ISO Solder Alloy 124 (Pb98Sn2)
Solder alloy 124 is a lead-based soldering alloy. Cited properties are appropriate for the as-fabricated (no temper or treatment) condition. 124 is the ISO numeric designation for this material. Older literature may refer to this material as S-Pb98Sn2, but this is now discouraged.
It has the lowest base cost among lead-based solder alloys. In addition, it has the highest ductility and the highest melting temperature.
The graph bars on the material properties cards below compare solder alloy 124 to: lead-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
17 GPa 2.4 x 106 psi
Elongation at Break
46 %
Poisson's Ratio
0.44
Shear Modulus
5.8 GPa 0.85 x 106 psi
Tensile Strength: Ultimate (UTS)
27 MPa 3.8 x 103 psi
Thermal Properties
Latent Heat of Fusion
24 J/g
Melting Completion (Liquidus)
330 °C 620 °F
Melting Onset (Solidus)
320 °C 610 °F
Specific Heat Capacity
130 J/kg-K 0.031 BTU/lb-°F
Thermal Conductivity
22 W/m-K 13 BTU/h-ft-°F
Thermal Expansion
29 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
9.6 % IACS
Electrical Conductivity: Equal Weight (Specific)
7.7 % IACS
Otherwise Unclassified Properties
Base Metal Price
70 % relative
Density
11 g/cm3 700 lb/ft3
Embodied Carbon
4.1 kg CO2/kg material
Embodied Energy
68 MJ/kg 29 x 103 BTU/lb
Embodied Water
470 L/kg 56 gal/lb
Common Calculations
Stiffness to Weight: Axial
0.83 points
Stiffness to Weight: Bending
7.6 points
Strength to Weight: Axial
0.65 points
Strength to Weight: Bending
1.8 points
Thermal Diffusivity
15 mm2/s
Thermal Shock Resistance
3.9 points
Alloy Composition
| Pb | 97.2 to 98.2 | |
| Sn | 1.8 to 2.2 | |
| Sb | 0 to 0.12 | |
| 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