It will not work if just simply setting up bigger routing grids. It may
works if a clearance is set to match the grid. But it will be too large
for the fan out traces. I set up the clearance by via spec. (21 mil
clearance between vias so a 7/7mil trace can go through). I gave the
router a try. Some vias are still very close together. 

I received a phone call from Protel yesterday. There is no rule to meet
such requirement for neither 99SE nor DXP. However, I was asked to send
them the file for research. Hope a way will be found to work around...

I am just wondering how other Protel users do the fan out vias. How many
people actually use the auto router for fan out option? Are most of the
jobs manually done by the designer(s)?

Thank you for all the replied!

Shuping

-----Original Message-----
From: Jon Elson [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, October 16, 2002 12:33 PM
To: Protel EDA Forum
Subject: Re: [PEDA] Fan out Via clearance


Shuping Lew wrote:

> Jon, Thank you very much for your replied.
>
> Could you describe some more details? ---How to set up different grids
> for Vias and traces? Grid setting for traces should be much smaller
than
> Via's... I'd like to set up 5mil for traces and 55 mil for vias so I
can
> run a trace in between. Is there any way to set up different grids for
> auto router?

Yes, you have a point, there.
The detailed way to do this probably to set a rule such that vias cannot
be

closer than some calculated amount to other vias on a different net.
(Does the autorouter follow such a rule?)  Make that clearance enough so
that
a track plus the clearance on each side can then make it through between
them.
I can never remember exactly which rules the autorouter follows, and
which
it ignores.  (The rules setup does tell you which ones are observed by
the
router.)

Note that the grid is not an absolute restriction on track endpoints,
however.
If the track ends on some other primitive, it is allowed to go off-grid
to
hit the center of that primitive.  That won't work for intermediate
track
segments, however.

Jon

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