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| Reply To: | (Designers Council Forum) |
| Date: | Tue, 26 Jun 2007 11:26:48 -0400 |
| Content-Type: | text/plain |
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Hi John,
+/- 10% is standard for most board shops.
I wouldn't worry about the impedance though,
if you've specified it in your drawing it should
be met along with the board thickness.
Regards,
Andre Demers, C.I.D.
Senior PCB Designer, Coordinator
cmrsummit Technologies
329 March Road, Suite 203
Kanata ON K2K 2E1
Canada
Telephone: 613.599.3881
Toll Free: 877.428.1229
Pager: 613.368.0506
Fax: 613.599.7889
[log in to unmask] <mailto:[log in to unmask]>
www.cmrsummit.com <http://www.cmrsummit.com/>
-----Original Message-----
From: DesignerCouncil [mailto:[log in to unmask]]On Behalf Of
Babcock John
Sent: Tuesday, June 26, 2007 11:21 AM
To: [log in to unmask]
Subject: [DC] Board Thickness Tolerance
Fellow Designers,
Long time lurker, first time poster. I've had a few posts over the
years, just not very many.
Ok here goes.
What is a good overall thickness tolerance to put on your dwg for a
0.125" thick board? This board is impedance controlled and should stay
pretty close to the 0.125" to meet our required impedance values.
I am kind of in a unique situation where we deal directly with an
assembly house and that assembly house farms out the board fab to
whoever gives them the best quote. So I never know which board house
will get the board. Hence I never know the capabilities of the board
house where the board gets sent to be made.
With that being said, XYZ board house wants to loosen up the tolerance
to +/- 0.012" on the overall board thickness. This would throw our
impedance calculations off.
Just kind of curious what everyone would expect as a good tolerance on a
0.125" board.
John Babcock, C.I.D.
PCB Designer III
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