I agree with Mario's observations , but I think that the preferences are
really driven by what toolset you are currently using.
In some CAD packages, using negative planes is easier,
and others it's easier to create positive planes .
Regards,
Andre Demers, C.I.D.
Senior PCB Designer, Coordinator
cmrsummit Technologies
329 March Road, Suite 203
Kanata ON K2K 2E1
Canada
Telephone: 613.599.3881
Toll Free: 877.428.1229
Pager: 613.368.0506
Fax: 613.599.7889
[log in to unmask] <mailto:[log in to unmask]>
www.cmrsummit.com <http://www.cmrsummit.com/>
-----Original Message-----
From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of
Mario Irigoyen
Sent: Thursday, July 19, 2007 10:59 AM
To: [log in to unmask]
Subject: Re: [DC] Planes: Negative vs. Positive?
My 2 cents:
Negative internal planes have very obvious advantages, auto pads
(segments, clearance), they do not have to be 'drawn' they are just
there and, unless you are using a very old tool set, splitting a plane
for multiple nets and/or routing a few traces is very easy. Positive
images on the other hand make for a very large database and have to
drawn (placed, inserted, created ...) for each instance. Positive images
are poured polygons or shape fills that require significant computing
power (and time) to 'calculate' the clearances, borders, connections and
so forth. Designs with many positive images are significantly slower to
open, edit, print, plot ...
I use negative planes exclusively on internal layers, positive on
external and internal signal layers.
Mario Irigoyen
-----Original Message-----
From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of
Silicon Valley Chapter - IPC
Sent: Thursday, July 19, 2007 8:35 AM
To: [log in to unmask]
Subject: [DC] Planes: Negative vs. Paositive?
The design team I work with is split one which to use, negative or
positive planes.
What are the pros and cons of each? What do most people prefer to work
with?
We are currently using 15.5.1 but evaluating 16.x for possible future
migration.
Thanks for your feedback.
Bob McCreight, C.I.D.
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