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ISO Solder Alloy 142 (Pb49Sn48Bi3)

Solder alloy 142 is a lead-based soldering alloy. Cited properties are appropriate for the as-fabricated (no temper or treatment) condition. 142 is the ISO numeric designation for this material. Older literature may refer to this material as S-Pb49Sn48Bi3, but this is now discouraged.

It has a fairly high electrical conductivity among lead-based solder alloys. In addition, it has the highest tensile strength and a fairly high embodied energy.

The graph bars on the material properties cards below compare solder alloy 142 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

33 GPa 4.8 x 106 psi

Elongation at Break

37 %

Poisson's Ratio


Shear Modulus

12 GPa 1.7 x 106 psi

Tensile Strength: Ultimate (UTS)

43 MPa 6.2 x 103 psi

Thermal Properties

Latent Heat of Fusion

42 J/g

Melting Completion (Liquidus)

210 °C 400 °F

Melting Onset (Solidus)

180 °C 350 °F

Specific Heat Capacity

170 J/kg-K 0.041 BTU/lb-°F

Thermal Conductivity

45 W/m-K 26 BTU/h-ft-°F

Thermal Expansion

25 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

11 % IACS

Electrical Conductivity: Equal Weight (Specific)

11 % IACS

Otherwise Unclassified Properties


9.3 g/cm3 580 lb/ft3

Embodied Carbon

9.4 kg CO2/kg material

Embodied Energy

160 MJ/kg 68 x 103 BTU/lb

Embodied Water

890 L/kg 110 gal/lb

Common Calculations

Stiffness to Weight: Axial

2.0 points

Stiffness to Weight: Bending

11 points

Strength to Weight: Axial

1.3 points

Strength to Weight: Bending

2.9 points

Thermal Diffusivity

28 mm2/s

Thermal Shock Resistance

3.7 points

Alloy Composition

Lead (Pb)Pb 47.4 to 50
Tin (Sn)Sn 47.5 to 48.5
Bismuth (Bi)Bi 2.5 to 3.5
Antimony (Sb)Sb 0 to 0.2
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