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October 2004

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Subject:
From:
Sara Gorcos <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Sara Gorcos <[log in to unmask]>
Date:
Wed, 27 Oct 2004 13:39:59 -0500
Content-Type:
text/plain
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text/plain (151 lines)
Hi Ken-
In regards to hand soldering flux residues not being reacted, this material
is very conductive and moisture absorbing and needs to be fully activated
using a secondary heating operation such as an Airvac work station and/or a
cure oven that allows the flux to reach activation temperature.  Here's a
couple links to other studies we have done dealing with activating flux
residues.
Here are the links:
http://www.residues.com/pdf/ProcessRx-09-04.pdf - this one is one of our
recent columns from Circuits Assembly and talks about the impact of flux
residues that are not fully activated
http://www.residues.com/pdfs/foresite_flux.pdf - this one touches
specifically on flux residues and hand soldering operations

We have quite a few studies dealing with flux residues, and you can find
most of them at http://www.residues.com/resources_case.html


Sara Gorcos
Foresite, Inc.
1982 S. Elizabeth St.
Kokomo, IN 46902
(765)457-8095
www.residues.com
 


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ken Patel
Sent: Wednesday, October 27, 2004 12:56 PM
To: [log in to unmask]
Subject: Re: [TN] No Clean


Sara,
For hand soldering and touch-up operation, flux will not be exposed to
higher temperature like that reflow soldering. Will that be an issue and if
so how one should resolve it? Is the hand soldering flux made to take care
of the ionic contamination?

Looks like it's s big issue to many of us.

Re,
Ken Patel

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Sara Gorcos
Sent: Wednesday, October 27, 2004 9:29 AM
To: [log in to unmask]
Subject: Re: [TN] No Clean

Hi Ted & TN Listserv,
We have found that by doing general board extractions for ion chromatography
analysis limits our understanding of the pockets of contamination that occur
around specific components and in comparative areas such as the bottom of
the board vs. the top.  By combining Ion Chromatography with a new localized
extraction technology is giving us a greater understanding of these pockets
of contamination.  No clean flux processes deposit different levels of flux
activator in different areas of the board.  Touch-up and repair adds to
these areas.  We have found more failures due to stray voltage in these
areas of thick or heavier fluxes that do not get full heat activation
through using a localized extraction approach. Here is a link to an article
we recently published in our column for Circuitnet that might give you a
better understanding of how to guage cleanliness in a no clean process, and
what issues are encountered by contaminants being left on boards.  It also
outlines some recommended limits for various contaminant types in
determining cleanliness http://www.residues.com/pdf/FailureOfACircuit.pdf

Sara Gorcos
Foresite, Inc.
1982 S. Elizabeth St.
Kokomo, IN 46902
(765)457-8095
www.residues.com



-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ted Kong
Sent: Monday, October 25, 2004 4:48 PM
To: [log in to unmask]
Subject: [TN] No Clean


Hi All,

What is the best method to measure the cleaningness of
a board that use no-clean process?

Thanks all in advance.

Ted Kong




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