gEDA-user: Re: Newbie PCB DRC questions

[Vaughn Treude <vltreude@xxxxxxxx>]

I forgot to thank everyone for their helpful responses to my question. 
The ensuing message thread also brought up additional interesting
information.  

I was able to complete my board and get the files to the board house for
production.  I did end up doing a lot of manual modification to the
auto-routed traces; but had I been more experienced I think there would
have been less of this. For example, it would have made sense to
manually connect the isolation capacitors to their respective IC's, and
THEN run the auto-route, because the auto-router knew nothing of these
location considerations.  I'll know better next time.  :=)

Thanks again!
Vaughn

On Mon, 2006-10-02 at 10:27, Vaughn Treude wrote:
> Hello everyone:
> I've been checking my board layout with the Design Rule Checker command
> in PCB.  I was encountering some mysterious behavior and wondering if
> anybody could explain this a little.
> 
> 1. The default minimum spacing is 10 mils, yet DRC flags everything that
> is exactly 10 mils. This is a problem because the auto-router put traces
> 10 mils apart in many places.  I tried changing the minimum spacing to
> 9.9  or 9, but apparently that's not valid because it does not retain
> that value.  (In fact, the preferences dialog experiences an error if I
> do this, and refuses to close the second time I bring it up.)  So I set
> the min-spacing to 5 mils and DRC found a few problems in the lines I'd
> added manually, which I was able to correct.  Does this mean the actual
> minimum spacing should be 15 mils or something like that, so that
> auto-routed traces will pass the DRC 10 mil guideline?
> 
> 2. I've been seeing "potential for broken trace" error a lot.  In some
> cases I can see that a line has some unnecessary jags in it which I've
> then straightened out.  In other cases the only problem seems to be that
> two connecting lines that go in the same direction have for some reason
> not been merged into a single line.  It's my understanding that if the
> trace _looks_ continuous (at a pretty high zoom) it _is_ continuous.  Is
> DRC flagging nonexistent errors here or is my understanding incorrect?
> 
> 3. Sometimes when DRC reports "copper areas too close", I go to the
> coordinates specified in the message and I cannot for the life of me
> find anything closer than 10 mils. (And I still have it checking for 5
> mil spacings.) Does DRC sometimes get fooled into thinking that
> connected lines should be separated?  Or am I misinterpreting the
> errors?
> 
> Thanks!
> Vaughn T
> 
> 



_______________________________________________
geda-user mailing list
geda-user@xxxxxxxxxxxxxx
http://www.seul.org/cgi-bin/mailman/listinfo/geda-user