Hi Ed - based on the details you provided, here is what I believe is
happening - Many of the OA type fluxes contain a significant chlorine
content and also consider you have a potential fluorine contribution from
the flux interacting with the PTFE insulation. Copper loves to react with
both Cl and F with the reaction producing a corrosion product that has a
characteristic blue/green optical appearance. The corrosion product can be
identified by its unique crystal structure using XRD techniques. It appears
you are dealing with a case of poor cleaning as there is flux being trapped
under the insulation and it is causing a corrosion reaction. One method of
avoiding this issue is to carefully apply the flux to the stripped wire in
such a manner as the flux does not contact the wired/non-stripped
insulation interface. The best way to clean this is to not allow it to
happen during the initial processing - trying to get that interface clean
is difficult and hard to confirm "clean".

Dave Hillman
Rockwell Collins
[log in to unmask]

On Fri, Nov 3, 2017 at 10:39 AM, Ed Popielarski <[log in to unmask]>
wrote:

> Hi Technetters,
>
> I have 2 questions:
>
> 1: How is this oxide formed?
> 2: is there a "safe" way to clean it after the fact?
>
> On very rare occasion, we have a "verdigris" outbreak on Tin plated solid
> Cu wire. The insulation tends to not be well adhered (PTFE) when this
> "breaks out" The stripped wire looks "normal" but when soldered with OA
> flux (either hand or wave) it starts showing a blue-green oxidation at the
> insulation/wire interface. Wetting is marginal at best. Scrapping the wire
> and going to a different manufacturer usually resolves it, but there's
> still labor involved since it doesn't show up until later in the process &
> must be reworked.
>
> Thanks in advance!
>
> Regards,
>
> Ed Popielarski
> Engineering Manager
>
> [cid:[log in to unmask]]
>                                970 NE 21st Ct.
>                               Oak Harbor, Wa. 98277
>
>                               Ph: 360-675-1322
>                               Fx: 206-624-0695
>                               Cl: 360-544-2289
>
>
>
>        "It's one kind of victory to slay a beast, move a mountain, and
> cross a chasm, but it's another kind altogether to realize that the beast,
> the mountain, and the chasm were of your own design."
> https://goo.gl/maps/mMjg43rXeFB2
>