This is what we ask for:

We use a 0.050" pad with a 0.200" clearance diameter.  The clearance
diameter needs to be clear of soldermask, silkscreen and outer layer traces.

Two fiducials per board are required.  The two fiducials should be
diagonally as far apart from each other as possible.  If the board has parts
on both sides, the board needs fiducials on both sides.  It is OK for the
top and bottom fiducials to have the same X-Y location.

In addition to the fiducials listed above, if a component has a pitch of
0.025" or less, it needs a single local fiducial.  (This is based on the
requirements of our placement equipment.  Some assemblers prefer two local
fiducials.)  The local fiducial should be placed as close to the center of
the component's land pattern as possible.  For this reason, we recommend
that the fiducial be added to your library geometry for the part.


At 18:09 5/3/96 -0700, Tim Grotheer wrote:
>Greetings:
>
>I'm looking for some standard specs on placement, size, dimensions, etc on 
>fiducial marks for PCBs. Can you offers any suggestions as to where I 
>might find some impromptu info without having to purchase massive volumes 
>of specifcations???
>
>TIA,
>TG
>
>
>
>

-Pat-

-------------
Patrick McGuine
Nicolet Instrument
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(608) 276-6334