This means they would like to maintain a minimum hole to adjancent
conductor spacing of 8.5 mils.  This can be a drill to utility plane
clearance, conductor of any metal that is an isolated net from the drill
hole.  Taken generally as PTH's, but as stated they are also requiring
this of NPTH's.

As a note, a design rule check on the layout to the 8.5 mil minimum will
not ensure this condition is met.  The fabricator will have a positional
tolerance that must be added to ensure the final version meets the
minimum of 8.5 mils.   

They are likely looking to avoid any CAF potentials.


Jeffrey Bush
Director, Quality Assurance and Technical Support
VERMONT CIRCUITS INCORPORATED 
           76 Technology Drive - POB 1890 
              Brattleboro, Vermont 05302
                Voice - 802.257.4571 ext 37 
                    Fax - 802.257.0011
                       <http://www.vtcircuits.com/> 
                           

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Genny Gibbard
Sent: Friday, February 03, 2006 10:52 AM
To: [log in to unmask]
Subject: [TN] In layman's terms, please?

What does "minimum drill to metal spacing less than 8.5mils is not
allowed" mean?

We must respond to a customer that our design meets this.

Thank you once again for sharing your wisdom...

Genny 

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