Well, here's my two cents.  To answer your question - Yes.
          
          ANY dissimilarity of metals will cause some degree of 
          corrosion through the difference of electronegativity.  
          You can't get away from it.  There's another thing that 
          happens, more exotic, based on Fick's Law for the physical 
          migration of one metal into another in a way similar to the 
          way two gases mix.  Alright.  Big deal.  So what?
          
          1.  Any electronegativity of elements chart will show
              0.6 volts for Nickel and Gold.  Nickel is the more 
              anodic and gold is the more cathodic.
          
          2.  There are two kinds of compatibility of metals charts 
              that I've found.  
          
              One type used by UL places an upper limit of 0.6 volts
              electronegativity between dissimilar metal combinations.
              The rule for this type of chart is "stay with a 
              combination equal to or less than 0.6 volts."
          
              Another, places the dissimilar metals into groups.
              The groups divide the various metals by allowing no more 
              than 0.25 volts as the upper limit in difference with 
              electronegativity.  The rule for this chart is "stay 
              within the group."
          
              Unfortunately, the UL chart based on 0.6 volts says that 
              it's OK to mix nickel and gold.  The other chart that 
              groups the metals says that it's NOT.
          
          I would suggest avoiding it.  I'm sure alot of other people 
          have good input on this.


______________________________ Reply Separator _________________________________
Subject: assy:compatibility gold vs. tin/lead
Author:  [log in to unmask] at internet-mail
Date:    5/22/96 11:12 AM


          
We have instances where tin/lead coated pins are inserted into gold plated 
sockets, etc.  Components even have gold/tin-lead or gold/tin interfaces, 
such as an IC socket with a gold contact with a tin sleeve.  Mil-Std-889B 
indicates gold as being incompatible with tin or tin/lead.  Has anyone 
looked into this issue and is there a potential for corrosion formation and 
associated problems?  Again, I just referring to mechanical contact ( not 
soldering ).
          
Thanks,
Jack Tippit
Wilcox Electric
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