Laser soldering system calibration based on computer vision

Due to fine pitch BGA chips, acquiring high quality joints without detrimental effects on other components of chip needs accurate alignment of the unit in packaging technique. We developed an integrated laser-soldering system which combines a computer vision. Based on the analysis of experimental data, we find that lens distortions and assembly angular errors of X-Y stage play a distinct role in introducing positioning errors. For the sake of satisfying positioning accuracy of end-effector and precision specification of packaging technique, an algorithm based on straight line method is built to abate distortions of image, and a compensation algorithm for calibrating positioning of the non-vertical X-Y positioning stage is also developed. Finally, experimental results and comparative data to evaluate the performance of these approaches are reported