Steven,

The IPC-4562 seems geared more to the copper foil and less with the
finished plated up copper thickness, at least from my quick glance at
it.  Here are my thoughts and the way I would do it as I see a couple of
differenct scenarios play out.  

If it is internal foil/copper-core, see what level of material they can
procure and what that can be held to.

If it is external or sequential lamination (would could have a couple of
plating cycles on exposed layers), what I would do in this particular
case is:
1. Spec on the stack-up in a note (or on the stack-up) of what you want
as the finished copper thickness to be.  Have the vendor buy into doing
this as I'm sure some can control to this level.  But note this will
probably result in a an up-charge.  

2.  Then also have a note that requires a cross-section to be done in
several places of one board for verification purposes. This could be
done in the coupons (less precise) or scrap one of the boards and use it
for the cross sections.  That results in a little fall-out but gives you
better data on your boards.  If there is a particular spot you wish
tested than indicate that, don't leave it up to them to guess.

All in all, get the vendor to buy into it, and have the notes on the
drawing indicating what is wanted and hold the vendor to it.  If it
doesn't meet the drawing requirements, you can always reject it.

Hope this helps,

-Jeffrey 

________________________________

JEFFREY A. JENKINS
SR. PCB/CAD Designer CID+
L-3 COMMUNICATIONS LINKABIT DIVSION
3033 Science Park Rd. 
San Diego, CA 92121
Tel:  (858) 552-9832
Fax:  (858) 552-9487
[log in to unmask]

 

-----Original Message-----
From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of
Steve Roy
Sent: Thursday, October 22, 2009 10:28 AM
To: [log in to unmask]
Subject: [DC] Finished copper thickness...

Hello,

I'm trying to use a copper plane for a small amount (less than 1 ohm) of
resistance and I need to have my 2 oz. finished copper thickness
consistently .0028 inches +/- .0005 inches).  How can I tell if my
copper
weight is consistent across the entire board or plane?  Is there a
specific
IPC standard (besides IPC 4562) that I should call out on my fab drawing
to
hold the board shop to a tight tolerance?

Thanks in advance...

Steven D. Roy, CID
PCB Designer
Audio Authority Corp.
2048 Mercer Road
Lexington, KY  40511-1071
(859) 233-4599 X-159
[log in to unmask]

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