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Solder & Low-Melting Alloy Pb50Sn50 vs Pb65Sn35

Solder & Low-Melting Alloy · grade comparison

Solder & Low-Melting Alloy Pb50Sn50 and Pb65Sn35 are both solder & low-melting alloy grades. Pb50Sn50 is the stronger of the two: yield strength 27 MPa (3.92 ksi) against 21 MPa (3.05 ksi) for Pb65Sn35, about 29% more; tensile strength follows at 42 MPa (6.09 ksi) vs 33 MPa (4.79 ksi). Pb50Sn50 is harder — 14 HB against 12 HB for Pb65Sn35 — which matters for wear surfaces and threads. Pb50Sn50 is lighter (8.85 g/cm³ vs 9.5 g/cm³ for Pb65Sn35) and Pb65Sn35 is stiffer (26 GPa vs 23 GPa).

Pb50Sn50Choose it when strength drives the design, or when surface hardness matters.

Pb50Sn50 vs Pb65Sn35: properties

Pb50Sn50Pb65Sn35

Mechanical

Strength, stiffness, ductility and hardness at room temperature.

Elastic (Young's) Modulus

23 GPa3.3 Msi
26 GPa3.8 Msi

Shear Modulus

8.5 GPa1.2 Msi
9.5 GPa1.4 Msi

Bulk Modulus

36 GPa5.2 Msi
43 GPa6.2 Msi

Tensile Strength (Ultimate)

42 MPa6.1 ksi
33 MPa4.8 ksi

Yield Strength (0.2% offset)

27 MPa3.9 ksi
21 MPa3 ksi

Shear Strength

34 MPa4.9 ksi
26 MPa3.8 ksi

Fatigue Strength (Endurance Limit)

14 MPa2 ksi
11 MPa1.6 ksi

Hardness, Brinell

14 HB
12 HB

Hardness, Vickers

13 HV
—

Same in both: Poisson's Ratio 0.4 · Elongation at Break 55%

Physical

Density and transition temperatures.

Density

8.85 g/cm³0.32 lb/in³
9.5 g/cm³0.34 lb/in³

Liquidus Temperature

216°C421 °F
247°C477 °F

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

Thermal

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

Thermal Conductivity

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

Specific Heat Capacity

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

Thermal Expansion (CTE, 20–100 °C)

24.5 µm/m·K13.6 µin/in·°F
25 µm/m·K13.9 µin/in·°F

Latent Heat of Fusion

42 J/g18.1 BTU/lb
38 J/g16.3 BTU/lb

Same in both: Max Service Temperature (continuous) 100°C212 °F · Min Service Temperature -60°C-76 °F

Electrical

Conductivity and insulation.

Electrical Conductivity

10.9 % IACS
9.5 % IACS

Electrical Resistivity

1.58×10⁻⁷ Ω·m6.22 µΩ·in
1.8×10⁻⁷ Ω·m7.09 µΩ·in

Chemical & Environmental

Corrosion and environmental resistance (0–100 scores).

Galvanic Potential (seawater, vs SCE)

-0.32 V
-0.5 V

Same in both: Corrosion Resistance 45 / 100

Manufacturability

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

Machinability Rating (AISI 1212 = 100 %)

35%
—

Weldability

15 / 100
20 / 100

Formability (cold)

95 / 100
90 / 100

Castability

90 / 100
85 / 100

Brazeability / Solderability

98 / 100
88 / 100

Polishability

20 / 100
30 / 100

Same in both: Machinability 30 / 100

Sustainability

Primary-production footprint per kilogram.

Embodied Energy (primary production)

160 MJ/kg68,788 BTU/lb
128 MJ/kg55,030 BTU/lb

Embodied Carbon (primary production)

10.5 kg CO₂/kg
6.7 kg CO₂/kg

Embodied Water

450 L/kg53.9 gal/lb
300 L/kg35.9 gal/lb

Same in both: Typical Recycled Content 45%

Common Calculations

Ratios derived from the values above.

Specific Strength (UTS / density)

5 kN·m/kg
3 kN·m/kg

Specific Stiffness (E / density)

2.6 MN·m/kg
2.7 MN·m/kg

Modulus of Resilience

16 kJ/m³
8 kJ/m³

Thermal Diffusivity

32.1 mm²/s
28.4 mm²/s

Thermal Shock Resistance Index

4
2

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 scalePb50Sn50Pb65Sn35

Manufacturing and finishing

CapabilityPb50Sn50Pb65Sn35
Default condition——
Relative cost$$$$ High$$$$ High
Min. machined wall——
Best machined surface——

Pb50Sn50 vs Pb65Sn35 — frequently asked

Is Pb50Sn50 stronger than Pb65Sn35?

Yes. Pb50Sn50 has a typical yield strength of 27 MPa (3.92 ksi) against 21 MPa (3.05 ksi) for Pb65Sn35 — about 29% more. Tensile strength is 42 MPa (6.09 ksi) vs 33 MPa (4.79 ksi).

Which is cheaper, Pb50Sn50 or Pb65Sn35?

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 welds better, Pb50Sn50 or Pb65Sn35?

Pb65Sn35. Its weldability rates poor (20/100) against poor (15/100) for Pb50Sn50.

Ready to make it?

Upload a CAD file and FabDigit prices the part in Pb50Sn50 and Pb65Sn35 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.