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May 2003

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Subject:
From:
Bill Decray <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Wed, 28 May 2003 14:15:41 -0400
Content-Type:
text/plain
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text/plain (94 lines)
I agree it look like a open to me as well. Since it is at a angle it will be
very difficult to place a weld there. As far as the finish copper half oz
foil should have been used unless a waiver from the customer was provided to
use 1 oz. I would also ask for a cross section of the board as well. How did
the open pass electrical test?
Just my thoughts.


Highest Regards,

William W. DeCray III
PHONE:(434) 237-6391 ext 115
CELL:   (434) 851-6115
FAX:    (434) 237-1324


-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Steve
Gregory
Sent: Wednesday, May 28, 2003 1:53 PM
To: [log in to unmask]
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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