Responding to Thomas Tindale's request for information about tin-tin vs.
tin-goldcontacts.  Some years back, I was working on a project that involved
putting some ceramic IC quad packs in sockets, pairing tin with gold
contacts.  A fellow I considered a contact expert told me gold to gold was
best, but the fact that half the contact was gold made it better than tin to
tin.  I was shocked when, much later, I learned that gold to tin was inferior
to a tin to tin contact.  Sorry I don't have more details or references, but
this experience did make an impression on me.

Louis Hart