John,
I don't know if you got an answer yet, but I'm not sure I understand the
question. High-rel PBs where CAF resistance and other reliability issues
are a concern anything closer than 0.006 inches potentially becomes
problematic.
Dewey

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of John Burke
Sent: Monday, October 15, 2007 1:45 PM
To: [log in to unmask]
Subject: [TN] Inner layer spacing for reliability

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

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
To unsubscribe, send a message to [log in to unmask] with following text
in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to
[log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
Search the archives of previous posts at:
http://listserv.ipc.org/archives
Please visit IPC web site
http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100
ext.2815
-----------------------------------------------------

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------