Pick and Place center point offset

[aske.carstensen]

Hi,

I have an problem with the default pick and place file generator. It doesn't return the center of the footprint with some of my components. 

I couldn't find any information how fusion defines the footprints centroid, thus I guessed that is was the center point of the device. 

Have I misunderstood something or is there an bug? 

Thank you in advance

[jorge_garcia · Accepted solution]

Hi @aske.carstensen,

The pick and place tool actually calculates the center of the component using it's maximum copper dimensions. If you look at the component picture, it's origin doesn't really lie on on the physical center of the part and in the general case it doesn't so this is as expected.

For placing components the most important thing is have the actual center.

Let me know if there's anything else I can do for you.

Best Regards,

[aske.carstensen]

Thanks for the quick answer and support Jorge Garcia. By the way, it's awesome with all the new support/teaching you and your team have added to youtube in 2022, kudos!

[AMI8008]

I found this Post as I am having a similar problem, however in this case the 'center' is not calculated correctly and I don't seem to understand how I can get this fixed.  Now I have to manually change the pick & place output file in order for the pick and place machine to do its work.  In this case its a SD card module. Its origin on the PCB is X13.97 , Y10.16 as you can see in the screen capture.  However the pick and place output is X14.45, Y16.08   Understand that the P&P processor calculates the Center of the footprint, however in this case its far off from any center you could think of.

Is there a way, that we can overrule the P&P processor and force it to use the original center position as defined in the footprint OR the P&P to calculate the center correctly.

Thanks for any reply and help on this matter,

Rgds,  Arno

PS: I have attached the lbr file in case somebody wants to have a look at it. 

[jorge_garcia]

Hi @AMI8008,

I hope you're doing well. So looking at the number you are giving, it visually looks correct to me. The physical centroid is about a half mm to the right and a little bit under 6mm north of the actual origin.

The ULP has no mechanism to overwrite the centroid position that is calculated in this case it looks like it did things correctly. For now you will have to manually change the file.

With that said I struggle to understand what is going on with PnP machine to require you to make this change.

Let me know if there's anything else I can do for you.

Best Regards,

[AMI8008]

Hi Jorge,

thanks for your quick reply.

As I now understand the working (algorithm) of PnP ULP process, the 'problem' is with the Vision recognition of the PnP machine.  The solution was to change the contrast of the Vision (camera) to the point where it would recognize the two solder pads on the side, the same pads the ULP algorithm would use to calculate the center of the part.

The problem with the SD card module is that it looks like a large IC/BGA and due to the high reflection of the metal case, the PnP Vision would default to the outer contour of the part/module.

With some tweaking of the PnP Vision system, it will now recognize the same center / coordinate as the PnP output file.

Thanks for getting me on the right track towards finding the solution.

Regards,

Arno

PS: added two pictures that show the Vision camera and the 'problem' that caused the offset.