Enrico- Ah, but the voids are often not spheres and the XRAY is not black & white! So your equation would need to also include comparative densities (contrast ratios) between the void and adjacent non-void regimes. Add to this that there is stuff internal to the board and on the opposite side of the board, and estimating area is about all you can do, unless you get a highly detailed CT scan! Typically, people bring up practical problems in this forum. Is this a practical problem? Can you share some snapshots of how the IPC guidelines are either too permissive or too conservative in certain situations? Basically, the IPC guidelines are in place to establish relatively easy-to-measure characteristics to serve as a basis for civilized discussion amongst the various stakeholders for an electronic assembly. Presently, the area of voiding is the standard we're using. Lots of software packages do an automated calculation of this, and I'm not aware of practical problems with the results. Zero voids as measured with an XRAY does not mean there's actual contact being made, so it's not a perfect measurement. You can still have "head-in-pillow", "champagne voids" too small to be picked up on the XRAY, brittle intermetallics, etc., which will either prevent connection entirely or substantially reduce useful life. But your suggested changes won't help with any of these. Wayne From: Enrico Galbiati [mailto:[log in to unmask]] Sent: Tuesday, May 12, 2015 10:12 AM To: TechNet E-Mail Forum; Wayne Thayer Subject: Re: [TN] Voiding evaluation If you are considering the missing mass (and I agree on it), the volume of the voids is more appropriate. Also the evaluation of the volume of the voids can be done easily with the X-rays: you just sum the void diameters raised to power 3 (instead of power 2 as in case of the evaluation of the area) and divide the result by the solder joint diameter raised to power 3 too. So the evaluation of the volume is not more complicated than the evaluation of the area.