Do you have examples as png/jpg or something ?

> I think I will have to build them with concentric chains of end to end=
> pads.

If you accept roundings at the corners that would work, if you want
sharp corners !=3D90=C2=B0 && < 180=C2=B0, then I'm at loss = since pcb don't support
polygons in element files.

I think it's sane to require:
. closed polygon (first point connects with last point)
. no self-intersections
. no holes

One could have a chain of incr. thicker pads, starting with the
thinnest on the polygon perimeter and the thickest at the polygon
center - or
=C2=A0one could fill the interiour first, and then fill the corners to some=
minimun radius.

I guess it's more economical to fill the interiour first, but filling the perimeter first gives you the same corner radius for all corners.

Using perimeter first and filling a square (for ease of modelling)
using a corner radius r, first line is 2*r thick. Using an overlap
of o, the next line will have thickness of 2*R, where
sqrt(2)*2*r - o + R =3D sqrt(2)*R # think going from corner to next line ce= nter
i.e. (sqrt(2)2r - o)/(sqrt(2) - 1) =3D R, or if o =3D f*r
next line with is 2R =3D (2sqrt(2) - f)/(sqrt(2) - 1) * 2*r or
R/r =3D k =3D (2sqrt(2) - f)/(sqrt(2) - 1), and if h =3D square height
then h/2 >=3D k^(n-1) * r, n =3D number of lines (pads)

soo, if h =3D 10mm, r =3D 0.3mm, o =3D 0.1; then we need 3 lines (pads)
around to fill the square (I think...).

Using center first, we put a circle in the center and then fill the
corners to some limit.

I'd think I like perimeter first even tough there will be a lot
of overlapping pads along the edges.

> Luckily, not many eagle and kicad footprints use them. Once
> implemented, it will work for kicad and eagle sourced footprints.

If there only is a few of them, maybe it's feasable to manually make new fp's for them.

Regards,
/Karl Hammar

Your contemplations mirror= mine.

I do not have example pictures as I do not run eagle o= r kicad :-)

I have only encountered a trapezoidal pad in kica= d once, for an edge mount SMA footprint.

The polygons found m= ost often thus far with eagle have been five sided, i.e. a rectangle with a= bit of one corner lopped off.

The madparts ( http://madparts.org/ ) footprint editing tool app= ears to=20 generate pads in much the same way, with a central pad, and a ring of=20 smaller pads, even if the pad being rendered is rectangular, presumably=20 to deal with pad geometry in a consistent, generic way.

I= may end up generating two footprints, one with a best effort rendered ring= of pads and central pad much like you describe, and another version of the= footprint with the polygon outline rendered in silk lines with text overla= id "polygonal pad missing" or somesuch to make it pretty obvious = 1) where it needs to go, and 2) it's incomplete and need additional han= d editing.

It should be noted that even though Eagle allo= ws a footprint to include "polygonal" copper features, in additio= n to/as opposed to "pads" on the copper layer, all of the feature= s end up being drawn with a raster of fine lines in the gerber, rather than= being flashed as apertures like they're supposed to be.

<= div>Cheers,

Erich