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Solder & Low-Melting Alloy Sn40Pb60 vs Sn63Pb37Sb

Solder & Low-Melting Alloy · grade comparison

Solder & Low-Melting Alloy Sn40Pb60 and Sn63Pb37Sb are both solder & low-melting alloy grades. Sn63Pb37Sb is the stronger of the two: yield strength 38 MPa (5.51 ksi) against 22 MPa (3.19 ksi) for Sn40Pb60, about 73% more; tensile strength follows at 58 MPa (8.41 ksi) vs 38 MPa (5.51 ksi). In exchange, Sn40Pb60 is the more ductile: elongation 55% versus 32% for Sn63Pb37Sb, and Sn63Pb37Sb is harder (16 HB vs 12 HB). Sn63Pb37Sb is lighter (8.4 g/cm³ vs 9.29 g/cm³ for Sn40Pb60) and Sn63Pb37Sb is stiffer (32 GPa vs 25 GPa). On the shop floor, Sn40Pb60 machines more easily (fair vs poor).

Sn40Pb60Choose it when the part is bent, formed or impact-loaded, or when the part is machined in volume.

Sn63Pb37SbChoose it when strength drives the design, or when weight is the constraint.

Sn40Pb60 vs Sn63Pb37Sb: properties

Sn40Pb60Sn63Pb37Sb

Mechanical

Strength, stiffness, ductility and hardness at room temperature.

Elastic (Young's) Modulus

25 GPa3.6 Msi
32 GPa4.6 Msi

Shear Modulus

9.5 GPa1.4 Msi
12.5 GPa1.8 Msi

Bulk Modulus

42 GPa6.1 Msi
50 GPa7.3 Msi

Tensile Strength (Ultimate)

38 MPa5.5 ksi
58 MPa8.4 ksi

Yield Strength (0.2% offset)

22 MPa3.2 ksi
38 MPa5.5 ksi

Elongation at Break

55%
32%

Compressive Strength

40 MPa5.8 ksi
—

Shear Strength

34 MPa4.9 ksi
38 MPa5.5 ksi

Fatigue Strength (Endurance Limit)

14 MPa2 ksi
15 MPa2.2 ksi

Hardness, Brinell

12 HB
16 HB

Hardness, Vickers

13 HV
—

Same in both: Poisson's Ratio 0.4

Physical

Density and transition temperatures.

Density

9.29 g/cm³0.34 lb/in³
8.4 g/cm³0.3 lb/in³

Liquidus Temperature

238°C460 °F
185°C365 °F

Same in both: Melting Point (Solidus) 183°C361 °F

Thermal

How each material carries heat and how hot it can run.

Thermal Conductivity

44 W/m·K25.4 BTU/hr·ft·°F
50 W/m·K28.9 BTU/hr·ft·°F

Specific Heat Capacity

176 J/kg·K0.04 BTU/lb·°F
170 J/kg·K0.04 BTU/lb·°F

Latent Heat of Fusion

39 J/g16.8 BTU/lb
42 J/g18.1 BTU/lb

Same in both: Thermal Expansion (CTE, 20–100 °C) 24.5 µm/m·K13.6 µin/in·°F · Max Service Temperature (continuous) 100°C212 °F · Min Service Temperature -55°C-67 °F

Electrical

Conductivity and insulation.

Electrical Conductivity

10.1 % IACS
11.5 % IACS

Electrical Resistivity

1.7×10⁻⁷ Ω·m6.69 µΩ·in
1.5×10⁻⁷ Ω·m5.91 µΩ·in

Chemical & Environmental

Corrosion and environmental resistance (0–100 scores).

Galvanic Potential (seawater, vs SCE)

-0.32 V
-0.5 V

Corrosion Resistance

45 / 100
40 / 100

Manufacturability

FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.

Machinability

35 / 100
20 / 100

Formability (cold)

95 / 100
90 / 100

Polishability

30 / 100
25 / 100

Weldability

—
20 / 100

Same in both: Castability 95 / 100 · Brazeability / Solderability 100 / 100

Sustainability

Primary-production footprint per kilogram.

Embodied Energy (primary production)

115 MJ/kg49,441 BTU/lb
210 MJ/kg90,284 BTU/lb

Embodied Carbon (primary production)

7.5 kg CO₂/kg
11 kg CO₂/kg

Embodied Water

300 L/kg35.9 gal/lb
320 L/kg38.3 gal/lb

Typical Recycled Content

50%
30%

Common Calculations

Ratios derived from the values above.

Specific Strength (UTS / density)

4 kN·m/kg
7 kN·m/kg

Specific Stiffness (E / density)

2.7 MN·m/kg
3.8 MN·m/kg

Modulus of Resilience

10 kJ/m³
23 kJ/m³

Thermal Diffusivity

26.9 mm²/s
35 mm²/s

Thermal Shock Resistance Index

3
4

Strength versus weight

Yield strength against density for every solder & low-melting alloy grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.

125102050891011Density (g/cm³)Yield strength (MPa) — log scaleSn63Pb37SbSn40Pb60

Manufacturing and finishing

CapabilitySn40Pb60Sn63Pb37Sb
Default condition——
Relative cost$$$$ High$$$$ High
Min. machined wall——
Best machined surface——

Sn40Pb60 vs Sn63Pb37Sb — frequently asked

Is Sn63Pb37Sb stronger than Sn40Pb60?

Yes. Sn63Pb37Sb has a typical yield strength of 38 MPa (5.51 ksi) against 22 MPa (3.19 ksi) for Sn40Pb60 — about 73% more. Tensile strength is 58 MPa (8.41 ksi) vs 38 MPa (5.51 ksi).

Which is cheaper, Sn40Pb60 or Sn63Pb37Sb?

Both sit in the same relative cost tier ($$$$, high); the part price will be decided by machining time, tolerance and quantity rather than by the material.

Which is easier to machine, Sn40Pb60 or Sn63Pb37Sb?

Sn40Pb60. Its machinability rates fair (35/100) against poor (20/100) for Sn63Pb37Sb.

Ready to make it?

Upload a CAD file and FabDigit prices the part in Sn40Pb60 and Sn63Pb37Sb side by side — material, machining time, tolerance and finish in one quote. Certified material data ships with the order on request.

Typical handbook values for the conditions named above, normalised for comparison. Hardness on non-Brinell scales is converted approximately for charting only. Request certified data with your order for design-critical properties.