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InBi Alloy
Indium-Bismuth (InBi) Alloy
A low-temperature solder alloy combining indium and bismuth for delicate electronic applications.
The InBi alloy is designed for applications where an ultra-low melting point and minimal thermal stress are essential. Typically composed of approximately 66% indium and 34% bismuth, it exhibits a melting point of around 72°C, with moderate electrical resistivity and thermal conductivity that make it ideal for cryogenic soldering, flexible electronics, and advanced packaging.
| Property | Value | Notes |
|---|---|---|
| Composition | In ~66%, Bi ~34% | Binary eutectic ratio for ultra-low melting performance |
| Melting Point | ~72°C | Ideal for temperature-sensitive assemblies |
| Electrical Resistivity | ~40 µΩ·cm | Balanced conductivity for precision applications |
| Thermal Conductivity | ~25 W/m·K | Facilitates efficient heat dissipation |
| Mechanical Strength | ~5 MPa | Lower strength reflecting high ductility |
Conceptual 3D Microstructure
A simplified 3D model representing alternating eutectic layers of indium and bismuth.
Applications
Ultra-Low Temp Soldering
Minimizes thermal stress on delicate substrates.
Flexible Electronics
Ideal for bendable devices and wearables.
Cryogenic Sensors
Provides reliable performance at extremely low temperatures.
Advanced Packaging
Supports high-density assembly with minimal thermal impact.
Element Breakdown
Symbol: In
Atomic Number: 49
Key Role in InBi: Provides ductility and lowers the melting point.
Fun Fact: Indium is critical for forming reliable low-temp solder joints.
Symbol: Bi
Atomic Number: 83
Key Role in InBi: Enhances fluidity and further reduces the melting point.
Fun Fact: Bismuth contributes unique low-temp properties to the alloy.
Performance Comparison: Melting Point
Comparison of melting points among popular solder alloys. The InBi alloy's ~72°C melting point is ideal for ultra-low temperature processing.
Advantages Over Traditional Solders
| Property | 63Pb/37Sn (Lead-Based) | SAC (Lead-Free) | InPb | InBi Alloy |
|---|---|---|---|---|
| Melting Point (°C) | 183 | 217 | 125 | 72 |
| Electrical Resistivity (µΩ·cm) | 20 | 15 | 30 | 40 |
| Thermal Conductivity (W/m·K) | 35 | 60 | 40 | 25 |
| Mechanical Strength (MPa) | 26 | 40 | 6 | 5 |
Manufacturing & Production
The InBi alloy is produced by melting high-purity indium and bismuth under controlled conditions to achieve the eutectic composition. Its ultra-low melting point reduces energy usage and thermal stress during soldering, making it ideal for precision, low-temp applications.
Safety & Handling
- Molten InBi must be handled with proper protective gear to avoid burns.
- Work in well-ventilated areas and follow environmental guidelines for bismuth.
- Recycle materials responsibly due to the scarcity of indium.