Fiducials

[Anonymous]

Hi,

I'm creating my first PCB and therefore I need a round fiducial with a 1mm Pad and 3mm clearance around. Can anybody help me how to create the clearance? 

Thanks,

Jakob

[RichardHammerl · Accepted solution]

Hi @Anonymous 

thanks for your request and being part of the Fusion Electronics community. 

You could draw the fiducial by yourself or you cold also look into the marks.lbr. It also contains a number of footprints that can be used as fiducials. Please check for it with the Library Manager in the "Available" tab. 

In case you prefer to create your own, for example, use a PAD  or a HOLE with 1mm drill diameter and draw a filled circle in the layers tRestrict and bRestrict. A filled circle is drawn with a line with of 0. The area in the restricted layers will be kept clear of copper. 

I hope this helps.

Regards,

[Anonymous]

Hi @RichardHammerl ,

thank you for your fast and helpful reply. 

Regards,

Jakob

[robert1356]

Two questions about this.  I've tried it two different ways.

1. creating the fiducials in the PCB view using 'DRAW:CIRCLE' (line width = 0) and creating a circle for each layer I need:

1mm copper, 2mm for each of tRestrict, tKeepout, vRestrict, tStop

2. creating a part in a library that has a copper circle (not a pad) and then adding the various restrict,keepout,stop layers.  AND I created a 3D model that is empty. (it has the circle for the footprint, but that's all, no body - the fiducial doesn't have a body).

In BOTH cases, the tStop does NOT seem to prevent my stop mask from displaying in the 3D view.  In other words, the stop mask covers the copper even though it should not.

In the 2nd case, a square "dummy body" is created.  I can turn this off display of the body, but I shouldn't have to.  If I create a 3D model, but there's nothing in it, then I would think Fusion should NOT ADD a dummy body.

If I create a copper PAD in the 2nd case, I can't add it from the PCB layout view,  I have to add it in the schematic (which means I also need a symbol and component definition).  And it still doesn't seem to work correctly. I created a 1mm x 1mm pad with 100% roundness.  I turned off Thermals, Stop and Cream and created my own tStop, tRestrict, vRestrict and tKeepout.  The tStop seems to only apply to the PAD itself, not the 2mm circle I created

There definitely appears to be a bug in the solder mask generation for the 3D view.  

Using the 2nd approach, with the PAD and the manually larger tStop circle, DOES appear to generate the correct gerbers.

[jorge_garcia]

Hi @robert1356 ,

The second approach is considered the official correct approach. I know you get the dummy 3D model, we are working on making this better, but for now it's preferable to put up with the dummy 3D model then to draw the fiducial on the PCB.

I'm not sure why the tstop doesn't open the copper. Are you drawing the tStop as a filled circle? It needs to be filled in order for the copper to be exposed.

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

Best Regards,

[robert1356]

Thank you, I will experiment with the COMPONENT approach.  Both with a copper circle and with a circular PAD to see if I can get the stop mask working correctly in the 3D view. 

[TrippyLighting]

Something must have recently changed, because this worked. The Fiducial has a round SMD pad in the middle.

Surrounded by two circles with width, one on the tRestrict and one on the tStop layer:

On the board this results in the solder mask not being kept off the area in the tStop layer.

This worked previously until I changed a component in the library and updated the board design from that library. 

This is also only a problem in the 3D model. The CAM preview shows this properly.

[TrippyLighting]

Looks like I simply needed to enable "Stop Layer Geometry" when pushing to the 3D PCB: