Solder & Low-Melting Alloy Sn40Pb60-SN40B
Grade
ASTM Sn40 · JIS H40A · GB HLSnPb40-60
SN40B = antimonial grade
Pick the antimonial grade (Sb 1.8–2.4 %) when you need 46 MPa strength, 15 HB hardness and suppression of low-temperature tin pest; do not use it on zinc-bearing or galvanized base metal.
Values for the SN40B condition
What is Sn40Pb60-SN40B?
Sn40Pb60-SN40B is Sn40Pb60 in the SN40B grade — pick the antimonial grade (Sb 1.8–2.4 %) when you need 46 MPa strength, 15 HB hardness and suppression of low-temperature tin pest; do not use it on zinc-bearing or galvanized base metal. Sn40Pb60-SN40B has a yield strength of 22 MPa (3.19 ksi) and a tensile strength of 46 MPa (6.67 ksi) — weaker than 70% of solder & low-melting alloy grades. Elongation at break is 35% and the elastic modulus is 25 GPa (3.63 Msi). Sn40Pb60-SN40B has a density of 9.29 g/cm³ (0.336 lb/in³), heavier than 62% of solder & low-melting alloy grades. It melts at 183°C (361 °F).
Sn40Pb60-SN40B properties
Typical room-temperature values for Sn40Pb60-SN40B; 6 are specific to this condition. Other listed values are Sn40Pb60 reference data and may not represent this condition. Bars are the position among solder & low-melting alloy grades.
Physical3
Sn40Pb60-SN40B has a density of 9.29 g/cm³ (0.336 lb/in³), heavier than 62% of solder & low-melting alloy grades. It melts at 183°C (361 °F).
Mechanical12
Sn40Pb60-SN40B has a yield strength of 22 MPa (3.19 ksi) and a tensile strength of 46 MPa (6.67 ksi) — weaker than 70% of solder & low-melting alloy grades. Elongation at break is 35% and the elastic modulus is 25 GPa (3.63 Msi).
Thermal6
Sn40Pb60-SN40B is rated for continuous service to 110°C (230 °F). It conducts heat at 44 W/m·K (25.4 BTU/hr·ft·°F), worse than 52% of solder & low-melting alloy grades. Thermal expansion is 24.5 µm/m·K (13.6 µin/in·°F).
Electrical3
Sn40Pb60-SN40B conducts electricity at 10.1 % IACS, better than 57% 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 Sn40Pb60-SN40B takes about 115 MJ of energy and emits 7.5 kg of CO₂ — less than 67% of solder & low-melting alloy grades. Typical recycled content is 50%.
Manufacturability6
Sn40Pb60-SN40B's machinability is fair (35/100, better than 58% of solder & low-melting alloy grades); formability excellent (95/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Sn40Pb60-SN40B
Is Sn40Pb60 easy to machine?
Extremely soft and prone to smearing on the tool — use sharp, large positive-rake tools, low speed and generous lubricant. Parts are normally cast, extruded or scraped to shape rather than cut.
Can Sn40Pb60 be welded?
Not fusion welded; the alloy is itself the filler. Join with iron, wave or dip soldering using activated rosin or organic-acid flux — it wets copper, brass and tin-plated steel, while aluminium requires a dedicated flux.
Can Sn40Pb60 be formed, bent or molded?
The wide 183–238 °C pasty region allows the alloy to be paddled and smoothed with a wooden float in the semi-molten state; at room temperature it extrudes into wire and rolls into foil with little effort.
What surface finishes work on Sn40Pb60?
Flux residues must be removed after soldering (IPA or water wash) to prevent corrosion. The surface can be painted or tin-lead plated for appearance; polishing gains little, and lead-bearing dust requires respiratory protection.
Sn40Pb60 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 |
|---|---|---|
| SnASTM B32 Sn40 / GB/T 3131 HLSnPb40-60 | 39.5 – 40.5 | 40 |
| SbSn40A grade; Sn40B grade is 1.8–2.4% | ≤ 0.12 | 0.05 |
| Bi | ≤ 0.1 | |
| Cu | ≤ 0.08 | |
| Ag | ≤ 0.02 | |
| As | ≤ 0.03 | |
| Fe | ≤ 0.02 | |
| Zn | ≤ 0.01 | |
| Al | ≤ 0.01 | |
| Cd | ≤ 0 | |
| Pbbalance, about 59.5–60.5% | balance |
Sn40Pb60-SN40B — frequently asked
What is Sn40Pb60-SN40B used for?
Sn40Pb60-SN40B is typically used for automotive body filler solder, wiped plumbing joints and general metal joining. In short: lead-rich body solder; very wide pasty range; shaped while semi-molten.
What is the yield strength of Sn40Pb60-SN40B?
Sn40Pb60-SN40B has a typical yield strength of 22 MPa (3.19 ksi) and a tensile strength of 46 MPa (6.67 ksi) — weaker than 70% of solder & low-melting alloy grades.
Is Sn40Pb60-SN40B easy to machine?
Not especially — machinability is rated fair (35/100, better than 58% of solder & low-melting alloy grades). Extremely soft and prone to smearing on the tool — use sharp, large positive-rake tools, low speed and generous lubricant. Parts are normally cast, extruded or scraped to shape rather than cut.
Can Sn40Pb60-SN40B be welded?
Not fusion welded; the alloy is itself the filler. Join with iron, wave or dip soldering using activated rosin or organic-acid flux — it wets copper, brass and tin-plated steel, while aluminium requires a dedicated flux.
What surface finishes work on Sn40Pb60-SN40B?
Flux residues must be removed after soldering (IPA or water wash) to prevent corrosion. The surface can be painted or tin-lead plated for appearance; polishing gains little, and lead-bearing dust requires respiratory protection.
Can Sn40Pb60-SN40B be formed, bent or molded?
The wide 183–238 °C pasty region allows the alloy to be paddled and smoothed with a wooden float in the semi-molten state; at room temperature it extrudes into wire and rolls into foil with little effort.
What is the maximum service temperature of Sn40Pb60-SN40B?
Sn40Pb60-SN40B 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.
Sources
- ASTM B32 Standard Specification for Solder Metal — ASTM International (2020)
- J-STD-006 Requirements for Electronic Grade Solder Alloys — IPC/JEDEC (2013)
- GB/T 3131 (2020)
- ASM Handbook Vol.3 Alloy Phase Diagrams / Vol.6 Welding, Brazing and Soldering — Solder Alloy Properties — ASM International (1993)
- Properties of Tin-Lead Solder Alloys, NIST/ITRI compilations — NIST / International Tin Research Institute (2002)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.