Hi Bob,
Thank you for the response.  I have looked over IPC 2221 and can only find 
the location tolerance for Class A,B or C PCB's, (table 9.3).  Can I ask 
you where in 2221 you found the information for second stage drill 
tolerance?

Thanks again.
Tom


Tom Burek, CID+

VEHICULAR INSTRUMENTATION SYSTEMS BUSINESS UNIT
INSTRUMENTATION AND SPECIALTY CONTROLS DIVISION
287 27 Road | Grand Junction, CO 81503 | http://ametekvis.com
Phone:  970.257-2486  email: [log in to unmask]
 



From:   "Bob Hammond" <[log in to unmask]>
To:     "'TechNet E-Mail Forum'" <[log in to unmask]>, "'Tom Burek'" 
<[log in to unmask]>
Cc:     "'Joseph Ciukaj'" <[log in to unmask]>
Date:   06/20/2012 05:47 PM
Subject:        RE: [TN] Standard fabrication drill tolerances



Hi Tom:

I believe the following comments will answer your questions. Our answers 
are
based on the IPC Class 2 Specs (axial tolerance):

1st Stage (PRIMARY IMAGE) location tolerance for drilled unplated hole is
+/- .003 inch per the IPC 2221 spec.

2nd Stage (PRIMARY to Secondary) location tolerance for drilled unplated
hole is +/- .005 inch per the IPC 2221 spec.

Please do not hesitate to contact me if I can be of further assistance.
Bob Hammond- QC Manager 



-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Tom Burek
Sent: Tuesday, June 19, 2012 2:20 PM
To: [log in to unmask]
Subject: [TN] Standard fabrication drill tolerances

Hi,
These questions are directed primarily at the PCB fabrication 
professionals
out there, but any input is welcome.

What is the standard location tolerance for a first stage drilled hole,
(unplated)?
What is the standard location tolerance for a second stage drilled hole
(unplated)?

Lets assume IPC Class 2.
I tried looking through IPC 6012 and IPC-2221 but cold not find any
indication of what first stage drilled holes or second stage drilled 
holes.
Where can I find any industry documentation used by the PCB fabricators to
identify this information?

Thank you in advance.

Tom Burek, CID+



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