Drilling hole sizes -- what are the differences?

Seeed Services Fusion PCB/ PCBA Services
#1

Hi,

In the specifications, the “drilling hole” is listed as a minimum of 0.3mm, and the finish hole is listed at a minimum of 0.8mm. What is the difference between these?

For example, if I want the smallest possible vias to connect my layers, could I use a hole drill size of 0.3mm? Or do I have to use 0.8mm?

Thanks,
Michael

#2

0.3 vias available.
0.8 - smallest mounting hole, i think… mounting hole drilling in the end processing. they has not copper layer inside

#3

0.3 vias accessible.

0.8 - littlest mounting gap, I think… mounting opening penetrating at last handling. they has not copper layer inside