(hey Scott, long time no see.... So you're back to using "NVISION"
mailboxes, eh?)

 I don't know if you've received other responses because I'm in digest
mode, but from my experience silkscreen is notoriously inaccurate, and
shouldn't be used for critical alignment.
I would put small copper targets or something, because they can't be
"misregistered" with the other copper features on the surface layer.
Board marking is covered in IPC-A-600, but it is only regarding legibility,
not registration. As a general rule I wouldn't trust silkscreen to be more
accurate than +/-10mils, but that is just me talking.

nice to "see" you again, good luck

Jack Olson
Caterpillar, Inc.





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Date:    Mon, 24 Jun 2002 17:06:06 -0700
From:    Scott Lefebvre <[log in to unmask]>
Subject: IPC spec on silkscreen alignment.

Is there a IPC spec on silkscreen alignment I could not find one.  I have a
component outline that is used for a LLP package to confirm alignment on
the board.  Do to the fact this component has not leads it is important to
assure it is properly align to footprint.  I have found that the silkscreen
is off .003" in one direction and .011" in the other.  The CELL is correct
and I know it's not the data being sent to the board manufacture.  Any help
in this matter would be appreciated.

Scott L

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