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From: "Erich Heinzle (a1039181 AT gmail DOT com) [via geda-user AT delorie DOT com]" <geda-user AT delorie DOT com>
Date: Tue, 24 Jan 2017 08:08:54 +1030
Message-ID: <CAHUm0tMMGcnMoVBO+4yq=tnF2Co25R00+KMSfmZd8rwSMuRtEA@mail.gmail.com>
Subject: Re: [geda-user] QFN packages solder mask
To: geda-user <geda-user AT delorie DOT com>
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Precedence: bulk

It may not be too hard to get fped to generate the "dot" pads
described by DJ, since fped allows custom solder mask apertures to be
defined as a type of pad.

Some extra code to grow the clearance and minimize the dot size would
need to take effect if the pad type is "mask".

More interestingly, it might not be too hard to get the gEDA exporter
to do a run of (pad + mask) footprint generation, followed by a solder
mask footprint generation run.

Food for thought,

Erich.


....Quoting from the fped documentation:

=================================

Pads
- -

Pads are similar to rectangles, but they also have a name.

pad "<name>" <point-a> <point-b> [<type>]

Variables can be expanded in a pad's name by prefixing their name with
a dollar sign. The ${name} syntax is also available.

Example:

vec @(1mm, 1mm)
pad "1" @ .

Pads normally affect the surface copper layer, the solder mask layer,
and the solder paste layer. This can be modified with the optional
type argument:

Type Layers
--------- -------------------------------------
(default) copper, solder mask, and solder paste
bare copper and solder mask
trace copper without solder mask opening
paste solder paste
mask solder mask

Typical uses:
- "bare": connectors printed directly on the PCB
- "trace": connections or antennas
- "paste": sparse solder paste, e.g., for QFN center pads
- "mask": non-standard mask openings, e.g., for solder mask defined
  pads

On Wed, Jan 18, 2017 at 8:30 AM, DJ Delorie <dj AT delorie DOT com> wrote:
>
> The usual trick is to overlap multiple pads, each with their own mask
> geometries.  For example, you could have a normal pad for each edge
> land, with a minimal mask setting, and a "dot" pad overlapping it with a
> larger pad setting that just reaches the same spot around the segment
> perimeter but overlaps between adjacent pads.