[volt-nuts] Low thermal EMF solder

Bruce Griffiths bruce.griffiths at xtra.co.nz
Fri Dec 18 03:18:15 UTC 2009


Mark Sims wrote:
> Bruce,
>
> The Cd:Sn eutectic point is at 30:70,   but the magic low thermal emf foo powers seem to happen in the 60:40 to 70:30 range...  at least that is what all the references that I have found say. 		 	   		
>    
According to an article in  J Sci Instruments thermal emf against copper 
is about 300nV/C for the eutectic.

If you read Russian the following article from 1956 covers a wide range 
of Cd Sn solder compositions and temperatures:
http://www.springerlink.com/content/wj11xr8737770103/fulltext.pdf?page=1

http://books.google.co.nz/books?id=dunqt1rt4sAC&pg=PA266&lpg=PA266&dq=cadmium+tin+thermal+emf&source=bl&ots=oUwLjlaFW5&sig=khJZ0LAoiemkoNL6nuLpV8vKFws&hl=en&ei=9e8qS9m3LZGGswOtzLXWAw&sa=X&oi=book_result&ct=result&resnum=6&ved=0CCAQ6AEwBQ#v=onepage&q=cadmium%20tin%20thermal%20emf&f=false 
<http://books.google.co.nz/books?id=dunqt1rt4sAC&pg=PA266&lpg=PA266&dq=cadmium+tin+thermal+emf&source=bl&ots=oUwLjlaFW5&sig=khJZ0LAoiemkoNL6nuLpV8vKFws&hl=en&ei=9e8qS9m3LZGGswOtzLXWAw&sa=X&oi=book_result&ct=result&resnum=6&ved=0CCAQ6AEwBQ#v=onepage&q=cadmium%20tin%20thermal%20emf&f=false>
suggests a low Sn lead tin solder (Sn:Pb 10:90)

http://www.iop.org/EJ/abstract/0022-3735/9/12/029
Suggest a minimum in the thermoemf at about 18% tin.
See the Czech article for the theoretical basis.

Bruce




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