Thanks, JaMi for your detailed reply.

When I wrote "rule for polygon clearance of 12mil", I was referring to a
"Clearance Constraint" for Object Kind = Polygon.
I cannot get Protel99SE to do what I want so I will draw what I want with
Fills, Circles, and Tracks.

Thanks for the suggestions.
Cam

-----Original Message-----
From: JaMi Smith [mailto:[EMAIL PROTECTED] 
Sent: August 31, 2004 12:02 PM
To: Protel EDA Forum
Cc: JaMi Smith
Subject: Re: [PEDA] Net with large clearance and polygon


Cam,

Firstly, what "rule for polygon clearance of 12mil" are you talking about?
There is a rule under "Manufacturing" for "Polygon Connect Style" and also
one for "Power Plane Connect Style" and also "Power Plane Clearance", but
not one for "Polygon Clearance".

You may be speaking of some specific "Clearance Constraint" that you have
set up that you have named "polygon clearance", but you will have to explain
that one to me.

I believe that the simple answer to your question would be to set the
"Polygon Connect Style" rule under "Manufacturing" to "Relief Connect", and
then than set up an additional "Clearance Constraint" rule which applies to
"Scopes" of "Board", "Board", and the "Connectivity" of "Same Nets", with
the clearance of 12 mils, and enable this Clearance Rule at the same time
that you "Pour" your Polygon Planes with a "Clearance Constraint" rule
enabled which applies to "Scopes" of "Board", "Board", and the
"Connectivity" of "Different Nets" with the clearance set to 97 mils (i.e.
enable both rules, but only these two rules, at the time of the "Pour" of
the Polygon Plane).

If that fails, read on.

I am not quite sure that what you want can be done in P99SE with a specific
"rule" that would be set up by "class" etc., that wouldn't apply to the
whole net EARTH as a whole, or otherwise be complex enough to screw up.

I encounter the problem all of the time, where I want my Polygon Planes to
have a larger clearance or setback than my normal clearances, which sounds
something like what you are trying to describe below.

The trick is to remember that a Polygon Plane clearance is really pretty
"dumb", in that it is actually defined by the "clearance rule" ("Clearance
Constraint") in effect at the time of the actual Polygon "Pour" (i.e.: Each
time you generate a Polygon or "Re-Pour" ("Rebuild") it).

I generally make a "Design Rule" for "Clearance Constraint" which I name
"Clearance PP (for Polygon Plane)", with the "Scopes" of "Board", "Board",
and the "Connectivity" of "Different Nets", and the specific clearance that
I want, which in your case would be 12 mils, but in my case it would be
larger than the normal clearance for everything else.

Normally, this "rule" would be "off" (no "check" in the "Enabled" box) for
normal routing and board work, but then when I am ready to make my Polygon
Planes, I disable (turn off) all of the other "Clearance Constraint" rules,
and enable (turn
on) only my "Clearance - PP (Polygon Plane)" rule, and than make or "Pour"
my Polygon Planes.

Again, please remember that every time that you "Pour" or "Re-Pour" (Build
or
Rebuild) a Polygon Plane, that it "Pours" at the "Clearance Constraint" in
effect at that time, and that this means that if you have a Polygon Plane
already set up, and you double-click on the Polygon Plane to open it's
Dialogue Box for any reason, that if you click "Yes" to the question
"Rebuild 1 Polygons?", that you are liable to change the clearance of your
Polygon Plane. If you really do have to "Re-Pour" the Polygon Plane, you
will have to go into your "Design Rules" and enable and disable the
appropriate rules, and then change them back again when you are done with
all of your "Pours".

Needless to say, if you want to have different clearances for different
Polygon Planes, such as for example for Polygon Planes on different layers,
then the "trick" to accomplishing this is simply to "Pour" (or "Re-Pour")
them with different "Clearance Constraints" in effect at the time of each
"Pour" (or "Re-Pour").

Sometimes you may even need different "segments" of a single Polygon Plane
in different areas to have different clearances, such as for example an area
around certain "controlled impedance transmission lines" which may need
larger clearances. This can be easily done by actually making up your
Polygon Plane with not a single Polygon Plane, but using several different
but overlapping Polygon Planes of the same net name, and "Re-Pouring" the
different segments with different "Clearance Constraints" in effect for each
"Pour". You may end up with a few little "uglies" here and there, where the
planes overlap, but that's what an occasional little floating piece of
"track" of the same net name (overlaid on the plane at that spot) is
designed to be used for, to clean it up, aesthetically speaking.

Yeah, I know it's a pain, but that's Protel. What else would you expect?

While someone else may come up with some other way to accomplish what you
want to do, for me this is a simple and effective way to accomplish the task
that works reliably for me from board to board (design to design), without
any repercussions or side effects, excepting the "Re-Pour" issue.

Unfortunately, in this case, like so many other things in Protel, you simply
have to manually override the system to get it to do what you want it to do,
and every time that you have to do something like this, you have to take the
chance that it will not be seen or understood by someone else down the line,
which means that someone else could easily screw up the design, in this case
simply by "Rebuilding 1 polygons" [sic] (I don't think that Protel can
actually "Rebuild" more than "1" "polygons" at a time, can it?). To prevent
such a problem from happening in the future, you might place a "Note" just
outside of the board perimeter, on some unused mechanical layer, or possibly
the same layer you use for the board outline (or even on the Top Overlay,
but again, just outside the board outline), something to the effect of:
"DESIGN NOTE: Polygon Planes poured with 97 mil clearance using
"Clearance-PP Constraint".

Yeah, I know, some idiot will still mess it up somewhere down the line in a
future revision, but what do you expect with this software.

Don't forget that you may have to "juggle" the "Clearance Constraint" Design
Rules a little bit when it comes time to do your DRC, or you might want to
actually run a few separate DRCs with different Rules in effect (possibly
using a "copy" of the database where you would delete the Polygon Planes
with the smaller clearance so that you could check everything else). Here
again Protel's preprogrammed "intelligence" (or specifically the lack
thereof) really shines thru, but then again, I don't think that I have ever
done a design in Protel where the DRC didn't screw up somewhere and complain
about something that wasn't really an error (don't get me started on this
one . . . ). Please remember that the board is built to your "Gerbers" and
not to your DRC, and that sometimes the DRC may claim that something is
wrong where the board is actually right.

I hope this helps to answer some the issues you raise with your question.

JaMi

----- Original Message -----
From: "Cam Andruik" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Thursday, August 26, 2004 1:55 PM
Subject: [PEDA] Net with large clearance and polygon


> Help please.
> I want to set the net EARTH to have a clearance of 97mil.  This is no 
> problem, but when I place a EARTH net Polygon Pour it stays away from 
> everything, including the EARTH Through Hole Pads by 97mils. Cannot 
> figure out how to edit the rules so the Polygon will stay away from 
> all nets by 97mils except EARTH net which should default to the rule 
> for polygon clearance of 12mil. Any suggestions greatly appreciated.
>






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