to laser output power and output time. These results demonstrate that the fine and uniform microstructure is obtained for SnAgCu solder and the micro Vickers hardness reaches to the maximum value of 38.3 N at the condition of laser output power of 16 W and laser output time of 0.8 s. The good consistency between the experimental and simulation results proves that the finite element model may effectively predict the temperature distribution and stress distribution, which provides a new pathway for the optimization of the laser soldering parameters in the application of electronic components and PCB.