Dip the end of the wire into a small amount of methylene chloride until 
the enamel softens or crazes. Then gently wipe with a clean cotton cloth.

Warning! Methylene chloride is toxic and very volatile; make sure you do 
not breathe it in and keep the bottle well stoppered.

In a former life, it was possible to obtain commercial wire strippers 
based on methylene chloride, often in the form of a gel. I have no idea 
whether these are still available but some of them were remarkably 
effective.

Brian

On 17/07/2014 20:46, Steve Gregory wrote:
> Hi All!
>
> I'm trying to deal with all the smoke that's here in Boise today, it's
> probably the worst smoke I've ever been in. The jet stream has made a dip
> and is carrying all the smoke from the fires in Washington, Oregon, and the
> fire north of us in Boise county right into the Treasure Valley and it's
> all packing up against the mountains to the west of us (cough, cough..)
>
> Anyways, I have a question about a little custom inductor from Vishay Hirel
> that we have here. It appears that we have a certain datecode batch of
> these where the insulation on the part of the wire that gets soldered into
> the board wasn't stripped and tinned high enough, and now when we try to
> install them into the board the insulation prevents wetting at the top of
> the board and we have insulation in the solder joint which of course is a
> defect:
>
> http://stevezeva.homestead.com/Vishay_Inductor.jpg
>
> The picture is of one that we pulled out of a board, and you can see that
> the insulation goes down past the shoulders and into what is supposed to be
> the solderable area.
>
> I think I know the answer to my next question, but I'll ask it anyway. Is
> there any clever way to remove that insulation without damaging the
> inductor? The picture makes this inductor look huge, but it's not, it's
> maybe .250" in diameter, and the wire is a pretty small gage too.
>
> I tried dipping it first in a lead-free tinning pot set at 600 C., no luck,
> then 700 C., no luck, then 800 C., and no luck. I was able to darken the
> insulation and melt the yellow tape that wraps the inductor, but that's
> about it. I'm think that the only way to remove this insulation is
> mechanically...which will be a trick because the inductor and wire is
> pretty small.
>
> Hate to scrap these things because they are long lead custom inductors. But
> we can't use them like they are....
>
> Steve
>

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