Re: gEDA: Problems with connection scanning

[sdb@cloud9.net (Stuart Brorson)]

> For example some board have tons of tiny squares that are not connected
> together to perform coverage equalization, copper savings etc. My manufacturer
> didn't want any such thing. It's probably necessary only in very big series or
> in some extra cheapo processes or I don't know what. I can see it on PCI cards.

That's called "thieving".  Usually, PCB manufacturers *do* want that
-- they place it into the design themselves.  And not just cheapo
boards use it.  My biggest board was a 20 layer SONET interface board
for a major router (not done with gEDA, BTW  :-( ) which would retail
for $20,000.00.  (Or maybe the BOM cost was $20K. . . .  I forget.)
It had thieving. 

I would be curious to know why your mfr doesn't want thieving.  Maybe
they will put it in themselves?

My understanding is that manufacturers want theiving because it means
they need to dissolve less Cu in their etch baths, which means they
have to change the bath less often.  Also, it helps with the
mechanical strains on the board if you have an even copper balance on
both sides of the board.  If you have a copper imbalance, your board
can tend to warp.

Stuart