SMD pad custom shape primitives

Layout Footprints
#1

Hello all,

I’m using KiCad 5.1.8 on Linux and I’m having a hard time trying to create a customized SMD pad shape.
What I need (I think) is the possibility to create a polygon consisting of straight lines and arcs.
The problem is, in the custom shape primitives section I can create arcs but not as a part of a polygon.
Am I overlooking something?
The footprint I need is for the Wurth 744031100 SMD inductor.
The pic shown is the footprint made in Eagle V7.
I hope somebody can point me into the right direction.

Screenshot_20201212_195142
Screenshot_20201212_195142612×536 2.19 KB

#2

KiCad’s drawing capabilities are quite limited. It’s not a mechanical CAD program.

One solution is to create a pad layout in a mechanical CAD program, and then import it as a .dxf file. FreeCAD, together with the “StepUp” plugin has a lot of custom capabilities, but it has a steep learning curve.

A simple intermediate solution is to draw a few simple shapes on any layer, and at least one pad on a copper layer, then select all those parts and make a custom pad from it with the popup menu.

It needs at least one single “real” pad because that is used as the attachment point for PCB tracks.
You can also draw an arc segment for the inner round part, and then roughly overlay a coarse polygon, but is it really important? Just a coarse approximation of 3 to 5 line segments of the arc is good enough, and there is no reason to spend more time on it.

I would make the arc’s in the corners a bit bigger though. Pads are used for the solder stencil also, and round ed corners help with releasing the solder paste from the stencil.
[Edit:] Ah, indeed. I forgot to add the link that BlackCoffee did not forget.

#3

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#4

That’s disappointing. We are in the transition from Eagle V7 to KiCad and I like very much Pcbnew.
But library creation and management is a disaster.
Creating custom shaped pads in Eagle footprints (despite the limitations in Eagle) is much
easier and faster than in KiCad.
At least for KiCad V5, it looks like the devs have been mainly focussing on Eeschema, Pcbnew and 3D viewer. Library creation was an afterthought. Probably because (correct me if I’m wrong) the majority of the footprints are generated by scripts and the majority of the users are hobbyists that don’t want to spend time with creating footprints…
After some more duckduckgoing I discovered that more people stumbled over this.
There’s also an issue here: https://gitlab.com/kicad/code/kicad/-/issues/4493
However, there’s no assignee or milestone set. Apparently it’s not considered important enough.
As a “solution”, I’ll use segments to approximate an arc.
Thank you for trying to help.

#5

It’s in the merge request linked to in that issue. Arcs in polygons (actually closed curves; polygon has only straight lines by definition) will be part of v6.

#6

Great. One question though. How is that going to solve the problem now?
I don’t want to be sarcastic. I’m just pragmatic. At the moment V6 is going to be released we probably have to wait till V6.2.x has been released before we can consider it to use for production… Which means we are stuck with V5 for at least another year or so.
I’m not complaining. Just realistic.

#7

I don’t know, I can’t help with that. I just responded to

And I often want to give “FYI” details so that people know what to expect later.

I think there won’t be 6.2, there will be 6.0.1 etc. and then v7, or at most 6.1.x. That’s insignificant for your issue, of course.

Then to practical matters. If you have only a few such footprints to make, you can use for example approximation and this issue doesn’t matter much. If you have many, it’s not too difficult to create shapes in another program as was suggested because it pays itself back quickly after learning the workflow. In any case I wouldn’t call this a “disaster”. I of course understand this is a missing feature and we are much delighted to get it in the next major version.

#8

Which is what I’m going to do.
I only wanted confirmation that I wasn’t overlooking something.
I didn’t want to sound grouchy or so.
This thread has served it’s purpose and can be closed.
Thanks for all the replies.

#9

I have used the Wurth inductors and you don’t need it follow that artistic footprint.
The complex curve can be safely simplified to a polygon or overlapping rectangular pads

#10

In today’s world of being able to dial-in to Micro viewing, we forget the reality of what it is…

Grab a PCB and look at a pad, in particular, the hole - could you even see straight edges if it had them, and would it matter…

Drawing this took only a few seconds. Adding a couple of clicks to Copy, Paste, Mirror and ‘Make Pad From Shape’ shouldn’t be too much effort…

pad.mov

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