On an allied question to the one on inner layer for voltage what is the
minimum drilled hole to copper inner layer clearance?

I have an engineer wanting 6 mil drill to copper nominal which would,
allowing for a 2 mil drilling tolerance give 4 mil drill to copper on the
internal layer.

I might be off track but to me that is too close even though the voltage is
a few volts (crazing, wicking issues etc).

What are experiences on this type of high density close drill to copper
clearance especially with lead free process temperatures?

Inputs gratefully received,

John
 
 
John Burke
 
(408) 515 4992

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