Indium plating

Indium is a metal similar to tin in many ways, such as color hue, corrosion resistance, and spreadability, and its melting point is as low as 157°C. As it is also the softest among metals, it is used to improve the lubricity of bearings and solderability of electronic parts.

Type of plating Features (characteristic value)
Indium plating - Excels in lubricity because it is softer than lead plating.
- Has good alkali resistance though it is sensitive to inorganic acids.
- Improves glass-metal bonding force due to high conformability to glass.
Indium alloy plating - The melting point of 52 indium-48 tin alloy is 117°C, while that of tin is 232°C.
- Indium-tin alloy plating or indium-lead alloy plating is obtained by heat treatment after indium plating on tin or lead by using the low melting point.

Adoption examples

Indium plating

Hardness comparison between plating films
and metallurgically prepared metals

(From “Kuromu Mekki”; Matsuhei Kishi, Nikkan Kogyo Shimbun Ltd.)