Computer Numerical Control (CNC)
I am using a #78 drill bit to drill the vias on this PCB. It is covered with white celophane type of tape as this was used to test my through plating using conductive liquid. (See this article.)
The machine drilled the small holes very well and could not be done by hand without breaking the small bit. I have also used #87 drill bits which drill around 10mil holes!