Deng RongJun:  Keep in mind that IPC-572A is not a Specification, but a Guideline, which means that it provides guidance and does not provide hard requirements to be met.  
That is why the statement in section 9.3.3 does not specify the diameter range of the as-drilled hole for which the roughness value of < 25 μm holds true.

Tom Newton, IPC 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Deng RongJun
Sent: Wednesday, September 6, 2017 4:54 AM
To: Technet <[log in to unmask]>
Subject: [TN] PCB hole wall Roughness

Fellow TechNetters:

IPC DR-572A 9.3.3 has defined that the maximum allowable roughness is recommended to be 25 μm. Is this for all size drilled holes? 
Sometimes I head from PCB fabricator that the drill hole roughness is depends on hole size, ex.: 0.5-0.8mm drill hole roughness <25.4 μm, 0.8-2.6mm drill hole roughness <30 μm.
The hole wall roughness will cause blow hole in solder joint during wave or selective soldering if moisture go in to PCB inside. So we need to control the roughness on hole wall surface.
Is anyone have experience on this?   What roughness is reasonable for PCB hole?

Best regards
Deng