> To move forward with some projects, PCB needs to understand more about
> the physical stackup of the board. Harry mentioned once that the
> drawing layer stack should BE the physical layer stack. I.e. the
> topmost copper layer in the menus should represent the component side
> copper, the next ones the inner planes, and the last one the solder
> side copper.
> Anyway, does anyone object to this type of change?
Do it! Sounds great!
One thing: You forgot to mention layers like silk, outline, solder
mask, paste mask, and so on. Here's a list of layers we probably
want to support, from top to bottom:
DRC layer
top keepout layer
drill (maybe support more than one drill layer to allow for e.g.
plated vs. non-plated holes)
outline (& other mechanical notations)
top silkscreen
top paste mask
top solder mask
top Cu
(an arbitrary number of intermediate Cu layers)
bottom Cu
bottom solder mask
bottom paste mask
bottom silkscreen
bottom keepout layer
Some of these layers correspond to functionality not yet supported by
PCB (e.g. keepouts). However, if we can at least provide hooks for
them now, that would be a great thing.
(And if I forgot one, please forgive me.....)
Also, please take a look at how gerbv handles layers starting with the
gerbv-2.0.0 releases. This is not my work; it is Julian's, and it's
absolutely great. Moreover, it makes a lot of sense. It allows one
to assign different colors to layers, turn them on an off
(visibility), add and delete them, and move their order using
drag-and-drop. Anyway, it shows how PCB should handle the layers,
IMO.
> The projects that need this type of conceptual change are:
>
> * The layer types thing (i.e. drawing layers can be more than "just
> copper") (this is more of a "we should solve both problems together,
> to avoid headaches later" issue).
See above.
> * Blind/buried vias.
>
> * Any type of 3-D renderer.
>
> It would also allow us to cut/paste/tile boards with different
> stackups more reliably, by canonicalizing them. Currently, merging
> boards is sensitive to the order of layers, without regard to which
> are component/solder/inner.
Yes, yes, yes! Yay!
> There was also some discussion of getting rid of the "layer groups"
> concept and forcing one drawing layer per physical layer. I suspect
> we'd need to be able to color tagged nets differently to make up for
> this type of loss. Thoughts?
Yes, please get rid of it. The concept doesn't exist anywhere else in
layout land. There are two ways to make up for it:
1. Allow highlighting of nets by netname. That is, you open a dialog
box, type in the netname, click OK, and the corresponding net changes
color to white. I think we can do at least some of that right now,
right? Using this mechanism you can easily identify which planes are
GND, which are power, and which are some random net. That's what the
layer groups concept is meant to allow for, but doesn't do it as
neatly.
2. Allow for PCB to merge layers during export. Then, you can draw
GND planes on one layer and signal nets on another. Then, when you
export, you can merge the two layers together into one Gerber. This
accomplishes the same thing as the layer groups concept -- keeping
nets of different classes separate until the very end, when they end
up in teh same Gerber. Of course, I don't have a good idea about how
you would use the UI to specify which two layers to merge......
Thanks for the ping!
Stuart
_______________________________________________
geda-dev mailing list
[email protected]
http://www.seul.org/cgi-bin/mailman/listinfo/geda-dev
