A NEW SPI TOOL for Defect Prevention

摘要

Solder paste deposit imbalance is a key factor in the formation of many reflow soldering defects, including tombstones, drawbridges, non-wet opens, head-in-pillow, and tilted QFNs. A new automated solder paste inspection (SPI) routine can check for paste volume imbalance to preempt the defects prior to component placement. SPI machines measure solder paste deposit characteristics such as volume, height, area and position. Then they compare the values against programmed control limits. If all the values are within the control limits, then the print is considered a Pass; if one or more deposits are outside the control limits, the print is rejected as a Fail. The most commonly checked parameters are volume and position.