Menu (ESC)

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


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


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

Lead (Pb)Pb 97.2 to 98.2
Tin (Sn)Sn 1.8 to 2.2
Antimony (Sb)Sb 0 to 0.12
Bismuth (Bi)Bi 0 to 0.1
Silver (Ag)Ag 0 to 0.1
Indium (In)In 0 to 0.1
Copper (Cu)Cu 0 to 0.080
Gold (Au)Au 0 to 0.050
Arsenic (As)As 0 to 0.030
Iron (Fe)Fe 0 to 0.020
Nickel (Ni)Ni 0 to 0.010
Cadmium (Cd)Cd 0 to 0.0020
Aluminum (Al)Al 0 to 0.0010
Zinc (Zn)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