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November 2012

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Subject:
From:
Guy Ramsey <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Guy Ramsey <[log in to unmask]>
Date:
Tue, 6 Nov 2012 10:20:29 -0500
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text/plain
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text/plain (87 lines)
Exactly.
 
While working as a consultant, I participated in resolving an unplanned for
disaster. The company we were helping moved a product from a line using
water soluble flux and cleaning to a line, in another country, that was
"no-clean". The transition required much tighter process controls and much
better process planning than expected.

Guy
 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman
Sent: Tuesday, November 06, 2012 8:27 AM
To: [log in to unmask]
Subject: Re: [TN] Limits on flux residue

Hi Wayne - no, the JSTD-001 committee has not addressed that aspect of No
Clean processing because there are a number of product use environment
influences and process parameters that come into play on what is acceptable
and unacceptable. Your description would lead me to believe that someone has
taken extreme liberty in calling something a "no clean" 
process. One of the things that we have found most interesting in the
implementation of a no clean process for a couple of our products is that
many folks believe "no clean" is a sloppy process and you can leave flux
residue anywhere on the assembly in uncontrolled quantities. But the reality
is that "no clean" solder processing requires very careful control of
what/how much/where you allow flux residues to exist. In my view, a "no
clean" process actually is a much tighter controlled process than a process
that utilizes cleaning to insure that product functionality is not impacted.

Dave Hillman
Rockwell Collins
[log in to unmask]



From:   "Thayer, Wayne - IS" <[log in to unmask]>
To:     <[log in to unmask]>
Date:   11/05/2012 05:52 PM
Subject:        [TN] Limits on flux residue
Sent by:        TechNet <[log in to unmask]>



Is there a spec somewhere which limits the amount of residue allowed for no
clean processing?  I just saw a board where a BGA was about 70%
"underfilled" by flux residue.  No, this was not a flux/underfill product! 
 A quick look at JSTD-001 Section 8 didn't seem to have specific guidance on
this condition.

Wayne Thayer

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