Hello TechNet,

We all know the IPC-A-610 requirements on BGA voids, namely "30% or less voiding of any ball in the X-Ray image area" as acceptable condition.
The % value indicated pertains to a cumulated value from a 2D topside view of an X-ray image like on all MXI (Manual X-ray Inspection) systems.

How to manage such requirement for 3D AXI (Automated X-ray Inspection) systems that work on a completely different "slice" approach?
For a given BGA, 3D AXI systems will rely on few slices (e.g. 3) of the BGA joint with a variable section where the voiding criterion will not be applicable as is.

Also, how to ensure a 3D AXI process is well under control?
For manual X-ray inspection, everything relies on the operator and it is easy to judge the adequate knowledge and experience of the operator.
For 3D AXI, there is no operator, everything relies on the programing and the program set-up and tuning is rather tricky, typically requiring the support of a MXI.

The recently released IPC-7095D provides excellent guidance on both MXI and AXI (see an extract below), but does not address the implementation of actual voiding requirements in AXI systems.

Extract from IPC-7095D §7.3.3 :
What generally distinguishes AXI systems from MXI systems is AXI systems are in-line capable and do not require an operator to make pass/fail decisions. MXI equipment is almost exclusively a transmission X-ray technology, whereas AXI
equipment can be transmission, cross-section or a combination. MXI systems deliver much better resolution and much higher quality images, and as a result are much more accurate in manual mode. Some MXI systems provide automatic routines, including step and repeat, auto BGA, QFN, area void and solder pad analysis, but these are secondary to their main function being an X-ray microscope.
AXI systems are also faster. In many cases an MXI system is used to verify the AXI results and help fine tune the AXI auto inspection parameters.

Thanks in advance for your feedbacks.

Best regards,

AG