Miguel,
I'm not aware of a specific reference, but I can share my experiences.
In any hi-rel application, the mil-specs restricted us to R or RMA type
fluxes for good reason.  This applied to both component leads and wire,
stranded or solid to prevent the long-term corrosion possibilities resulting
from flux wicking up the strand(s) under the insulation.  Due to the
capillary action, it is VERY difficult to remove all the residues.  They may
be very diluted as you get further up the wire, but the residues are still
there.  RMA flux basically deactivates in the soldering process leaving a
non-corrosive residue for the most part.  As mentioned in another response,
even RMA flux residue left on stranded wires will react with exposed copper
in the presence of an electrolyte to form non-corrosive green copper
abietate.  We have occurrences of this from time to time and is an indicator
of incomplete cleaning.  Water-soluble fluxes, I understand, remain
corrosive and will continue in the presence of moisture.  In summary, do not
use them for any insulated wire soldering operation.  If residual WS flux
can't be completely removed, don't use it.

R. G. Blomberg
Honeywell –SASSO
Staff Production Engineer
(727) 539-5534 voice
727-539-4469 Fax
[log in to unmask]



-----Original Message-----
From: Miguel Vallejo [mailto:[log in to unmask]]
Sent: Saturday, November 06, 1999 2:57 AM
To: [log in to unmask]
Subject: [TN] Soldering Stranded Wires


Hi,
Is there a documented reference for recommended flux type for soldering
stranded wires?
Currently, we only use RMA or No-clean types. My understanding regarding
water soluble fluxes is that they are highly corrosive and that it's
difficult (if not impossible through a regular cleaning process) to
remove the flux from underneath the insulation. I'm trying to
substantiate this claim. Any help will be appreciated.

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