Re: gEDA-user: Re: Board fabrication -- outline

[Peter Clifton <pcjc2@xxxxxxxxx>]

> Well, I think there is something wrong with my outline file 
> (board.group2.gbr from http://www.ssalewski.de/board.tar.gz). I 
> created a new layer called outline and have drawn only the 
> outline-rectangle into this layer. So board.group2.gbr should 
> contain only this rectangle. But viewing file board.group2.gbr 
> with gerbv shows footprints too. Now I have done a test creating 
> a new pcb file, inserting a footprint and some copper traces, 
> then renamed existing layer unused to outline and draw the 
> outline rectangle to this layer. This way the outline file 
> board.group2.gbr contains only the outline rectangle, and no 
> other graphical elements.
> 
> I think i should try to fix this before I send board data to 
> manufactory. Maybe this is a bug in current version of pcb which 
> now supports more than 8 layers?

I have seen this in PCB too. PCB doesn't yet support "mechanical" layers
such as used for board outlines or cutouts. As a result, if you use any
through hole parts (or vias), a pad (or via) is placed on every layer's
gerber output.

I "fixed" the problem by temporarily hacking PCB to avoid printing these
parts into the gerber file. I think a more workable solution is to take
your finished layout file, make a copy, then remove everything except
the board outline. 

Someone more familiar with PCB will be able to tell you if the gerbers
produced without any components will line up correctly with the copy
with components (I don't know what PCB takes as the gerber origin). I
think that as long as the board outline surrounds ALL of the items in
the layout, the copy with _just_ the board outline will line up ok.

Regards

Peter Clifton




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