Metallic indium features unique physical and chemical properties: low melting point (~156.6°C), excellent softness and ductility, plus the capability to wet non-metallic surfaces such as glass and ceramics.

Indium-based bonding wires are generally alloys of indium with tin, silver, lead and other metals, engineered to achieve lower melting points or higher mechanical strength. They address challenges that conventional medium and high-temperature solders cannot resolve:

• Soldering temperature-sensitive components: 

Suitable for parts that cannot withstand high temperatures from traditional reflow soldering, such as molded MEMS sensors and GaAs detectors. For example, eutectic In52/Sn48 alloy has a melting point of only 118°C, ideal for this type of precision bonding.

• Bonding non-metallic materials: 

Pure indium (In100) and selected indium alloys can effectively wet glass, ceramics, quartz and other surfaces for hermetic sealing or bonding of optical components.

• Joining assemblies with mismatched thermal expansion coefficients: 

When joining two materials with vastly different thermal expansion rates (e.g. metal to ceramic), indium solder cushions stress thanks to its softness and prevents solder joint cracking.

• Step soldering processes: 

In multi-step assembly processes, low-melting indium solders will not disturb pre-existing medium/high-temperature solder joints.

• Vacuum devices: 

Used in packaging of electro-vacuum components and semiconductor lasers, leveraging its low vapor pressure and excellent hermeticity.

• Aerospace & defense: 

In-Pb solders offer superior fatigue resistance and low-temperature toughness. They are adopted in aerospace and military products, and reduce gold embrittlement especially when soldering gold-plated substrates.

• Cryogenic environments: 

Pure indium wire remains soft under cryogenic conditions, suitable for sealing and interconnection in extreme low-temperature applications. 

With low melting temperature and flexible characteristics, indium-based solders play an irreplaceable role in high-end manufacturing sectors including precision electronics, optoelectronics and aerospace.

Performance Features 

• Low melting point, outstanding softness and ductility

• High purity, low impurity content

• Minimal oxidation, bright and full solder joints

• High alloy density

Product Information 

Contact our engineers for other indium-containing alloy grades.