Perhaps, more descript observations are necessary.

Thank you Mr. Arivett for taking the first "crack."
.......................................................
I might have used "barrel" cracking loosely because this might be a very
specific cause.

Mr. Arivett's suggestion to compare drill hole size to engineered size
will be done and posted; however, note that not much pad lifting is
going on, and the z-axis of the epoxy wall is linear from knee to knee.
The deviation is mostly in the middle where it appears the plug shrunk
and pulled the barrel inwards.

These observations do not occur with any other hole in the board except
the resin filled signal holes.

Mr. Arivett pointed to curing; however, our material is twice cured at
149 degrees Celsius (rather than once as suggested by the manufacturer).  

Additional information Mr. Arivett did not have was that the holes were
NOT filled via electroless deposition.

What's puzzling is the appearance of the "shrinkage" in that the barrel
walls look like an hour glass.  Plating is very even and at least 1 mil,
and NOT ALL barrels crack.

Thank you Mr. Arivett,
and others who might have a suggestion or two,

The Condor  


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