You say that nothing changed, which is probably true
from your side of the fence, but the fabricator chooses
drill bits over-sized knowing that the plating will affect
the finished diameter. When they see your new note
for silver, they WILL choose smaller drill bits, knowing
the plating is thin and consistent compared to HASL.

So, as long as the finished hole is within tolerance
specified on the drawing, they did their job and should
be congratulated.
If the designer chose a hole size that is too small at
the low tolerance to insert the component easily,
there is no real mystery there, eh?


hope I read the situation correctly,
Jack



>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Croslin, Robert
> Sent: Tuesday, May 27, 2008 10:57 AM
> To: [log in to unmask]
> Subject: [TN] PTH's With Immersion Silver
>
> We've been using immersion silver on our boards for quite a while with
> great success, but in a recent run of a new product, we had the boards
> come in with the PTH's used to mount RCA and audio connectors smaller
> that usual.  The parts came in on the large end so it became very
> difficult for the operator to insert them into the board.  Both holes
> and parts were in tolerance and the holes were specified at the
> recommended diameters.  Our CM has a woman who spent 20 years working in
> pcb fab houses and she tells me that it's not at all unusual to have IS
> boards with reduced ID's on the holes as opposed to HASL.  Has anyone
> else experienced this?  If this is the case, we'll have to adjust for
> this in the future, but it would be useful to know if this was an
> anomaly or a normal condition?
>
>

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