Solder & Low-Melting Alloy Pb65Sn35 vs Pb78Sn20Sb2
Solder & Low-Melting Alloy · grade comparison
Solder & Low-Melting Alloy Pb65Sn35 and Pb78Sn20Sb2 are both solder & low-melting alloy grades. Pb65Sn35 is the stronger of the two: tensile strength 33 MPa (4.79 ksi) against 31 MPa (4.5 ksi) for Pb78Sn20Sb2, about 6% more. Pb65Sn35 is the more ductile: elongation 55% versus 45% for Pb78Sn20Sb2. Pb65Sn35 is lighter (9.5 g/cm³ vs 10.1 g/cm³ for Pb78Sn20Sb2) and Pb78Sn20Sb2 runs hotter in service (110°C vs 100°C continuous). On the shop floor, Pb78Sn20Sb2 machines more easily (fair vs poor).
Pb65Sn35Choose it when strength drives the design, or when the part is bent, formed or impact-loaded.
Pb78Sn20Sb2Choose it when the part sees heat, or when the part is machined in volume.
Pb65Sn35 vs Pb78Sn20Sb2: 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
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Shear Strength
Fatigue Strength (Endurance Limit)
Same in both: Poisson's Ratio 0.4 · Hardness, Brinell 12 HB
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
Max Service Temperature (continuous)
Same in both: Min Service Temperature -60°C-76 °F
Electrical
Conductivity and insulation.
Electrical Conductivity
Electrical Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.5 V · Corrosion Resistance 45 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Formability (cold)
Castability
Brazeability / Solderability
Polishability
Same in both: Weldability 20 / 100
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Embodied Water
Typical Recycled Content
Common Calculations
Ratios derived from the values above.
Specific Stiffness (E / density)
Thermal Diffusivity
Same in both: Specific Strength (UTS / density) 3 kN·m/kg · Modulus of Resilience 8 kJ/m³ · Thermal Shock Resistance Index 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.
Manufacturing and finishing
| Capability | Pb65Sn35 | Pb78Sn20Sb2 |
|---|---|---|
| Default condition | — | — |
| Relative cost | $$$$ High | $$$$ High |
| Min. machined wall | — | — |
| Best machined surface | — | — |
Pb65Sn35 vs Pb78Sn20Sb2 — frequently asked
Is Pb65Sn35 stronger than Pb78Sn20Sb2?
Yes. Pb65Sn35 has a typical tensile strength of 33 MPa (4.79 ksi) against 31 MPa (4.5 ksi) for Pb78Sn20Sb2 — about 6% more.
Which is cheaper, Pb65Sn35 or Pb78Sn20Sb2?
Both sit in the same relative cost tier ($$$$, high); the part price will be decided by machining time, tolerance and quantity rather than by the material.
Which is easier to machine, Pb65Sn35 or Pb78Sn20Sb2?
Pb78Sn20Sb2. Its machinability rates fair (40/100) against poor (30/100) for Pb65Sn35.
Ready to make it?
Upload a CAD file and FabDigit prices the part in Pb65Sn35 and Pb78Sn20Sb2 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.