FEDEVEL
Platform forum

JohnsonMiller , 07-22-2022, 02:15 AM

When Altium generates P&P data, in the coordinate data we have 3 sets, Center-X/Y, Ref-X/Y, and Pad-X/Y. What does each set mean?
I used to include only Center-X/Y, but my assembly house is asking for all three sets, Any comments?

robertferanec , 07-22-2022, 09:06 AM

Assembly house may mostly need 0,0 position of your footprint (I think that is the Ref, but I would need to check). The 0,0 position should be in the center of gravity for smt components (for many components it is the center of the component). The 0,0 position for through hole is not important, but I often place it on pin 1 as it is then easier to draw dimensions and specify position of through hole connectors.

I am not sure why they would need all three.

qdrives , 07-22-2022, 03:45 PM

The center X/Y is is created by Altium as the center of the pads.
The Ref X/Y are the reference point you have in the footprint. This can be pin 1 if the reference is set there.
The pad X/Y is the position of pin 1.

In my pick&place file I put both the center X/Y and the reference X/Y. On almost all components these X and Y are the same, except for the through hole connectors (which I also do NOT have on pin1)

WhoKnewKnows , 07-23-2022, 09:15 AM

Reading this conversation, it seems It behooves the designer to provide only a single source of placement positions in the P&P file and confirm each component has the intended XY centroid. This view can be turned on in the 3D view of the PCB design space.

It seems risky to include multiple similar sources of information for the same purpose.

By the way, when a CM asks for something unusual, ask them why they think they want it. Often, the reply is something like, This is what other customers send us. Not sure if it's actually used on the shop floor.

qdrives , 07-23-2022, 01:19 PM

@WhoKnewKnows The P&P is a single file, but it contains multiple columns with data. I would prefer the reference point, but I include the center as that is what Altium exports as default.
My experience with CMs is that they just want to get what they always get. I am yet to meet one that asks for something else/more. Even worse, if you try to do so, it is more often a remarks like "we do not need it" but in a way that should read like "we do not want it". I wonder how much progress there can be if they keep that up.

WhoKnewKnows , 07-23-2022, 05:38 PM

Thanks @qdrives I edited my previous remark.