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July 2003

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Subject:
From:
Roger Stoops <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Wed, 2 Jul 2003 13:15:41 -0400
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Hiya folks!

We are having some difficulty getting a flex supplier to build a circuit to our specs.  The issue has to do with coverlay tolerance.  They are requesting we open the coverlay openings so that they can use +/-0.50mm location tolerance.  This allows for exposed copper between pads/lands to be soldered during installation.  We have asked for +/-0.20mm tolerance, but might live with +/-0.25mm to +/-0.30mm.  They **keep** coming back asking for the loose tolerance each time we say no.  We have already taken into consideration the annular ring and adhesive squeeze-out, and cannot enlarge the openings by more than .10 or .15mm.

These are typically 2 to 4 layer flex circuits with plated holes, polyimide lam with thermoset acrylic adhesive.

Am I just being to picky? hardnosed? stiff-necked? all the above?
What tolerances can I expect or ask for?
Any alternatives or other details I may not be aware of?  (Don't assume I know a lot about flex.. thanks.)

Looking forward to your assistance,
Sincerely,

Roger M. Stoops, CID 
Trimble Navigation Ltd., Dayton, OH, USA
Ph: +01 937.245.5288
Fax: +01 937.233.7511 

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