In a message dated 10/05/2000 9:55:18 AM Central Daylight Time,
[log in to unmask] writes:

Hi Jim!

I'd have to agree with Daan. Very rarely, if ever, have I used local
fiducials.

As long as there is some good global fiducials, I've never found the need to
use Locals...this includes placing 15.7-mil pitch parts and MicroBGA's...

-Steve Gregory-

> Hi Jim,
>
>  One solution could be to place the local fiducials underneath the
components.
>  Another solution: don't use them.
>  And do you really need a 0.150 (inch ?) keep out area ?
>
>  Kind regards,
>
>  Daan Terstegge
>  SMT Centre
>  Signaal Communications
>  Unclassified mail
>  Personal Website: http://www.smtinfo.net
>
>  >>> Jim Kittel <[log in to unmask]> 10/05 3:25 pm >>>
>  TechNetters,
>
>  With so much emphasis on reducing circuit board feature sizes by use of
>  micro BGA's, micro lead frames, micro vias, etc. the use of local fiducials
>  becomes a real burden.  For example, our typical fiducial is a 0.048 circle
>  with a 0.150 keep out area.  This keep out area is approaching the size of
>  flash memories, micro BGA's, 0402 chips, etc.
>
>  Has anyone figured out a way to work around this local fiducial problem?
Is
>  anyone grouping these parts into some kind of symmetric clusters?  Any
>  ideas?
>
>  Jim Kittel

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