Jim, Guy, Nancy and others,
I respectfully submit the following:
If the intent for the 50% hole fill allowance (in regard to PTHs with
thermal or conductor planes) is to be limited to class 2 then the exception
should be listed directly under "Acceptable - Class 2" not under "Defect -
Class 3" on page 6-7 and table 6-2 should have a note that flags this
allowance for Class 2.
As we all know, it is impossible to clearly and concisely write with the
English language in such a manner that all readers will properly understand
the meaning or intent of the words that is or are being conveyed.
Having not participated in the IPC-A-610 meetings (as Guy  referred to), I
and others do not have the luxury of understand the intent of certain
requirements -- all that is affored to us is the written words.
In this case, the intent may have been to limit the 50% hole fill
requirement to class 2 but the printed words do not support this beyond the
shadow of a doubt.
I will prepare a Standard Improvement Form for IPC-A-610C and forward to IPC
so the committee can fill more hours with antiquated prose about this
subject.
I on the other hand still believe that 50% hole fill on most class 3
products will not cause a problem in terms of long term reliability even
under extreme conditions as apposed to reworking the solder connection.
This statement is made under the premise that a well defined, developed and
controlled process is utilized.
If there is any objective evidence that 50% hole fill is a problem, I along
with Sir Werner would like to review the data, hardware, photomicrographs,
cross-sections, etc.

Steve Sauer

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