Indium Corporation Engineered Solder Materials Indalloy® Alloys Liquid at Room Temperature

Several low melting point Indalloy® alloys are liquid at room temperature. These gallium-based alloys are non-toxic replacements for mercury. The gallium-based alloys have far lower vapor pressure than mercury, reducing both the amount and toxicity of metal vapor exposure. Excellent Thermal and Electrical Conductivity Metals conduct heat and electricity with their valence electrons. This very effective conduction mechanism is a property of liquid as well as solid metals and alloys. Accordingly, liquid metals have thermal conductivity far superior to non-metallic liquids. Liquid metals are used in applications for dissipating concentrated heat loads such as thermal interfaces for microprocessors, reactors, and heat exchangers. Liquid gallium alloys are inherently high density and low viscosity (similar to that of water, <8 cP at room temperature1). As an electrically conductive metal, gallium alloys are used for mercury replacements in switches and contacts. Wetting to Metallic and Non-Metallic Surfaces These alloys will wet to most metallic and non-metallic surfaces. This wetting behavior and lubricity enable gallium alloys to serve as high temperature lubricants in journal bearings. However, gallium will attack (it alloys with) some metals, even at room temperature. At higher temperatures, gallium dissolves most metals although the refractory metals, particularly tungsten and tantalum, are resistant to this dissolution. Columbium, titanium, and molybdenum also have this resistance, but less than tungsten and tantalum.2,3 Structural materials such as steel, stainless steel, and nickel alloys can generally tolerate gallium service up to the 300– 500°C range. However, even at ambient temperatures, gallium is particularly aggressive in dissolving aluminum; care should be taken to avoid contact with aluminum components. Like indium, gallium and gallium alloys have the ability to wet to many non-metallic surfaces such as glass and quartz. Gently rubbing the gallium alloy onto the surface may help induce wetting.