Juki develops solder paste misalignment tool

With OPASS technology, the placement machine can automatically detect and compensate for misalignment of the solder paste to produce high-quality boards regardless of the process errors beforehand. "The OPASS system developed by Juki ensures that customers can achieve high first-pass yields regardless of circuit pattern variations between board lots," said Bob Black, CEO. While board makers strive to keep variations between lots to an absolute minimum, it is not possible for them to eliminate forward expansion and scaling completely. This means that the pads are not exactly in the same positions as they were on the previous lot. When the boards are fed into the stencil printer for solder paste there can be slight offsets from the solder paste print to the pad location. In larger parts that can be a very small percentage of the pad size, but in smaller parts like 01005, 0201 or even 0402, the solder could be halfway off of the pad. Likewise with ceramic or flexible boards, print repeatability can be difficult to achieve, causing further solder paste alignment problems. There also is cause for concern on double-sided boards because boards tend to contract after the first side reflow process. With the increased use of lead-free solder, the properties of the self-alignment effects have changed.