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Re: gEDA-user: cylindrical SMT power resistor pad design: how to do a semi-circular cutout


On Jun 27, 2009, at 4:26 AM, S. Aguinaga wrote:



  Do you
  fellows have some pointers for me to generate the semi-circular cut
  out?


You will need to generate the semi circle with many small rectangles.
Their recommended footprint looks like it is generated with 7 rectangles.

PNG image
If you make a pad with all of these rectangles with the same pad name they will be one pad, if you don't PCB will complain that the pads are shorted.
If you want a semi circle you probably will need 20 segments or so, this one uses 5.
now with outlines. the black semi circle is approximated by the inside rectangles, there are gaps and excesses, but you can see that you get your approximation, and on the scale your working on this is good enough, as shown in your data sheet. This footprint looks like it is designed to keep the part aligned with surface tension during reflow soldering

PNG image
happy footprinting. You might want to make a script to calculate out the semi circle points. 

steve

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