Connector Finishes: Tin in Place of Gold

Gold has been the natural choice as a contact material for low-voltage circuits (dry circuits) because of its properties and characteristics. In addition to having low electrical resistivity, it is not attacked by most chemicals and does not form surface oxides and sulphides so that good electrical contact is made with minimal force, even at low voltages. The rapidly escalating price of gold has motivated the investigation of less costly connector finishes. Some of these developments are reviewed. In particular, tin and its alloys form thin oxide films which may be easily broken, so that low-resistance metal-to-metal contact can be established with the underlying tin base. Changes in connector design are aiding the development of new contact materials.