Solder & Low-Melting Alloy Sn63Pb37Sb vs Sn91Zn9
Solder & Low-Melting Alloy · grade comparison
Solder & Low-Melting Alloy Sn63Pb37Sb and Sn91Zn9 are both solder & low-melting alloy grades. Sn91Zn9 is the stronger of the two: tensile strength 65 MPa (9.43 ksi) against 58 MPa (8.41 ksi) for Sn63Pb37Sb, about 12% more. Sn91Zn9 is the more ductile: elongation 40% versus 32% for Sn63Pb37Sb, and Sn91Zn9 is harder (21 HB vs 16 HB). Sn91Zn9 is lighter (7.27 g/cm³ vs 8.4 g/cm³ for Sn63Pb37Sb) and Sn91Zn9 is stiffer (40 GPa vs 32 GPa). On the shop floor, Sn91Zn9 machines more easily (30 vs 20 out of 100) and Sn63Pb37Sb welds better (poor vs not recommended).
Sn63Pb37SbChoose it when it will be welded.
Sn91Zn9Choose it when strength drives the design, or when the part is bent, formed or impact-loaded.
Sn63Pb37Sb vs Sn91Zn9: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all solder & low-melting alloy grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
How to read these bars
- One bar per material. A full bar is the highest value among all solder & low-melting alloy grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Elastic (Young's) Modulus
Shear Modulus
Bulk Modulus
Poisson's Ratio
Tensile Strength (Ultimate)
Elongation at Break
Shear Strength
Fatigue Strength (Endurance Limit)
Hardness, Brinell
Hardness, Vickers
Same in both: Yield Strength (0.2% offset) 38 MPa5.5 ksi
Physical
Density and transition temperatures.
Density
Melting Point (Solidus)
Liquidus Temperature
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Specific Heat Capacity
Thermal Expansion (CTE, 20–100 °C)
Latent Heat of Fusion
Same in both: Max Service Temperature (continuous) 100°C212 °F · Min Service Temperature -55°C-67 °F
Electrical
Conductivity and insulation.
Electrical Conductivity
Electrical Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Galvanic Potential (seawater, vs SCE)
Corrosion Resistance
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Weldability
Formability (cold)
Castability
Brazeability / Solderability
Polishability
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Embodied Water
Same in both: Typical Recycled Content 30%
Common Calculations
Ratios derived from the values above.
Specific Strength (UTS / density)
Specific Stiffness (E / density)
Modulus of Resilience
Thermal Diffusivity
Same in both: Thermal Shock Resistance Index 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.
Manufacturing and finishing
| Capability | Sn63Pb37Sb | Sn91Zn9 |
|---|---|---|
| Default condition | — | — |
| Relative cost | $$$$ High | $$$$ High |
| Min. machined wall | — | — |
| Best machined surface | — | — |
Sn63Pb37Sb vs Sn91Zn9 — frequently asked
Is Sn91Zn9 stronger than Sn63Pb37Sb?
Yes. Sn91Zn9 has a typical tensile strength of 65 MPa (9.43 ksi) against 58 MPa (8.41 ksi) for Sn63Pb37Sb — about 12% more.
Which is cheaper, Sn63Pb37Sb or Sn91Zn9?
Both sit in the same relative cost tier ($$$$, high); the part price will be decided by machining time, tolerance and quantity rather than by the material.
Which is easier to machine, Sn63Pb37Sb or Sn91Zn9?
Sn91Zn9, by a small margin. Both rate poor for machinability — 30/100 against 20/100 for Sn63Pb37Sb; for welding the order is Sn63Pb37Sb first (poor, 20/100) then Sn91Zn9 (not recommended, 10/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in Sn63Pb37Sb and Sn91Zn9 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.