In a message dated 6/5/98 9:30:54 AM Pacific Daylight Time,
[log in to unmask] writes:

>
>  Hello everyone,
>
>  I am trying to find out if anyone is still requiring local fidutials on
fine
>  pitch patterns.
>
>  Does anyone REALLY use them?
>
>  They  consume a lot of real estate.  Todays placement machines do an
>  excellent job using only the global fidutials.
>
>  Your responses are greatly appreciated !
>
>
>  Russ Vertefeuille
>  Sr. Project Eng.
>  Honeywell, BCAS
>  Glendale, AZ
>

Hi Russ,

     Global fiducials are fine IF the pick and place program was generated
from a CAD file with centroids for everything.

     If you don't have a CAD file to create the program (which happens more
often than I think it should), I'm grateful for the local
fiducials...sometimes those will be the only fiducials on the board I
get....it's kinda' funny sometimes, there will be enough locals to choke a
horse, but no globals. Or, you'll have fiducials all over the topside, but
nada on the bottom...how does THAT happen? Oh well...

     Also when generating the pick and place program without the CAD file, you
can dial your fine pitch placement accuracy in a lot easier and the placement
is much more consistent when there's local fiducials.

-Steve Gregory-

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