Re: gEDA-user: Has anyone used SSOP28.fp?

["L.J.H. Timmerman" <bert.timmerman@xxxxxxxxx>]

Hi Dave and all,

If I remember this correct (on top of my head) the Gerber exporter
ignores 1 mil lines by:
<code>
  if (gc->width == 1)
    return;
</code>

It might be possible to filter out 1 mil (or a smaller, specific width)
lines and arcs for paste layers by ignore everything wider than 1 mil in
a similar way in the mentioned stencil-hid.

<code>
  if (gc->width > 1)
    return;
</code>

Filtering could/should be done in in the stencil_draw_* () functions.

The stencil_fill_* () functions should translate any outline parameters
to arcs and lines.

In this way those lines and arcs could be in the footprint without
breaking the new-lib footprint file format.

If you need boilerplate code for exporting of DXF entities let me now, I
got a dxf lib for writing to files (not reading) from my DXF exporter
hid.

Just my EUR 0.02

Kind regards,

Bert Timmerman.


On Thu, 2007-06-07 at 09:04 -0700, Dave N6NZ wrote:
> L.J.H. Timmerman wrote:
> > Hi Dave and all,
> > 
> > On Wed, 2007-06-06 at 11:24 -0700, Dave N6NZ wrote:
> > 
> >> a) pcb paste layer gerber is directly from the pad layer, and I think in 
> >> many cases that lays down too much solder.  I haven't experimented 
> >> enough to be able to say for sure.  I'd like to see some paste layer 
> >> control added to the footprint definition.
> >>
> > Since this is on a per thickness, per material basis for the stencil
> > involved, I think this could be better handled in a specific "stencil"
> > exporter with a configurable positive(=larger) or negative(=smaller)
> > offset value for the pad-outline.
> 
> That would be cool.  But I also think you want to be able so specify 
> different shrinks on a per-footprint/pad basis.  For example, for those 
> packages with a big heat-sink pad, that pad may want a different shrink 
> from the rest of the pins on the package, and different from the 
> default.  So, I could see some kind of format like:
> 
> default -10% # any footprint, any pad
> sot223.2 -30% # sot223 footprint, pin #2 gets special treatment
> 
> Maybe something like that should even go into the footprint definition? 
> (I'm thinking newlib here, I never use the M4 stuff.)
> 
> But in the end, I think the pad size adjustment in pcb should apply to 
> what is written to the paste layer gerber.  Converting to pad outline 
> vectors is better done in the gerber previewer or some other gerber 
> reader, since that yields a more general tool suite.  Of course, I won't 
> complain if pcb directly puts out the file that I need :)
> 
> > 
> >> b) My current method for prepping a file for the laser cutter is a bit 
> >> of a kludge.  Ideally, I'd like to see the gerber previewer have the 
> >> option of exporting .dxf of the pad outlines from the paste layer.
> >>
> > If the exporter can be made configurable for not doing fill operations
> > on a pads in a pads-only-mode, then it's also possible to do this for a
> > DXF exporter.
> 
> Yes, the fill just gets in the way as far as my laser cutting s/w is 
> concerned.
> 
> -dave



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