In a message dated 5/29/99 5:26:06 AM Central Daylight Time,
[log in to unmask] writes:

Hello Brian

Could you tell us the type of cored solder that was used and was any VOC free
low solids flux used to help soldering.  I have seen were unreacted flux of
this type attached the solder joint and opened the circuit.  (these fluxes
are very good at soldering and leaving a benign residue (no clean) if
properly activated per the mfg's thermal requirements).

The second question that comes to mind would be is there any cleaning
solution used on this wire solder joint and if so what was the method of
cleaning.  Because if water soluble flux is used and cleaned with water or
one of the bench top cleaners then the residues that were left behind would
be capable of this corrosive attack.

Interesting Opportunity to learn

Terry Munson
CSL Inc.
765-457-8095

<< Hi Netters
 I've had an incident where two fine wires twisted and soldered together in a
transformer assembly have gone open circuit. When the assembly is stripped
down the twisted wires appear to have a residual solder coverage but
insufficient to provide a proper solder joint. there is also a light powdery
residue all over. It's as if the wires were soldered OK originally and some
chemical reaction has stripped the majority of the solder away and left a
corrosion product. The joint is within a sealed assembly, is covered locally
in a protective tape and the transformer is impregnated before wiring. Does
anyone have any history or knowledge of any reaction between transformer
varnish and solder? I appear to remember some problems with phenolic fumes
attacking metals however I've never seen solder attacked in this way. Perhaps
David Copperfield's been in town !!
 Any feedback appreciated.
 Bryan Kerr
 Alenia Marconi Scotland
  >>

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