Steve,
It appears that the only copper remaining at the
reduced area is the copper foil-which if your supplier started with 1 ounce
foil that is what the thickness is in the particular area.
It looks to me that something prevented the
electrolytic copper from plating but it was detected before
etching
and "touched-up" prior to etching.(Do you know if
your supplier does pattern or panel plating?) I don't think electrically it
will cause a problem unless it is high current net.
Tony
----- Original Message -----
Sent: Wednesday, May 28, 2003 1:53
PM
Subject: [TN] Trace thickness
problem...
Hi all!
I'd like your opinion on something. We're
building a prototype assembly for a customer, and discovered something at
final inspection that we didn't see when we received the bare fabs. We
ordered 16-boards in four, 4-up panels.
We found a trace that has a
spot where it looks like it didn't plate up during final plating. Take a
look at "Trace Thickness" at http://www.stevezeva.homestead.com
There's 4-boards we've found that have this problem, 1 on one panel,
and 3 on another panel, and of course they're all built up. The 6012 says
that thickness can't be reduced by more than 20% of the minimum conductor
thickness. I can't really tell if it's 20% or 50%.
I've sent pictures
both to our customer and the fab vendor. The customer wants the spot
repaired, and there are a number of ways to do that. The fab vendor says
it's not a problem because the stack-up drawing calls out 1-oz. copper after
plating on the surface layer, and they said that there's more like 2-oz. on
the surface layer, so there shouldn't be any problem, at least that's what I
was told, I didn't speak to anyone directly. The stack-up is on my page too,
look at "Stack-up"...
The first question that comes to my mind, if
1-oz after plating was called on the stack-up, why was 2-oz plated? Or is
that normal?. The drawing references our customers internal spec for
fabrication, but it uses MIL-PRF-55110 for references.
What are your
opinions about this?
Thanks everyone!
-Steve
Gregory-
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