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March 2009

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Subject:
From:
Douglas Pauls <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, [log in to unmask]
Date:
Tue, 10 Mar 2009 07:26:00 -0500
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Jim,
Sorry to say, I think your boards are toast.  Flux does wick up under 
insulation and no cleaning process that I have ever seen totally removes 
it. Given a very active flux, you probably already have corrosion in the 
wires.  Now, if you can replace the discrete wires, you might still be 
able to salvage the board.  I would remove all the wires and have ion 
chromatography done on the assembly itself.  That should give you an idea 
of how effective your overall cleaning process was.

Doug Pauls
Rockwell Collins



Jim West <[log in to unmask]> 
Sent by: TechNet <[log in to unmask]>
03/09/2009 06:44 PM
Please respond to
TechNet E-Mail Forum <[log in to unmask]>; Please respond to
Jim West <[log in to unmask]>


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Subject
[TN] Wrong flux used






During selective soldering, our operator used an IA flux (superior flux
75), which we normally use to dress up the soldering nozzle to create a
smooth flow of solder.  The flux was applied by a spray fluxer.  The
operator used the wrong bottle when reloading the spray fluxer.

We ran the boards through a wash system hoping to remove the IA flux. 

The soldering operation involves discrete wires and I would think that the
flux would wick up under the wire insulation and not be reachable for
cleaning. 
 
My questions are:

If the flux has wicked up under the wire insulator and can not be reached 
by cleaning, will this type of flux 
cause issues with the copper wire?

Will cleaning the boards be enough to say that no harm will be done, or
will this flux cause latent issues due to it's aggressiveness? (other
components were touched by this flux, i.e. SMT ceramic capacitors,
resistors)


Flux information 
Superior soft soldering flux:
"The inorganic acid (IA) zinc chloride fluxes, commonly referred to as
"acid fluxes," are used for industrial soft soldering applications with
tin/lead, tin/silver, and other solder combinations. These fluxes 
typically
contain a combination of zinc chloride, hydrochloric acid, and ammonium
chloride and are used for soldering stainless steels, brass, copper, and
other metals."

Thanks,
Jim

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