Steve if a tin plated surface is showing pink copper after soldering
it suggests that the copper is unsolderable, strictly  the plating is
not leaching but simply dewetting off the wire and dissolving into the
surrounding solder.
It is possible to plate a surface which is unsolderable. You could
probably verify this by blowing hot air onto the wire, wrapping a
piece onto the barrel of your iron or otherwise heating it without
adding solder and watching what happens.

This makes for a difficult problem, it might be possible to do some
type of pre-dipping using a more persistent flux cleaning and then
assembling, if you are using a rapidly dissipating no clean this could
be dispersed before it has had a chance to get the tin to wet the poor
surface. Alternatively a more active flux and then cleaning but this
is fraught with risk especially if you are using sleeved or multi
stranded wire where you are likely to get capillary of materials into
undesirable areas.  As a rule/guide you should have a least 1/8" inch
of original surface showing before sleeving.

Alternative fix would be for you to try  removing the tin mechanically
using fine grit "wet and Dry" abrasive paper. You used to be able get
special  tweezers - looked more like tongs with abrasive pads - for
dressing wires prior to hand soldering. Maybe you still can.

Mike

----- Original Message -----
From: "Stephen R. Gregory" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, December 12, 2000 12:32 AM
Subject: [TN] Tin Plate Leaching...


> Hey ya'll,
>
> I'm wondering if any of you have ever had a problem with pure tin
plating
> over copper (Tin plated buss wire specifically), leaching from the
copper and
> leaving it exposed? This is from hand-soldering operations...just
> wondering....what did you do to resolve the problem?
>
> -Steve Gregory-
>
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