I have a question for the fab-guys out there :

Is it likely for a bare board that shrinkage or expansion is different in X- and Y-directions ? Or maybe even a stretch in X and a shrinkage in Y ?   Or is it more common that both values are the same ?

The question behind this question is whether a pick&place machine that uses only 2 fiducials can compensate for both dimensional inaccuracy and rotation of the board in the conveyor. I think this is possible, but only if dimensional changes in X and Y are equal.

Kind regards

Daan Terstegge
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Personal website: http://surf.to/smtinfo

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