Gerry,
I don't think that the RS 274X standard is the issue. This standard has
been around for a long time. Generally, if there is a problem it is due to
the interpretation of the standard by CAD and CAM system developers. I had
a lot of experience with this issue because I ran a software development
group who developed CAM and pre-production analysis software. We also
owned a number of service bureaus. Therefore, I saw data from any number
of CAD and CAM systems. As a service bureau we had to be able to read
whatever was thrown our way regardless whether it matched the standard or
not. Whenever possible, I would contact individuals who produced
"incorrect" data to get them to put pressure on their software vendor to
correct the problem.
I have been involved in many meetings with CAD vendors including IPC
sponsored events. Generally, the CAD vendors do not put much effort into
output translators because good output is not viewed as a feature that
sells more systems. They put their emphasis on routing, placement, etc.
In more than one meeting I was told, point blank, that output did not get
much development effort. As a result, many of the RS 274X outputs from the
CAD systems, though correct per the format spec, are very poor.
This leaves the CAM vendor with the responsibility of trying to read every
flavor and interpretation of RS 274X. One of the biggest issues is
polygons. CAM systems attempt to police valid polygons. They are required
to do this because they must produce photoplotter output and, therefore,
the polygons must match the requirements of the photoplotter. I would
venture to guess that most of the polygons that VALOR CAM says are illegal
would not plot if sent directly to the photoplotter. In this case, the CAM
software must be robust enough to handle the illegal polygons and make them
plottable. It is too bad that the CAM systems must compensate, but until
we can get the CAD vendors to produce good output it is the way it has to
be.
Dave Roesler
TRI-C Design, Inc.
----------
> From: Gerald G. Gagnon <[log in to unmask]>
> To: [log in to unmask]
> Subject: Re: [DC] RS274X format problem
> Date: Thursday, October 15, 1998 7:20 AM
>
> Hi All
>
> The recent posts regarding RS274X have been very timely as I have seen a
> rash of problems with a vendor not being able to read these files into
> their VALOR CAM system due to "illegal polygon fills". I believe this
> issue is different than the compositing issues from this thread. Other
> board shops either do not seem to have the problem or have developed
> suitable workarounds to keep their jobs going.
>
> What concerns me most is whether or not this is an RS274X standard
> issue, a CAD RS274X translator issue, or a board shop CAM RS274X issue.
>
> Any comments?
>
> Regards
>
> Gerry Gagnon
>
> Interconnect Technology
> AlphaServers Platform Development
> 129 Parker Street
> Mail Stop: PKO3-1/20C
> Maynard, MA 01754-2198
>
> ' Phone: (978)493-1210
> * Fax: (978)493-0941
> * Email: [log in to unmask]
>
>
>
>
>
>
> -----Original Message-----
> From: Hawes, Adam [mailto:[log in to unmask]]
> Sent: Thursday, October 15, 1998 3:35 AM
> To: [log in to unmask]
> Subject: Re: [DC] RS274X format problem
>
> Dennis,
>
> You're not alone.......
>
> Composite layers are when the CAM software uses several layers to create
> one
> artwork layer i.e. what exists as one layer in Allegro e.g. your power
> plane
> is made up of several layers in the CAM environment. (forgive me if you
> already knew this!)
>
> The fabricator only has a limited number of layers available to play
> with
> and we have had a problem with RS274X, especially on boards with several
> PWR/GND layers, where the fabricator has complained of not having enough
> layers to complete all the composites.
>
> I believe there is a Skill routine on the Cadence Web site that allows
> you
> to reduce the number of layers needed for composites. I've never used it
> so
> I don't know how reliable it is or if it's any good. Other than that,
> the
> only thing I can suggest is that you talk to your fabricator.
>
> Hope this helps.
>
> Adam Hawes
>
> > -----Original Message-----
> > From: Dennis Ward [SMTP:[log in to unmask]]
> > Sent: Wednesday, October 14, 1998 12:49 AM
> > To: [log in to unmask]
> > Subject: [DC] RS274X format problem
> >
> > Hello,
> >
> > The fab house I'm using has encountered a problem importing my RS274X
> > artwork.
> > I believe their software is having a hard time compositing(?) the
> power
> > plane layers.
> > I'm still unsure what exactly is happening - I plan on visiting them
> > tomorrow and see
> > first hand.
> >
> > My software (output) - Allegro designer - version 13
> > Theirs (Input) - Tibor Davos - version unknown.
> >
> > Has anyone else experienced any difficulties with RS274X formatted
> power
> > and ground planes
> > generated from Allegro??
> >
> > Any (I do mean ANY) help would be appreciated.
> >
> > Thanks
> > Dennis Ward
> > Net to Net Technologies
> >
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