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Solder & Low-Melting Alloy Sn70Pb30-Sn70B

Grade

ASTM Sn70 · JIS H70A, Z3282 H70A · GB HLSnPb70-30

Sn70B = antimonial grade

Pick for slightly higher strength and creep resistance on plain copper/steel; avoid on zinc or cadmium coatings.

High cost $$$$
Request a quote in Sn70Pb30-Sn70BSn70Pb30 overview

Values for the Sn70B condition

Other Sn70Pb30 tempers and conditions

Sn70Pb30 is listed in 2 conditions; see the grade overview at Sn70Pb30.

Compare all 2 conditionsHide
Condition · open for datasheetBest forYield MPaTensile MPaElong. %HardnessConductivity
Sn70A
Low-antimony grade
Pick where antimony must be kept low (zinc/galvanized or cadmium-plated substrates, some electronics specs).30464014 HB12.3 % IACS
Sn70BThis page
Antimonial grade
Pick for slightly higher strength and creep resistance on plain copper/steel; avoid on zinc or cadmium coatings.35523216 HB11.8 % IACS

What is Sn70Pb30-Sn70B?

Sn70Pb30-Sn70B is Sn70Pb30 in the Sn70B grade — pick for slightly higher strength and creep resistance on plain copper/steel; avoid on zinc or cadmium coatings. Sn70Pb30-Sn70B has a yield strength of 35 MPa (5.08 ksi) and a tensile strength of 52 MPa (7.54 ksi) — stronger than 81% of solder & low-melting alloy grades. Elongation at break is 32% and the elastic modulus is 31 GPa (4.5 Msi). Sn70Pb30-Sn70B has a density of 8.17 g/cm³ (0.295 lb/in³), lighter than 59% of solder & low-melting alloy grades. It melts at 183°C (361 °F).

Advantages

  • High strength — 35 MPa (5.08 ksi), better than 81% of solder & low-melting alloy grades
  • High electrical conductivity — 11.8 % IACS, better than 78% of solder & low-melting alloy grades

Limitations

  • Difficult to weld — 10/100, worse than 94% of solder & low-melting alloy grades
  • Hard to polish — 20/100, worse than 88% of solder & low-melting alloy grades

Sn70Pb30-Sn70B properties

Typical room-temperature values for Sn70Pb30-Sn70B; 16 are specific to this condition. Other listed values are Sn70Pb30 reference data and may not represent this condition. Bars are the position among solder & low-melting alloy grades.

Physical3

Sn70Pb30-Sn70B has a density of 8.17 g/cm³ (0.295 lb/in³), lighter than 59% of solder & low-melting alloy grades. It melts at 183°C (361 °F).

Density8.17 g/cm³0.3 lb/in³
Melting Point (Solidus)183°C361 °F
Liquidus Temperature192°C378 °F

Mechanical10

Sn70Pb30-Sn70B has a yield strength of 35 MPa (5.08 ksi) and a tensile strength of 52 MPa (7.54 ksi) — stronger than 81% of solder & low-melting alloy grades. Elongation at break is 32% and the elastic modulus is 31 GPa (4.5 Msi).

Elastic (Young's) Modulus31 GPa4.5 Msi
Shear Modulus11 GPa1.6 Msi
Bulk Modulus45 GPa6.5 Msi
Poisson's Ratio0.39
Tensile Strength (Ultimate)52 MPa7.5 ksi
Yield Strength (0.2% offset)35 MPa5.1 ksi
Elongation at Break32%
Shear Strength38 MPa5.5 ksi
Fatigue Strength (Endurance Limit)23 MPa3.3 ksi
Hardness, Brinell16 HB

Thermal6

Sn70Pb30-Sn70B is rated for continuous service to 110°C (230 °F). It conducts heat at 50 W/m·K (28.9 BTU/hr·ft·°F), better than 63% of solder & low-melting alloy grades. Thermal expansion is 24 µm/m·K (13.3 µin/in·°F).

Thermal Conductivity50 W/m·K28.9 BTU/hr·ft·°F
Specific Heat Capacity180 J/kg·K0.04 BTU/lb·°F
Thermal Expansion (CTE, 20–100 °C)24 µm/m·K13.3 µin/in·°F
Latent Heat of Fusion45 J/g19.3 BTU/lb
Max Service Temperature (continuous)110°C230 °F
Min Service Temperature-55°C-67 °F

Electrical3

Sn70Pb30-Sn70B conducts electricity at 11.8 % IACS, better than 78% of solder & low-melting alloy grades.

Electrical Conductivity11.8 % IACS
Electrical Resistivity1.46×10⁻⁷ Ω·m5.75 µΩ·in
Magnetic Responsenon-magnetic

Chemical & Environmental3

Corrosion resistance is fair (38/100), worse than 90% of solder & low-melting alloy grades.

Galvanic Potential (seawater, vs SCE)-0.5 V
Corrosion ResistanceFair38/100
Chemical Resistance SummaryStable in dry air and neutral water; attacked by organic acids, chlorides and flux residues (white corrosion), and rapidly by nitric/acetic acid. Lead leaching bars potable-water and food contact.

Sustainability4

Producing a kilogram of Sn70Pb30-Sn70B takes about 190 MJ of energy and emits 12 kg of CO₂ — more than 50% of solder & low-melting alloy grades. Typical recycled content is 30%.

Embodied Energy (primary production)190 MJ/kg81,685 BTU/lb
Embodied Carbon (primary production)12 kg CO₂/kg
Embodied Water300 L/kg35.9 gal/lb
Typical Recycled Content30%

Manufacturability6

Sn70Pb30-Sn70B's machinability is poor (32/100, better than 53% of solder & low-melting alloy grades); weldability not recommended (10/100); formability excellent (88/100).

MachinabilityPoor32/100
WeldabilityNot recommended10/100
Formability (cold)Excellent88/100
CastabilityExcellent90/100
Brazeability / SolderabilityExcellent98/100
PolishabilityPoor20/100

Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.

Working with Sn70Pb30-Sn70B

Is Sn70Pb30 easy to machine?

Very soft and gummy — use sharp high-rake tools, high speed, low feed and paraffin/kerosene lube; parts smear and load abrasives, so cast or extrude to shape instead.

Can Sn70Pb30 be welded?

Not arc-weldable; joints are made by remelting the solder itself (iron, wave, dip or reflow) at 230–260 °C with rosin or activated flux.

Can Sn70Pb30 be formed, bent or molded?

Freely extruded into wire and rolled into foil at room temperature; casts easily into bars/ingots at 250–280 °C — avoid moving joints while in the 183–192 °C pasty range or fillets become grainy and disturbed.

What surface finishes work on Sn70Pb30?

No plating or anodizing; keep flux residues cleaned off (saponifier or IPA) to prevent white corrosion, and handle as a lead-bearing material with RoHS/potable-water restrictions.

Sn70Pb30 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.

ElementSpec limit (wt %)Nominal
Sntin, primary constituent69.5 – 71.570
Sb0.20–0.50 % in the antimonial 'B' grade≤ 0.120.05
Cuimpurity limit≤ 0.080.03
Biimpurity limit≤ 0.250.05
Asimpurity limit≤ 0.030.01
Feimpurity limit≤ 0.020.01
Znimpurity limit — degrades wetting≤ 0.010
Alimpurity limit — degrades wetting≤ 0.010
Cdimpurity limit≤ 0.010
Agimpurity limit≤ 0.050.01
Pbbalance—

Sn70Pb30-Sn70B — frequently asked

What is Sn70Pb30-Sn70B used for?

Sn70Pb30-Sn70B is typically used for general purpose soldering, sheet metal joining and radiator repair. In short: tin-rich Sn-Pb solder; wider pasty range than eutectic; good wetting on oxidised surfaces.

What is the yield strength of Sn70Pb30-Sn70B?

Sn70Pb30-Sn70B has a typical yield strength of 35 MPa (5.08 ksi) and a tensile strength of 52 MPa (7.54 ksi) — stronger than 81% of solder & low-melting alloy grades. Strength varies by condition: see the 2 listed tempers.

Is Sn70Pb30-Sn70B easy to machine?

Not especially — machinability is rated poor (32/100, better than 53% of solder & low-melting alloy grades). Very soft and gummy — use sharp high-rake tools, high speed, low feed and paraffin/kerosene lube; parts smear and load abrasives, so cast or extrude to shape instead.

Can Sn70Pb30-Sn70B be welded?

Not readily — weldability is rated not recommended (10/100). Not arc-weldable; joints are made by remelting the solder itself (iron, wave, dip or reflow) at 230–260 °C with rosin or activated flux.

What surface finishes work on Sn70Pb30-Sn70B?

No plating or anodizing; keep flux residues cleaned off (saponifier or IPA) to prevent white corrosion, and handle as a lead-bearing material with RoHS/potable-water restrictions.

Can Sn70Pb30-Sn70B be formed, bent or molded?

Freely extruded into wire and rolled into foil at room temperature; casts easily into bars/ingots at 250–280 °C — avoid moving joints while in the 183–192 °C pasty range or fillets become grainy and disturbed.

What is the maximum service temperature of Sn70Pb30-Sn70B?

Sn70Pb30-Sn70B 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

  1. ASTM B32 — Standard Specification for Solder Metal — ASTM International (2020)
  2. J-STD-006 — Requirements for Electronic Grade Solder Alloys — IPC (2013)
  3. JIS Z 3282 — Soft solders (H70A) — JSA (2017)
  4. GB/T 3131 — (HLSnPb70-30) (2020)
  5. ASM Handbook Vol. 3 — Alloy Phase Diagrams (Sn-Pb) — ASM International (1992)
  6. ASM Handbook Vol. 2 — Properties of Solders and Low-Melting Alloys — ASM International (1990)
  7. Sn-Pb solder alloy data (bar, wire, paste) — AIM Solder / Indium Corporation (2023)

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.