Michael,

The testing we did was undertaken to see what we might need to change in 
our existing designs, after we had made a decision on laminates and finish that 
would be suitable for our particular needs.  So the only finishes we tested 
were ImAg and ENiG, using no-clean, and .062 boards.  We assembled boards 
using our existing lead/hole/pad ratios, and then ratios on either side of 
those.  What we found was that there was not a large difference, but the 
ratios in that chart worked well, and fortunately (with no intended bias) were 
our existing design standards.  The hole sizes are slightly larger than what had 
been normally used in the industry for SnPb solder, it turned out that while 
they weren't optimal for our old SnPb wave, they are for SAC.  We did note 
that in all ratios, the ImAg seemed to fill a bit better, though both finishes 
passed the 75% requirement.

This hasn't been a cure all, we have found assemblies failing the 75% 
requirement on occasion, but only when our manufacturinjg process was not 
properly controlled.  So there isn't a lot of room for error, but that's lead-free.

Pete

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