"Steve Wiseman" <
sjwiseman@...> writes:
> Do you have links for complex stuff?
The really interesting boards are all NDA. I have them so I can fix
pcb bugs. Suffice to say, one of them was the reason PCB can do more
than 16 layers.
> Then again, my first real gEDA project ought to be a toy, rather than
> a 12-layer 4-thou uBGA monstrosity, I guess :)
12@4 isn't that hard for PCB. I think the prime factor at the moment
is how "busy" your ground/power planes are, because of how we manage
polygons.
> trace spreading, trace fattening, trace centring,
I've thought of these. The global puller was supposed to be that, but
I discovered that the always-arc technique I used produced good
results with a lot less work. I still want to do that, though -
something like "copper hates other copper, proportional to how close
they are, up to a point". So, you'd say "I can do 8/8 rules, but I'd
prefer 20/20 when it fits". You'd want automatic necking too. I
figured out the math once, but never wrote the code.
> teardrops
Got that one. At least, for the types of teardrops I like. There
doesn't seem to be a "standard" for teardrops. Mine are designed to
minimize mechanical strain between the trace and the annulus.
> and pad expansion,
That can probably be a plugin. "expand pads to the most that our
space rules allow" would be easy. Checking for traces between would
be harder, but not a lot so.
> solder thieving,
Which kind?
> copper balancing, etchant use minimisation,
What I do is just plop a rectangle over the whole board when I'm done,
that fills in all the big areas with copper.
> It might be easier to do it by hand, if the board's
> small... Rules-based stuff is hard, and people are clever.
I think some of those are better as house-specific plug-ins, too.
Part of our (pcb's) task is to provide the right hooks to make writing
those easier.
> For sure - teardrops are great. They can be bettered, though.
I once thought of a plug-in that fattened the traces leaving all vias
to the diameter of the via's copper, for a short distance, when the
rules allowed it.
> 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.
It wasn't the drilling. I was removing a jumper block and the abuse
fractured the connection.