N Cook wrote:



You might find that a tool is already available which works for this
purpose. I'm thinking of the things for scraping the enamel off
transformer winding wi
http://www.buerklin.com/gruppen/KapL/L115880.asp

Chris

But those are RoHS compliant.

More to the point, for removing laquer , not hard tin , from round
surface.
Ok, it was just a thought. I was imagining the round pin of a T03 when I
thought of that.

I just tried a Skarstan blade , singly, in its normal wooden
handle and it scrapped the hard tin off some of the flat leads of the
latest batch of TIP35C/36C power trannies that I bought. Down to the
copper with no difficulty, I think I can ignore the tin-pest developinmg
on the narrow edges as long as the main surface contact areas are
functionally solderable.

Do you mean tin pest or whiskers? I would have thought that the edges would
be the worst place for whiskers to sprout from.

As for solderability, I would have thought that if the pins are exposed to a
sufficient quantity of sufficiently hot SnPb solder for a sufficient time,
then the tin would dissolve into the solder, like fine copper wire has an
annoying tendency to do. If overheating of the semiconductor device is a
risk, then perhaps it could be done in a couple of goes, allowing to cool
in between. The resulting tin-rich solder could either be removed and
replaced with fresh solder, or just diluted with more fresh solder.

I'm sure there would be plenty of people interested if you find a good
technique for small-scale use.

Chris