It makes sense to give your supplier more tolerance on the low end if you
can, after all, there is no lead soldered in a via, so why not give more?

I have used +.003/-.006 for vias in the range of .012 to .020 diameter.

Cliff Lamson, C.I.D.
PCB Design Manager
Plexus Technology Group
940 Main Campus Dr., Suite 200
Raleigh, NC 27606
919-807-8047
The Product Realization Company
http://www.plexus.com/

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