KB: Calculate component Pick and Place Center of a footprint

Altium Designer Altium Designer
How is the Centroid data determined for a footprint? How does it determine center if the footprint has no Pad primitives?

Solution Details

To decide what is the center of a component, Altium calculates this by finding the midpoint between the two outermost pads in a footprint. It does not use mechanical or copper data in a footprint, just pad information.


The pick and place file starts at the absolute minimum of your design sheet (lower left corner). You can find this point by drawing a line or a track and draw this to the lower left corner. You will find you hit a boundary somewhere. Now add up the center location of the component and you will have the location (minus the location of your manual PCB origin location). If the component does not have a pad, it does not have a centre location. So your location will be absolute minimum + 0.

As a consequence, Center-X/Y coordinates could end up being offset from the component centroid for a non-symmetric footprint (e.g. edge connector) and way off for footprint without any pad primitive (e.g. fiducial mark).  In those cases, it is recommended to reference Ref-X/Y instead.


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