PCB Connector sizes


I created several parts and now I need to finalize the connector holes. The part maker gives the End Hole Diameter, then I need to calculate the drill hole diameter, annular ring, copper in the hole, and maybe an extra space between copper and pin in the hole.

Are there any math formulas to compute these dimension or any table with common connector holes ?


Assuming you are using Inkscape as your svg editor, the hole diameter in pcb is set by

hole size = pad_diameter - (2 * stroke-width)

so for a .1 header pad that wants to be a 0.038in hole and the ring size set at 20 thou (so at the recommended scale, a stroke-width of 20) we need a 0.078in pad diameter to produce:

0.038 = 0.078 - (2 * 0.02)

I think the other editors set the hole sizes differently but I use Inkscape.


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I reformulate, I need a hole of a diameter x.

What should be the size of the ring ?

Typically in Fritzing the ring size is set to 20 thou. In a svg with the scale set to 10.41667 (as specified in the part format file, and thus what I used above) that means the stroke width is set to 20 ( because drawing units are in thousands of an inch at that scale.) For other scales you would need to adjust the stroke-width to the value that will create a 20 thou (or whatever other size you want) in real world units.