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Solder & Low-Melting Alloy Pb50Sn50 vs Pb70Sn30

Solder & Low-Melting Alloy · grade comparison

Solder & Low-Melting Alloy Pb50Sn50 and Pb70Sn30 are both solder & low-melting alloy grades. Pb50Sn50 is the stronger of the two: yield strength 27 MPa (3.92 ksi) against 22 MPa (3.19 ksi) for Pb70Sn30, about 23% more; tensile strength follows at 42 MPa (6.09 ksi) vs 38 MPa (5.51 ksi). Pb50Sn50 is the more ductile: elongation 55% versus 45% for Pb70Sn30, and Pb50Sn50 is harder (14 HB vs 12 HB). Pb50Sn50 is lighter (8.85 g/cm³ vs 9.7 g/cm³ for Pb70Sn30) and Pb70Sn30 is stiffer (25 GPa vs 23 GPa).

Pb50Sn50Choose it when strength drives the design, or when the part is bent, formed or impact-loaded.

Pb50Sn50 vs Pb70Sn30: properties

Pb50Sn50Pb70Sn30

Mechanical

Strength, stiffness, ductility and hardness at room temperature.

Elastic (Young's) Modulus

23 GPa3.3 Msi
25 GPa3.6 Msi

Shear Modulus

8.5 GPa1.2 Msi
9 GPa1.3 Msi

Bulk Modulus

36 GPa5.2 Msi
42 GPa6.1 Msi

Tensile Strength (Ultimate)

42 MPa6.1 ksi
38 MPa5.5 ksi

Yield Strength (0.2% offset)

27 MPa3.9 ksi
22 MPa3.2 ksi

Elongation at Break

55%
45%

Shear Strength

34 MPa4.9 ksi
26 MPa3.8 ksi

Fatigue Strength (Endurance Limit)

14 MPa2 ksi
—

Hardness, Brinell

14 HB
12 HB

Hardness, Vickers

13 HV
—

Same in both: Poisson's Ratio 0.4

Physical

Density and transition temperatures.

Density

8.85 g/cm³0.32 lb/in³
9.7 g/cm³0.35 lb/in³

Liquidus Temperature

216°C421 °F
255°C491 °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
46 W/m·K26.6 BTU/hr·ft·°F

Specific Heat Capacity

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

Thermal Expansion (CTE, 20–100 °C)

24.5 µm/m·K13.6 µin/in·°F
26 µm/m·K14.4 µin/in·°F

Latent Heat of Fusion

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

Min Service Temperature

-60°C-76 °F
-55°C-67 °F

Same in both: Max Service Temperature (continuous) 100°C212 °F

Electrical

Conductivity and insulation.

Electrical Conductivity

10.9 % IACS
9 % IACS

Electrical Resistivity

1.58×10⁻⁷ Ω·m6.22 µΩ·in
1.9×10⁻⁷ Ω·m7.48 µΩ·in

Chemical & Environmental

Corrosion and environmental resistance (0–100 scores).

Galvanic Potential (seawater, vs SCE)

-0.32 V
-0.53 V

Corrosion Resistance

45 / 100
55 / 100

Manufacturability

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

Machinability Rating (AISI 1212 = 100 %)

35%
—

Formability (cold)

95 / 100
90 / 100

Castability

90 / 100
85 / 100

Brazeability / Solderability

98 / 100
92 / 100

Polishability

20 / 100
35 / 100

Same in both: Machinability 30 / 100 · Weldability 15 / 100

Sustainability

Primary-production footprint per kilogram.

Embodied Energy (primary production)

160 MJ/kg68,788 BTU/lb
96 MJ/kg41,273 BTU/lb

Embodied Carbon (primary production)

10.5 kg CO₂/kg
6.1 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
4 kN·m/kg

Modulus of Resilience

16 kJ/m³
10 kJ/m³

Thermal Diffusivity

32.1 mm²/s
30.6 mm²/s

Thermal Shock Resistance Index

4
3

Same in both: Specific Stiffness (E / density) 2.6 MN·m/kg

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 scalePb50Sn50Pb70Sn30

Manufacturing and finishing

CapabilityPb50Sn50Pb70Sn30
Default condition——
Relative cost$$$$ High$$$$ High
Min. machined wall——
Best machined surface——

Pb50Sn50 vs Pb70Sn30 — frequently asked

Is Pb50Sn50 stronger than Pb70Sn30?

Yes. Pb50Sn50 has a typical yield strength of 27 MPa (3.92 ksi) against 22 MPa (3.19 ksi) for Pb70Sn30 — about 23% more. Tensile strength is 42 MPa (6.09 ksi) vs 38 MPa (5.51 ksi).

Which is cheaper, Pb50Sn50 or Pb70Sn30?

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.

When should I choose Pb50Sn50 over Pb70Sn30?

Pick Pb50Sn50 when strength drives the design, or when the part is bent, formed or impact-loaded.

Ready to make it?

Upload a CAD file and FabDigit prices the part in Pb50Sn50 and Pb70Sn30 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.