On 13 Nov 2007 16:42:45 -0500, DJ Delorie <
dj@...> wrote:
> Well, at least it can be done - I've seen a number of really complex
> boards get done with it. All the developers are users too, and we're
> actively working on it these days.
Do you have links for complex stuff? Things like BlackfinOne are an
order of magnitude or two simpler than I'd like...
Then again, my first real gEDA project ought to be a toy, rather than
a 12-layer 4-thou uBGA monstrosity, I guess :)
> > Some of the macros you'd want to improve yield as far as possible
> > aren't built-in, since they're tactics you wouldn't want to be using
> > for real.
>
> Like?
For home etching, to give yourself the best possible chance, I'd say
you wanted as many as possible out of: trace spreading, trace
fattening, trace centring, teardrops and pad expansion, solder
thieving, copper balancing, etchant use minimisation, are all
tempting. They'd all need to be balanced against each other, too. Far
from trivial. It might be easier to do it by hand, if the board's
small... Rules-based stuff is hard, and people are clever.
> Me, I have a teardrop plugin for PCB (gEDA) that I use on all my
> boards, home etched or otherwise. I had one board's trace break right
> at the annulus while reworking a connector, and decided I didn't want
> to have to debug that again.
For sure - teardrops are great. They can be bettered, though. And,
interestingly, real PCB shops don't care if they're there or not.
Holes are drilled before etching (to allow PTH), so the via pads don't
break out enough to be worth protecting.
Steve