Re: gEDA-user: home-made 4 layer board idea

[gene glick <carzrgr8@xxxxxxxxxxxxx>]

my favorite layout guy once explained the notion of datum lines (I think 
that's what they are called).  Anyway, if you use an arbitrary line 
(datum) in the center of your board, and reference all measurements to 
it, the tolerances are only from that imaginary 1/2 way point to the 
edges.  It's better than if the reference is on an edge, then the 
tolerance adds up along the entire length.

maybe the size of your boards, and your trace widths don't matter in 
this case?

just my $0.05 worth :)

gene

DJ Delorie wrote:
> > how about layer registration?  If the tolerances are out of whack, 
> > nothing will line up very well.
>
> I think if the individual layers are accurate (or at least equally
> distorted), lining up the drilled clad shouldn't be a problem - just
> add two corner holes, drill them separately on each board, and pin
> them to line up the boards.  I think this is an easier problem to
> solve than lining up the etch resist on opposite sides of one board.
>
>
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