Indium metal will ‘adhere’ to itself at room temperature. Many materials will cold weld with enough force, but indium is unique in that it can bond to itself with very little pressure. In fact, higher purity oxide-free wire can be tricky to handle for just that reason – it bonds to itself with any amount of glancing contact. This property can make pure indium tricky to handle, but it can be utilized to create a metal bond without the heat that is necessary with traditional soldering. Check out my brief demo video by clicking on the photo above
With no heat source, a bond (which will remain solid up to 157°C) can be formed between two indium-coated parts. This bond will also endure cryogenic temperatures, which we will discuss in another post. If you are familiar with ultra-sonic welding, this is similar in that the bond is as strong as the base material when performed correctly. Luckily, cold welding with indium doesn’t require a specialized press with a frequency generator and amplifier – manual assembly can literally be done by hand.
How can you make this unique property work for you? You can use it to create a solder bond at room temperature. You will need to make sure the parts have indium applied to each substrate (plated, pre-soldered, sputtered, etc…), and make sure the indium surfaces are clean and oxide-free. Then simply press the two parts together. As stated before, bonding requires very little pressure, and can affect a very strong bond. If you need help with this, contact our team of Application Engineers.
This post is part of the “6 Strange Properties of Indium” series.