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From: "Erich Heinzle (a1039181 AT gmail DOT com) [via geda-help AT delorie DOT com]" <geda-help AT delorie DOT com>
Date: Thu, 27 Jan 2022 20:32:24 +1030
Message-ID: <CAHUm0tN41Ym=7O18A90YHPA-F=idx5OkHLB9Pm=ykZMJ=8_-5w@mail.gmail.com>
Subject: Re: [geda-help] geda pcb: footprint with non rectangular pads
To: "Vladimir Zhbanov (vzhbanov AT gmail DOT com) [via geda-help AT delorie DOT com]" <geda-help AT delorie DOT com>
Content-Type: text/plain; charset="UTF-8"
Reply-To: geda-help AT delorie DOT com

There appears to be a range of recommended land patterns for the VQFN
20 3.0x3.0.0.9 mm Microchip ICs.

https://www.microchip.com/en-us/support/package-drawings

Some of them have rectangular pads.

If you want to have arbitrary polygons in footprints, you may wish to
implement the footprint in pcb-rnd, as it allows a polygons to be
drawn and used as the copper shape in a custom padstack. You will not
be able to successfully export the footprint to gEDA PCB as there is
no internal support in gEDA PCB for polygonal SMD pads.

Similarly, pcb-rnd allows custom polygons to be specified for the
various apertures, i.e. soldermask, stencil, etc, or they can be
autogenerated in the padstack property editor.

translate2geda has to skip non rectangular or circular polygonal pads
when converting to gEDA PCB because there is no easy way to draw the
polygonal pad shapes.

It is worth mentioning the tutorial

http://www.penguin.cz/~utx/pstoedit-pcb/

which shows conversion of pdf or postscript land patterns to gEDA PCB
footprints using the pstoedit utility.

As of version 3.76, pstoedit also supports export to pcb-rnd's native
footprint format, allowing to export paths as well as polygons.

http://www.calvina.de/pstoedit/changelog.htm

Regards,

Erich.

On Thu, Jan 27, 2022 at 6:20 PM Klaus Rudolph (lts-rudolph AT gmx DOT de)
[via geda-help AT delorie DOT com] <geda-help AT delorie DOT com> wrote:
>
> I want to create a board with a VQFN 20 package which has non
> rectangular pads.
>
> A detailed drawing can be seen here:
> https://ww1.microchip.com/downloads/en/DeviceDoc/ATtiny806_1606_Data_Sheet_40002029A.pdf
> Section 34.2 20-Pin VQFN
>
> As you can see, the pads at the corner have a non rectangular shape.
>
> I read http://pcb.geda-project.org/pcb-cvs/pcb.html#Library-Creation
> and there was mentioned:
>
> 10.2.1 Creating Newlib Footprints
> "Currently a rectangle or polygon may not be used as a pad. "
>
> Is there any chance to create a footprint for PCB for VQFN-20 as given
> in the above linked data sheet with non rectangular pads?
>
> Thanks
> Klaus
>