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Solder & Low-Melting Alloy Sn63Pb37Sb vs Sn95.8Ag3.5Cu0.7

Solder & Low-Melting Alloy · grade comparison

Solder & Low-Melting Alloy Sn63Pb37Sb and Sn95.8Ag3.5Cu0.7 are both solder & low-melting alloy grades. Sn63Pb37Sb is the stronger of the two: yield strength 38 MPa (5.51 ksi) against 30 MPa (4.35 ksi) for Sn95.8Ag3.5Cu0.7, about 27% 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 Sn95.8Ag3.5Cu0.7 — which matters for wear surfaces and threads. Sn95.8Ag3.5Cu0.7 is lighter (7.4 g/cm³ vs 8.4 g/cm³ for Sn63Pb37Sb) and Sn95.8Ag3.5Cu0.7 is stiffer (50 GPa vs 32 GPa). On the shop floor, Sn95.8Ag3.5Cu0.7 welds better (30 vs 20 out of 100).

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

Sn95.8Ag3.5Cu0.7Choose it when weight is the constraint, or when the part sees heat.

Sn63Pb37Sb vs Sn95.8Ag3.5Cu0.7: properties

Sn63Pb37SbSn95.8Ag3.5Cu0.7

Mechanical

Strength, stiffness, ductility and hardness at room temperature.

Elastic (Young's) Modulus

32 GPa4.6 Msi
50 GPa7.3 Msi

Shear Modulus

12.5 GPa1.8 Msi
18.5 GPa2.7 Msi

Bulk Modulus

50 GPa7.3 Msi
56 GPa8.1 Msi

Poisson's Ratio

0.4
0.36

Tensile Strength (Ultimate)

58 MPa8.4 ksi
45 MPa6.5 ksi

Yield Strength (0.2% offset)

38 MPa5.5 ksi
30 MPa4.4 ksi

Elongation at Break

32%
35%

Shear Strength

38 MPa5.5 ksi
32 MPa4.6 ksi

Fatigue Strength (Endurance Limit)

15 MPa2.2 ksi
20 MPa2.9 ksi

Hardness, Brinell

16 HB
14 HB

Hardness, Vickers

—
15 HV

Physical

Density and transition temperatures.

Density

8.4 g/cm³0.3 lb/in³
7.4 g/cm³0.27 lb/in³

Melting Point (Solidus)

183°C361 °F
217°C423 °F

Liquidus Temperature

185°C365 °F
219°C426 °F

Thermal

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

Thermal Conductivity

50 W/m·K28.9 BTU/hr·ft·°F
58 W/m·K33.5 BTU/hr·ft·°F

Specific Heat Capacity

170 J/kg·K0.04 BTU/lb·°F
230 J/kg·K0.05 BTU/lb·°F

Thermal Expansion (CTE, 20–100 °C)

24.5 µm/m·K13.6 µin/in·°F
22 µm/m·K12.2 µin/in·°F

Latent Heat of Fusion

42 J/g18.1 BTU/lb
62 J/g26.7 BTU/lb

Max Service Temperature (continuous)

100°C212 °F
125°C257 °F

Same in both: Min Service Temperature -55°C-67 °F

Electrical

Conductivity and insulation.

Electrical Conductivity

11.5 % IACS
13 % IACS

Electrical Resistivity

1.5×10⁻⁷ Ω·m5.91 µΩ·in
1.3×10⁻⁷ Ω·m5.12 µΩ·in

Chemical & Environmental

Corrosion and environmental resistance (0–100 scores).

Same in both: Galvanic Potential (seawater, vs SCE) -0.5 V · Corrosion Resistance 40 / 100

Manufacturability

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

Weldability

20 / 100
30 / 100

Formability (cold)

90 / 100
85 / 100

Castability

95 / 100
90 / 100

Brazeability / Solderability

100 / 100
95 / 100

Same in both: Machinability 20 / 100 · Polishability 25 / 100

Sustainability

Primary-production footprint per kilogram.

Embodied Energy (primary production)

210 MJ/kg90,284 BTU/lb
360 MJ/kg154,772 BTU/lb

Embodied Carbon (primary production)

11 kg CO₂/kg
19 kg CO₂/kg

Embodied Water

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

Same in both: Typical Recycled Content 30%

Common Calculations

Ratios derived from the values above.

Specific Strength (UTS / density)

7 kN·m/kg
6 kN·m/kg

Specific Stiffness (E / density)

3.8 MN·m/kg
6.8 MN·m/kg

Modulus of Resilience

23 kJ/m³
9 kJ/m³

Thermal Diffusivity

35 mm²/s
34.1 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 scaleSn63Pb37SbSn95.8Ag3.5Cu0.7

Manufacturing and finishing

CapabilitySn63Pb37SbSn95.8Ag3.5Cu0.7
Default condition——
Relative cost$$$$ High$$$$ High
Min. machined wall——
Best machined surface——

Sn63Pb37Sb vs Sn95.8Ag3.5Cu0.7 — frequently asked

Is Sn63Pb37Sb stronger than Sn95.8Ag3.5Cu0.7?

Yes. Sn63Pb37Sb has a typical yield strength of 38 MPa (5.51 ksi) against 30 MPa (4.35 ksi) for Sn95.8Ag3.5Cu0.7 — about 27% more. Tensile strength is 58 MPa (8.41 ksi) vs 45 MPa (6.53 ksi).

Which is cheaper, Sn63Pb37Sb or Sn95.8Ag3.5Cu0.7?

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, Sn63Pb37Sb or Sn95.8Ag3.5Cu0.7?

Sn95.8Ag3.5Cu0.7. Its weldability rates poor (30/100) against poor (20/100) for Sn63Pb37Sb.

Ready to make it?

Upload a CAD file and FabDigit prices the part in Sn63Pb37Sb and Sn95.8Ag3.5Cu0.7 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.