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-----Solutions to Problems with de-wetting while "Tin / lead" dipping Alumel and Chromel contact pins
November 3, 2009
Hi
I am trying to tin / lead (63/37) dip 3 types of contact (later to be fitted to a connector) The portion of the contact to be dipped is
0.215" with a diameter of 0.033"
1. Gold plated - As you would expect no problems here !
2. Alumel - 95% Nickel, 5 % Aluminium - de-wetting of up to 50%
3. Chromel - 90% Nickel, 10 % Chromium - de-wetting of up to 50%
We have plated both 2 and 3 with a copper flash (120 ± 30 micro inches) and found an improvement but it still isn't by any means a perfect process with about 50% success
In addition my main concern is that of course I must not change the thermocouple properties of these contacts (2 and 3)
Related questions !
I now have a large box of contacts which I can not use is, can any one recommend a way of removing the tin / lead and copper flash with out any damage to the base material ?
Does any one know of a method to plate these contacts as opposed to hand dipping them ?
Is copper the best plating to use prior to the dip ?
product designer - London, UK
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