[volt-nuts] cadmium solder alloy for low thermal emf?

[Andy Bardagjy]

Ah, that email left the gate before it was ready.

Indium still does make Cd bearing solders, just not pastes.

Andy Bardagjy
bardagjy.com


On Thu, May 30, 2013 at 12:51 PM, Andy Bardagjy <andy at bardagjy.com> wrote:

> A few months ago I send Indium an email inquiring about low thermal EMF
> solders. A good choice is Sn10Pb90, or Indalloy 159.
>
> Andy Bardagjy
> bardagjy.com
>
>
> On Thu, May 30, 2013 at 5:05 AM, Andreas Jahn <Andreas_-_Jahn at t-online.de>wrote:
>
>>
>> Hello
>>
>>
>>  I do not imagine cadmium bearing solder being easy to acquire.  The
>>> Wikipedia entry for solder says Pb90Sn10 can be used as a replacement
>>> for Cd70Sn30 in low thermal EMF applications:
>>>
>>> http://en.wikipedia.org/wiki/**Solder<http://en.wikipedia.org/wiki/Solder>
>>>
>>> On Thu, 30 May 2013 04:00:19 +0200, Volker Esper <ailer2 at t-online.de>
>>> wrote:
>>>
>>>
>>>> By the way: does anyone know, if Agilent uses special solder alloy? I've
>>>> heard that a cadmium containing solder is used to get extremely low
>>>> thermoelectric voltages (or voltage differences).
>>>>
>>>> Is that right? If so, which alloy has to be used?
>>>>
>>>> Thanks
>>>>
>>>> Volker
>>>>
>>>>
>> Within LT AN86 Cd60Sn40 is recommended for a limited temperature range of
>> 0 to around 40 degrees.
>> http://cds.linear.com/docs/en/**application-note/an86f.pdf<http://cds.linear.com/docs/en/application-note/an86f.pdf>
>>
>> But: the thermal EMF is only zero against copper.
>> Most precision integrated (hermetical) cirquits use Kovar. (39uV/K
>> against copper)
>> Relay contacts will be either copper berillium or another material.
>> So in most cases a optimized solder for copper/copper connections will
>> not be useful.
>>
>> On the other side Cd containing solders create very poisonous damps when
>> being heated.
>>
>> With best regards
>>
>> Andreas
>>
>>
>>
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>
>