On Wednesday 24 May 2006 05:36, Kevin Lineberry wrote:
> > You can specify this with the DRC tool, under the clearance tab --  there
> > is actually a setting for minimum distances between pads and  traces,
> > pads and vias, vias and traces, etc, etc.
>
>  I have just looked, and you are right, the drc enables this. One 
> question: It seems the drc does not allow to specify the layer, for
> example, I  don't mind wires go near to pads on the top layer, but I don't
> want it on  the bottom layer (because I only solder on the bottom, and I
> want a  larger error margin for my soldering). Is it correct that this is
> not included in  the drc, and is this the same in most other leading cad
> systems.


This is the same reason I want more spacing if available.  For boards with 
soldermask, this is not an issue, especially since I specify that soldermask 
should cover the vias.

But for what you're asking, there is not, to my knowledge, any way to do this 
directly.  But there *may* be a round-about way to achieve this -- autoroute 
the board, then make the top layer invisible, highlight the rest (bottom 
layer) and rip it up.  Then change the spacings and re-route.  I have not 
actually tried this, but the theory seems so valid in my head right now.  
BTW, the auto-router allows the ability to route only 1 layer at a time, but 
using this to try to achieve different spacings for top vs bottom layers 
would produce totally different results.

Cheers,
-Neil.
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