A highlight of the technology forum was the presentation by Thorsten Niermeyer, Sales Director & Product Manager, Koh Young Technology, focusing on the importance of the 3rd dimension in solder paste measurement. Entitled "Solder Paste Printing Process control,” Niermeyer started off by emphasizing that "paste is the foundation of the solder process and hence process control should be applied for this important process.” The measurement of the paste, therefore, must not stop at presence/absence, but include height, area and volume information, he added. Why is the 3rd dimension so important in the paste measurement? The deviations that occur in the process such as insufficient or excess, are the ones that lead to post solder defects defined in the IPC 610 standard. Insufficient solder is a difficult defect to be detected with post solder AOI and impossible to be measured on an in-circuit tester, but these solder joints are the first to fail in the field. With the increasing quantity of hidden solder joints, such as BGAs, CSPs or flip chips, the control and measurement of paste deposits is even more important. Detecting defects on (or under) these components requires expensive x-ray equipment and the repair process is much more delicate and time consuming than on visible solder joints. For these reasons, Niermeyer stressed on the importance of preventing the placement of a typically expensive component onto an area of defective paste. The paste printing process as such has a large number of parameters that influence the print result. Hence an immediate measurement after the print would determine in time, if this PCB is "fit” to be sent for further processing. A result from a change on the screen printer could be instantly quantified and hence better process parameters can be established. This leads to faster process set-up and a cut in "time to volume” | 
