Hi Jack: A couple of questions.
1. What is the capacity of the solderpot?
2. What is the flux being used?
3. What is the material the pot is made of? 
4. Does the problem show up on a new pot charge or does it require time
to develop if so how long?
5. What is your definition of "polarized metal stuff"? Are you saying
magnetic or are we getting into dipole moments and ligand field theory?

	
Regards
	
Michael Barmuta
	
Staff Engineer
	
Fluke Corp.
	
Everett WA
	
425-446-6076

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Jack Evans
Sent: Wednesday, March 21, 2007 8:57 AM
To: [log in to unmask]
Subject: [TN] Whisker contamination is solder pot

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 Our tinning pot is obsolete and I can't go our and buy a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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