Subject: | |
From: | |
Reply To: | TechNet E-Mail Forum. |
Date: | Fri, 26 Mar 1999 05:54:25 -0500 |
Content-Type: | text/plain |
Parts/Attachments: |
|
|
Matthew Lamkin wrote:
> >Jeff Seeger wrote:
> > many snips for brevity <
[Matt Says >>>] done. Of course record of what is
> >done is allways taken & applied to the CAD file afterwards.
I knew that. But the practice is frightfully common, and
too many people take it lightly. No better forum than
this to point out "good intention/bad concept". Please
forgive me if my humour gets dark by 5am.
> >
> >> some alterations that my CAD package could not,
> >
> > Sure hope you have a scripting facility in that tool...
> >
> >[Matt Says >>>] A scripting utility? what for, what would that do?
Capture the mods/extensions for the benefit of the next
revision. Myself, I have enough of a time capturing
"what I meant" once, and to do a significant edit again
for a minor modification usually leads back to the "edit
the gerber files" mode. If the post-CAD tweaks can be
captured and automated, the torturous path is less of
a temptation. I have found that no matter how careful
and studious one is about back-feeding changes into the
CAD system, a mistake is inevitable.
> >[Matt Says >>>] My CAD package cannot create pads with a slot in them to
> >prevent the solder flowing
> >[Matt Says >>>] over them when wave soldered. However using GC-Prevue I have
> >been able to do this with
> >[Matt Says >>>] some clever manipulation of a bit of copper & layer merging.
>
Well, can't visualize the case but you get the idea. Any
editor that can't capture what it did and repeat it gets
used only as a viewer in our environment. Of course, it
really only moves the problem to a different level because
on more complex revisions you may need to edit the script.
Honestly we had to evolve to keeping multiple CAD tools so
that we didn't have "can't create" problems.
> >
> > Back to topic, I've seen difficulties w/274X - and the
> > more complex the artwork the more likely the troubles.
> >
> >[Matt Says >>>] I only once had problems, I usually design them out. Custom
> >apertures seemed to be
> >[Matt Says >>>] my only problem, but only because I did not know how to
> >create them (I do now).
Have had to gather a roster of viewers to see if we could
get agreement. One 274X file loaded back into source system
just fine, but we got three different results from three dif-
ferent readers. Distilling the problem to a managable case
and reading the spec showed the source tool was well behaved,
if non-intuitive in some defaults.
That was some time ago, and I think all the tools have improved.
They had to. But once in a while we encounter someone using an
old version...
--
Jeff Seeger Applied CAD Knowledge Inc
Chief Technical Officer Tyngsboro, MA 01879
jseeger "at" appliedcad "dot" com 978 649 9800
################################################################
TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c
################################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body:
To subscribe: SUBSCRIBE TechNet <your full name>
To unsubscribe: SIGNOFF TechNet
################################################################
Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information.
For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312
################################################################
|
|
|