Sn96.5Ag3.5 solder (tin-silver eutectic) Sn-Ag

spore: profile
id: solder-sn96-5ag3-5
spore_version: 0.2
family: tin-silver solder
name: Sn96.5Ag3.5 solder (tin-silver eutectic)
abbreviation: Sn-Ag
role: soft-solder alloy
category: metals
type: heavy-metals
summary: |
  Sn96.5Ag3.5 is a lead-free tin-silver solder. Its melting point is 221 °C, which the AIM and Kester datasheets both print, and NIST calls the Sn-3.5Ag composition a eutectic solder. The two datasheets disagree on tensile strength (8.36 ksi from AIM, 8900 psi from Kester) and on density (7.36 g/cm3 from Kester, 7.3 g/cm3 from the MBO safety data sheet), so both values are recorded side by side.
best_for: Lead-free soft soldering of electronic joints where one melting point at 221 °C is wanted
weakest_at: Low tensile and shear strength for structural loads, and no corrosion or space-environment test for this grade was found in the sources read
identity:
  formula: Sn96.5Ag3.5 (tin alloyed with silver, eutectic composition; tin and silver as printed in the Kester table)
  source: kester-soft-solder
  where: Technical data on soft solders table, Sn96.5Ag3.5 row (composition as printed)
  designations:
    - system: Trade name
      code: Sn96Ag
      note: MBO product name for the 96.5 Sn / 3.5 Ag alloy in its Lead Free alloys range
      source: mbo-sds
      where: Section 1, Available alloys list; Section 3, alloy composition table, Sn96Ag row
tags:
  applications:
    - electronics-and-chips
properties:
  - benchmark: melting_point
    label: Melting point (AIM common alloys table)
    value: 221
    unit: °C
    scope: material
    conditions:
      alloy: Sn96.5/Ag3.5 as printed in the AIM common solder alloys table
      form: solder alloy
    method: Melting Point (ºC) column of the AIM alloy table; the table gives a single value for this alloy
    status: ground
    source: aim-alloy-info
    where: Common solder alloys table, Sn96.5 row (Ag 3.5 column), Melting Point (ºC) column
  - benchmark: melting_point
    label: Solidus (Kester soft solder table)
    value: 221
    unit: °C
    scope: material
    conditions:
      alloy: Sn96.5Ag3.5 as printed in the Kester table
      liquidus_as_printed: e (the liquidus column prints e for this row; read here as eutectic, solidus equal to liquidus)
    method: Solidus °C column of the Kester technical data table
    status: ground
    source: kester-soft-solder
    where: Technical data on soft solders table, Sn96.5Ag3.5 row, Solidus °C column
  - benchmark: melting_point
    label: Melting point (NIST review of Sn-Ag solders)
    value: 221
    unit: °C
    scope: material
    conditions:
      alloy: Sn-3.5Ag eutectic solder as named in the NIST review
    method: Quoted in the NIST overview and conclusions as a melting point of 221°C
    status: ground
    source: nist-sn-ag-overview
    where: Overview and Conclusions section
  - benchmark: density
    label: Specific gravity (Kester table)
    value: 7.36
    unit: g/cm3
    scope: material
    conditions:
      alloy: Sn96.5Ag3.5 as printed in the Kester table
      basis: Specific Gravity g/cm3 column
    method: Specific Gravity column of the Kester technical data table
    status: ground
    source: kester-soft-solder
    where: Technical data on soft solders table, Sn96.5Ag3.5 row, Specific Gravity column
  - benchmark: density
    label: Density (MBO safety data sheet, physical characteristics table)
    value: 7.3
    unit: g/cm3
    scope: material
    conditions:
      alloy: Sn96Ag, the MBO name for the 96.5 Sn / 3.5 Ag alloy
      basis: Density ( g/cm3 ) column as printed to one decimal
    method: Density column of the physical characteristics table in the MBO safety data sheet
    status: ground
    note: The safety data sheet prints one decimal place; the Kester datasheet gives 7.36 g/cm3 for the same composition.
    source: mbo-sds
    where: Page 5 of 6, characteristics table (solidus, liquidus, density), Sn96Ag row
  - benchmark: density
    label: Density (NIST, Boulder database)
    value: 7.5
    unit: g/cm3
    scope: material
    conditions:
      alloy: bulk Sn-3.5Ag solder as named in the NIST page
      basis: value cited to the NIST Boulder database
    method: Printed in the Other Physical Properties section as ρ(g/cm3) = 7.5 (NIST Boulder database)
    status: ground
    note: The NIST page says a higher value quoted by two earlier sources is an error and does not use it.
    source: nist-sn-ag-other
    where: Other Physical Properties section
  - benchmark: density
    label: Density (NIST rule-of-mixtures value)
    value: 7.42
    unit: g/cm3
    scope: material
    conditions:
      alloy: Sn-3.5Ag as named in the NIST page
      basis: rule-of-mixtures calculation printed by NIST
    method: NIST's rule-of-mixtures figure, printed as Sn-3.5Ag = 7.42 g/cm3
    status: calculated
    source: nist-sn-ag-other
    where: Other Physical Properties section
  - benchmark: ultimate_tensile_strength
    label: Tensile strength (AIM technical information table)
    value: 8.36
    unit: ksi
    scope: material
    conditions:
      alloy: Sn96.5/Ag3.5 as printed in the AIM technical information table
      test: test temperature and strain rate not stated in the table
    method: TENSILE STRENGTH (ksi) column of the AIM technical information table
    status: ground
    note: The Kester table gives 8900 psi for the same composition; the two values are not reconciled here.
    source: aim-alloy-info
    where: Technical information on common and specialty alloys table, Sn96.5/Ag3.5 row, TENSILE STRENGTH (ksi) column
  - benchmark: ultimate_tensile_strength
    label: Tensile strength (Kester table)
    value: 8900
    unit: psi
    scope: material
    conditions:
      alloy: Sn96.5Ag3.5 as printed in the Kester table
      test: test temperature and strain rate not stated in the table
    method: Tensile Strength PSI column of the Kester technical data table
    status: ground
    note: The AIM table gives 8.36 ksi for the same composition; the two values are recorded side by side.
    source: kester-soft-solder
    where: Technical data on soft solders table, Sn96.5Ag3.5 row, Tensile Strength PSI column
  - benchmark: yield_strength
    label: 0.2% yield strength (AIM technical information table)
    value: 7.08
    unit: ksi
    scope: material
    conditions:
      alloy: Sn96.5/Ag3.5 as printed in the AIM table
      offset: 0.2% yield
      test: test temperature not stated in the table
    method: 0.2% YIELD STRENGTH (ksi) column of the AIM technical information table
    status: ground
    source: aim-alloy-info
    where: Technical information on common and specialty alloys table, Sn96.5/Ag3.5 row, 0.2% YIELD STRENGTH (ksi) column
  - benchmark: shear_strength
    label: Shear strength (Kester table)
    value: 4600
    unit: psi
    scope: material
    conditions:
      alloy: Sn96.5Ag3.5 as printed in the Kester table
      test: shear test method not stated in the table
    method: Shear Strength PSI column of the Kester technical data table
    status: ground
    note: shear_strength is not in property-canon.yaml; used as printed. See gaps.
    source: kester-soft-solder
    where: Technical data on soft solders table, Sn96.5Ag3.5 row, Shear Strength PSI column
  - benchmark: electrical_conductivity
    label: Electrical conductivity (Kester table)
    value: 14
    unit: Cu%
    scope: material
    conditions:
      alloy: Sn96.5Ag3.5 as printed in the Kester table
      basis: column headed Electrical Conductivity Cu% as printed; the table does not define the scale further
    method: Electrical Conductivity Cu% column of the Kester technical data table
    status: ground
    note: electrical_conductivity is not in property-canon.yaml; used as printed. See gaps.
    source: kester-soft-solder
    where: Technical data on soft solders table, Sn96.5Ag3.5 row, Electrical Conductivity Cu% column
  - benchmark: cte
    label: Coefficient of thermal expansion (NIST overall average)
    value: 21.5
    unit: ppm/°C
    scope: material
    conditions:
      alloy: Sn3.5Ag as named in the NIST page
      basis: overall average value; individual values are in a table printed as an image
    method: Printed in the Coefficients of Thermal Expansion (CTE) section as about 21.5 ppm/°C
    status: ground
    source: nist-sn-ag-other
    where: Coefficients of Thermal Expansion (CTE) section
  - benchmark: creep_activation_energy
    label: Creep activation energy (fitted model, bulk Sn-3.5Ag)
    value: 41.57
    unit: kJ/mole
    scope: material
    conditions:
      alloy: bulk Sn-3.5Ag solder
      data: tensile creep data at tensile stress 2 to 64 MPa, strain rate range printed on the page, test temperature -10°C to 180°C
      model: hyperbolic sine creep model
    method: Q printed in the hyperbolic sine model fit (Equations 26 to 28); fitted by NIST, not measured directly
    status: calculated
    note: creep_activation_energy is not in property-canon.yaml; used as printed. See gaps.
    source: nist-sn-ag-bulk
    where: Data Analysis, hyperbolic sine model (Figure 9, Equations 26 to 28)
corrosion: []
risks:
  hazards:
    - text: The MBO safety data sheet says the product is not classified as dangerous and has no GHS label elements, but notes it could cause burns during soldering and may produce or release fumes.
      ghs: []
      source: mbo-sds
      where: Section 2, Hazards identification; Section 15, Regulatory information
  failure_risks:
    - mode: Low strength under structural load
      trigger: Structural or mechanical load carried by a solder joint
      consequence: Kester lists 8900 psi tensile strength and 4600 psi shear strength; AIM lists 8.36 ksi tensile and 7.08 ksi 0.2% yield strength for the same composition.
      severity: moderate
      source: kester-soft-solder
      where: Technical data on soft solders table, Tensile and Shear columns
    - mode: Creep under sustained load at elevated temperature
      trigger: Sustained tensile stress in the 2 to 64 MPa range tested by NIST, at temperatures from -10°C to 180°C
      consequence: NIST fits its bulk Sn-3.5Ag creep data with an activation energy of 41.57 kJ/mole; the page gives no creep life or time to failure.
      severity: moderate
      source: nist-sn-ag-bulk
      where: Data Analysis, Figure 8 and Figure 9
  handling:
    - text: The MBO data sheet recommends safety glasses, protective gloves, handwashing after use, good ventilation and a local fume extraction system during soldering.
      source: mbo-sds
      where: Section 2, Prevention
uses:
  - application: electronics-and-chips
    device: Soft-soldered electronic assemblies
    example: NIST's review calls the Sn-3.5Ag composition an eutectic solder and refers to solder joints of electronic assemblies in use.
    source: nist-sn-ag-overview
    where: Overview and Conclusions section
  - application: electronics-and-chips
    device: Lead-free solder alloy sold by MBO (product name Sn96Ag)
    example: The MBO safety data sheet gives the application of the alloy as soft soldering.
    source: mbo-sds
    where: Section 1, Application of the substance/preparation
supply:
  - subject: Tin
    producers:
      - country: China
        share_percent: 24.5
        year: 2025
      - country: Indonesia
        share_percent: 21
        year: 2025
      - country: Peru
        share_percent: 11.4
        year: 2025
      - country: Brazil
        share_percent: 9.7
        year: 2025
    recycling: 'USGS: about 17,000 tons of tin from old and new scrap was estimated to have been recycled in 2025, accounting for 22% of apparent consumption.'
    substitutes:
      - 'USGS: epoxy resins for solder are listed as substitutes for tin.'
    source: usgs-mcs2026-tin
    where: World Mine Production and Reserves table, 2025e, tin content (shares calculated by Space Mushroom against the 290,000 t world total); Recycling; Substitutes
  - subject: Silver
    producers:
      - country: Mexico
        share_percent: 24.2
        year: 2025
      - country: Peru
        share_percent: 13.8
        year: 2025
      - country: China
        share_percent: 13.1
        year: 2025
      - country: Bolivia
        share_percent: 5.8
        year: 2025
    critical_lists:
      - list: USGS 2025 List of Critical Minerals (silver added in the 2025 list, per the USGS chapter)
        listed: true
    recycling: 'USGS: approximately 1,000 tons of silver was recovered from new and old scrap in 2025, about 11% of apparent consumption.'
    substitutes:
      - 'USGS: the substitutes text covers photography and surgical uses; it does not name a substitute for silver in solder.'
    source: usgs-mcs2026-silver
    where: World Mine Production and Reserves table, 2025e (shares calculated by Space Mushroom against the 26,000 t world total); Recycling; Substitutes; Events, Trends and Issues (critical list)
story:
  recipe:
    line: Sn96.5Ag3.5 is a binary alloy of tin and silver. The Kester table prints its composition as Sn96.5Ag3.5 and the AIM table as Sn96.5/Ag3.5. The MBO safety data sheet lists the same two elements for its Sn96Ag alloy.
    parts:
      - name: Tin
        symbol: Sn
        share: 96.5 (percent, as printed in the composition column of the MBO sheet)
        role: Matrix metal of the solder; it forms most of the joint.
      - name: Silver
        symbol: Ag
        share: 3.5 (percent, as printed in the composition column of the MBO sheet)
        role: Alloying element. Wikipedia's Solder article says the eutectic tin-silver alloy tends to form platelets of Ag3Sn.
  risk_groups:
    - title: For people
      level: 0
      verdict: Not classified as dangerous
      lead: The supplier safety data sheet for this alloy does not classify it, but it lists burn and fume hazards during soldering.
      points:
        - label: The alloy
          line: The MBO safety data sheet says the product is not classified as dangerous and has no GHS label elements.
        - label: Soldering
          line: The same sheet says the product could cause burns during soldering and may produce or release fumes. It recommends safety glasses, protective gloves, good ventilation and local fume extraction.
    - title: Handling and storage
      points:
        - label: Ventilation
          line: Use fume extraction at the soldering point, as the MBO sheet recommends.
  why: Sn96.5Ag3.5 is a lead-free tin-silver solder. The Wikipedia Solder article says that lead-free solders "have been increasing in use due to regulatory requirements". NIST calls the Sn-3.5Ag composition a eutectic solder, which means one melting point rather than a melting range.
  uses:
    - where: Soft soldering of electronic assemblies
      line: NIST's review refers to solder joints of electronic assemblies in use and calls the composition an eutectic solder. The MBO data sheet lists its application as soft soldering.
  can_do:
    - label: Melting point
      benchmark: melting_point
      line: Melts at 221 °C as a eutectic. The AIM and Kester datasheets both print 221 °C.
    - label: Tensile strength
      benchmark: ultimate_tensile_strength
      line: Carries a tensile strength of 8.36 ksi in the AIM table and 8900 psi in the Kester table. The two datasheets differ, so both are recorded.
    - label: Yield strength
      benchmark: yield_strength
      line: Has a 0.2% yield strength of 7.08 ksi in the AIM table.
    - label: Electrical conductivity
      benchmark: electrical_conductivity
      line: Conducts electricity at a Kester Cu% reading of 14.
  compare: The sources agree on the melting point, 221 °C, which is a single temperature for this eutectic composition. They do not agree on density, with 7.36 g/cm3 from Kester, 7.3 g/cm3 from the MBO sheet, 7.5 g/cm3 from the NIST Boulder database, and 7.42 g/cm3 from NIST's rule-of-mixtures figure. The tensile strength also differs between AIM (8.36 ksi) and Kester (8900 psi). No like-for-like comparison with SAC alloys or tin-lead solders is made here, because those grades were not read in this run.
  compare_rows:
    - label: Melting point
      benchmark: melting_point
    - label: Density
      benchmark: density
    - label: Tensile strength
      benchmark: ultimate_tensile_strength
  handling:
    - Wear safety glasses and protective gloves when soldering, and wash hands after use, as the MBO sheet recommends.
    - Use good ventilation and local fume extraction at the soldering point.
    - The alloy is not classified as dangerous in the sheet read here, but soldering can cause burns and release fumes.
  good_for:
    - Lead-free soft soldering of electronic joints where a single melting point of 221 °C is wanted.
    - Joints that carry light mechanical load, where the datasheets give tensile strengths of 8.36 ksi (AIM) and 8900 psi (Kester).
  watch_out:
    - Low tensile and shear strength (8900 psi tensile and 4600 psi shear in the Kester table).
    - 'Creep at elevated temperature: NIST''s bulk data cover -10°C to 180°C, and its fitted activation energy is 41.57 kJ/mole.'
    - The sources disagree on tensile strength and density, so use the value and source that match your test.
  verdict: Sn96.5Ag3.5 is a simple lead-free eutectic solder. The datasheets agree on its 221 °C melting point, but its strength values disagree between sources, and no space-environment or corrosion test for this grade was found.
media: []
documents:
  - title: 'AIM alloy information: common and specialty solder alloys (PDF)'
    type: datasheet
    url: https://aimsolder.com/wp-content/uploads/legacy-files/alloy_information.pdf
  - title: 'Kester: Technical data on soft solders, Alloy Properties (PDF)'
    type: datasheet
    url: https://www.kester.com/Portals/0/Documents/Knowledge%20Base/Alloy%20Properties.pdf
  - title: 'MBO Lead Free alloys: Material and Safety Data Sheet (RS Components copy, PDF)'
    type: sds
    url: https://docs.rs-online.com/1615/0900766b8128cb0a.pdf
    year: 2011
  - title: 'NIST: Review and Analysis of Lead-Free Solder Material Properties, Sn-Ag overview'
    type: report
    url: https://www.msed.nist.gov/solder/clech/Sn-Ag_Overview.htm
  - title: 'NIST: Sn-Ag bulk solder properties (tensile creep)'
    type: report
    url: https://www.msed.nist.gov/solder/clech/Sn-Ag_Bulk.htm
  - title: 'NIST: Other properties of Sn-3.5Ag'
    type: report
    url: https://www.metallurgy.nist.gov/solder/clech/Sn-Ag_Other.htm
  - title: 'USGS Mineral Commodity Summaries 2026: Tin (PDF)'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-tin.pdf
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Silver (PDF)'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-silver.pdf
    year: 2026
gaps:
  - No corrosion, oxidation or ageing test for Sn96.5Ag3.5 was found in the sources read, so the corrosion section is empty.
  - No space-flight, vacuum or thermal-cycling result for this grade was found. The planner's note about space-hardware use is not confirmed by any source read in this run.
  - No UNS, EN, AISI or ASTM designation was printed in the sources read for this alloy; only the MBO trade name Sn96Ag is listed.
  - The Brinell hardness value for this alloy (17.0 in the Kester table) has no unit printed, so it is left out.
  - The AIM uniform elongation value (0.69 in the technical table) has no unit printed, so it is left out.
  - The 0.01% yield strength (5.39 ksi in the AIM table) is not in property-canon.yaml and is left out.
  - Elastic modulus and surface tension are blank for this alloy in the Kester table, and NIST gives no printed value for them.
  - Specific heat, thermal conductivity and electrical resistivity were not printed for this composition in the pages read.
  - The NIST page on bulk tensile creep prints its data as figures and exponent-form rates, which cannot be copied as printed; those rates are left out.
  - 'Silver''s hazard data (PubChem GHS) could not be read: the PubChem page returned a verification challenge in this run.'
  - Abundance of tin and silver in the crust was not found in a source read in this run.
  - Tin's status on the USGS 2025 critical list and on the EU critical raw materials list was not stated in the tin chapter read here; EU list status for silver was not checked.
  - Wikipedia's Solder article writes the eutectic as 22/78 Sn-Ag (wt.%), which does not match the 3.5 percent silver printed by the datasheets and NIST; that article is not used for composition.
  - Sources disagree on tensile strength (AIM 8.36 ksi, Kester 8900 psi) and density (Kester 7.36, MBO 7.3, NIST 7.42 and 7.5 g/cm3). Both values are recorded and neither is preferred.
sources:
  aim-alloy-info:
    title: 'AIM: Alloy Information, common and specialty solder alloys'
    id: AIM, alloy_information.pdf (legacy file)
    url: https://aimsolder.com/wp-content/uploads/legacy-files/alloy_information.pdf
    kind: datasheet
    license: supplier document, linked not reproduced
  kester-soft-solder:
    title: 'Kester: Technical Data on Soft Solders (Alloy Properties)'
    id: Kester, Knowledge Base, Alloy Properties.pdf
    url: https://www.kester.com/Portals/0/Documents/Knowledge%20Base/Alloy%20Properties.pdf
    kind: datasheet
    license: supplier document, linked not reproduced
  mbo-sds:
    title: 'MBO Lead Free alloys: Material and Safety Data Sheet (supplied by RS Components)'
    id: Document 1194-F, update number 02, updated 11/03/11
    url: https://docs.rs-online.com/1615/0900766b8128cb0a.pdf
    year: 2011
    kind: datasheet
    license: supplier document, linked not reproduced
  nist-sn-ag-overview:
    title: 'NIST: Review and Analysis of Lead-Free Solder Material Properties, Sn-Ag overview'
    url: https://www.msed.nist.gov/solder/clech/Sn-Ag_Overview.htm
    kind: report
    license: public domain (NIST)
  nist-sn-ag-bulk:
    title: 'NIST: Sn-Ag bulk solder properties, tensile creep and hyperbolic sine model'
    url: https://www.msed.nist.gov/solder/clech/Sn-Ag_Bulk.htm
    kind: report
    license: public domain (NIST)
  nist-sn-ag-other:
    title: 'NIST: Other Properties of Sn-3.5Ag (density, coefficient of thermal expansion)'
    url: https://www.metallurgy.nist.gov/solder/clech/Sn-Ag_Other.htm
    kind: report
    license: public domain (NIST)
  usgs-mcs2026-tin:
    title: 'Mineral Commodity Summaries 2026: Tin'
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-tin.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-mcs2026-silver:
    title: 'Mineral Commodity Summaries 2026: Silver'
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-silver.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  wikipedia-solder:
    title: Solder (Wikipedia), used for history and composition context only
    url: https://en.wikipedia.org/wiki/Solder
    kind: web
    license: CC BY-SA 4.0
license: CC-BY-4.0
updated: '2026-11-01'
review:
  status: draft
  method: assistant
  checked_values: 14
  unreachable: 0
  caveats: 2
  note: Written by an AI assistant on 2026-11-01 from datasheets and NIST pages read in this run. Values are copied as printed; two property names (shear_strength, electrical_conductivity, creep_activation_energy) are not in the canonical list.