Solder & Low-Melting Alloy Pb78Sn20Sb2
ISO 9453-137
Pb78Sn20Sb2 is a high-lead, antimony-strengthened Sn-Pb solder intended for filling and seam work where creep resistance must exceed that of plain 20/80 (20 MPa yield, 31 MPa tensile, 45% elongation, 12 HB, service to 110 °C).
Reference datasheet — Pb78Sn20Sb2 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the Cast condition
Pb78Sn20Sb2 tempers and conditions
Pb78Sn20Sb2 is supplied in one standard condition, Cast. Cast is the default FabDigit quotes; the values on this page are for it.
Supply forms, finishes and certifications
Ways Pb78Sn20Sb2 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
CORED | Flux-cored wire | Supply form |
FOIL | Rolled foil / stamped preform | Supply form |
WIRE | Solid extruded wire | Supply form |
What is Pb78Sn20Sb2?
Pb78Sn20Sb2 is a high-lead, antimony-strengthened Sn-Pb solder intended for filling and seam work where creep resistance must exceed that of plain 20/80 (20 MPa yield, 31 MPa tensile, 45% elongation, 12 HB, service to 110 °C). It is used as body-filling and structural filler solder and is supplied cast, as wire, cored wire and foil. The wide pasty range of about 185–270 °C makes it easy to wipe and shape but requires an undisturbed freeze, strength is the lowest of the antimonial group, and the alloy is lead-bearing. Pb74Sn25Sb1 is the nearest grade when slightly better wetting is wanted. Pb78Sn20Sb2 has a density of 10.1 g/cm³ (0.365 lb/in³), heavier than 79% of solder & low-melting alloy grades. It melts at 185°C (365 °F). Pb78Sn20Sb2 has a yield strength of 20 MPa (2.9 ksi) and a tensile strength of 31 MPa (4.5 ksi) — weaker than 74% of solder & low-melting alloy grades. Elongation at break is 45% and the elastic modulus is 25 GPa (3.63 Msi).
What is Pb78Sn20Sb2 used for?
- auto body seam filling
- structural filling solder
- low-cost strengthened joints
Advantages
- Ductile — tolerates forming and impact — 45%, better than 84% of solder & low-melting alloy grades
- Polishes to a fine finish — 55/100, better than 77% of solder & low-melting alloy grades
- Low embodied carbon — 4.7 kg CO₂/kg, better than 75% of solder & low-melting alloy grades
Limitations
- Heavy — 10.1 g/cm³ (0.365 lb/in³), worse than 79% of solder & low-melting alloy grades
Pb78Sn20Sb2 properties
Typical room-temperature values for Pb78Sn20Sb2-Cast; bars are the position among solder & low-melting alloy grades.
Physical3
Pb78Sn20Sb2 has a density of 10.1 g/cm³ (0.365 lb/in³), heavier than 79% of solder & low-melting alloy grades. It melts at 185°C (365 °F).
Mechanical10
Pb78Sn20Sb2 has a yield strength of 20 MPa (2.9 ksi) and a tensile strength of 31 MPa (4.5 ksi) — weaker than 74% of solder & low-melting alloy grades. Elongation at break is 45% and the elastic modulus is 25 GPa (3.63 Msi).
Thermal6
Pb78Sn20Sb2 is rated for continuous service to 110°C (230 °F). It conducts heat at 38 W/m·K (22 BTU/hr·ft·°F), worse than 60% of solder & low-melting alloy grades. Thermal expansion is 27 µm/m·K (15 µin/in·°F).
Electrical3
Pb78Sn20Sb2 conducts electricity at 10 % IACS, better than 54% of solder & low-melting alloy grades.
Chemical & Environmental3
Corrosion resistance is fair (45/100), worse than 52% of solder & low-melting alloy grades.
Sustainability4
Producing a kilogram of Pb78Sn20Sb2 takes about 88 MJ of energy and emits 4.7 kg of CO₂ — less than 73% of solder & low-melting alloy grades. Typical recycled content is 60%.
Manufacturability7
Pb78Sn20Sb2's machinability is fair (40/100, better than 65% of solder & low-melting alloy grades); weldability poor (20/100); formability excellent (85/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the solder & low-melting alloy family
Yield strength against density for every solder & low-melting alloy grade FabDigit runs. Pb78Sn20Sb2 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Pb78Sn20Sb2
Is Pb78Sn20Sb2 easy to machine?
Extremely soft and gummy — use sharp high-rake tools, generous clearance and low cutting forces; parts are normally cast or extruded to shape instead of machined.
Can Pb78Sn20Sb2 be welded?
Not fusion-welded; joined by torch, iron or wave/pot soldering at 280–320 °C with an active flux, and joints can be re-melted for repair.
Can Pb78Sn20Sb2 be formed, bent or molded?
Wide pasty range (≈185–270 °C) makes it ideal for wiping and filling; keep the joint undisturbed through solidification to avoid hot-tear-like disturbed joints.
Pb78Sn20Sb2 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Sn | 19.5 – 20.5 | 20 |
| Sbantimonial strengthening addition | 1.8 – 2.4 | 2 |
| Biimpurity limit | ≤ 0.25 | |
| Cuimpurity limit | ≤ 0.08 | |
| Feimpurity limit | ≤ 0.02 | |
| Asimpurity limit | ≤ 0.03 | |
| Znimpurity limit | ≤ 0.01 | |
| Alimpurity limit | ≤ 0.01 | |
| Pbremainder, ≈78 % | balance |
What surface finishes work on Pb78Sn20Sb2?
Files, sands and buffs easily; neutralise and wash off flux residues, then prime/paint — the surface tarnishes and is not suitable for decorative bright plating without an intermediate layer.
Equivalent designations
Standards and trade names that resolve to Solder & Low-Melting Alloy Pb78Sn20Sb2 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- ISO
- 9453-137
How much does Pb78Sn20Sb2 cost?
Pb78Sn20Sb2 is a high-cost solder & low-melting alloy ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Pb78Sn20Sb2 — frequently asked
What is Pb78Sn20Sb2 used for?
Pb78Sn20Sb2 is typically used for auto body seam filling, structural filling solder and low-cost strengthened joints. In short: high-lead filling solder; widest pasty range for wiping; creep-resistant 20/80 substitute.
What is the yield strength of Pb78Sn20Sb2?
Pb78Sn20Sb2 has a typical yield strength of 20 MPa (2.9 ksi) and a tensile strength of 31 MPa (4.5 ksi) — weaker than 74% of solder & low-melting alloy grades.
Is Pb78Sn20Sb2 easy to machine?
Not especially — machinability is rated fair (40/100, better than 65% of solder & low-melting alloy grades). Extremely soft and gummy — use sharp high-rake tools, generous clearance and low cutting forces; parts are normally cast or extruded to shape instead of machined.
Can Pb78Sn20Sb2 be welded?
Not readily — weldability is rated poor (20/100). Not fusion-welded; joined by torch, iron or wave/pot soldering at 280–320 °C with an active flux, and joints can be re-melted for repair.
What surface finishes work on Pb78Sn20Sb2?
Files, sands and buffs easily; neutralise and wash off flux residues, then prime/paint — the surface tarnishes and is not suitable for decorative bright plating without an intermediate layer.
Can Pb78Sn20Sb2 be formed, bent or molded?
Wide pasty range (≈185–270 °C) makes it ideal for wiping and filling; keep the joint undisturbed through solidification to avoid hot-tear-like disturbed joints.
What is the maximum service temperature of Pb78Sn20Sb2?
Pb78Sn20Sb2 is rated for continuous use to about 110°C (230 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does Pb78Sn20Sb2 cost?
Pb78Sn20Sb2 is a high-cost solder & low-melting alloy ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- ASTM B32 — Standard Specification for Solder Metal — ASTM International (2020)
- GB/T 3131 (2020)
- ASM Handbook Vol. 6 — Welding, Brazing and Soldering (Solder Alloy Properties) — ASM International (1993)
- NIST Properties of Lead-Free / Lead-Bearing Solders database — NIST (2002)
- Sn20Pb80 antimonial body/plumbing solder datasheets — Indium Corporation / AIM Solder (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.