I used to make all of my PC boards. Used a drill press attachment that is made for a Dremel tool. Drill bits used have 1/8" shanks.
Personally, I was never a big fan of cobalt drill bits over HSS, they didn't seem to last any longer and they are about three times the price. You can drill 2024-T3 a looooong time with HSS, but the real test is when you use that same bit on 7075-T6. That's when you know for sure that it is dull.Cobalt-steel or titanium-nitride-coated HSS will last indefinitely for drilling aluminum... unless abused.
Cobalt bits are good for drilling hard steel.Personally, I was never a big fan of cobalt drill bits over HSS,