Doing away with the net tie pad clearance

[electrophile]

I have a net tie that connects two ground planes. However, because of the pad clearance, the copper pour goes around the pads and causes gaps as shown in the image. I initially thought that setting the pad with negative clearance would solve this issue but it won’t let me set that. How do I do this and also is this recommended?

[BobZ]

I am not sure what I am looking at in your screen shot; I feel like it could benefit from some arrows and labels. You mention ground planes but the red looks like odd shaped traces around a couple of round pads.

But: I had what may be a similar issue. The solution was: Make sure that the keyword field in your net tie footprint says “net tie” at the beginning.

[electrophile]

The red part is a fill on the F.Cu layer. The blue is B.Cu. GND and GNDA are two copper pours.

@BobZ

But: I had what may be a similar issue. The solution was: Make sure that the keyword field in your net tie footprint says “net tie” at the beginning.

It does.

[BobZ]

Maybe I am the only one, but I still do not understand the image. Where is the net tie?

[electrophile]

It’s the small strip that connects the two blue planes. One side is marked GNDA and the other is GND. Essentially its connecting the GNDA and GND planes at a single point on the B.Cu layer. Here is what it looks like on the B.Cu side.

[eelik]

Can you attach the pcb file here, or strip off everything except the relevant items and attach it here? Or create a new self-standing example file?

[paulvdh]

@BobZ

Maybe I am the only one,

Same here. I see two via’s or THT pads, but don’t know what they are or how they’re used.
I also do not see two different copper zones for:

@electrophile

GND and GNDA are two copper pours.

I’m guessing it’s a 4 layer PCB and the other layers are not shown.

So follow eeliks advice. Zip up a simplified version of your project and post it here.

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In a more general sense the use of separate GND planes for digital and analog GND is deprecated, and often it’s better to use a single big GND zone for the whole PCB in combination with attention of how the currents flow through the GND plane.

[BobZ]

@paulvdh

Same here. I see two via’s or THT pads, but don’t know what they are or how they’re used.

Thank you. That suggests that I am not stupid.

@paulvdh

In a more general sense the use of separate GND planes for digital and analog GND is deprecated, and often it’s better to use a single big GND zone for the whole PCB in combination with attention of how the currents flow through the GND plane.

I suspect (as with so many other things) that the numbers matter. So there may be a difference between a buck controller chip regulating 1 Amp and one regulating 30 Amps. Thinking about how the currents flow is probably valid but that requires a bit more judgement.

[Cerebus]

Edit the footprint for the net tie (probably just the local instance in pcbnew using the right click menu) and set “Pad connection to zones” to “solid”.

From a quick experiment it looks like that does what you appear to want.