As the most commonly used control components in non-standard automation control, it is very important to understand relay contact materials and life span. Selecting relays with ideal contact materials and longer life span can reduce maintenance costs and lower equipment failure rates.

Electrical contacts are available in a wide range of metals and alloys, sizes and styles, and the selection of contacts needs to take into account the materials, ratings and styles in order to meet the requirements of a particular application as precisely as possible. Failure to do so may result in contact problems or even early contact failure.

Depending on the application, alloys such as palladium, platinum, gold, silver, silver-nickel, and tungsten can be used for contacting. Mainly silver alloy compounds, AgCdO and AgSnO, and AgInSnO are widely used in general purpose and power relays for medium to high current switching.

AgCdO has become very popular due to its excellent resistance to erosion and soldering as well as its very high electrical and thermal conductivity. AgCdO is produced by mixing silver and cadmium oxide using powder metallurgy techniques, and is a material that has electrical conductivity and contact resistance close to that of silver (using slightly higher contact pressures), but has excellent erosion and soldering due to the soldering resistance and arc quenching properties inherent in cadmium oxide. Resistance.

AgInSnO as well as AgSnO have become good alternatives to AgCdO contacts, and the use of cadmium in contacts and batteries is restricted in many parts of the world. Therefore, AgSnO2 (12), which are about 15% harder than AgCdO, are a good choice. In addition, AgSnO contacts are suitable for high surge loads, such as tungsten lamps, where the steady state current is low. Although more resistant to soldering, AgInSn and AgSn contacts have higher volume resistance (lower conductivity) than Ag and AgCdO contacts.

Due to their resistance to soldering, the above contacts are very popular in the automotive industry.