Prediction of Micro Pitch Motion of a Microsensor Component during Laser Soldering Interconnection Process

Generally, the purpose of soldering is to provide a robust joint. However, for a microsensor assembly, precise position or appropriate pose of the component in operation is also a major concern to ensure monitoring the target effectively. In the present work, a three-dimensional finite element thermal-mechanical indirectly coupled model was developed to investigate the pitch motion induced by laser irradiation during the soldering process. Two kinds of subroutines were designed for modeling the behavior of the laser and the elements above the melting point. The laser soldering includes two independent processes: pre-bumping and reflow. Results on both processes indicate that the pitch angle becomes to be dominant during the solder solidification. Two different pitch motion mechanisms in pre-bumping and reflow were discussed in detail. Pitch angle obtained from the finite element analysis is in good agreement with that from the experiment