The Advantages of Silver Tin Oxide for Electrical Contacts

Posted by checon on August 30th, 2017

Pure silver has the highest electrical conductivity of all the metals, and it resists oxidation so you don’t have to worry about corrosion. While you would expect this to make it a highly desirable material for electrical contacts, pure silver electrical contacts also have some serious down sides. Silver gets soft at low temperatures, is susceptible to mechanical wear and reacts with sulphur compounds. The silver sulfide that forms as a result increases resistivity and can lead to permanent damage of the system. That’s why silver tin oxide is a better choice for electrical contacts.

All the Advantages of Silver

Tin, cadmium and zinc are all materials that can be combined with silver to form silver-metal oxides. This group of materials is one of the most popular for constructing contacts for low voltage devices and applications because they preserve the outstanding properties of pure silver. They still have very low contact resistance, which means they conduct nearly as well as silver. Welding, which is necessary to connect contacts, tends to increase resistance, but silver-metal oxides are less effected by welding than other materials that might be used to construct electrical contacts.

Without the Disadvantages of Silver

In addition to conducting nearly as well as silver, silver-metal oxides preforms even better in other ways. For example, they’re much stronger so they don’t wear down as easily as silver. They’re also more rigid and have higher melting points, so they don’t go soft as easily as pure silver. By combining silver with other metals, materials experts have created alternatives with all the positive attributes of silver without the negative ones.

Or the Disadvantages of Other Silver-Metal Oxides

While all the silver-metal oxides are an improvement over silver for the construction of electrical contacts, silver tin oxide has advantages over the others that have made it an industry favorite. For example, it has lower arc erosion and withstands the increased resistance due to welding even better than other silver-metal oxides. While silver cadmium oxide also preforms well, cadmium is highly toxic. By using tin instead, fewer workers are put at risk and the eventual release of cadmium into the environment can be avoided. 

If you need electrical contacts that give optimum performance at low voltages, are mechanically durable and completely non-toxic, silver tin oxide is the right material choice. It’s an industry favorite for a reason. You’ll get the low resistance you need from silver without the susceptibility to mechanical wear that pure silver is infamous for.