Indium is an element that is listed in the periodic table with 49 as its atomic number, and has the symbol ‘IN’. The element itself is classified as rare and is not easily found in the crust of the Earth. Indium is a soft metal that is very malleable. It is also quite fusible. Its melting point is much greater than that of sodium, but remains lower than tin or other elements such as lithium. The chemical properties of indium are quite similar to other elements such as thallium and gallium. In fact, indium can easily be interchanged with these two elements, if you only consider their chemical properties.
Physically, indium has a silvery-white appearance. It is quite malleable and ductile, thus allowing it to be turned into different shapes quite easily. Just like sodium, indium is one of the softest metals available. In fact, it is so soft that you can simply take a knife and cut through it. Because it is so ductile and malleable, indium is used in a variety of different applications.
Indium was initially used for coating ball bearings. The element rose to popularity during World War II and was mainly used for covering the bearings that were used in the aircraft engines. After the war had ended, new uses were found for this element, thus causing an increase in production. Indium is currently used in soldering and many different types of electronics items. The indium bonding process is also generally used to infuse indium with other metals, creating rare earth alloys.
Currently, indium is most popularly used in light-emitting diodes and laser emitting diodes. It is also used as a direct substitute for mercury in standard alkaline batteries. Indium prevents the zinc in the battery from corroding. If the zinc corrodes, it releases hydrogen gas.
Indium bonding is also used most popularly in sputtering target bonding applications. The process is carried out at a temperature of 170 degrees Celsius and is regarded as a soldering process. Compared to other available bonds, the reason indium bonding is widely preferred is mainly because of its thermal conductivity. Indium is extremely efficient when it comes to removing heat from a target.
Compared to other bonding solders, indium is also highly malleable. This significantly reduces the risk of cracking, which can occur due to a mismatch between coefficients of thermal expansion of the backing plate and the target itself. This is a highly advanced process that is carried out by companies that have high powered machinery.