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Experimental design has proved to be a useful statistical tool in reducing process variation. The technique has been applied to a wide range of processes, including electronics assembly and soldering processes. For effective SMT assembly the screen printing of solder paste requires tight process control, especially as pad geometries become ever smaller. However, printing of solder paste is a rather complex process which is affected by machine, material, environmental and human factors, which make it difficult to characterise effectively. This paper examines the practical application of experimental design to solder paste printing for SMT and also the results from a number of experiments carried out on a semi‐automatic ‘clamshell’ type screen printer. The experimentation concentrates on the important printer and squeegee parameters and their effect on paste deposition, with measured solder paste height and ‘measle’ diagrams used as process outputs. The usefulness of the experimental results in determining the best printer settings, as well as the problems encountered during the experimentation, are highlighted.

Electronics exhibitions are the same the world over, very tiring affairs. If your stand is busy, time flies; if not, the strain is more noticeable.

The UK is a leader in the implementation of surface mount technology, and SMARTEX '91 sponsored by the SMART Group is one of only a few shows organised worldwide which is dedicated solely to this field. Perhaps it was not surprising then that this year's three‐day event proved a great success.