Mobile SIMcards are coated with Gold, why we cant use other metals or Alloys for conductivity.
I don't know for sure. My first instinct is that it's because gold can't corrode.
Also, it's conductivity is very high.
Silver is very conductive, but it oxidizes. Gold is more expensive, but you need very little of it when you're plating electronic contacts.
We can and do use other coatings. Palladium for instance is quite popular. It's just an issue of required properties (chemical, electric) vs price.
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