At 01:40 PM 3/8/01 -0500, Larry Carter wrote:
>After importing a custom library from OrCAD 9.2 I noticed two issues.
>1.  In OrCAD I defined a square area on the top solder mask as a copper pour
>  and did not see it after importing to Protel 99 SP 6. (Help states that 
> OrCAD
>  copper pours will convert to polygons)

OrCAD and Protel treat polygons in a different way. OrCAD's name for any 
shape, if I recall correctly, is "obstacle." I thought that particularly 
appropriate....

Anyway, a solder mask polygon would not have a net assigment, and sometimes 
a copper pour in Protel with no net assignment will be invisible, it 
depends on the settings. That polygon might be there, but invisible. As to 
how to make it visible, I'd have to fiddle with it myself to figure that 
out, and I might use the sledgehammer of last resort, looking at the ASCII 
database directly, or perhaps the slightly more subtle spreadsheet. I don't 
remember about polygons and spreadsheets, though.... More below.

>2.  Also I have pads in OrCAD that are defined as rectangular for the top 
>copper and solder mask but the top paste is defined as oblong with 
>different length and width dim.  Protel makes the top paste the same as 
>the top layer.

Protel is not generally a padstack-oriented program as is OrCAD Layout. 
Unless one places primitives on the paste mask layer, the paste mask is 
generated by design rule, not by padstack definition. I suspect that Protel 
simply ignores the paste mask layer when importing footprints; since there 
would be *many* complications in making a more thorough translation.

Database translations are *typically* full of glitches like this. A 
translated design must always be checked thoroughly, especially with 
respect to any unusual features.

Protel's pad definition system is not as powerful as the padstacks used by 
some other programs, but, in practice, it is quite adequate, it being 
possible to make special features such as a custom paste mask shape by 
adding primitives to the footprint. The payoff of the Protel system is that 
it is much simpler and easier to use for most work. Padstacks tend to be 
rather unfriendly and cumbersome critters.

(Protel has a limited padstack capability in the pad edit dialog; it allows 
different shapes and sizes on top, mid, and bottom layers, but a full 
padstack controls the representation of the pad on all layers, and it is 
not uncommon that polygons would be allowed.)



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Abdulrahman Lomax
P.O. Box 690
El Verano, CA 95433

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