On  1 Nov 96 at 8:18, dmyers wrote:

 >        We have seen problems with the RS274-X format. It seems that
 >     our customers supply all RS274-x data with no flashed
 >     apertures. Instead the use hundreds of macros.
 >      
 >        The first thing that happens is you read the data in through
 >     your design input software. (IGI, Valor, Orbotech, whatever) and
 >     the data is interpretted very quickly with little human
 >     intervention. So far so good.
 >
 >        However, when you decide to check your work, run analysis or
 >     DRCs, you find that you have no idea what diameter your
 >     pads are. If you need to extract a netlist for Test issues,
 >     then your really


 Whew. Macros instead of flashed circles?  I would be interested to
know which CAD package does that.  I use the macros extensively on
my surface mount pads to customize and to round off the sharp corners
on rectangular pads. I am very pleased with the result in the copper,
soldermask, and paste stencil.

 If I knew my board vendor was making extensive edits to my gerber
output, I would fix the problem and generate correct files. Do your
customers know you do this? Extensive edits defeat the purpose of 
RS-274-X, of course.

 The netlist problem is a big one. perhaps the software vendors can
be persuaded to implement EDIF. I don't hold out much hope for a
groundswell of support for IPC-D-356.


 >     stumped. If your CAM operators need to make any edits, for
 >     instance change an .062" diameter pad to .064" for etch
 >     compensation or meeting annular ring requirements, then you
 >     will be spending a very long time making these edits, during
 >     which, you will probably make an error. And creating a
 >     soldermask is impossible.
 >
 >        We have finally come to the conclusion that it is just too 
 >     difficult to deal with this format as it is received today.
 >     When we do receive it, we have our design input operators spend
 >     the day converting all of the "macros" into flashes. We are
 >     then left with the big task of comparing the original data to
 >     the editted data in order to verify that the human intervention
 >     (at this very critical stage) did not cause an error.
 >
 >        Hope this helps.

---
Ross LaGue          < [log in to unmask] >          Dayton, Ohio

***************************************************************************
* TechNet mail list is provided as a service by IPC using SmartList v3.05 *
***************************************************************************
* To unsubscribe from this list at any time, send a message to:           *
* [log in to unmask] with <subject: unsubscribe> and no text.        *
***************************************************************************