Should I specify the diameter of holes on my PCB as before plating (tool size) or after plating (finished)?
Michael Leonard says finished
Olimex says tool sizes
Pcbex says finished
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Thank you for any thoughts.
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\$\begingroup\$ shouldnt really matter. When you generate your gerbers or drill files, it will specify the dimensions that you have selected on your design. \$\endgroup\$– efox29Dec 26, 2014 at 10:15
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1\$\begingroup\$ @efox29, I think OP's question is, do the dimensions in the drill file indicate the size of the drill used or the finished size of the hole after plating? And given that either is possible, which one is better. \$\endgroup\$– The PhotonDec 26, 2014 at 17:55
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The easy answer is that you should specify whatever your supplier requires.
Normal industry practice, in my experience, is to specify finished diameters for both plated and unplated holes. That's certainly what we use in our libraries. If you're using some oddball supplier that requires something different you can always edit the PCB file or the NC drill file to accommodate them. I'd prefer to have the PCB maker responsible for delivering the boards with holes made right to the specified tolerance, not to tell them to use some drill of specified size that will then cut an oversize hole, that is then plated down by some unknown amount..
Note that specifying finished diameters means that plated and unplated holes specified as the same size will generally use different tools.
answered Dec 26, 2014 at 10:19