Indium Plating

Q: We are interested in learning more about indium plating. Can you give me some information and references on this process? S. E.

A: Indium is a very soft silver colored metal with a melting point of 311°F. An early important application of this material was developed during the Second World War. A layer of indium over an electroplated silver-lead alloy made an extremely fine bearing for certain types of airplane engine parts. Today indium is used in a number of other applications particularly in the electronics area.

Indium can be plated from cyanide, sulfate, sulfamate and fluoborate baths. The sulfamate bath is probably the most commonly used bath. There are a number of sources of information on this interesting plating bath. The Metal Finishing 2005 Guidebook & Directory, Metal Finishing Publications, www.metalfinishing.com has a brief section on the process. You can also find information on indium plating at the Indium Corp. web site, www.indium.com. Search this site using the term “electroplating.”