Combine SMT, THT and custom shape Footprint

Hi everyone

I have a problem I couldn’t yet figure out by myself.

I have made a somewhat special footprint and even tough the copper is interpreted correctly I am blessed with hundreds of DRC errors.

I combined a SMD pad, a custom shape and a THT pad. The first two I was able to combine via the “Edith Pad as Graphic shape”. However, I can’t figure out, how to connect the THT as well. I could assign the THT pad to the same pin number, but that’s nod desired as I then can connect to that too, which is particularly not the idea of this footprint.

Can please someone help me out? Thanks in advance



banana_Solder.kicad_mod (1.6 KB)

Hi @Rundumeli

Please supply OS and Kicad version.

What are you trying to achieve?
Do you want two pads joined together or a single SMD pad with an attached graphic circle or a THT pad with an attached disc?

Did you try to create this footprint in a Personal Library with the Footprint Editor, or making changes directly on the PCB Editor?

Your DRC violations seem to all be clearance violations. Have you checked your Constraints in
File > Board Setup > Design Rules?

Hi
I had a very similar issue, that now I can’t replicate but that I will try to explain.

I wanted to have a footprint were pads had connections between them in the footprint in library and not in the PCB, since those connections weren’t straight wires but shapes like mentioned by @Rundumeli.
I couldn’t make it work without DRC violations.

Thanks

I think if you want to have no/minimal DRC complaints you are going to have to make a compromise on this requirement. You need all your copper to be on the same net for it to be one pad with allowable overlapping/touching areas.

However, I can’t figure out, how to connect the THT as well. I could assign the THT pad to the same pin number, but that’s nod desired as I then can connect to that too, which is particularly not the idea of this footprint.

Your desire is a little bit unclear to me. If the THT belongs to the same potential than the THT is connected to the same copper and than it’s always allowed to connect a track to that copper. So assigning the THT the same pad-number “Pad1” is normally the correct thing to do.
If you want additionally that all the tracks connect to “Pad1” only through the smd-pad as connection point: than you should draw a “rule out area” around the THT-pad.
You could extend the rule area so that a connection is also not possible to the custom shape (polygon) area.

example_FP.kicad_mod (4.3 KB)

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I think the ideal requirement is to allow tracks to connect to the SMT part of the “pad” (see 2nd image in OPs post) but not the THT pad . . .

I too am unclear about the OPs requirements.

I am also guessing to OP’s intentions.

What I do know:
With the “Edit pad as graphic shapes”, you are still editing a single pad.

What you can do is create “aperture pads”. Aperture pads do not have copper, (nor a pad number), but they can be used to create solder mask, solder stencil and other features.

So combing this you can:

  1. Add graphics to the THT pad, as that is apparently the pad you want to connect to.
  2. Make sure the graphics are big enough to overlap with the location of the SMT pads.
  3. Change the SMT pads to aperture pads.

Sorry on my part for not explain enough what I am trying to do.
My goal is to create a footprint to solder in a solder type banana socket. However, instead allowing to connect directly to the THT pad, I only want connections to be made via the SMD pad. The custom shape in between is design to been cut through, if required.
The picture in the original post shows the correct use of that footprint.

The idea from @ mf_ibfeew comes to my desire the closest. I haven’t thought of adding “rule out area”

By the way, my footprint is attached in the original post. The footprint was design in Kicad6, but I just updated to 7 in hope to get this feature done.

This works now!

banana_Solder.kicad_mod (4.1 KB)

After changing the violation rule “Footprint component type doesn’t match footprint pads” to ignore, I have now no DRC regarding this subject any more.

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Great!

Just one word of caution:
Banana plugs usually require a bit of force to connect. Make sure there is plenty of copper to cope with any PCB movement.

What do you mean exactly?

I used a different banana socket in the past, butt I want to try this solder types for easier board assembly.

@jmk means, that the copper ring to solder the banana seems to be a bit narrow. That is in respect to the mechanical force that the banana with a plug being plugged in applies to the solder.
In the past, I‘ve reworked dozends of banana sockets in Fluke (!) DMMs.
Even a really wide solder ring won‘t solve that problem, it reduces it if you are lucky.

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Yes, I had to repair a Fluke too, but the socket will use look like this:


https://www.digikey.ch/en/products/detail/keystone-electronics/575-8/318495
So it is embedded in the PCB itself and solder will connect via the front, back and between.

I could form the custom shape even more to a teardrop shape to release stress at least there, but I’m not sure if that adds that much.

But if that connector fails, the footprint is designed to allow regular screw mounted sockets too. And the PCBs are not going to waste.

Sounds good to me!:+1:

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