Lead alloys other than antimonial lead (Pb-Sn-Ag, Pb-Sn-Sb, Pb-Bi, Pb-Se) Pb alloys

spore: profile
id: lead-solder-alloys
spore_version: 0.2
family: low-melting-metals-and-solders
name: Lead alloys other than antimonial lead (Pb-Sn-Ag, Pb-Sn-Sb, Pb-Bi, Pb-Se)
abbreviation: Pb alloys
role: lead-bearing solders (Pb-Sn-Ag, Pb-Ag-Sn, Pb-Sn-Sb), a lead-bismuth eutectic coolant alloy, and lead selenide
category: metals
type: heavy-metals
summary: |
  This profile covers the lead alloys that are not lead-antimony and not the plain tin-lead solders. Sn62/Pb36/Ag2 is a eutectic solder that AIM lists at 179 degC. The Pb-97.5/Ag-1.5/Sn-1 high-temperature solder is printed by two suppliers with a solidus and liquidus both at 309 degC. A Sn60/Pb39/Sb1 solder carries a melting range of about 183 to 190 degC and about 50 W/m K conductivity. Lead-bismuth eutectic is 44.5 % lead and 55.5 % bismuth (Wikipedia). Lead selenide is a rock-salt compound with a density of 8100 kg/m3 and a melting point of 1078 degC (WebElements). Every lead alloy in this group is toxic: the US NIOSH limit is 0.050 mg/m3 as an eight-hour average for lead. The tin-lead solders are described in solder-sn-pb, and antimonial lead is described in antimonial-lead.
best_for: Solder joints that need a single, defined melting point and a high-temperature joint (the Pb-Ag-Sn alloy melts at 309 degC), where RoHS compliance is not required
weakest_at: Lead toxicity and the regulatory limits that follow from it, and the lack of a sourced lead-bismuth density or melting point in this profile; pure-tin finishes that replace these solders grow tin whiskers
identity:
  formula: Sn62/Pb36/Ag2 solder (62 % tin, 36 % lead, 2 % silver by weight); Pb97.5Ag1.5Sn1 solder (97.5 % lead, 1.5 % silver, 1 % tin by weight, as printed by Lucas-Milhaupt); Sn60/Pb39/Sb1 solder (about 60 % tin, 39 % lead, 1 % antimony); Pb-Bi eutectic (44.5 % lead, 55.5 % bismuth); PbSe (lead selenide, one lead and one selenium per formula unit)
  source: aim-sn62
  where: Sn62/Pb36/Ag2 Typical Alloy Composition block (Sn 62.0, Pb 36.0, Ag 2.0); Pb-Ag-Sn composition from Lucas-Milhaupt Nominal Composition line; Sn60/Pb39/Sb1 from the Goodfellow page; Pb-Bi from the Wikipedia introduction; PbSe from the WebElements page
tags:
  environments: []
  stresses: []
  applications:
    - electronics-and-chips
properties:
  - benchmark: melting_point
    label: Melting point, Sn62/Pb36/Ag2 eutectic (AIM)
    value: 179
    unit: °C
    scope: material
    conditions:
      alloy: Sn62/Pb36/Ag2
      basis: eutectic, one melting point printed
    method: Value printed on a manufacturer data sheet
    status: ground
    source: aim-sn62
    where: 'Features: Liquidus 179°C (354°F); Description: eutectic alloy with a melting point of 179°C; Typical Melting Temperature block'
  - benchmark: melting_point
    label: Melting range, Sn62Pb36Ag02 (Kester table)
    value: 179
    value_high: 189
    bound: range
    unit: °C
    scope: material
    conditions:
      alloy: Sn62Pb36Ag02 as printed in the Kester table
      basis: solidus and liquidus columns
    method: Value printed in a soft-solder property table (Kester, 2005 copy)
    status: ground
    note: The Kester table gives a liquidus 10 degC above the AIM eutectic figure for the row it prints as Sn62Pb36Ag02. The range is kept as printed, and the AIM eutectic figure is the one used in the summary.
    source: kester
    where: 'Table row Sn62Pb36Ag02: solidus 179 C, liquidus 189 C (columns ''Solidus'' and ''Liquidus'', degC)'
  - benchmark: melting_point
    label: Solidus and liquidus, Pb97.5Ag1.5Sn1 (Lucas-Milhaupt)
    value: 309
    unit: °C
    scope: material
    conditions:
      alloy: 'Pb97.5Ag1.5Sn1 as printed by the supplier (Nominal Composition: Lead 97.50, Silver 1.50, Tin 1.00)'
      basis: solidus and liquidus both printed as 309 degC (588 degF), so the alloy behaves as a eutectic
    method: Value printed on a supplier product page
    status: ground
    source: lucas-pb-ag
    where: Solidus and Liquidus lines (both 588 °F, 309 °C)
  - benchmark: max_brazing_temperature
    label: Maximum recommended brazing temperature, Pb97.5Ag1.5Sn1
    value: 364
    unit: °C
    scope: material
    conditions:
      alloy: Pb97.5Ag1.5Sn1 as printed by the supplier
      basis: supplier's maximum recommended brazing temperature
    method: Value printed on a supplier product page (the name is not in property-canon; it is a supplier-specific temperature)
    status: ground
    source: lucas-pb-ag
    where: Max Recommended Brazing Temperature line (688 °F, 364 °C)
  - benchmark: density
    label: Specific gravity, Pb97.5Ag1.5Sn1 (Kester table)
    value: 11.28
    unit: '-'
    scope: material
    conditions:
      alloy: Sn1Pb97.5Ag1.5 as printed in the Kester table
      basis: Specific Gravity column (no unit printed; the number is a pure ratio)
    method: Value printed in a soft-solder property table
    status: ground
    source: kester
    where: 'Table row Sn1Pb97.5Ag1.5: Specific Gravity column (11.28)'
  - benchmark: density
    label: Density, Sn63/Pb37 eutectic (AIM)
    value: 8.4
    unit: g/cm3
    scope: material
    conditions:
      alloy: Sn63/Pb37 eutectic
      temperature: not stated on the sheet
    method: Value printed on a manufacturer data sheet (the sheet also prints 0.303 lb/in3)
    status: ground
    source: aimtek-6337
    where: 'Density line: 0.303 lb./in³ (8.40 g/cm³)'
  - benchmark: density
    label: Density, Sn60/Pb40 (AIM)
    value: 8.49
    unit: g/cm3
    scope: material
    conditions:
      alloy: Sn60/Pb40 nominal composition
      temperature: not stated on the sheet
    method: Value printed on a manufacturer data sheet (the sheet also prints 0.3068 lb/in3)
    status: ground
    source: aimtek-6040
    where: 'Density line: 0.3068 lb./in³ (8.49 g/cm³)'
  - benchmark: density
    label: Specific weight, Sn60/Pb40 cored wire (Cynel-Unipress)
    value: 8.5
    unit: g/cm3
    scope: material
    conditions:
      alloy: Sn60Pb40 (ISO 9453 designation)
      basis: printed as approximately 8,50 g/cm3 on the sheet; written here as 8.5 with the approximate sign dropped
    method: Value printed on a manufacturer data sheet
    status: ground
    source: cynel-sn60pb40
    where: Section 2.6 Specific weight (approximately 8,50 g/cm3)
  - benchmark: density
    label: Density, PbSe (lead selenide)
    value: 8100
    unit: kg/m3
    scope: material
    conditions:
      compound: PbSe, rock-salt structure
      temperature: not stated on the page
    method: Value printed on a reference database page
    status: ground
    source: webelements-pbse
    where: 'Density: 8100 kg m-3 line'
  - benchmark: melting_point
    label: Melting point, PbSe (lead selenide)
    value: 1078
    unit: °C
    scope: material
    conditions:
      compound: PbSe, rock-salt structure
    method: Value printed on a reference database page
    status: ground
    note: A second database lists 1088 degC, which this profile does not use because that page was not opened in this run.
    source: webelements-pbse
    where: 'Melting point: 1078°C line'
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, Sn63/Pb37 eutectic (AIM)
    value: 43
    unit: MPa
    scope: material
    conditions:
      alloy: Sn63/Pb37 eutectic
      product_form: not stated on the sheet
      test_method: not stated on the sheet
    method: Value printed on a manufacturer data sheet (the sheet prints 6240 psi)
    status: ground
    note: The sheet does not name the test standard, product form or temper, so treat it as indicative.
    source: aimtek-6337
    where: 'Tensile Strength block: 6240 psi (43 MPa)'
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, Sn60/Pb40 (AIM)
    value: 44.13
    unit: MPa
    scope: material
    conditions:
      alloy: Sn60/Pb40 nominal composition
      product_form: not stated on the sheet
      test_method: not stated on the sheet
    method: Value printed on a manufacturer data sheet (the sheet prints 6400 psi)
    status: ground
    note: The Cynel sheet gives 535 kg/cm2 for the same alloy in a different product form (cored wire). The two sheets do not state the test method, so the difference is not resolved here.
    source: aimtek-6040
    where: 'Tensile Strength block: 6400 psi (44.13 MPa)'
  - benchmark: ultimate_tensile_strength
    label: Tensile strength at break, Sn60/Pb40 cored wire (Cynel-Unipress)
    value: 535
    unit: kg/cm2
    scope: material
    conditions:
      alloy: Sn60Pb40 (ISO 9453 designation)
      product_form: cored solder wire
      test_method: not stated on the sheet
    method: Value printed on a manufacturer data sheet in the unit the sheet uses
    status: ground
    source: cynel-sn60pb40
    where: 'Section 2.9: Tensile strength at break 535 kg/cm2'
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, Pb97.5Ag1.5Sn1 (Kester table)
    value: 3600
    unit: psi
    scope: material
    conditions:
      alloy: Sn1Pb97.5Ag1.5 as printed in the Kester table
      test_method: not stated in the table
    method: Value printed in a soft-solder property table (Tensile Strength PSI column)
    status: ground
    source: kester
    where: 'Table row Sn1Pb97.5Ag1.5: Tensile Strength PSI column (3600)'
  - benchmark: elongation
    label: Elongation at break, Sn60/Pb40 cored wire (Cynel-Unipress)
    value: 40
    unit: '%'
    scope: material
    conditions:
      alloy: Sn60Pb40 (ISO 9453 designation)
      product_form: cored solder wire
      test_method: not stated on the sheet
    method: Value printed on a manufacturer data sheet
    status: ground
    source: cynel-sn60pb40
    where: 'Section 2.10: Elongation at break 40%'
  - benchmark: thermal_conductivity
    label: Thermal conductivity, Sn60/Pb40 cored wire (Cynel-Unipress)
    value: 49
    unit: W/m·K
    scope: material
    conditions:
      alloy: Sn60Pb40 (ISO 9453 designation)
      temperature: not stated on the sheet
    method: Value printed on a manufacturer data sheet
    status: ground
    source: cynel-sn60pb40
    where: 'Section 2.8: Thermal conductivity 49 W/m·K'
  - benchmark: thermal_conductivity
    label: Thermal conductivity, Sn60/Pb39/Sb1 (Goodfellow)
    value: 50
    unit: W/m·K
    scope: material
    conditions:
      alloy: Sn60/Pb39/Sb1 as printed by the supplier
      basis: printed as around 50 W/m·K (approximate)
    method: Approximate value printed on a materials information page
    status: ground
    source: goodfellow-pbsnsb
    where: Electrical and thermal properties paragraph (around 50 W/m·K)
  - benchmark: electrical_resistivity
    label: Electrical resistivity, Sn63/Pb37 eutectic (AIM)
    value: 0.0000145
    unit: ohm-cm
    scope: material
    conditions:
      alloy: Sn63/Pb37 eutectic
      temperature: not stated on the sheet
    method: Value printed on a manufacturer data sheet (printed as 1.45 x 10 -5 ohm-cm; written in decimal form)
    status: ground
    source: aimtek-6337
    where: 'Electrical Resistivity line: 1.45 x 10 -5 ohm-cm'
  - benchmark: electrical_resistivity
    label: Electrical resistivity, Sn60/Pb39/Sb1 (Goodfellow)
    value: 12
    value_high: 14
    bound: range
    unit: μΩ·cm
    scope: material
    conditions:
      alloy: Sn60/Pb39/Sb1 as printed by the supplier
      temperature: not stated
    method: Range printed on a materials information page
    status: ground
    source: goodfellow-pbsnsb
    where: Electrical and thermal properties paragraph (12–14 μΩ·cm)
  - benchmark: melting_point
    label: Melting range, Sn60/Pb39/Sb1 (Goodfellow)
    value: 183
    value_high: 190
    bound: range
    unit: °C
    scope: material
    conditions:
      alloy: Sn60/Pb39/Sb1 as printed by the supplier
      basis: eutectic temperature printed as around 183 to 190 degC, described as a narrow melting range
    method: Range printed on a materials information page
    status: ground
    note: A search listing for a different Pb-Sn-Sb solder (about 27.5 Sn, 71 Pb, 1.5 Sb) gives a 188 to 250 degC range. That listing was not opened in this run, so it is not used.
    source: goodfellow-pbsnsb
    where: Melting or eutectic temperature paragraph ('around 183–190 °C', 'a narrow melting range')
  - benchmark: melting_point
    label: Melting range, Sn60/Pb40 cored wire (Cynel-Unipress)
    value: 183
    value_high: 190
    bound: range
    unit: °C
    scope: material
    conditions:
      alloy: Sn60Pb40 (ISO 9453 designation)
      product_form: cored solder wire
    method: Range printed on a manufacturer data sheet (solidus/liquidus)
    status: ground
    source: cynel-sn60pb40
    where: 'Section 2.5: Melting point (solidus/liquidus) 183/190 °C'
  - benchmark: melting_point
    label: Melting range, Sn60/Pb40 (AIM)
    value: 183
    value_high: 191
    bound: range
    unit: °C
    scope: material
    conditions:
      alloy: Sn60/Pb40 nominal composition
    method: Range printed on a manufacturer data sheet (solidus and liquidus)
    status: ground
    source: aimtek-6040
    where: 'Melting Temperature block: Solidus (Flow point) 361°F (183°C); Liquidus (Melt point) 376°F (191°C)'
corrosion:
  - environment: Humid heat, 85 °C and 85 % relative humidity, no applied voltage, up to 1000 hours (tin corrosion under QFN packages on solder-paste boards)
    headline: In an 85 °C and 85 % humidity test the 63/37 paste did not show the tin-corrosion failure seen with SAC305, which corroded faster.
    effect: A Cookson Electronics and MSLCircuits study found tin corrosion products under QFN and large passive parts after 500 hours. The authors say flux chemistry had the greatest effect and that SAC305 corroded faster than 63Sn37Pb. Reflow conditions had almost no effect. The failure was not seen with the 63/37 paste used.
    rating: low
    conditions:
      exposure: 85 °C and 85 % RH, no applied voltage, readings at 250, 500, 750 and 1000 hours
      comparison: SAC305 solder pastes on the same boards
      flux: three solder-paste flux chemistries
    source: cookson-2010
    where: Executive Summary; Introduction (63/37 paste bullet); Summary of MSLCircuits failure analysis
  - environment: Pure tin plating with no lead, such as connector pins and relays in space hardware
    headline: Tin-lead solder is the only method the Aerospace Corporation review found to stop tin whiskers consistently.
    effect: The review states that the only consistently demonstrated method of precluding tin whiskers is a minimum percentage of lead in the solder. A tin whisker can short two conductors at low voltage and high impedance; a short stays in place unless the current is high enough to fuse the whisker, generally more than 50 mA.
    rating: moderate
    conditions:
      basis: literature review of tin-whisker mechanisms and mitigation; not a corrosion test of the solder itself
    source: barr2007
    where: Section 1 (lead as the mitigation); Section 2 (short-circuit text)
risks:
  hazards:
    - text: Lead is toxic. The NIOSH pocket guide gives a time-weighted average limit of 0.050 mg/m3 (8 hours) and an IDLH of 100 mg/m3 as Pb. Exposure can be by inhalation, ingestion, and skin or eye contact.
      ghs: []
      source: niosh-lead
      where: Exposure limits and exposure routes; Target Organs line (blood, central nervous system, kidneys among others)
    - text: The OSHA permissible exposure limit for lead is a time-weighted average of 0.050 mg/m3, which matches the NIOSH recommended limit.
      ghs: []
      source: niosh-lead
      where: OSHA PEL line (1910.1025, TWA 0.050 mg/m3)
    - text: The Sn60/Pb40 wire is classed as a professional-use product because of its lead content and cannot be sold to private consumers. The sheet does not state a GHS classification.
      ghs: []
      source: cynel-sn60pb40
      where: Section 1 (General characteristics)
    - text: Use with adequate ventilation and proper personal protective equipment. Do not dispose of hazardous materials in non-approved containers.
      ghs: []
      source: aim-sn62
      where: Safety block
  failure_risks:
    - mode: Tin whisker short circuit on pure tin plating (the failure that lead in solder prevents)
      trigger: Pure tin plating with no lead, over time, with stress or in closely spaced circuits
      consequence: Whiskers can short neighbouring conductors. The review says a short can stay in place indefinitely unless the current is high enough to fuse the whisker, generally more than 50 mA.
      severity: moderate
      source: barr2007
      where: Section 2 (Problems metal whiskers can cause)
    - mode: Lead-free parts entering aerospace assemblies
      trigger: Exemptions for high-reliability aerospace electronics that do not cover parts the supplier changed to lead-free without a new part number
      consequence: The NASA review says the exemptions will not protect these assemblies from the introduction of lead-free parts, and that some suppliers switch to lead-free without changing part numbers or serial numbers.
      severity: moderate
      source: nasa-bok-2005
      where: Introduction, paragraph on exemptions and part identification
  side_effects:
    - text: Flux residues from the cored wire may remain on the joint after soldering. The sheet says they need not be removed, and recommends alcohol-based solvents if washing is needed.
      affects: The soldered surface
      source: cynel-sn60pb40
      where: Section 3 (SW26 flux)
  handling:
    - text: Store at room temperature in a dry place, out of reach of children.
      source: cynel-sn60pb40
      where: Section 4.5 (Storage)
    - text: Recommended soldering tip temperature is 340 to 400 °C for the Sn60/Pb40 cored wire.
      source: cynel-sn60pb40
      where: Section 2.12
    - text: Use with adequate ventilation and proper personal protective equipment. Refer to the safety data sheet for emergency information.
      source: aim-sn62
      where: Safety block
  mitigations:
    - text: Specify a tin-lead alloy rather than pure tin plating where whisker growth matters. The Aerospace Corporation review calls a minimum lead content the only consistently demonstrated whisker preventer.
      source: barr2007
      where: Abstract and Section 1
supply:
  - subject: Tin
    producers:
      - country: China
        thousand_t: 71
        year: 2025
      - country: Indonesia
        thousand_t: 61
        year: 2025
      - country: Peru
        thousand_t: 33
        year: 2025
      - country: Brazil
        thousand_t: 28
        year: 2025
      - country: Congo (Kinshasa)
        thousand_t: 27
        year: 2025
    world_total: 290,000 t of tin content (2025e, rounded), as printed
    critical_lists: []
    recycling: 'USGS: about 17,000 tons of tin from old and new scrap was recycled in 2025. Tin has not been mined or smelted in the United States since 1993.'
    substitutes:
      - 'USGS: epoxy resins for solder; other substitutes listed are for cans, bronze, bearing metals and some chemicals.'
    source: usgs-mcs2026-tin
    where: Domestic Production and Use; Recycling; World Mine Production and Reserves table (2025e, metric tons of tin content); Substitutes
  - subject: Lead
    producers:
      - country: China
        thousand_t: 1900
        year: 2025
      - country: Australia
        thousand_t: 480
        year: 2025
      - country: Peru
        thousand_t: 290
        year: 2025
      - country: Russia
        thousand_t: 260
        year: 2025
      - country: India
        thousand_t: 220
        year: 2025
    world_total: 4,500 thousand t of lead content (2025e, rounded), as printed
    critical_lists:
      - list: USGS 2025 List of Critical Minerals (lead added in the 2025 list)
        listed: true
    recycling: 'USGS: an estimated 1 million tons of secondary lead was produced in 2025, equal to 70% of apparent domestic consumption, nearly all from old scrap, mostly lead-acid batteries.'
    substitutes:
      - 'USGS: tin has replaced lead in solder for potable water systems, and the electronics industry has moved toward lead-free solders.'
    source: usgs-mcs2026-lead
    where: Events, Trends and Issues (critical-list paragraph); World Mine Production and Reserves table (2025e, thousand metric tons of lead content); Recycling; Substitutes
media: []
documents:
  - title: Sn62/Pb36/Ag2 solder alloy technical data sheet (AIM)
    type: datasheet
    url: https://aimsolder.com/wp-content/uploads/legacy-files/alloy_sn62-pb36-ag2_tds.pdf
  - title: AIMTEK High Purity 63% Tin/37% Lead Solder data sheet
    type: datasheet
    url: https://aimtek.com/wp-content/uploads/2022/08/Aimtek-63-37-Tin-Lead-Solder-Technical-Data-Sheet.pdf
    year: 2022
  - title: AIMTEK 60% Tin/40% Lead Solder data sheet
    type: datasheet
    url: https://aimtek.com/wp-content/uploads/2022/08/Aimtek-60-40-Tin-Lead-Solder-Technical-Data-Sheet.pdf
    year: 2022
  - title: Cynel-Unipress technical data sheet, Sn60Pb40 cored solder wire (ISO 9453)
    type: datasheet
    url: https://ormix.lv/lv/catalog/showpdf/name/68ac979d42cb80508f9a5c4e8896ef9c.pdf
    year: 2022
  - title: Technical Data on Soft Solders (Kester alloy property table)
    type: datasheet
    url: https://hallaweb.jlab.org/tech/Detectors/public_html/manuals/data_sheets-manuals/J-L/K/kester/Alloy%2520Properties%2520(08Dec05).pdf
    year: 2005
  - title: Lucas-Milhaupt product page, 97.5Pb1.5Ag1Sn solder
    type: datasheet
    url: https://www.lucasmilhaupt.com/EN/Products/97.5Pb1.5Ag1Sn.htm
  - title: Mitigating and Preventing the Growth of Tin and Other Metal Whiskers on Critical Hardware (The Aerospace Corporation)
    type: paper
    url: https://nepp.nasa.gov/whisker./reference/tech_papers/2007-barr-paper-mitigating-whiskers.pdf
    year: 2007
  - title: Tin Corrosion under QFN Packages at Elevated Temperature and Humidity (Cookson / MSLCircuits)
    type: paper
    url: https://www.electronics.org/system/files/technical_resource/E11%26S04_02.pdf
    year: 2010
  - title: 'Lead-Free Soldering for Space Applications: Lead-Free Solder Body of Knowledge (NASA)'
    type: report
    url: https://xdevs.com/doc/NASA/lead-free%20solder%20bok%20report%206-21-%202005.pdf
    year: 2005
  - title: 'NIOSH Pocket Guide to Chemical Hazards: Lead'
    type: database
    url: https://www.cdc.gov/niosh/npg/npgd0368.html
  - title: 'USGS Mineral Commodity Summaries 2026: Lead'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-lead.pdf
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Tin'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-tin.pdf
    year: 2026
  - title: 'WebElements: lead selenide (compound data)'
    type: database
    url: https://webelements.co.uk/compounds/lead/lead_selenide.html
  - title: 'Goodfellow: Tin/Lead/Antimony alloy material information'
    type: datasheet
    url: https://www.goodfellow.com/usa/resources/tin-lead-antimony-alloy-material-information/
gaps:
  - 'Lead-bismuth eutectic melting point and density: not found in a source opened in this run. The OECD NEA handbook page returned HTTP 403, the Argonne LBE property page is blocked by a bot check, and the open Pb-Bi density paper (ISU) could not be reached. Wikipedia gives composition and a melting point, but the brief limits Wikipedia to composition and history, so no LBE property is recorded.'
  - The Pb-Bi composition percentages come from Wikipedia, which does not state whether they are atomic or weight percentages.
  - '1.5Sn-97.5Pb-1Ag as requested: the sources printed the alloy as 97.5Pb/1.5Ag/1Sn (Lucas-Milhaupt and Kester). The request''s silver and tin values were not found in a source, so the printed composition is recorded.'
  - 'Sn62/Pb36/Ag2: no density, tensile strength or elongation was found in a source opened in this run. The Kester table row for this alloy prints a specific-gravity value that does not fit a tin-lead solder, so it was not used.'
  - 'Pb-Sn-Sb: only one source was opened (Goodfellow, a reseller). It gives composition and a range but no density or mechanical numbers. A search listing for another Pb-Sn-Sb solder was not opened and is not used.'
  - 'Lead selenide: density and melting point come from one database page (WebElements). No corrosion, hazard or supply data for PbSe were found in a source opened in this run, and no GHS classification was checked.'
  - Maximum recommended brazing temperature for the Pb-Ag-Sn alloy is recorded under a supplier-specific name (max_brazing_temperature), not a property in spores/property-canon.yaml.
  - 'Tin supply: the USGS 2026 tin summary read in this run did not mention a critical-minerals list, so critical_lists is empty for tin. Bismuth and selenium supply (including the critical-mineral status of each) were not checked.'
  - No UNS, EN, AMS or ASTM designation for the Pb-Ag-Sn, Pb-Sn-Sb, Pb-Bi or PbSe grades was printed in a source read in this run; designations are left out. No ASTM or other designation for Sn62/Pb36/Ag2 was printed in a source read in this run.
  - Hazard data rest on the NIOSH page and the supplier safety statements. No PubChem or SDS GHS classification was read for the lead alloys or PbSe in this run.
sources:
  aim-sn62:
    title: AIM Sn62/Pb36/Ag2 solder alloy technical data sheet
    id: AIM Electropure, document rev NF4
    url: https://aimsolder.com/wp-content/uploads/legacy-files/alloy_sn62-pb36-ag2_tds.pdf
    kind: datasheet
    license: supplier document, linked not reproduced
  aimtek-6337:
    title: AIMTEK High Purity 63% Tin/37% Lead Solder data sheet
    id: AIMTEK, Inc., Auburn MA
    url: https://aimtek.com/wp-content/uploads/2022/08/Aimtek-63-37-Tin-Lead-Solder-Technical-Data-Sheet.pdf
    year: 2022
    kind: datasheet
    license: supplier document, linked not reproduced
  aimtek-6040:
    title: AIMTEK 60% Tin/40% Lead Solder data sheet
    id: AIMTEK, Inc., Auburn MA
    url: https://aimtek.com/wp-content/uploads/2022/08/Aimtek-60-40-Tin-Lead-Solder-Technical-Data-Sheet.pdf
    year: 2022
    kind: datasheet
    license: supplier document, linked not reproduced
  cynel-sn60pb40:
    title: Cynel-Unipress technical data sheet, Sn60Pb40 cored solder wire with SW26 flux
    id: Cynel-Unipress Sp. z o.o., Warsaw; ISO 9453:2014
    url: https://ormix.lv/lv/catalog/showpdf/name/68ac979d42cb80508f9a5c4e8896ef9c.pdf
    year: 2022
    kind: datasheet
    license: supplier document, linked not reproduced
  kester:
    title: Technical Data on Soft Solders (Kester alloy property table)
    id: Kester, soft solder alloy properties table (copy dated 08 Dec 2005)
    url: https://hallaweb.jlab.org/tech/Detectors/public_html/manuals/data_sheets-manuals/J-L/K/kester/Alloy%2520Properties%2520(08Dec05).pdf
    year: 2005
    kind: datasheet
    license: manufacturer table, linked not reproduced
  lucas-pb-ag:
    title: Lucas-Milhaupt product page, 97.5Pb1.5Ag1Sn solder
    id: Lucas-Milhaupt
    url: https://www.lucasmilhaupt.com/EN/Products/97.5Pb1.5Ag1Sn.htm
    kind: datasheet
    license: supplier page, linked not reproduced
  goodfellow-pbsnsb:
    title: 'Goodfellow: Tin/Lead/Antimony alloy material information'
    id: Goodfellow Metals
    url: https://www.goodfellow.com/usa/resources/tin-lead-antimony-alloy-material-information/
    kind: web
    license: supplier page, linked not reproduced
  webelements-pbse:
    title: 'WebElements: lead selenide (compound data)'
    id: WebElements, University of Sheffield
    url: https://webelements.co.uk/compounds/lead/lead_selenide.html
    kind: database
    license: web database, linked not reproduced
  barr2007:
    title: Mitigating and Preventing the Growth of Tin and Other Metal Whiskers on Critical Hardware
    id: Stephanie Barr, The Aerospace Corporation, 2007
    url: https://nepp.nasa.gov/whisker./reference/tech_papers/2007-barr-paper-mitigating-whiskers.pdf
    year: 2007
    kind: paper
    license: copyright The Aerospace Corporation (cited, not reproduced)
  cookson-2010:
    title: Tin Corrosion under QFN Packages at Elevated Temperature and Humidity
    id: K. Tellefsen et al., Cookson Electronics, IPC Midwest 2010
    url: https://www.electronics.org/system/files/technical_resource/E11%26S04_02.pdf
    year: 2010
    kind: paper
    license: copyright of the authors (cited, not reproduced)
  nasa-bok-2005:
    title: 'Lead-Free Soldering for Space Applications: Lead-Free Solder Body of Knowledge (Kurt Kessel, NASA KSC)'
    id: NASA NEPP, April 2005 state of technology report (copy hosted on xdevs.com)
    url: https://xdevs.com/doc/NASA/lead-free%20solder%20bok%20report%206-21-%202005.pdf
    year: 2005
    kind: report
    license: public domain (NASA)
  niosh-lead:
    title: 'NIOSH Pocket Guide to Chemical Hazards: Lead'
    id: NIOSH / CDC, npgd0368
    url: https://www.cdc.gov/niosh/npg/npgd0368.html
    kind: web
    license: public domain (US government)
  usgs-mcs2026-lead:
    title: Mineral Commodity Summaries 2026, Lead
    id: USGS MCS 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-lead.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-mcs2026-tin:
    title: Mineral Commodity Summaries 2026, Tin
    id: USGS MCS 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-tin.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  wikipedia-lbe:
    title: Lead-bismuth eutectic (Wikipedia; composition and history only)
    id: Wikipedia contributors
    url: https://en.wikipedia.org/wiki/Lead-bismuth_eutectic
    kind: web
    license: CC BY-SA 4.0
license: CC-BY-4.0
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 22
  unreachable: 2
  caveats: 3
  note: Read by an AI assistant on 2026-10-26 from the data sheets, NASA, Aerospace Corporation, Cookson, USGS, NIOSH, Lucas-Milhaupt, Goodfellow and WebElements pages listed in sources. The LBE handbook and Argonne page could not be opened.
story:
  recipe:
    line: 'Sn62/Pb36/Ag2 is a ternary solder alloy: tin, lead and silver melted together. It is a eutectic, so it has one melting point (179 °C, AIM). Other lead alloys in this profile are the Pb-Ag-Sn high-temperature solder (lead 97.5 %, silver 1.5 %, tin 1 %), the Sn60/Pb39/Sb1 solder, the lead-bismuth eutectic (lead 44.5 %, bismuth 55.5 %, as printed by Wikipedia) and lead selenide (PbSe), which is a compound rather than a solder.'
    parts:
      - name: Tin
        symbol: Sn
        share_percent: 62
        role: The main metal of the solder. It wets copper and copper alloys well.
      - name: Lead
        symbol: Pb
        share_percent: 36
        role: Lowers the melting point of the tin and gives the eutectic its single melting point.
      - name: Silver
        symbol: Ag
        share_percent: 2
        role: Added in small amounts to the eutectic. The AIM sheet gives the typical composition as 2.0 % silver.
  risk_groups:
    - title: For people
      verdict: Lead is toxic; limit exposure
      lead: Every alloy in this group contains lead, which NIOSH lists with a time-weighted average limit of 0.050 mg/m3 and an IDLH of 100 mg/m3 as Pb.
      points:
        - label: Exposure limits
          line: The NIOSH and OSHA limit for an eight-hour average is 0.050 mg/m3 of lead. Target organs listed by NIOSH include the blood, the central nervous system and the kidneys.
        - label: Use
          line: The Sn60/Pb40 wire is sold for professional use only because of its lead content. The AIM sheet asks users to work with adequate ventilation and personal protective equipment.
    - title: In service
      verdict: Pure tin finishes grow whiskers
      lead: Lead in the solder is the mitigation for tin whiskers. The Aerospace Corporation review says a minimum lead content is the only consistently demonstrated way to stop them.
      points:
        - label: Whisker shorts
          line: A tin whisker can short neighbouring conductors at low voltage. Unless the current is above about 50 mA, the short can stay in place indefinitely.
        - label: Aerospace exemptions
          line: NASA states that exemptions for high-reliability aerospace electronics do not protect those assemblies from lead-free parts that suppliers introduce without changing part numbers.
    - title: Handling and storage
      points:
        - label: Storage
          line: The Sn60/Pb40 sheet calls for storage at room temperature in a dry place, out of reach of children.
        - label: Soldering
          line: Recommended soldering tip temperature is 340 to 400 °C for the Sn60/Pb40 cored wire. The SW26 flux residues need not be removed, but alcohol-based solvents are recommended for washing.
  why: Tin-lead solders have a long track record in electronics, and this group covers the variants that a designer might specify when lead is still allowed. Sn62/Pb36/Ag2 gives a single melting point at 179 °C. The Pb-Ag-Sn alloy has a melting point near 309 °C, which makes it the high-melting option in this group. The Sn60/Pb39/Sb1 solder has a melting range of about 183 to 190 °C. The lead-bismuth and lead selenide entries are included for completeness; their key numbers were not found in a source opened in this run. The tin-lead solders themselves are described in solder-sn-pb, and antimonial lead, a battery and shielding alloy, is described in antimonial-lead.
  uses:
    - where: Wave soldering and printed-circuit assembly
      line: AIM lists Sn63/Pb37 as used for general soldering of copper and copper alloys and ferrous alloys, and states that the high-purity grade reduces dross by 12 to 18 %. The Sn60/Pb40 cored wire is sold for industrial electronics where RoHS compliance is not required.
    - where: High-reliability and aerospace electronics
      line: A NASA review of lead-free soldering says that high-reliability aerospace users still depend on tin-lead for assemblies, and that the exemptions for those assemblies do not protect them from lead-free parts entering the supply chain.
    - where: Pb-Ag-Sn high-temperature joints
      line: Lucas-Milhaupt lists the 97.5 % lead alloy with a solidus and liquidus both at 309 °C and a maximum recommended brazing temperature of 364 °C, so it is used where the joint must stay solid at a much higher temperature than the tin-lead eutectic.
  can_do:
    - label: Single melting point
      benchmark: melting_point
      value: 179 °C
      line: The Sn62/Pb36/Ag2 alloy is a eutectic with one melting point at 179 °C (354 °F). A Sn62 Pb36 Ag02 row in the Kester table gives a 179 to 189 °C range instead, so the two sources do not agree on the top of the range.
    - label: High-temperature solder
      benchmark: melting_point
      value: 309 °C
      line: The Pb-Ag-Sn solder is printed with a solidus and liquidus both at 309 °C, and its supplier gives a maximum recommended brazing temperature of 364 °C.
    - label: Density
      benchmark: density
      value: 8.4 g/cm3
      line: The Sn63/Pb37 eutectic has a density of 8.40 g/cm3 (AIM). The Sn60/Pb40 alloy is 8.49 g/cm3 (AIM) and about 8.5 g/cm3 (Cynel-Unipress).
    - label: Strength
      benchmark: ultimate_tensile_strength
      value: 43 MPa
      line: The Sn63/Pb37 eutectic breaks at 43 MPa (6240 psi) per AIM, and the Sn60/Pb40 alloy at 44.13 MPa (6400 psi). Cynel gives 535 kg/cm2 for its Sn60/Pb40 cored wire. The sheets do not name the test method.
    - label: Thermal conductivity
      benchmark: thermal_conductivity
      value: 49 W/m·K
      line: The Sn60/Pb40 cored wire has a thermal conductivity of 49 W/m·K. Goodfellow gives around 50 W/m·K for its Sn60/Pb39/Sb1 solder.
  compare: 'Compared with the tin-lead eutectic in solder-sn-pb, the silver-bearing Sn62/Pb36/Ag2 solder gives the same kind of single melting point at 179 °C, while the Pb-Ag-Sn high-temperature solder melts at 309 °C and has a specific gravity of 11.28, against 8.40 g/cm3 for the Sn63/Pb37 eutectic. The Sn60/Pb39/Sb1 solder has a melting range rather than a single point. Lead selenide is in a different class altogether: it is a rock-salt compound with a density of 8100 kg/m3 and a melting point of 1078 °C, and it is not used as a solder. The table compares the family on its melting point, density and tensile strength.'
  compare_rows:
    - label: Melting point
      benchmark: melting_point
    - label: Density
      benchmark: density
    - label: Tensile strength
      benchmark: ultimate_tensile_strength
  handling:
    - Use ventilation and personal protective equipment. NIOSH sets the lead limit at 0.050 mg/m3 for an eight-hour average.
    - Store the solder wire at room temperature in a dry place, out of reach of children.
    - Solder at 340 to 400 °C with the Sn60/Pb40 cored wire, and do not dispose of hazardous materials in non-approved containers.
  good_for:
    - A defined melting point. The Sn62/Pb36/Ag2 eutectic melts at 179 °C (AIM), with one value rather than a range.
    - A high-temperature joint. The Pb-Ag-Sn alloy has a solidus and liquidus both at 309 °C (Lucas-Milhaupt).
    - Whisker resistance. The Aerospace Corporation review says lead in the solder is the only consistently demonstrated whisker preventer.
  watch_out:
    - 'Lead toxicity: the NIOSH limit is 0.050 mg/m3 as an eight-hour average. The Sn60/Pb40 wire is restricted to professional use.'
    - The sources disagree on some values. Sn62/Pb36/Ag2 has a 179 to 189 °C range in the Kester table and a single 179 °C eutectic from AIM, and the Sn60/Pb40 tensile strength is 44.13 MPa (AIM) against 535 kg/cm2 (Cynel).
    - 'Lead-free rules: the NASA review says exemptions do not stop lead-free parts from reaching aerospace assemblies, so lead content cannot be assumed in a supply chain.'
  verdict: Lead alloys still give the most defined melting points for tin-lead solder, but lead toxicity and lead-free rules limit where they can be used. Lead-bismuth and lead selenide need sources that were not available in this run.