Dennis Fritz, (Denny) 

As David mentioned, the 40% "resin recession"/ "hole wall-pull-away" in
IPC-ML-950 came from the Mil spec, MIL-P-55110, where it is was called only
"resin recession" but, some of the the smarties looking for "reason to
reject" said we cannot tell the difference between "hole-wall-pullaway" and
"resin recession" and they classified it all in thr "resin recession
category.  It first appeared in the "C" (circa 1978) when MIL-P-55110 was
merged with MIL-P-55640.  MIL-P-55640 was almost never imposed by the
military agencies.  The 40% was accepted in  MIL-P-55110 as a safe acceptable
limit that many of us who were military suppliers could meet, as we were
getting hit with rejections because "hole-wall-pull-away" was now included by
some quality functions in the "resin recession" category. The number was
strickly out of the air and was number that G. Smith who was in control NSA
could agree with.  I think that IPC-RB-276 is the first document that even
classified resin recession and hole- wall pull-away in one document.
 Accordingly, some suppliers supplying to the MIL spec. use the only category
mentioned in the spec. which is "resin recession" and the other probale
defectf, "hole-wall-pull-away" regardless of amount is not counted.
 IPC-RB-276 attemped to put everybody on an even ground get people to
evaluate it the same and to inform people that it might exist and when you
see it, it is not a defect.  As for the military specification, I do not
believe either characteristic is mentioned in MIL-PRF-31032.

With IPC-ML-950 we used to get many calls such as: is it the combination of
all the blips on one side; if the copper bulges and the dielectric is even;
is it realy resin recession; where did the 40% come from; where does the tail
of the hole-wall-pull-away end and do I count it in my measurement.
 Hopefully. this has all gone away with IPC-RB-276 and IPC-6012 and
MIL-PRF-31032 even though I still see it in lot of company specs. which
require both IPC-RB-276 and the 40% limit.    

Hope the above does not confuse you client, with or without translation .

Phil Hinton 
[log in to unmask]         

***************************************************************************
* TechNet mail list is provided as a service by IPC using SmartList v3.05 *
***************************************************************************
* To unsubscribe from this list at any time, send a message to:           *
* [log in to unmask] with <subject: unsubscribe> and no text.        *
***************************************************************************