Improving BGA solder joint quality is an ongoing goal for SMT engineers, especially when working with fine-pitch BGA components. In general, BGAs with a ball pitch of 0.8 mm or less are considered fine-pitch devices, although the exact definition may vary slightly among manufacturers.
BGA soldering is challenging because all the solder joints are located underneath the component body. After reflow, it is difficult to inspect the solder joints visually or with AOI (Automated Optical Inspection) equipment. In some cases, even X-ray inspection cannot reliably determine whether a BGA has open or false solder joints. Certain X-ray systems with oblique-angle imaging or 5DX technology may be able to detect some BGA soldering defects. However, these systems are expensive, and their cost may make them impractical for routine, in-line inspection in high-volume production.
