>I feel the generally accepted industry standard for the determination of
PAD
>SIZE is the following:
>
>NOMINAL Finished Holes Size + (2 x annular ring requirement) + .010"
>(manufacturing tolerance) = Pad size.
>
>Example:  .035 FHS + .004 - .001 = NOMINAL Finished Hole Size = .0365" + (2
x
>.002) + .010 = .0505".  I have not read 55110 for a while so just determine
>what the annular ring is and plug it in.  Hope it helps.
>
Andy, I think  your  0.010 mfg. adder is a bit  small.  Certainly, the
pad/hole combo is attainable, but I wouldn't plan on it for a run of
production boards where you might be looking for low piece price.  We've
heard from Mr. Slade of HADCO, but what do the other board manufacturers
think?  Is my 12 to 14 mil adder too conservative?  Heck, I'm still using 8
and 8 ;-)  !

Tom Hybiske
General Atronics Corp.

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