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InSn Alloy
Indium-Tin (InSn) Alloy
The low‐melting, high‐reliability solder alloy for advanced electronics and cryogenic applications.
Indium-Tin eutectic alloy is a lead‐free solder known for its extremely low melting point (~120°C) and excellent ductility. It’s widely used in applications requiring low-temperature bonding, flexible electronics, and even cryogenic sensors.
| Property | Value | Notes |
|---|---|---|
| Composition | In ~52%, Sn ~48% | Eutectic ratio for optimal low-temperature performance |
| Melting Point | ~120°C | Significantly lower than most traditional solders |
| Electrical Resistivity | ~80 µΩ·cm | Higher than common Pb- or SAC-based solders |
| Thermal Conductivity | ~25 W/m·K | Facilitates efficient heat dissipation |
| Mechanical Strength | ~7 MPa | Lower strength due to high ductility |
Conceptual 3D Microstructure
Simplified 3D model representing alternating layers of indium and tin in a eutectic microstructure.
Applications
Low-Temperature Soldering
Ideal for applications where heat damage must be minimized.
Flexible Electronics
Its ductility makes it perfect for bendable and wearable devices.
Cryogenic Sensors
Reliable performance even at extremely low temperatures.
High-Reliability Interconnects
Used in critical applications where low processing temperatures are key.
Element Breakdown
Symbol: In
Atomic Number: 49
Key Role in InSn: Provides ductility and a low melting point.
Fun Fact: Indium is one of the few metals that is soft enough to be cut with a knife and is used in touchscreens and LCDs.
Symbol: Sn
Atomic Number: 50
Key Role in InSn: Imparts excellent wetting properties essential for soldering.
Fun Fact: Tin has been used in alloys since ancient times and remains vital in modern solder technology.
Performance Comparison: Melting Point
Comparison of melting points among common solder alloys. Notice how InSn’s low melting point enables low-temperature processing.
Advantages Over Traditional Solders
| Property | 63Pb/37Sn (Lead-Based) | SAC (Lead-Free) | InSn Eutectic |
|---|---|---|---|
| Melting Point (°C) | 183 | 217 | 120 |
| Tensile Strength (MPa) | 26 | 40 | 7 |
| Electrical Resistivity (µΩ·cm) | 20 | 15 | 80 |
| Thermal Conductivity (W/m·K) | 35 | 60 | 25 |
| CTE (×10⁻⁶/K) | 25 | 22 | 35 |
Manufacturing & Production
InSn alloy is produced by melting high-purity indium and tin in the eutectic ratio. Its low melting temperature not only saves energy but also requires precise temperature control. The alloy is typically cast into wires, foils, or solder pastes used in advanced electronics.
Safety & Handling
- Solid InSn alloy is non-toxic; however, molten alloy must be handled with care to avoid burns.
- Indium is a scarce resource; recycling is recommended.
- Standard soldering safety protocols should be followed during processing.