Grade B Tin is a high-purity refined tin with a minimum tin content of 99.95%. It is widely used where excellent chemical cleanliness, good electrical performance, and reliable processing are required—without the cost of ultra-high-purity tin.
General Information
| Property | Value |
|---|---|
| Purity | ≥ 99.95% Sn |
| Allotropic Form | β-Tin (White Tin) |
| Crystal Structure | Body-Centered Tetragonal (BCT) |
| Mechanical Strength | Very low |
Applicable Standards
| Standard | Designation |
|---|---|
| ASTM | B339 |
| ISO | 21948 |
| EN | 610 |
| JIS | H2108 |
Chemical Composition (Typical Limits)
| Element | Max Content (%) |
|---|---|
| Tin (Sn) | ≥ 99.95 |
| Lead (Pb) | ≤ 0.02 |
| Copper (Cu) | ≤ 0.02 |
| Iron (Fe) | ≤ 0.01 |
| Antimony (Sb) | ≤ 0.01 |
| Bismuth (Bi) | ≤ 0.005 |
| Arsenic (As) | ≤ 0.005 |
Mechanical Properties
| Property | Typical Value |
|---|---|
| Tensile Strength | 15 – 22 MPa |
| Yield Strength | Very low |
| Elongation | 35 – 45% |
| Hardness | ~6 – 8 HV |
| Ductility | Excellent |
| Creep Resistance | Low – Moderate |
Physical Properties
| Property | Value |
|---|---|
| Density | 7.31 g/cm³ |
| Melting Point | 231.9 °C |
| Electrical Conductivity | ~14 – 15% IACS |
| Thermal Conductivity | ~65 – 66 W/m·K |
| Magnetic Behavior | Diamagnetic |
| Appearance | Bright silvery-white |
Strengthening & Metallurgical Behavior
Grade B Tin is not heat treatable. Its slightly improved dimensional stability compared to Grade A tin comes from mild solid-solution strengthening due to trace impurities and limited work hardening.
Compared to ultra-pure tin, Grade B exhibits lower tin-whisker risk and better service stability in coatings and solder applications.
Key Characteristics
✔ High purity with improved stability
✔ Excellent solderability and wetting
✔ Good corrosion resistance
✔ Reduced whisker formation vs ultra-pure tin
✔ Cost-effective alternative to Grade A
❌ Not suitable for structural applications
❌ Still soft and creep-prone
Refining & Processing Properties
| Process | Performance |
|---|---|
| Melting | Excellent |
| Casting | Excellent |
| Rolling / Foil | Very good |
| Machining | Poor (too soft) |
| Solder Compatibility | Excellent |
Available Forms
Tin ingots / pigs
Tin bars
Granules / shots
Tin wire
Tin anodes (plating)
Alloy feedstock
Applications of Grade B Tin
Electronics & Electrical
Lead-free solder alloys
Electroplating anodes
Electrical coatings
Industrial & Manufacturing
Tinplate production
Chemical containers
Float glass bath maintenance
Metallurgy
Alloy master metal
Precision casting alloys
Advantages
✔ Optimal purity–cost balance
✔ Excellent processability
✔ Reduced tin-whisker risk
✔ Widely accepted in regulated industries
Limitations
❌ Lower purity than Grade A
❌ Not for ultra-critical semiconductor use
❌ Soft mechanical behavior
Grade Comparison
| Feature | Grade B (99.95%) | Grade A (99.99%) | Grade C (99.90%) |
|---|---|---|---|
| Purity | High | Ultra-high | Medium-high |
| Cost | Medium | High | Lower |
| Electronics Use | Good | Critical | General |
| Whisker Risk | Low | Higher | Lower |
| Industrial Use | Excellent | Good | Excellent |
Why Choose Grade B Tin?
Choose Grade B Tin when high purity is required without extreme cost, electronics reliability matters, and consistent alloying behavior is essential.
Engineering Insight:
Grade B Tin is the most versatile premium-industrial tin grade worldwide.