Antipad inner layer in kicad6?

Layout
1

I am trying to use the RF connector: https://www.carlisleit.com/wp-content/pdfs/specifications/TMB-V5F2-3LC%20Rev%203.PDF

The suggested footprint has an antipad in the inner layer, to my understanding, that is critical to the part impedance matching performance.

I can generate the top layer with freecad kicadsteup, but I do not know how to add the antipad.

I have searched the forum and there was some discussion about antipad, but I still don’t have a clear solution yet.

In this part, the center pin is only on the top layer, no via going to the other layers at all.

I know that I can create rule area as a circle to block the fill in the inner layer, but I have to do that for each connector I use on the board, which is painful. I hope there is a systematic way to solve this.

Thanks

2

I’m not expert enough in Kicad to know if there is an easy way to do this, but in other PCB layout software, the way I’ve accomplished this is to draw an extremely small pad (like 1 mil diameter) and then use a large keep-out area around it. The photoplotter will not be able to image a pad that small, so it is effectively invisible.

3

In general terms, there are no easy ways to anything worthwhile doing.

You simply create, or derive, a mew footprint as part of your project library.
Define that centre contact as an SMD pad in that foorprint.
Tht’s it.

4

How can I put that center pad in the inner layer?
It seems in kicad, all the footprint are on the top or bottom layer, but the center pad (andipad) should go to the inner layer.
How can I accomplish this?
I have read it seems people can edit the footprint file and put some pad in the inner layer, but I didn’t find an documentation about that.

Thanks

5

Which layer did you put this small pad?
I don’t know how can I put this in a footprint at the inner layer.
The top layer for the footprint have other shape defined in the connector documents.

Thanks

6

Before I go into details. I use version 6.99.
KiCad does not support this directly, though there is a way for everything.

  • Select footprint in question.
  • Edit with ctrl+e
  • add a normal pad
  • under ‘Copper layers’ select ‘Connected layers only’
  • define a ridiculous hole size like 0.01 mm or so, that way you get a solid pad
    You might have to play around what settings work out best.
  • Place a copper track on the layer you need.
    That ‘pad’ then shows up connected only on that layer.

You may need to remove that tiny ‘non-hole’ from the drill file.
My guess is the pcb fab house would simply ignore a ‘non-hole’.

7

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