Why is it that you
need tolerances that tight? In inches they are requesting .007" which is
high.
they shouldn't have to go higher then .005"
(.127mm) I think they are adding registration with drill
tolerance.
Get them to break down their tolerances or what
issues make them require this tolerance.
I can see if they have a .004" drill tolerance and
a .003" registration.
Don't force them to do tighter tolerances then they
request. That is what they are comfortable with.
I am sure there are places that can do your
request, but at what cost. Shop around a little more.
Chris Robertson
Design
Engineer
Lockheed-Martin Technology Services
4912 Research
Dr.
Huntsville, AL 35805
(256) 722-2626
[log in to unmask]
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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