What it reveals
- BGA and QFN joints — ball collapse, bridging, head-in-pillow.
- Voids — size, distribution and whether they sit at the interface.
- Through-hole fill — barrel fill and voiding after wave or selective solder.
Why 3D
2D images superimpose every layer. 3D CT reconstruction slices the joint so the inspection can measure a void inside a specific ball instead of guessing from a silhouette.
Where it fits
First article, process qualification and failure analysis use 3D; routine production often uses 2D plus sampling. The inspection plan should say which applies to which package, so coverage is deliberate.
