Agreed.  For vias we look for a callout of a maximum number, like .010"
max.  This give the fabricator latitude on what drill size to use based
on their specific processes and capabilities.  This also provides a
safeguard for designs that need a larger via for thermal or electrical
capacity.    

Jeffrey Bush
Director, Quality Assurance and Technical Support
VERMONT CIRCUITS INCORPORATED 
           76 Technology Drive - POB 1890 
              Brattleboro, Vermont 05302
                Voice - 802.257.4571 ext 21
                    Fax - 802.257.0011
                       <http://www.vtcircuits.com/> 
                           

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Werner Engelmaier
Sent: Monday, April 24, 2006 2:21 PM
To: [log in to unmask]
Subject: Re: [TN] Drill specification

Hi Jeffrey,
Specifying finished hole sizes made sense when we needed clearance for
pin
insertion--for vias the drilled hole diameter is important and the
finished hole
size not at all.



Werner

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