[volt-nuts] Low thermal EMF solder

[Mark Sims]

I am in the process of making some low thermal EMF cadmium-tin solder. This material has not been manufactured in a very long time and is pretty much unobtainable these days (despite it being listed as the product of several companies in India). It gives the safety geeks apoplectic fits at the mere mention of the first syllable of "cadmium"...

I have seen references to 60:40 solder and 70:30 Cd:Sn solder. At one time I saw a table that showed the characteristics of a few type of Cd:Sn solders, but have been unable to locate it. Does anybody have any references to the properties of Cd:Sn solders?
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[Bruce Griffiths]

Post by Mark Sims
I am in the process of making some low thermal EMF cadmium-tin solder. This material has not been manufactured in a very long time and is pretty much unobtainable these days (despite it being listed as the product of several companies in India). It gives the safety geeks apoplectic fits at the mere mention of the first syllable of "cadmium"...
I have seen references to 60:40 solder and 70:30 Cd:Sn solder. At one time I saw a table that showed the characteristics of a few type of Cd:Sn solders, but have been unable to locate it. Does anybody have any references to the properties of Cd:Sn solders?

The cadmium tin eutectic has low thermal emf and a 30:70 Cd:Sn composition.
For some micophtographs of the structure of the solid eutectic:
http://www.aimehq.org/search/docs/Volume%20071/071-48.pdf

Bruce

[Bruce Griffiths]

Post by Bruce Griffiths

Post by Mark Sims
I am in the process of making some low thermal EMF cadmium-tin
solder. This material has not been manufactured in a very long time
and is pretty much unobtainable these days (despite it being listed
as the product of several companies in India). It gives the safety
geeks apoplectic fits at the mere mention of the first syllable of
"cadmium"...
I have seen references to 60:40 solder and 70:30 Cd:Sn solder. At
one time I saw a table that showed the characteristics of a few type
of Cd:Sn solders, but have been unable to locate it. Does anybody
have any references to the properties of Cd:Sn solders?

The cadmium tin eutectic has low thermal emf and a 30:70 Cd:Sn
composition.
http://www.aimehq.org/search/docs/Volume%20071/071-48.pdf
Bruce

For a plot of the melting point vs composition see:
http://resources.metapress.com/pdf-preview.axd?code=hu72j65756220274&size=largest
<http://resources.metapress.com/pdf-preview.axd?code=hu72j65756220274&size=largest>

Which establishes that the eutectic has an approximate composition of
30:70 Cd:Sn.

For the full article on the Cadmium tin system:
http://www.springerlink.com/content/hu72j65756220274/

Bruce

[Mark Sims]

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.
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[Bruce Griffiths]

Post by Mark Sims
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

[Alan Scrimgeour]

There's some seriosly nutty volt work going on at this Chinese forum.

http://bbs.38hot.net/

Unfortunately the Google and Babel translations aren't much better than gibberish:
http://uk.babelfish.yahoo.com/translate_url?doit=done&tt=url&intl=1&fr=bf-home&trurl=http%3A%2F%2Fbbs.38hot.net%2F&lp=zh_en&btnTrUrl=Translate


I wish it was in English.




There's incredible looking work here with the LTZ1000:
http://bbs.38hot.net/read.php?tid=1276
Translated:
http://translate.google.com/translate?u=http%3A%2F%2Fbbs.38hot.net%2Fread.php%3Ftid%3D1276&sl=zh-CN&tl=en&hl=&ie=UTF-8


Here someone does a top ten precision resistors chart (I think).
Check out the dismantled counterfeit precision resistors near the bottom. Unbelievable:
http://66.196.80.202/babelfish/translate_url_content?.intl=uk&lp=zh_en&trurl=http%3a%2f%2fbbs.38hot.net%2fread.php%3ftid%3d291


Alan