Re: gEDA-user: Silkscreen over pads

[sdb@xxxxxxxxxx (Stuart Brorson)]

> Nevermind -- I just checked the gerbers I sent to the fab in gerbv,
> and the overlapping silk has clearly been deleted.  And yet, there it
> is right there in green and white on the boards that came back.  How
> could this happen?  Is it that pcb writes the complete silk layer to
> the gerber along with commands to delete the overlapping portion?
> (I'm pretty ignorant about the gerber format, so forgive me if this is
> a silly question...)
> 
> If this is so, then it would seem that pcbexpress.com ignores these
> "delete" commands.  Am I justified in telling them to re-do the boards
> at their expense?  They might complain, since I didn't use the "free"
> gerber viewer they recommend to check my files, ViewMate from
> www.pentalogix.com.  Of course, that gerber viewer runs only on
> Windows on is only free as in free beer.

FWIW, I have also had problems with boards at ExpressPCB.  In my case
they did not put thermals or reliefs from drilled holes onto a board
with a GND plane on the back layer.  Therefore, all my through holes
were shorted to GND.

I looked at my Gerbers with GCPrevue (a very popular freeware Windoze
viewer) as well as with gerbv.  Both programs showed that the reliefs
were there.  I took some screenshots of the Gerbers (in GCPrevue), as
well as some digital photos of my board.  I then wrote a quick MS Word
doc describing the problem & sent it to ExpressPCB.  They did fix the
problem, and sent me respun boards free of charge, a move I respect.
You can probably do the same with your boards.  I think it's best to
send some documentation so they can see the problem. 

Nonetheless, I wouldn't recommend sending them boards to fab in the
future.  Their software doesn't seem to work well with the Gerber
exported by PCB.  I wonder if their mfg software has problems with
other CAD tools also? The best vendor I have used for PCB designs is
Advanced Circuits (www.4pcb.com); I think other people on this list
will second this recommendation.   

Stuart