[time-nuts] HP 5370B low frequency modulation

Dr Bruce Griffiths bruce.griffiths at xtra.co.nz
Mon Jul 23 10:28:57 EDT 2007

Brooke Clarke wrote:
> ); SAEximRunCond expanded to false
> Errors-To: time-nuts-bounces+bruce.griffiths=xtra.co.nz+bruce.griffiths=xtra.co.nz at febo.com
> Hi Didier:
> Would you elaborate on the comment "Gold plated connectors are a well known 
> example."  Do you mean when soldered with Lead Tin solder instead of a silver 
> bearing solder or something else?
> Have Fun,
> Brooke Clarke
> http://www.PRC68.com
> http://www.precisionclock.com
> Didier Juges wrote:
>> ); SAEximRunCond expanded to false
>> Errors-To: time-nuts-bounces+brooke=pacific.net+brooke=pacific.net at febo.com
>> I have seen cold solder joints on thermal fuses and certain types of
>> capacitors, while the rest of the instrument was fine with no sign of
>> corrosion.
>> I think it has to do with the metal used for certain component leads. Either
>> they were never soldered well, or interface corrosion developed over time.
>> Gold plated connectors are a well known example.
>> Didier KO4BB

Gold dissolves in the solder and a gold -tin intermetallic compound is 
formed which severely reduces the joint integrity and ductility.
This can be circumvented by keeping the gold concentration in the solder 
below 4%. Tin plating over the gold before soldering is sometimes used 
to ensure this.


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