At 06:36 AM 3/13/2002 -0500, [EMAIL PROTECTED] wrote:

>Ah, but the radius of curvature at the "corners" is much smaller, leading to
>a stress point for peel to start, which is what started this discussion.
>Protel's version of rounded pads are actually better in that respect.

For a pad with x > y, the radius of curvature of the ends is y/2.

For a rounded rectangle as Tango defined it, the radius of curvature is 
y/4. This is not enough difference, I suspect, to cause a significant 
increase in peelability. A square pad has a radius of curvature of the 
process resolution. Say 1 mil. That -- for normal sized pads -- is a big 
difference.

Regardless, this is a design decision the outcome of which may vary from 
designer to designer even with the same design situation, and there are 
many situations. The software should not force the designer's choice.

Protel should really support complex and off-center pad shapes directly. 
But short of that, allowing true hexagons (unambiguous in the gerber), 
rounded rectangles, and ellipses (maybe), would be a small step in the 
right direction. Likewise allowing square draws in the gerber would allow 
drawing true squares. But that is another topic.

Abdulrahman Lomax
Easthampton, Massachusetts USA

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