Relay contacts are available in a variety of metals and alloys, sizes, and styles. When selecting electrical contacts, it’s important to consider the material, rating, and style to precisely match the requirements of a specific application. Failure to do so can lead to contact problems or even premature contact failure. Depending on the application, electrical contacts can be made using alloys such as palladium, platinum, gold, silver, silver nickel, and tungsten. Primarily, silver alloy compounds,  AgCdO, AgSnO, and AgInSnO, are widely used in general-purpose and power relays for medium- to high-current switching. AgInSnO contacts and silver tin oxide AgSnO contacts have emerged as promising alternatives to AgCdO contacts. In many regions of the world, the use of cadmium in contacts and batteries is restricted. Therefore, tin oxide contacts, which are approximately 15% harder than AgCdO (12) contacts, are a good alternative. Furthermore, AgInTnO contacts are suitable for high-surge loads, such as tungsten filament lamps, where the steady-state current is low. While more resistant to soldering, AgInSn contacts and AgSn contacts have higher volume resistance (lower conductivity) than Ag contacts and AgCdO contacts. Due to their soldering resistance, these contacts are very popular in the automotive industry, where 12VDC inductive loads often cause material transfer.

Pure silver contacts has the highest electrical and thermal conductivity of all metals, low contact resistance, and is inexpensive and widely used. However, its contacts tarnish due to sulfur.

Copper-silver contacts has better wear resistance and a lower tendency to weld, but its contact resistance is slightly higher.

Silver-cadmium contacts has a minimal tendency to weld, but offers excellent wear resistance and arc extinguishing properties. Silver-tungsten has high hardness and a melting point, offering excellent arc resistance. However, as it is not a precious metal, it requires high contact pressure, resulting in relatively high contact resistance and poor corrosion resistance.

Silver-nickel contacts has the same electrical conductivity as silver and excellent arc resistance.

Silver-palladium contacts offers low contact wear, a higher hardness, and a higher price.

Silver-copper contacts has excellent corrosion resistance and is primarily used in low-current circuits.