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Solder & Low-Melting Alloy Sn50Pb32Cd18 vs Sn63Pb37Sb

Solder & Low-Melting Alloy · grade comparison

Solder & Low-Melting Alloy Sn50Pb32Cd18 and Sn63Pb37Sb are both solder & low-melting alloy grades. Sn63Pb37Sb is the stronger of the two: yield strength 38 MPa (5.51 ksi) against 25 MPa (3.63 ksi) for Sn50Pb32Cd18, about 52% more; tensile strength follows at 58 MPa (8.41 ksi) vs 45 MPa (6.53 ksi). Sn63Pb37Sb is harder — 16 HB against 14 HB for Sn50Pb32Cd18 — which matters for wear surfaces and threads. Sn63Pb37Sb is stiffer (32 GPa vs 28 GPa) and Sn63Pb37Sb runs hotter in service (100°C vs 70°C continuous). On the shop floor, Sn50Pb32Cd18 machines more easily (30 vs 20 out of 100).

Sn50Pb32Cd18Choose it when the part is machined in volume.

Sn63Pb37SbChoose it when strength drives the design, or when surface hardness matters.

Sn50Pb32Cd18 vs Sn63Pb37Sb: properties

Sn50Pb32Cd18Sn63Pb37Sb

Mechanical

Strength, stiffness, ductility and hardness at room temperature.

Elastic (Young's) Modulus

28 GPa4.1 Msi
32 GPa4.6 Msi

Shear Modulus

10.5 GPa1.5 Msi
12.5 GPa1.8 Msi

Bulk Modulus

38 GPa5.5 Msi
50 GPa7.3 Msi

Poisson's Ratio

0.36
0.4

Tensile Strength (Ultimate)

45 MPa6.5 ksi
58 MPa8.4 ksi

Yield Strength (0.2% offset)

25 MPa3.6 ksi
38 MPa5.5 ksi

Elongation at Break

35%
32%

Shear Strength

30 MPa4.4 ksi
38 MPa5.5 ksi

Fatigue Strength (Endurance Limit)

14 MPa2 ksi
15 MPa2.2 ksi

Hardness, Brinell

14 HB
16 HB

Physical

Density and transition temperatures.

Density

8.5 g/cm³0.31 lb/in³
8.4 g/cm³0.3 lb/in³

Melting Point (Solidus)

145°C293 °F
183°C361 °F

Liquidus Temperature

145°C293 °F
185°C365 °F

Thermal

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

Thermal Conductivity

45 W/m·K26 BTU/hr·ft·°F
50 W/m·K28.9 BTU/hr·ft·°F

Specific Heat Capacity

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

Thermal Expansion (CTE, 20–100 °C)

27 µm/m·K15 µin/in·°F
24.5 µm/m·K13.6 µin/in·°F

Latent Heat of Fusion

40 J/g17.2 BTU/lb
42 J/g18.1 BTU/lb

Max Service Temperature (continuous)

70°C158 °F
100°C212 °F

Min Service Temperature

-60°C-76 °F
-55°C-67 °F

Electrical

Conductivity and insulation.

Electrical Conductivity

10 % 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)

-0.55 V
-0.5 V

Corrosion Resistance

35 / 100
40 / 100

Manufacturability

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

Machinability

30 / 100
20 / 100

Castability

90 / 100
95 / 100

Brazeability / Solderability

95 / 100
100 / 100

Same in both: Weldability 20 / 100 · Formability (cold) 90 / 100 · Polishability 25 / 100

Sustainability

Primary-production footprint per kilogram.

Embodied Energy (primary production)

180 MJ/kg77,386 BTU/lb
210 MJ/kg90,284 BTU/lb

Embodied Carbon (primary production)

9.8 kg CO₂/kg
11 kg CO₂/kg

Typical Recycled Content

25%
30%

Same in both: Embodied Water 320 L/kg38.3 gal/lb

Common Calculations

Ratios derived from the values above.

Specific Strength (UTS / density)

5 kN·m/kg
7 kN·m/kg

Specific Stiffness (E / density)

3.3 MN·m/kg
3.8 MN·m/kg

Modulus of Resilience

11 kJ/m³
23 kJ/m³

Thermal Diffusivity

28.6 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 scaleSn63Pb37SbSn50Pb32Cd18

Manufacturing and finishing

CapabilitySn50Pb32Cd18Sn63Pb37Sb
Default condition——
Relative cost$$$$ High$$$$ High
Min. machined wall——
Best machined surface——

Sn50Pb32Cd18 vs Sn63Pb37Sb — frequently asked

Is Sn63Pb37Sb stronger than Sn50Pb32Cd18?

Yes. Sn63Pb37Sb has a typical yield strength of 38 MPa (5.51 ksi) against 25 MPa (3.63 ksi) for Sn50Pb32Cd18 — about 52% more. Tensile strength is 58 MPa (8.41 ksi) vs 45 MPa (6.53 ksi).

Which is cheaper, Sn50Pb32Cd18 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, Sn50Pb32Cd18 or Sn63Pb37Sb?

Sn50Pb32Cd18, by a small margin. Both rate poor for machinability — 30/100 against 20/100 for Sn63Pb37Sb.

Ready to make it?

Upload a CAD file and FabDigit prices the part in Sn50Pb32Cd18 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.