Hi Folks,
We use a small solder pot with a nitrogen atmosphere to pre tin components. 
We are using Kester ultra pure 63/37 bar solder at 260C (500F) and tinning in 
the neighborhood of 500 components per month, then the solder is changed. 
The problem that we are seeing is some kind of contamination in the way of 
very small, fine, hairlike, polarized metal stuff.  Analysis of this stuff claims 
that it is copper or iron, but we can't get a real good sample to know exactly 
what it is. Kester has been sent samples and they have come back with 
nothing and I have had an outside lab, as well as our own look at this solder 
with nothing definitive as to what it is or where it comes from.  I have tried 
three different lots of solder and the problem continues to show up on  a 
random basis. Our tinning pot is obsolete and I can't go our and buy a new 
pot, so that option is not available.  Just wondering if anyone else has ran into 
this problem and possibly found a solution?

Thanks,
Jack Evans,
Aeroflex Colorado Springs

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