Solder paste printing in six-sigma-quality

The solder paste printing is one important part of the manufacturing process. More than 50% of all defects of SMT-boards are caused by the printing process. Six-sigma-quality is one common important goal of manufacturing processes. Another criterions or such a quality are a defect rate of about 3,4 DPM (defects per million) or a process capability C_pk > 1,5. The printed solder paste volume, the printed area; the height and the deviations (x/y) are the most important quality characteristics, to evaluate the printing quality. The paper shows some practical experiments and the associated results, to optimize the printing process.