Hi all,

Let me just drop my two bucks worth. I think (and apply) that one
"local" fiducial should be fine for most picknplace machines (not all,
of course). I'm not sure I get the "rotational accuracy" needing two.
You should be getting the "rotational accuracy" (if this is what you
mean) from the two (and often times three) "global" fiducials placed on
the board. A single fiducial placed locally per device, and often times
grouped for cells should be acceptable.

Also, I only go with local fiducials on parts with pins on less than
.025" (.64mm) pitch. Some might question the .025" parts, but I don't
place fiducials on them. Just me.

Mitch
Sr Hardware Engineer

---------Included Message----------
>      Date: Fri, 26 Jan 2001 16:15:25 -0800
>      From: "[log in to unmask]" <[log in to unmask]>
>      Reply-To: <[log in to unmask]>
>      To: <[log in to unmask]>
>      Subject: Re: [DC] DC IPC Design rules for Fiducial clearances
>
>      > My two cents, I would agree with Cyrus, there, to my
knowledge,
>      is no use
>      > for the
>      > fiducials after placement is done, the only reason to go with
either
>      > one fiducial under the part or two fiducials on a diagonal, (as
far as I
>      > know)
>      > would be to increase the speed at which the machine could align
and place
>      > the parts.
>
>      The advantage of 2 fiducials is rotational accuracy as opposed
to
>      just locational for 1 fiducial.
>
>
>      Dave Farthing
>      Gordian Design Services
>
>      direct any spam to: [log in to unmask]
>
>
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