A difficult component....How can you add Pads to a 3D Model?

Suppose you have this diode component…

A 20mm(width) x 25mm(height) x 1.2mm(thick) tinned copper plate mounted vertically on a PCB.

Attached to that vertical plate are two diodes oriented vertically such that each diode has one lead attached to the PCB via normal pads on the PCB at the foot or base of the plate…but the leads at the other end are soldered to the copper plate near the top.

How could you depict this in a schematic and in PCBNEW?

Thanks .!

Diode_Plates|498x500

[Edit] Added RolliePollie’s picture directly so there is no need to click links and switch between windows or tabs.

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Normally the pads are not part of the 3D model, but part of the Footprint. So in your case, the 3Dmodel probably should just be the two diodes and the piece of metal in between. For the pads you create them in the Footprint editor, just like any other pads.

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I upped him one level just in case.

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I added a picture of the component.

I’m not sure how to depict the connections to the vertical plate.

Thanks again

The ‘heat sync’ is a component.

This is tricky because you have a conflicting scope issue here if I’m seeing the picture correctly. The issue is you probably want your schematic to accurately describe the electrical function of your project. But in KiCad the schematic is expected to only describe on-board connections. The pairs of diodes only have one connection directly to the board each, and the other end they are soldered to the metal tab which is then soldered to the board. For the pair that is easily viewable in that picture, D2 and D3 appear to be connected to H2, and all 3 are treated as separate components.

Two solutions that I can think of:

  1. Compromise and on the schematic (and then PCB) consider the diode pair to heatsink as a single component with 3 or 4 pins (I can’t tell if the tab only has one pad on the side near the camera, or if as I suspect there is a solder tab on both sides). That way when you create the footprint the position of all the solder points are locked relative to each other. You will need to make sure you somehow account for the 3 parts when ordering as the KiCad BOM will only generate 1 line item for the set of 3.
  2. Or you can create your own custom diode symbols that only have 1 pin each (the second one drawn with graphical lines) and another symbol for the metal tab/heat sink also with a fake pin made with graphical lines. When placing the symbols use wires to the actual pins and graphical lines to connect the diodes and tab together. (Note, you won’t get any non-dashed graphical lines in v5.x, I think there might be other line styles coming in v6 but don’t quote me on this.) You will then give the diodes a single pad footprint and the tab it’s own footprint and you will need to place each individually on the PCB. But your BOM will have all 3 parts without any post-processing.

There may be other solutions that I’m not thinking of, but hopefully this will get you headed in a direction that works for you.

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Have you considered to make two KiCad projects for this?

The first KiCad project would then be just a small rectangular PCB with the two diodes, and you can export a 3D model of it.

Then you can use that exported 3D model in larger projects.

The only problem I see is that you would need a 3D model of a diode that has one bent and one straight leg, or you just ignore that and accept that the 3Dmodel of the 2 diode assembly is not perfect.

For the schematic symbol to represent your “module”, I would re-use the BAT54.
Its normally a 3-pin SOT-23 package, but this diode comes in multiple variants and has two diodes, Common Anode, Common Cathode, and diodes in series.

For the 3D part. You can create a 3D model of a diode in FreeCad (with the pins bend the correct way), which should be pretty easy to do and make a new PCB project only for this copper plate, as @paulvdh suggested.

If you can use FreeCAD or another 3D CAD program, then you may as well draw the whole diode board in that program.

Doing it as a separate KiCad project (and some compromises such as ignoring the straight pins) lets you do it completely in KiCad.

This is two PC boards one normal and the second a vertical small boardor a flexible board. And that vertical board can be a component itself.

Thanks for all the suggestions for a 3D model.

Is there any way to make a schematic for this situation that accurately reflects the component?
If it’s already been posted above my apologies I must have missed it.

I already posted:

… and some &^%$#@! to get over this silly *&^%$#@! 20 character minimum.