Overlap with Fiducials


#1

Hi,

I’m putting some fiducials which I need to fit within the courtyard of other large components. I am assuming that this is fine since the fiducials are typically used before the pick and place operation and I really have nowhere else to put them on my board (at least the 1mm ones). Is there a way I can get KiCad to ignore these, or should I just ignore this, or since it is a small board (36x36mm) should I just not put any fiducials? I have one placed under an ESP32 Wrover and another under a micro SD connector, because I just don’t have room anywhere else.


#2

As the main goal of fiducials are for alignment of a PCB in pick and place machines, I see no harm to place fiducials under other components.

I am not sure if fiducials for optical quality control machines.

Why would you want KiCad to “ignore” them?
Are you getting some kind of error messages?


#3

I am getting error messages during DRC about overlapping courtyards between the fiducials and other components.


#4

So you have checked, understood and can safely ignore the warning in this case.
Why is this a problem?


#5

I suppose you could remove the courtyards for your personal library if the error bothers you. Keeping in mind this is from someone that has never used/needed a fiducial. I’d check with the people assembling the board to be sure since they are the ones that need it.


#6

That is a question entirely related to manufacturing, which we cannot answer. It’s the type of thing that you need to ask your manufacturer.

On our line, we have two pick and place machines on the same conveyor (it’s a small line), both machines will need to use the fiducials. Two machines are used to increase throughput and allow more different parts to be loaded in the feeders.

If the first P&P puts a part over a fiducial, then the second P&P is stuck. So, you would need to ask your manufacturer.

Depends on how you manufacture them… For small boards they would normally be panelised and then you put the fiducials on the framework. Again, you need to ask your manufacturer.


#7

In this case they are under the more complicated parts that a standard pick and place machine might have trouble with. I’m not too concerned since if I were to mass manufacture them I’d panalize them and put the fiducials in the panel frame (though I’m not sure how to panalize something with KiCad). That’s a problem for the future. The board in question is at https://github.com/aaronw2/led-controller-wrover32, though I haven’t pushed the changes with the fiducials since there haven’t been any functionality changes, though some improvements were made to the layout and more grounding vias were added near the wi-fi antenna.


#8

Good point, the machines have limitations on both board size and working near the edge of the board. For small boards this means that the are panelised during stuffing.


#9

I think I’ll remove them then. My boards are quite small (36x36mm is one of my larger ones). My smallest is a 12v power boost board (22x11mm). I think the only way they could be assembled is if panalized anyway.