Printing Precision And Calibration Research Of Vision Screen Printing Equipment

SMT (Surface Mount Technology) is an important basic industry of the electronicinformation industry. As the miniaturization and the densification of electronic components,the requirement of the SMT equipment has become higher and higher. It’s necessary toimprove the printing precision and stability as the solder printing is important to the SMTproduct quality, which is the first process of the SMT product line. In this study,comprehensive errors analysis is conduct base on the relation between the process and theprinting defects of the auto-vision screen printer. A method of calibration and precisioncompensation is established which improve the printing precision and stability.Firstly, establish the equipment kinematic model base on the relation between processand printing defects and get the transformation of the multiple space coordinate systems.Conduct kinematic analysis of the alignment platform, including positive and inversekinematic model, singular configurations, workspace and end effectors pose, which builds atheoretical foundation for the error analysis.Secondly, the error analysis of auto-vision screen printer is researched. Vision alignmentsystem is analyzed. The influence coefficients of the input parameter are tested in thekinematic model and then establish and analyze the error model. Pre-position error andpositional deviation of printing height is researched in the transfer system. The relationbetween the printing pressure and defects is analyzed in the scraper system.Thirdly, establish a method of calibration base on error analysis to eliminate the grosserror, calibration the system error and limit the random error. According to the calibration data,a precision compensation is built to improve the printing precision and stability.Finally, an experiment of printing precision and stability between kinematic algorithmand calibration algorithm is conduct. The result demonstrates that the calibration andprecision compensation method has calibrated the error of equipment and improve theprinting precision and stability, which is valuable to the development of SMT industry.