Zinc is more electronegative than anything else on the the board, unless
there is a voltage ojn the board, no way will it plate out. I agree with
60C water to clean the board, and that may indeed allow some discoloration,
i.e. light corrosion, hopefully more cosmetic than functionally
deleterious. Insoluable salts may be an issue, but by their insolubility,
they also are usually more of a cosmetic issue than a functional one. The
bad actors here are the zinc, amine and chloride, if they can be
effectively removed, perhaps the boardds, less the wires can be saved.
However, are the boards worth saving? The wires most likely need removal
before c leaning and replacement after cleaning, and that means rework, and
then the boards need extensive cleaning and cleanliness assessment. All of
this is expensive.
Karen Tellefsen - Electrical Testing
[log in to unmask]
908-791-3069
Mike Fenner
<[log in to unmask]
OM> To
Sent by: TechNet [log in to unmask]
<[log in to unmask]> cc
Subject
03/10/2009 09:16 Re: [TN] Wrong flux used
AM
Please respond to
[log in to unmask]
m
Yes the wires are dead, turning back to the board: Considering the variety
of metals on PCB and the flux used could there be a problem with plating
out
of the Zinc (from flux) somewhere? Or some reactions making more or less
soluble salts, plus similar compounds with saponifier?
Also to get good penetration of the water will need a temp around 60C to
get
the water surface tension low enough. At those temperatures it's possible
the flux ionics will be active enough to cause darkening/ corrosion on some
surfaces.
Any proper chemists please feel free to dismiss or answer.
Regards
Mike
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Karen Tellefsen
Sent: Tuesday, March 10, 2009 12:43 PM
To: [log in to unmask]
Subject: Re: [TN] Wrong flux used
Yuck!
The flux wicked up the wires, those wires will fail. If the wires can be
replaced, you may be able to salvage the rest of the boards if you wash
them very thoroughly with hot DI water. A prewash with saponifier wouldn't
hurt. After washing, you will need to ensure that all the flux was
removed by ionic cleaniless measurements or extraction and IC.
Good luck
Karen Tellefsen - Electrical Testing
[log in to unmask]
Jim West
<[log in to unmask]
M> To
Sent by: TechNet [log in to unmask]
<[log in to unmask]> cc
Subject
03/09/2009 06:46 [TN] Wrong flux used
PM
Please respond to
TechNet E-Mail
Forum
<[log in to unmask]>
; Please respond
to
Jim West
<[log in to unmask]
M>
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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