gEDA-user: PCB DRC accuracy?

[Richard Rasker <rasker@xxxxxxxxxx>]

Hello,

I recently completed a rather intricate PCB with 0.8 mm pitch BGA's.

When I sent it off to a manufacturer (Eurocircuits), a ping-pong game
developed, with my design being rejected several times because it didn't
conform to the design rules for a regular production pool(*).

Now I found that when I enter a minimum copper distance of ï0.099 mm in
PCB, the DRC check fails to signal distances of 0.093 mm, which is why
the manufacturer rejected the design.

An example can be found here:
PCB: http://www.linetec.nl/electronics/mypcb.pcb
Screen shot: http://www.linetec.nl/electronics/mypcb.png
Grid: 0.1 mm

The offending point is found at X=7.9 mm and Y=16.5 mm.

So I wonder what tolerance PCB's DRC has? I realize that 0.006 mm (6
micron) is a tiny distance, but it can make all the difference between
an accepted and rejected board -- and thus delay in the manufacturing
process.

Thanks already,

Richard Rasker


*: ï0.1 mm for copper width, copper distance and end drill sizes, and
0.5 mm diameter vias. With these sizes, it is just possible to fan out
0.1 mm line from between a 0.8 mm pitch BGA device (this device isn't
included in the example PCB): two 0.5 mm vias at 0.8 mm distance leave
just enough space for a 0.1 mm line to pass in between with 0.1 mm
distance.



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