Re: gEDA-user: default pcb stackup change?

[Gabriel Paubert <paubert@xxxxxxx>]

On Sun, Apr 10, 2011 at 07:42:11PM -0400, DJ Delorie wrote:
> 
> I'm pondering a minor change in pcb's defaults to give us a more
> useful default stackup.  How's this?
> 
>   LAYERNAME (1, "top"),
>   LAYERNAME (2, "ground"),
>   LAYERNAME (3, "signal2"),
>   LAYERNAME (4, "signal3"),
>   LAYERNAME (5, "power"),
>   LAYERNAME (6, "bottom"),
>   LAYERNAME (7, "outline"),
>   LAYERNAME (8, "spare"),
> 
> This encompasses a few changes:
> 
> 1. Default to six-layer stackup.  You can ignore the signalN or
>    power/ground layers for smaller boards.  This covers nearly all PCB
>    users (2/4/6 layers), and the rest can edit the stackup as usual.
> 
> 2. Always include an "outline" layer.  Handling an empty outline layer
>    will need to be tweaked.
> 
> 3. Rename outer layers to top/bottom, which seems to be what other
>    packages (specifically, eagle and kicad) use.  Component/solder
>    isn't as obvious with SMT.  We've used front/back elsewhere before,
>    too, but that seems to be even less common.
> 
> 4. Make the default layers in the right order to reflect a physical
>    stackup.

I basically agree, but why stop here and not add a Z coordinate to each 
layer?

Bonus points for making it editable and consider layers with the same
Z coordinate as a "layer group" for the ones who insist in using it
(I have never had the need for them, I'd prefer to be able to edit 
some color attributes per net and per layer, although I'm aware that
this might be tricky for random nets).

Topmost layer should have a 0 Z-coord, increasing towards the bottom.
Negative Z-coords cold be used as a flag for outline/comments/ECO...
(The solder mask/paste/silk layer associated with a layer should
have the same Z-coord as the layer, maybe some attributes are 
necessary).

	Regards,
	Gabriel


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