Avoid Mating Gold With Tin
May 8, 2006
Avoid mating connectors with different material for the pins. Mate tin-to-tin pins or gold-to-gold pins, but not tin to gold.
The reason for this is oxidation, wear at the connection surface, and the transfer of metal from one contact to the other, are all caused by a phenomenon called "fretting." A connection is subject to very small motions (fretting) caused by vibration or by expansion and contraction as temperatures vary. Tin reacts with oxygen easily to form a tin oxide film on the contact surface with the result that the electrical connection at the contacts starts to deteriorate as the contact resistance increases. The effect is somewhat ameliorated when tin mates to tin. The mechanical action of making the connection forms cracks in the oxide allowing the softer tin to show through. But with tin and gold it's a different story. As the connection is made, tin tends to transfer to the gold pins, and eventually form a tin oxide layer on the gold. Because the gold surface is harder than tin, the oxide coating is less likely to crack or rub off, and can build up fairly quickly. So, if you are having problems with audio or control connections, check the metallic makeup of the pins in the connectors. If you have tin mated with gold, try changing the connector with the gold pins to tin. It will at least be an improvement over tin to gold. Better yet, change both to connectors with gold pins.
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