Yes Julien, I have seen this as well.  What a pain in the neck!  As you
found, the acceleration speed of the conveyor was shifting the part.  We
ended up slowing down the exit belt speed to help minimize it.

Thanks

Ryan Grant
Advanced Technology Engineer
MCMS
(208) 898-1145
[log in to unmask]


> -----Original Message-----
> From: Julien Bouchard [SMTP:[log in to unmask]]
> Sent: Monday, September 11, 2000 9:04 AM
> To:   [log in to unmask]
> Subject:      [TN] Displacement of PQFP with heat slug
>
> Hi everybody,
>         We currently have problems with some PQFP ( 208 and 240 pins )
> that have a
> piece of metal mold inside the IC to enhance the thermal exchange. Because
> of this metal, the IC is very heavy, in comparaison of other IC. After
> they
> have been place by the pick and place machine, they often move from there
> original position when the conveyor start or stop. It seem that the IC is
> so
> heavy, and is inertia is taller than the retention force of the paste. We
> try a lot of solution, but none of them give a good and constant result.
>         We want to know if someone have similar problem and if a good
> solutions
> have been found. Thank you.
>
> Julien Bouchard
> Matrox - Process Engineer
> Email : [log in to unmask]
>
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