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A little off subject?

So it is very interesting how lead can be good and bad additions to alloys.? ?My primary field is electronics and back in the 40's engineers found out that if you add lead to tin in solder it reduced the melting point, and if the ratio was 37:63 there was the perfect match and solid-liquid occurred at the same temperature (eutectic point).? ?Since my specialty was legacy electronics, I was the one to chase whiskers.? ?
So now lead is bad and the powers that be decided to remove lead from solder, Reduction Of Hazardous Substances (RoHS).??

Now a whole new problem arises Tin Whiskers, so here the story takes a twist.? ?In the 30's whiskers were an issue because things were plated in tin, and pure tin has whisker growth.? ?NASA found out that not only tin but zinc, gold and silver also grew whiskers.? This is an issue because the growths are small wires a few atoms wide that cause short circuits.? ?Spacecraft have had issues, control systems in power plants, had issues and since the introduction of Rohs internationally issues are starting to show up.? ?Some whiskers need a microscope to see but others are quite visible to the naked eye.? ?I have seen whiskers 1/2" long about 2 thous in diameter.? ?If looking at pure tin and you see a white "mold" those are whiskers.? ?They grow from the base metal one atom at a time.? ?Google tin whiskers and go to the NASA website.? ?So if you have electronics that operate strangely you may need to shave.? ?

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