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July 2008

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Subject:
From:
Graham Collins <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, [log in to unmask]
Date:
Tue, 8 Jul 2008 12:44:30 -0300
Content-Type:
text/plain
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Hey guys.
Thanks for all the opinions and info.  I'm stuck in the middle, on one
side is a designer saying that it means pre-finishing size, on the other
I've got a fabricator saying it means finished hole size.  The drawing
is ambiguous on this point.  I just want parts to build things with!!!

I do agree with Werner that it does not matter as they are only vias,
but once someone had inspected and measured something it became a
debate. 


regards,
 - Graham

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ken Bloomquist
Sent: Monday, July 07, 2008 7:57 PM
To: [log in to unmask]
Subject: Re: [TN] Flex specifications - tolerance on hole size

Hi Werner,

I like your thinking but... 

I'm not in the quality department, no offense to those of you who are,
but I wouldn't want to be ;-) But thinking like an inspector, how would
you verify that you got the right size holes if you don't call out a
finished hole size? I guess you could do a cross section but a pin gage
is a lot simpler.

Just thinking out loud,

KennyB

-----Original Message-----
From: Werner Engelmaier /* [mailto:[log in to unmask]]
Sent: Monday, July 07, 2008 3:36 PM
To: [log in to unmask]
Subject: Re: [TN] Flex specifications - tolerance on hole size

Hi Graham,
Why do you care what the finished hole size is? Do you put component
leads into 0.028"/+- 0.003" holes, that is 25 mils minimum?
The finished hole size specifications are an anachronism harking back to
the

THT-days-today they only should be specified for componet lead holes.
For vias the drilled hole diameter should be specified-it is much more
important.
Werner
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Pb-Free Soldering Processes-Survival, Quality, Reliability, July 17/18,
Thal, Switzerland Pb-Free Soldering Processes-Survival, Quality,
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Processes-Survival, Quality, Reliability, August 18, Orlando Reliability
Issues with Lead-Free Soldering Processes, September 22, Schaumburg
Failure Mode and Root Cause Analyses Reliability (Fatigue, Brittle
Fracture,

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Solder Joint Reliability: Parts 1 & 4, Oct. 9, Moscow, Russia Solder
Joint Reliability: Parts 1 & 4, Oct. 17, Timisoara, Rumania Solder Joint
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