Author: Dan Lilie
Abstract: It takes only one defective ball to render an arrayed component unusable. The ability to replace just a single sphere enables a package to be repaired – one that may be expensive, may otherwise be unavailable, or where reworking is more expediant than waiting for a replacement. As in most common SMD rework processes, at first the defect solder ball (if still existing) needs to be removed and then replaced by a fresh one. The actual challenge is to avoid harm to adjacent solder balls during the reflow process. This demands special handling solutions which will need to become even more refined if the trend towards component miniaturization continues. Rework devices without adapted tooling, force control and high-resolution optical alignment and placement systems will hit their limits pretty soon.
