ISO Solder Alloy 131 (Sn63Pb37Sb)
Solder alloy 131 is a tin-based soldering alloy. Cited properties are appropriate for the as-fabricated (no temper or treatment) condition. 131 is the ISO numeric designation for this material. Older literature may refer to this material as S-Sn63Pb37Sb, but this is now discouraged.
It has a moderately high ductility among the tin-based solder alloys in the database.
The graph bars on the material properties cards below compare solder alloy 131 to: tin-based solder alloys (top), all alloys in the same category (middle), and the entire database (bottom). A full bar means this is the highest value in the relevant set. A half-full bar means it's 50% of the highest, and so on.
Mechanical Properties
Elastic (Young's, Tensile) Modulus
38 GPa 5.5 x 106 psi
Elongation at Break
47 %
Poisson's Ratio
0.39
Shear Modulus
14 GPa 2.0 x 106 psi
Tensile Strength: Ultimate (UTS)
31 MPa 4.5 x 103 psi
Thermal Properties
Latent Heat of Fusion
46 J/g
Melting Completion (Liquidus)
180 °C 360 °F
Melting Onset (Solidus)
180 °C 360 °F
Specific Heat Capacity
190 J/kg-K 0.045 BTU/lb-°F
Thermal Conductivity
55 W/m-K 32 BTU/h-ft-°F
Thermal Expansion
25 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
11 % IACS
Electrical Conductivity: Equal Weight (Specific)
12 % IACS
Otherwise Unclassified Properties
Density
8.8 g/cm3 550 lb/ft3
Embodied Carbon
11 kg CO2/kg material
Embodied Energy
180 MJ/kg 79 x 103 BTU/lb
Embodied Water
940 L/kg 110 gal/lb
Common Calculations
Stiffness to Weight: Axial
2.4 points
Stiffness to Weight: Bending
13 points
Strength to Weight: Axial
1.0 points
Strength to Weight: Bending
2.5 points
Thermal Diffusivity
33 mm2/s
Thermal Shock Resistance
2.4 points
Alloy Composition
| Sn | 62.5 to 63.5 | |
| Pb | 35.5 to 37.3 | |
| Sb | 0.2 to 0.5 | |
| Bi | 0 to 0.1 | |
| Ag | 0 to 0.1 | |
| In | 0 to 0.1 | |
| Cu | 0 to 0.080 | |
| Au | 0 to 0.050 | |
| As | 0 to 0.030 | |
| Fe | 0 to 0.020 | |
| Ni | 0 to 0.010 | |
| Cd | 0 to 0.0020 | |
| Al | 0 to 0.0010 | |
| Zn | 0 to 0.0010 |
All values are % weight. Ranges represent what is permitted under applicable standards.
Followup Questions
Similar Alloys
Further Reading
ISO 9453: Soft solder alloys - Chemical compositions and forms