Larry,
I have been reading the responses on this thread with much interest.
The answers I heard were:
1) Your supplier is correct. It is easier to build.
2) There are designs which are benefited by non-functional pads, and
some which are not, depending on complexity, materials, and end-use
environment. Most designs, it seems, can function just fine without
them.
3) You are correct in that no one quoted a paper.
My 2 cents worth:
4) You (BFGoodrich) are responsible for your PWB designs, not your PWB
supplier. If field failures start coming in which are related to the
lack of inner layer pads, it is BFGoodrich which takes the hit.
(although if you are good, you will shift the blame to the supplier.)
5) I have typically retained the innerlayer pads on boards. I don't
have any experiences to tell you which way to go, since I do not risk
the problems. I would suggest that you post more specific design and
end-use info, so you could get responses closer to your needs.
6) Avionics Systems? Let me guess at the application. High complexity
and extreme vibration and temperature environment. Typical board may
cost $300-400. The fully assemblied card may cost $10,000 - $30,000,
and sell for $50,000+. Now, if the supplier charged you an extra
$15-$20 to keep the pads on the board, where is the trade-off? What is
the risk to life or equipment of intermittent operation?
7) If it were avionics in my plane, Plot the pads. It is a very cheap
reliability improvement, in an appropriate application.
Good Luck,
George Franck
Raytheon E-Systems
Falls Church Va.
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