Hello Kevin,

As Earl has noted, Boeing did an in depth study on resin recession a little
over 20 years ago and concluded that while the condition was undesirable
there was no apparent reliability issue so long as plating integrity was
intact.  No definable failure that could be assigned to the phenomena.
However, if I recall correctly, limits were set at the time to a number
roughly equal to the average amount of resin found on a hole wall. (~60%). I
don't know if this is still a working number.

I was working at Boeing at the time and a colleague Dr. Alan Smith lead a
team that did a solid study of the subject. Phil Tjelle was manager of the MR&
D group and was point man for Boeing in reporting the results and working
with the military and industry standards groups to get the problem classified
and resolved.

The effect appeared to be related to the degree of cure or completeness of
cross linking in the resin and was most evident after thermal stress testing.
Apparently the problem got the attention of the laminate suppliers and they
improved their resins as it is something that is rarely seen in cross section
anymore.

I would note also that it is possible that resin recession might sometimes
reported as hole wall pull away and hole wall pull away as resin recession as
they can look somewhat the same to the untrained eye but the mechanisms are
very different.

I believe that the IPC board acceptance specs cover the subject. Werner and a
few others here will likely have memories of this effect as well.

Kind regards,
Joe