We have built product with via holes only .010 off the edge of the routed 
edge or even routed them in half to act as an edge connector. This 
process usally adds cost or leads to shorts with some chassis part. As a 
rule high speed routing has a tolerance of +- .005" which may lead to 
trouble. 

If you review most peoples UL file you will find that they are required 
to have conductive surfaces .020"from the edge of the board. 

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On Thu, 26 Oct 1995, Thad McMillan wrote:

>      Does anyone have any comments regarding how close a plated or 
>      non-plated hole can be to the routed edge of a PCB.
>      
>      What is the typical recommended minimum.  I've been told that a plated 
>      via and associated copper can be down to .010" to a routed edge.
>      
>      I have personal concerns about how close a via can be before the 
>      routing process may damage a via.  Additionally the slop associated 
>      with the routed edge location.
>      
>      I'd appreciate any feedback.
>      
>      Thanks,
>      
>      [log in to unmask] 
> 
>