A system must use OVHM techniques to inspect these small joints and avoid indicating false positives.
Since image quality is crucial, OVHM techniques are a must for viewing vias.
An alternative to the 2-D systems with OVHM is a 3-D system with sophisticated computer tomography or 3-D imaging techniques to create a slice-by-slice analysis of the IC.
Three-dimensional (3-D) imaging systems build on the 2-D x-ray with OVHM system except both the x-ray source and detector move, and the software captures multiple images to compile the final 3-D image.
All x-ray testers, with or without OVHM, can perform the listed measurements to some degree.
Double-sided boards will require OVHM or 3-D techniques.
However, opens where a ball is present but has no contact with the substrate require OVHM or 3-D.
The other option is 2-D systems that rotate and tilt the components while maintaining highest magnification (OVHM technology).
The advantages of a 2-D system with OVHM are faster image acquisition and less cost.
However, the 2-D system with OVHM shows three opens (Figure 6).