Development ofanAutomated X-RayInspection MethodforMicrosolder Bumps

BGA,CSP,andflip-chip packages arewidely usedin printed circuit boards. Thesepackages useanarray ofsolder bumpsastheelectrical junction. Toreduce thefailures in manufacturing andafter long-term use, solder bumpinspection isstrongly required forquality control. Inthis paper, we propose anautomated inspection method formicro-solder bumpsusing anX-ray image. Thethickness, area, volume, and void ofthesolder bumpswereautomatically inspected bythis method. We introduced somecorrection techniques toreduce theeffects ofvariation intheX-ray intensity andthespatial non-uniformity intheimage. Inthis experiment, weevaluated accuracy andrepeatability. Theresults demonstrated that the accuracy andrepeatability mettherequirement foronline inspection. In conclusion, ourautomated methodfor inspecting micro-solder bumpsmaybeuseful inpractice.