{
  "spore": "profile",
  "id": "solder-sn42bi58",
  "spore_version": "0.2",
  "family": "low-melting-metals-and-solders",
  "name": "Sn42Bi58 low-temperature eutectic solder",
  "abbreviation": "Sn42Bi58",
  "role": "lead-free low-temperature solder alloy",
  "category": "electronics",
  "type": "solders",
  "summary": "Sn42Bi58 is a lead-free eutectic solder of 42 % tin and 58 % bismuth by weight, each within ±0.5 (AIM datasheet). Its melting point is 138 °C (280 °F), printed in both the AIM datasheet and the AIM alloy information sheet. The datasheet gives a density of 8.72 g/cc and a tensile strength of 8,000 psi, while the information sheet prints 9.71 ksi for the same alloy; neither states a test method, so the two strength values are shown side by side and not reconciled. The datasheet lists a thermal conductivity of 0.19 W/cm-°C at 85 °C and a coefficient of thermal expansion of 15 ppm/°C at 20 °C. AIM rates its thermal fatigue resistance as Poor.\n",
  "best_for": "Second-solder reflow on circuit boards and other low-temperature soldering, where the joint has to melt at 138 °C (AIM datasheet)",
  "weakest_at": "Thermal fatigue resistance, which AIM rates Poor against Excellent for SAC305, and a wetting rating of Fair",
  "identity": {
    "formula": "Sn-42Bi-58: 42 % tin and 58 % bismuth by weight, each ±0.5 (eutectic alloy)",
    "designations": [
      {
        "system": "Trade name",
        "code": "Sn42/Bi58",
        "source": "aim-tds",
        "where": "Title and Major Alloy Ingredients table"
      }
    ],
    "source": "aim-tds",
    "where": "Description section and Major Alloy Ingredients table (Sn 42 ± 0.5, Bi 58 ± 0.5)"
  },
  "tags": {
    "environments": [],
    "stresses": [
      "thermal-cycling"
    ],
    "applications": [
      "electronics-and-chips"
    ]
  },
  "properties": [
    {
      "benchmark": "melting_point",
      "label": "Eutectic melting point (AIM datasheet)",
      "value": 138,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "basis": "eutectic composition, 42 % Sn and 58 % Bi as printed; the datasheet also prints 280 °F"
      },
      "method": "Printed as the eutectic melting point in the Description and as a Features list item",
      "status": "ground",
      "source": "aim-tds",
      "where": "Features (Low Melting Point 138°C (280°F)) and Description paragraph",
      "source_detail": {
        "title": "Sn42/Bi58 lead-free solder alloy, technical data sheet",
        "id": "AIM, Document Rev # NF4",
        "url": "https://aimsolder.com/wp-content/uploads/alloy_sn42-bi58_tds.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier technical data sheet, cited not reproduced"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting point (AIM alloy information sheet)",
      "value": 138,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "basis": "Sn42/Bi58 row of the technical information table"
      },
      "method": "Value printed in the AIM alloy information sheet, which agrees with the datasheet",
      "status": "ground",
      "source": "aim-info",
      "where": "Technical Information table, Sn42/Bi58 row, Melting Point column (138)",
      "source_detail": {
        "title": "Alloy Information: common solder alloys, specialty solder alloys and technical information",
        "id": "AIM alloy information sheet (legacy file)",
        "url": "https://aimsolder.com/wp-content/uploads/legacy-files/alloy_information.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier information sheet, cited not reproduced"
      }
    },
    {
      "benchmark": "density",
      "label": "Density (AIM datasheet)",
      "value": 8.72,
      "bound": "exact",
      "unit": "g/cc",
      "scope": "material",
      "conditions": {
        "temperature": "not stated in the datasheet"
      },
      "method": "Value printed in the Properties table of the datasheet",
      "status": "ground",
      "source": "aim-tds",
      "where": "Properties table, Density g/cc row (8.72)",
      "source_detail": {
        "title": "Sn42/Bi58 lead-free solder alloy, technical data sheet",
        "id": "AIM, Document Rev # NF4",
        "url": "https://aimsolder.com/wp-content/uploads/alloy_sn42-bi58_tds.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier technical data sheet, cited not reproduced"
      }
    },
    {
      "benchmark": "density",
      "label": "Density (AIM alloy information sheet, as printed)",
      "value": 0.309,
      "bound": "exact",
      "unit": "lbs/in3",
      "scope": "material",
      "conditions": {
        "basis": "Bi58 row of the bismuth section of the alloy table, printed in lbs/in.3 and not converted"
      },
      "method": "Value printed in the Common and Specialty Solder Alloys table of the information sheet",
      "status": "ground",
      "source": "aim-info",
      "where": "Specialty Solder Alloys table, BISMUTH section, Bi58 row, Density column (.3090)",
      "source_detail": {
        "title": "Alloy Information: common solder alloys, specialty solder alloys and technical information",
        "id": "AIM alloy information sheet (legacy file)",
        "url": "https://aimsolder.com/wp-content/uploads/legacy-files/alloy_information.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier information sheet, cited not reproduced"
      }
    },
    {
      "benchmark": "electrical_resistivity",
      "label": "Electrical resistivity (AIM datasheet)",
      "value": 1.72,
      "bound": "exact",
      "unit": "µΩ-cm",
      "scope": "material",
      "conditions": {
        "temperature": "not stated in the datasheet"
      },
      "method": "Value printed in parentheses in the Electrical Conductivity row of the Properties table",
      "status": "ground",
      "source": "aim-tds",
      "where": "Properties table, Electrical Conductivity row, parenthesised value (1.72 µΩ-cm)",
      "source_detail": {
        "title": "Sn42/Bi58 lead-free solder alloy, technical data sheet",
        "id": "AIM, Document Rev # NF4",
        "url": "https://aimsolder.com/wp-content/uploads/alloy_sn42-bi58_tds.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier technical data sheet, cited not reproduced"
      }
    },
    {
      "benchmark": "electrical_conductivity",
      "label": "Electrical conductivity (AIM datasheet)",
      "value": 4.5,
      "bound": "exact",
      "unit": "% IACS",
      "scope": "material",
      "conditions": {
        "temperature": "not stated in the datasheet"
      },
      "method": "Value printed in the Properties table of the datasheet",
      "status": "ground",
      "source": "aim-tds",
      "where": "Properties table, Electrical Conductivity row (4.5 % of IACS)",
      "source_detail": {
        "title": "Sn42/Bi58 lead-free solder alloy, technical data sheet",
        "id": "AIM, Document Rev # NF4",
        "url": "https://aimsolder.com/wp-content/uploads/alloy_sn42-bi58_tds.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier technical data sheet, cited not reproduced"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity (AIM datasheet)",
      "value": 0.19,
      "bound": "exact",
      "unit": "W/cm-°C",
      "scope": "material",
      "conditions": {
        "temperature": "85 °C, as printed in the row label"
      },
      "method": "Value printed in the Properties table of the datasheet",
      "status": "ground",
      "source": "aim-tds",
      "where": "Properties table, Thermal Conductivity @ 85° C row (0.19 W/cm-° C)",
      "source_detail": {
        "title": "Sn42/Bi58 lead-free solder alloy, technical data sheet",
        "id": "AIM, Document Rev # NF4",
        "url": "https://aimsolder.com/wp-content/uploads/alloy_sn42-bi58_tds.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier technical data sheet, cited not reproduced"
      }
    },
    {
      "benchmark": "cte",
      "label": "Coefficient of thermal expansion (AIM datasheet)",
      "value": 15,
      "bound": "exact",
      "unit": "ppm/°C",
      "scope": "material",
      "conditions": {
        "temperature": "20 °C, as printed in the row label"
      },
      "method": "Value printed in the Properties table of the datasheet, printed as PPM/° C",
      "status": "ground",
      "source": "aim-tds",
      "where": "Properties table, Coefficient of Thermal Expansion @ 20° C row (15)",
      "source_detail": {
        "title": "Sn42/Bi58 lead-free solder alloy, technical data sheet",
        "id": "AIM, Document Rev # NF4",
        "url": "https://aimsolder.com/wp-content/uploads/alloy_sn42-bi58_tds.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier technical data sheet, cited not reproduced"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "Tensile strength (AIM datasheet)",
      "value": 8000,
      "bound": "exact",
      "unit": "psi",
      "scope": "material",
      "conditions": {
        "form": "as printed in the datasheet; the form and test method are not stated"
      },
      "method": "Value printed in the Properties table of the datasheet, printed as 8,000 PSI",
      "status": "ground",
      "note": "The AIM alloy information sheet prints 9.71 ksi for the same alloy (see the next row). Neither source states a test method, so the two values should not be compared directly.",
      "source": "aim-tds",
      "where": "Properties table, Tensile Strength PSI row (8,000)",
      "source_detail": {
        "title": "Sn42/Bi58 lead-free solder alloy, technical data sheet",
        "id": "AIM, Document Rev # NF4",
        "url": "https://aimsolder.com/wp-content/uploads/alloy_sn42-bi58_tds.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier technical data sheet, cited not reproduced"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "Tensile strength (AIM alloy information sheet)",
      "value": 9.71,
      "bound": "exact",
      "unit": "ksi",
      "scope": "material",
      "conditions": {
        "form": "as printed in the information sheet; the form and test method are not stated"
      },
      "method": "Value printed in the Technical Information table of the alloy information sheet",
      "status": "ground",
      "note": "The AIM datasheet prints 8,000 psi (8.0 ksi) for the same alloy. The sources disagree and neither states a test method.",
      "source": "aim-info",
      "where": "Technical Information table, Sn42/Bi58 row, Tensile Strength (ksi) column (9.71)",
      "source_detail": {
        "title": "Alloy Information: common solder alloys, specialty solder alloys and technical information",
        "id": "AIM alloy information sheet (legacy file)",
        "url": "https://aimsolder.com/wp-content/uploads/legacy-files/alloy_information.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier information sheet, cited not reproduced"
      }
    },
    {
      "benchmark": "yield_strength",
      "label": "0.2 % yield strength (AIM alloy information sheet)",
      "value": 6.03,
      "bound": "exact",
      "unit": "ksi",
      "scope": "material",
      "conditions": {
        "basis": "0.2 % yield strength, as printed in the column header",
        "form": "as printed; test method not stated"
      },
      "method": "Value printed in the Technical Information table of the alloy information sheet",
      "status": "ground",
      "source": "aim-info",
      "where": "Technical Information table, Sn42/Bi58 row, 0.2% Yield Strength (ksi) column (6.03)",
      "source_detail": {
        "title": "Alloy Information: common solder alloys, specialty solder alloys and technical information",
        "id": "AIM alloy information sheet (legacy file)",
        "url": "https://aimsolder.com/wp-content/uploads/legacy-files/alloy_information.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier information sheet, cited not reproduced"
      }
    },
    {
      "benchmark": "shear_strength",
      "label": "Shear strength (AIM datasheet)",
      "value": 500,
      "bound": "exact",
      "unit": "psi",
      "scope": "material",
      "conditions": {
        "test": "not stated in the datasheet"
      },
      "method": "Value printed in the Properties table of the datasheet",
      "status": "ground",
      "source": "aim-tds",
      "where": "Properties table, Shear Strength PSI row (500)",
      "source_detail": {
        "title": "Sn42/Bi58 lead-free solder alloy, technical data sheet",
        "id": "AIM, Document Rev # NF4",
        "url": "https://aimsolder.com/wp-content/uploads/alloy_sn42-bi58_tds.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier technical data sheet, cited not reproduced"
      }
    },
    {
      "benchmark": "elongation",
      "label": "Elongation (AIM datasheet)",
      "value": 55,
      "bound": "exact",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "test": "not stated in the datasheet"
      },
      "method": "Value printed in the Properties table of the datasheet",
      "status": "ground",
      "note": "The AIM alloy information sheet prints a uniform elongation of 1.3 for this alloy without a unit, so it is not recorded. The two sheets give different elongation figures.",
      "source": "aim-tds",
      "where": "Properties table, Elongation % row (55)",
      "source_detail": {
        "title": "Sn42/Bi58 lead-free solder alloy, technical data sheet",
        "id": "AIM, Document Rev # NF4",
        "url": "https://aimsolder.com/wp-content/uploads/alloy_sn42-bi58_tds.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier technical data sheet, cited not reproduced"
      }
    },
    {
      "benchmark": "latent_heat_of_fusion",
      "label": "Latent heat of fusion (AIM datasheet)",
      "value": 44.8,
      "bound": "exact",
      "unit": "J/g",
      "scope": "material",
      "conditions": {
        "basis": "eutectic alloy as printed"
      },
      "method": "Value printed in the Properties table of the datasheet",
      "status": "ground",
      "source": "aim-tds",
      "where": "Properties table, Latent Heat of Fusion J/g row (44.8)",
      "source_detail": {
        "title": "Sn42/Bi58 lead-free solder alloy, technical data sheet",
        "id": "AIM, Document Rev # NF4",
        "url": "https://aimsolder.com/wp-content/uploads/alloy_sn42-bi58_tds.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier technical data sheet, cited not reproduced"
      }
    },
    {
      "benchmark": "joint_strength",
      "label": "Joint strength (AIM alloy information sheet)",
      "value": 6800,
      "bound": "exact",
      "unit": "psi",
      "scope": "material",
      "conditions": {
        "basis": "joint strength column of the alloy performance table; the substrate and test method are not stated"
      },
      "method": "Value printed in the joint strength column of the alloy information sheet's performance table",
      "status": "ground",
      "source": "aim-info",
      "where": "Second performance table, Sn42/Bi58 row, Joint Strength (psi) column (6800)",
      "source_detail": {
        "title": "Alloy Information: common solder alloys, specialty solder alloys and technical information",
        "id": "AIM alloy information sheet (legacy file)",
        "url": "https://aimsolder.com/wp-content/uploads/legacy-files/alloy_information.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier information sheet, cited not reproduced"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting range, solidus to liquidus, Sn-58 wt% Bi (Kang et al. 2021)",
      "value": 130.2,
      "value_high": 139,
      "bound": "range",
      "unit": "ºC",
      "scope": "material",
      "conditions": {
        "basis": "Sn-58 wt% Bi, the same composition as Sn42/Bi58 (Bi at 58 %); the review cites earlier work for it and notes that the heating rate affects the value"
      },
      "method": "Range printed in the review's Section 2.1 text, which refers to its Table 1",
      "status": "ground",
      "source": "kang2021",
      "where": "Section 2.1, first melting-range sentence (solidus 130.2 ºC, liquidus 139 ºC, citing Table 1)",
      "source_detail": {
        "title": "Low Melting Temperature Sn-Bi Solder: Effect of Alloying and Nanoparticle Addition on the Microstructural, Thermal, Interfacial Bonding, and Mechanical Characteristics",
        "id": "Kang, Rajendran and Jung, Metals 2021, 11, 364, doi:10.3390/met11020364",
        "url": "https://mdpi-res.com/d_attachment/metals/metals-11-00364/article_deploy/metals-11-00364-v2.pdf",
        "year": 2021,
        "kind": "paper",
        "license": "CC BY 4.0"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "Tensile strength (NIST Table 1.2, row A6 Sn-58Bi)",
      "value": 8766,
      "bound": "exact",
      "unit": "psi",
      "scope": "material",
      "conditions": {
        "form": "not stated in the NIST table; the table credits the NCMS 1998 tensile programme",
        "alloy": "A6 Sn-58Bi, Bi 58 % by mass"
      },
      "method": "Value printed in the NIST table, which also prints 60.4 MPa for the same row",
      "status": "ground",
      "note": "The AIM datasheet prints 8,000 psi and the AIM information sheet prints 9.71 ksi for this alloy. The three values differ, no source prints a test method, so they are shown side by side and not reconciled.",
      "source": "nist-solder-db",
      "where": "Table 1.2 Tensile Properties of Lead-Free Solders, row A6 Sn-58Bi, Tensile Strength (psi) column (8,766; 60.4 MPa)",
      "source_detail": {
        "title": "Database for Solder Properties with Emphasis on New Lead-free Solders: Properties of Lead-Free Solders, Release 4.0",
        "id": "NIST and Colorado School of Mines, Release 4.0, dated 11 February 2002",
        "url": "https://www.metallurgy.nist.gov/solder/NIST_LeadfreeSolder_v4.pdf",
        "year": 2002,
        "kind": "database",
        "license": "NIST database, cited not reproduced"
      }
    },
    {
      "benchmark": "yield_strength",
      "label": "0.2 % offset yield strength (NIST Table 1.2, row A6 Sn-58Bi)",
      "value": 7119,
      "bound": "exact",
      "unit": "psi",
      "scope": "material",
      "conditions": {
        "basis": "0.2 % offset, as printed in the column heading",
        "form": "not stated in the NIST table"
      },
      "method": "Value printed in the NIST table, which also prints 49.1 MPa for the same row",
      "status": "ground",
      "note": "The AIM information sheet prints 6.03 ksi for the 0.2 % yield strength of this alloy. The two sources differ and neither prints a test method.",
      "source": "nist-solder-db",
      "where": "Table 1.2, row A6 Sn-58Bi, Yield Strength (0.2 % offset) psi column (7,119; 49.1 MPa)",
      "source_detail": {
        "title": "Database for Solder Properties with Emphasis on New Lead-free Solders: Properties of Lead-Free Solders, Release 4.0",
        "id": "NIST and Colorado School of Mines, Release 4.0, dated 11 February 2002",
        "url": "https://www.metallurgy.nist.gov/solder/NIST_LeadfreeSolder_v4.pdf",
        "year": 2002,
        "kind": "database",
        "license": "NIST database, cited not reproduced"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "label": "Elastic modulus (NIST Table 1.2, row A6 Sn-58Bi)",
      "value": 1720,
      "bound": "exact",
      "unit": "ksi",
      "scope": "material",
      "conditions": {
        "form": "not stated in the NIST table"
      },
      "method": "Value printed in the NIST table, which also prints 11.9 GPa for the same row",
      "status": "ground",
      "source": "nist-solder-db",
      "where": "Table 1.2, row A6 Sn-58Bi, Elastic Modulus ksi column (1,720; 11.9 GPa)",
      "source_detail": {
        "title": "Database for Solder Properties with Emphasis on New Lead-free Solders: Properties of Lead-Free Solders, Release 4.0",
        "id": "NIST and Colorado School of Mines, Release 4.0, dated 11 February 2002",
        "url": "https://www.metallurgy.nist.gov/solder/NIST_LeadfreeSolder_v4.pdf",
        "year": 2002,
        "kind": "database",
        "license": "NIST database, cited not reproduced"
      }
    },
    {
      "benchmark": "elongation",
      "label": "Total elongation (NIST Table 1.2, row A6 Sn-58Bi)",
      "value": 46,
      "bound": "exact",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "basis": "total elongation as printed; the same row prints a uniform elongation of 3 %",
        "form": "not stated in the NIST table"
      },
      "method": "Value printed in the NIST table",
      "status": "ground",
      "note": "The AIM datasheet prints 55 % elongation for this alloy. The two figures differ and neither source prints a test method.",
      "source": "nist-solder-db",
      "where": "Table 1.2, row A6 Sn-58Bi, Elongation Total (%) column (46)",
      "source_detail": {
        "title": "Database for Solder Properties with Emphasis on New Lead-free Solders: Properties of Lead-Free Solders, Release 4.0",
        "id": "NIST and Colorado School of Mines, Release 4.0, dated 11 February 2002",
        "url": "https://www.metallurgy.nist.gov/solder/NIST_LeadfreeSolder_v4.pdf",
        "year": 2002,
        "kind": "database",
        "license": "NIST database, cited not reproduced"
      }
    },
    {
      "benchmark": "shear_strength",
      "label": "Shear strength at room temperature (NIST Table 1.16, ring-and-plug)",
      "value": 48,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "test": "ring-and-plug shear test at 1 mm/min",
        "temperature": "room temperature, as printed in the column heading"
      },
      "method": "Value printed in the NIST table",
      "status": "ground",
      "note": "The AIM datasheet prints 500 psi shear strength with no test method, so the NIST and AIM values are not comparable.",
      "source": "nist-solder-db",
      "where": "Table 1.16 Mechanical Properties, Sn-58Bi row, Shear Strength Room column (48.0)",
      "source_detail": {
        "title": "Database for Solder Properties with Emphasis on New Lead-free Solders: Properties of Lead-Free Solders, Release 4.0",
        "id": "NIST and Colorado School of Mines, Release 4.0, dated 11 February 2002",
        "url": "https://www.metallurgy.nist.gov/solder/NIST_LeadfreeSolder_v4.pdf",
        "year": 2002,
        "kind": "database",
        "license": "NIST database, cited not reproduced"
      }
    },
    {
      "benchmark": "shear_strength",
      "label": "Shear strength at 100 °C (NIST Table 1.16, ring-and-plug)",
      "value": 15.6,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "test": "ring-and-plug shear test at 1 mm/min",
        "temperature": "100 °C, as printed in the column heading"
      },
      "method": "Value printed in the NIST table",
      "status": "ground",
      "source": "nist-solder-db",
      "where": "Table 1.16 Mechanical Properties, Sn-58Bi row, Shear Strength 100 ºC column (15.6)",
      "source_detail": {
        "title": "Database for Solder Properties with Emphasis on New Lead-free Solders: Properties of Lead-Free Solders, Release 4.0",
        "id": "NIST and Colorado School of Mines, Release 4.0, dated 11 February 2002",
        "url": "https://www.metallurgy.nist.gov/solder/NIST_LeadfreeSolder_v4.pdf",
        "year": 2002,
        "kind": "database",
        "license": "NIST database, cited not reproduced"
      }
    },
    {
      "benchmark": "electrical_resistivity",
      "label": "Electrical resistivity (NIST Table 2.2.19)",
      "value": 30,
      "value_high": 35,
      "bound": "range",
      "unit": "μΩ-cm",
      "scope": "material",
      "conditions": {
        "temperature": "not stated in the NIST table"
      },
      "method": "Range printed in the NIST table",
      "status": "ground",
      "note": "The AIM datasheet prints 1.72 µΩ-cm for this alloy. The NIST range is much higher, and the two are shown side by side and not reconciled.",
      "source": "nist-solder-db",
      "where": "Table 2.2.19, Sn-58Bi row, Electrical Resistivity (μΩ-cm) column (30 – 35)",
      "source_detail": {
        "title": "Database for Solder Properties with Emphasis on New Lead-free Solders: Properties of Lead-Free Solders, Release 4.0",
        "id": "NIST and Colorado School of Mines, Release 4.0, dated 11 February 2002",
        "url": "https://www.metallurgy.nist.gov/solder/NIST_LeadfreeSolder_v4.pdf",
        "year": 2002,
        "kind": "database",
        "license": "NIST database, cited not reproduced"
      }
    }
  ],
  "corrosion": [],
  "risks": {
    "hazards": [
      {
        "text": "PubChem lists bismuth as Not Classified in its summary, and says 324 of 382 company reports did not meet GHS hazard criteria. Four notifications from 58 of 382 reports carry hazard codes H370 and H372 (damage to organs), with the signal word Danger. The record covers bismuth, not this alloy, and does not say which bismuth form the reports cover.",
        "ghs": [
          "H370",
          "H372"
        ],
        "source": "pubchem-bismuth",
        "where": "Safety and Hazards, GHS Classification section (CID 5359367)"
      },
      {
        "text": "The AIM safety data sheet for Alloy Sn42-Bi58 NC 273LT (version 1.07, revised 5/17/2024) classifies the solder paste under CLP as Aquatic Chronic 1, H410 (very toxic to aquatic life with long lasting effects), with signal word Warning. Its composition table lists tin, a hydrogenated rosin and an amine salt, and no bismuth, so the sheet describes the paste, not the bare alloy.",
        "ghs": [
          "H410"
        ],
        "source": "aim-sds-nc273lt",
        "where": "Sections 2.1 and 2.2 (signal word Warning, H410 text), Section 3 composition table, Section 16"
      },
      {
        "text": "The same SDS says overexposure to fumes may irritate the respiratory tract, digestive system and eyes, and that overexposure to tin oxide fumes may cause benign pneumoconiosis (stannosis). It lists the product's own toxicity data as Not available.",
        "ghs": [],
        "source": "aim-sds-nc273lt",
        "where": "Section 11.1, Carcinogenicity conclusion and Section 11 product data"
      }
    ],
    "failure_risks": [
      {
        "mode": "Thermal fatigue of solder joints",
        "trigger": "Thermal cycling. AIM does not state the temperature range used for its rating.",
        "consequence": "AIM rates the thermal fatigue resistance of Sn42/Bi58 as Poor, the same as Sn63/Pb37 and against Excellent for SAC305, on the same table.",
        "severity": "high",
        "source": "aim-info",
        "where": "Second performance table, Thermal Fatigue Resistance column (Sn42/Bi58 Poor; SAC305 Excellent; Sn63/Pb37 Poor)"
      },
      {
        "mode": "Low wetting in soldering",
        "trigger": "Soldering with the alloy. AIM does not state the flux or test conditions behind the rating.",
        "consequence": "AIM rates the wetting characteristics of Sn42/Bi58 as Fair, against Excellent for SAC305 and Sn63/Pb37 on the same table.",
        "severity": "moderate",
        "source": "aim-info",
        "where": "Second performance table, Wetting Characteristics column (Sn42/Bi58 Fair)"
      },
      {
        "mode": "Low melting point limits the service temperature",
        "trigger": "Operating or reflow temperature at or above 138 °C",
        "consequence": "The alloy melts at 138 °C as printed. Neither datasheet gives a service temperature limit, so the usable temperature range is not stated in any source read.",
        "severity": "moderate",
        "source": "aim-tds",
        "where": "Features (Low Melting Point 138°C) and Description"
      }
    ],
    "side_effects": [],
    "handling": [
      {
        "text": "Use with adequate ventilation and proper personal protective equipment. Refer to the accompanying safety data sheet for emergency information. Do not dispose of hazardous materials in non-approved containers.",
        "source": "aim-tds",
        "where": "Safety section"
      },
      {
        "text": "Shelf life is 3 years for water-soluble cored wire made with this alloy. Other cored wire, solid wire and bar have an indefinite shelf life.",
        "source": "aim-tds",
        "where": "Handling and Storage section"
      },
      {
        "text": "The alloy is compatible with most electronic grade fluxes. Cleaning follows the flux manufacturer's data sheets.",
        "source": "aim-tds",
        "where": "Flux Compatibility and Cleaning sections"
      }
    ],
    "mitigations": []
  },
  "uses": [
    {
      "application": "electronics-and-chips",
      "device": "Second-solder reflow for circuit board assembly",
      "example": "AIM says Sn42/Bi58 is typically used for second-solder reflow in circuit board assembly, and for other low-temperature soldering requirements.",
      "source": "aim-tds",
      "where": "Description section"
    },
    {
      "application": "electronics-and-chips",
      "device": "Solder paste, solid and cored wire, foil, powder, bar, ingot and anode",
      "example": "AIM lists these forms for the alloy, which is the form range a buyer can choose from.",
      "source": "aim-tds",
      "where": "Description section"
    },
    {
      "application": "electronics-and-chips",
      "device": "Lead-free replacement in low-temperature solders",
      "example": "USGS says bismuth is a nontoxic replacement for lead in solders, and that cadmium, indium, lead and tin can partially replace bismuth in low-temperature solders.",
      "source": "usgs-bismuth-2026",
      "where": "Domestic Production and Use paragraph and Substitutes paragraph"
    }
  ],
  "supply": [
    {
      "subject": "Tin (mine production, world)",
      "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
        },
        {
          "country": "Congo (Kinshasa)",
          "share_percent": 9.3,
          "year": 2025
        }
      ],
      "critical_lists": [],
      "recycling": "USGS: about 17,000 tons of tin from old and new scrap was estimated to have been recycled in 2025.",
      "substitutes": [
        "USGS: epoxy resins are listed as substitutes for tin in solder."
      ],
      "source": "usgs-tin-2026",
      "where": "World Mine Production and Reserves table, 2025e column (world total 290,000 t). Shares calculated by Space Mushroom from China 71,000, Indonesia 61,000, Peru 33,000, Brazil 28,000 and Congo (Kinshasa) 27,000. Recycling and Substitutes sections."
    },
    {
      "subject": "Bismuth (refinery production, world)",
      "producers": [
        {
          "country": "China",
          "share_percent": 88,
          "year": 2025
        }
      ],
      "critical_lists": [],
      "recycling": "USGS: recycled bismuth-containing alloy scrap made up to 10% of U.S. bismuth apparent consumption for 2021 to 2025.",
      "substitutes": [
        "USGS: cadmium, indium, lead and tin can partially replace bismuth in low-temperature solders."
      ],
      "source": "usgs-bismuth-2026",
      "where": "Events, Trends, and Issues paragraph (printed 'China accounted for 88% of the bismuth world production in 2025'); estimated world production 16,000 tons in 2025; Import Sources (2021 to 2024): China 56%, Republic of Korea 22%, Germany 13%, other 9%; Recycling; Substitutes"
    }
  ],
  "media": [],
  "documents": [
    {
      "title": "AIM: Sn42/Bi58 lead-free solder alloy, technical data sheet (Document Rev # NF4)",
      "type": "datasheet",
      "url": "https://aimsolder.com/wp-content/uploads/alloy_sn42-bi58_tds.pdf"
    },
    {
      "title": "AIM: Alloy Information, common and specialty solder alloys with technical information",
      "type": "datasheet",
      "url": "https://aimsolder.com/wp-content/uploads/legacy-files/alloy_information.pdf"
    },
    {
      "title": "USGS Mineral Commodity Summaries 2026: Tin",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-tin.pdf",
      "year": 2026
    },
    {
      "title": "USGS Mineral Commodity Summaries 2026: Bismuth",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-bismuth.pdf",
      "year": 2026
    },
    {
      "title": "PubChem: Bismuth (CID 5359367), GHS classification summary",
      "type": "database",
      "url": "https://pubchem.ncbi.nlm.nih.gov/compound/5359367",
      "year": 2026
    },
    {
      "title": "AIM: Safety data sheet, Alloy Sn42-Bi58 NC 273LT (solder paste), version 1.07 revised 5/17/2024",
      "type": "sds",
      "url": "https://aimsolder.com/wp-content/uploads/alloy_sn42-bi58_nc273lt-clp_europe-english.pdf",
      "year": 2024
    },
    {
      "title": "Kang, Rajendran and Jung: Low Melting Temperature Sn-Bi Solder, Metals 2021, 11, 364",
      "type": "paper",
      "url": "https://mdpi-res.com/d_attachment/metals/metals-11-00364/article_deploy/metals-11-00364-v2.pdf",
      "year": 2021
    },
    {
      "title": "NIST and Colorado School of Mines: Database for Solder Properties, Properties of Lead-Free Solders, Release 4.0",
      "type": "database",
      "url": "https://www.metallurgy.nist.gov/solder/NIST_LeadfreeSolder_v4.pdf",
      "year": 2002
    }
  ],
  "gaps": [
    "No corrosion or ageing data for Sn42Bi58 in any source read this run. The corrosion list is empty, so no rate or environment is claimed.",
    "No UNS, EN, JIS, ASTM or AISI designation was found in the sources read. Only the AIM trade name Sn42/Bi58 is recorded.",
    "The safety data sheet read (AIM NC 273LT, version 1.07) covers the solder paste with flux, not the bare alloy. It lists tin, a hydrogenated rosin and an amine salt, and no bismuth. Hazard data for the bare alloy are not established, and the PubChem bismuth record covers bismuth metal, not this alloy.",
    "Tensile strength disagrees across three sources: 8,000 psi (AIM datasheet), 9.71 ksi (AIM information sheet) and 8,766 psi (NIST Table 1.2). No test method is printed in any of them, so no confirmed strength value is recorded.",
    "The NIST table values come from the NCMS 1998 tensile programme and older compilations. The specimen form is not printed for each row, so they are recorded with that caveat.",
    "Yield strength (6.03 ksi) and joint strength (6800 psi) rest on the AIM information sheet only. The datasheet does not print them, and neither gives a test method.",
    "Uniform elongation (1.3) and Brinell hardness (23) are printed without units in the AIM sheets, so they are left out rather than given a unit.",
    "The two AIM sheets give different elongation figures: 55 % in the datasheet and a unitless uniform elongation of 1.3 in the information sheet.",
    "Density is recorded in g/cc from the datasheet and in lbs/in3 from the information sheet as printed. No conversion between them was made.",
    "Thermal conductivity and CTE rest on one datasheet. The test temperature range for the CTE is not stated.",
    "No service temperature limit, creep data, or fatigue life test for Sn42Bi58 was found. The thermal fatigue rating is a qualitative AIM grade, not a measured cycle count.",
    "Critical-mineral status of tin and bismuth is not stated in the USGS chapters read. The EU critical raw materials list was not read for either metal.",
    "Sn-Bi reliability or ageing papers are paywalled or blocked this run (Springer, MDPI and a University of Limerick copy returned 403 or a browser check). No ageing value was taken from them.",
    "No space-environment data (outgassing, radiation, thermal vacuum, flight heritage) for Sn42Bi58 was searched for in this run.",
    "No environments tag is recorded because no source read names an environment.",
    "electrical_conductivity, shear_strength, latent_heat_of_fusion and joint_strength are not names in property-canon.yaml. They are used as written.",
    "The coefficient of thermal expansion printed for Sn-58Bi in NIST Table 2.2.19 (1.5) has no legible unit in the PDF text, so it is not recorded.",
    "The thermal conductivity of 57.26 W/(m.K) in NIST Table 2.2.2 belongs to Castin (Sn-2.5Ag-0.8Cu-0.5Sb), not Sn-58Bi, so it is not used.",
    "PubChem's tin GHS record could not be opened (browser check), and a REST lookup returned CID 5352425, which is lead. No tin hazard data are recorded.",
    "Elongation now has three figures: 55 % (AIM datasheet), total 46 % (NIST Table 1.2) and a unitless uniform 1.3 (AIM information sheet). They are not reconciled."
  ],
  "story": {
    "why": "Sn42Bi58 is a lead-free eutectic solder that melts at 138 °C, printed on both AIM sheets. The lower melting point is what makes it suited to second-solder reflow on circuit boards, the application AIM names first. Bismuth is the larger share of the alloy. The sources read here rate its thermal fatigue resistance Poor, which is the main trade against its low melting point.",
    "uses": [
      {
        "where": "Circuit board assembly",
        "line": "AIM says Sn42/Bi58 is typically used for second-solder reflow in circuit board assembly and for other low-temperature soldering requirements. The datasheet lists paste, solid and cored wire, foil, powder, bar, ingot and anode forms."
      },
      {
        "where": "Lead-free low-temperature solders",
        "line": "USGS says bismuth is a nontoxic replacement for lead in solders. It also says cadmium, indium, lead and tin can partially replace bismuth in low-temperature solders."
      }
    ],
    "can_do": [
      {
        "label": "Melting point",
        "line": "The eutectic melting point is 138 °C (280 °F), per the AIM datasheet and the AIM information sheet.",
        "benchmark": "melting_point",
        "scope": "material",
        "value": "138 °C"
      },
      {
        "label": "Tensile strength",
        "line": "The two AIM sheets disagree. The datasheet prints 8,000 psi and the information sheet prints 9.71 ksi for the same alloy, and neither gives a test method.",
        "benchmark": "ultimate_tensile_strength",
        "scope": "material",
        "value": "8,000 psi or 9.71 ksi"
      },
      {
        "label": "Joint strength",
        "line": "The AIM information sheet prints 6800 psi, the highest joint strength value in its performance table. The substrate and test method are not stated.",
        "benchmark": "joint_strength",
        "scope": "material",
        "value": "6800 psi"
      },
      {
        "label": "Thermal conductivity",
        "line": "The AIM datasheet prints 0.19 W/cm-°C at 85 °C.",
        "benchmark": "thermal_conductivity",
        "scope": "material",
        "value": "0.19 W/cm-°C"
      }
    ],
    "compare": "Sn42Bi58 melts lower than SAC305 and Sn63/Pb37 on the same AIM information sheet, which prints the melting point of each. Its joint strength of 6800 psi is the highest value in that sheet's performance table. Its thermal fatigue rating is Poor, the same as Sn63/Pb37 and below the Excellent rating for SAC305, and its wetting rating is Fair, below the Excellent rating given to both SAC305 and Sn63/Pb37. Its tensile strength is 9.71 ksi on the information sheet and 8,000 psi on the datasheet, and the two AIM sheets disagree. The sheet does not print a tensile value for SAC305, so no tensile comparison is made.",
    "compare_rows": [
      {
        "label": "Melting point",
        "benchmark": "melting_point",
        "scope": "material"
      },
      {
        "label": "Tensile strength",
        "benchmark": "ultimate_tensile_strength",
        "scope": "material"
      },
      {
        "label": "Thermal conductivity",
        "benchmark": "thermal_conductivity",
        "scope": "material"
      }
    ],
    "handling": [
      "Use with ventilation and protective equipment, and follow the safety data sheet for emergencies (AIM datasheet).",
      "Water-soluble cored wire has a 3-year shelf life. Other forms have an indefinite shelf life (AIM datasheet).",
      "Use an electronic grade flux and follow the flux maker's cleaning instructions (AIM datasheet)."
    ],
    "good_for": [
      "Second-solder reflow on circuit boards. The alloy melts at 138 °C as printed (AIM datasheet).",
      "Joint strength. AIM prints 6800 psi, the highest value in its joint strength table (AIM information sheet)."
    ],
    "watch_out": [
      "Thermal fatigue resistance is rated Poor by AIM, against Excellent for SAC305.",
      "Wetting is rated Fair by AIM, against Excellent for SAC305 and Sn63/Pb37.",
      "The two AIM sheets disagree on tensile strength (8,000 psi against 9.71 ksi), and neither gives a test method."
    ],
    "verdict": "Sn42Bi58 is the low-melting choice in the AIM range. It gives up thermal fatigue resistance and wetting for a 138 °C melting point, and the printed joint strength is high. The sources read here do not cover its corrosion, space or service-temperature behaviour.",
    "recipe": {
      "line": "Sn42Bi58 is a eutectic alloy of 42 % tin and 58 % bismuth by weight, each within ±0.5 (AIM datasheet). The datasheet also prints a table of maximum impurity levels, in percent, for twelve elements, set against the IPC standard it names.",
      "parts": [
        {
          "name": "Tin",
          "symbol": "Sn",
          "role": "42 % by weight, ±0.5 (AIM datasheet). The datasheet gives the composition only; no atomic weight is recorded here."
        },
        {
          "name": "Bismuth",
          "symbol": "Bi",
          "role": "58 % by weight, ±0.5 (AIM datasheet). The datasheet gives the composition only; no atomic weight is recorded here. Bismuth is the larger share of this eutectic."
        }
      ]
    },
    "risk_groups": [
      {
        "title": "For people",
        "lead": "The AIM datasheet asks for ventilation and protective equipment. The AIM safety data sheet read is for the NC 273LT solder paste, not the bare alloy, and classifies that paste as very toxic to aquatic life with long lasting effects (H410). The bare alloy's hazard classification is not established here.",
        "points": [
          {
            "label": "The alloy",
            "line": "AIM says to use the alloy with adequate ventilation and proper personal protective equipment, and to follow the safety data sheet for emergencies."
          },
          {
            "label": "Bismuth in PubChem",
            "line": "PubChem's bismuth record says 324 of 382 company reports did not meet GHS hazard criteria, and four notifications from 58 reports carry H370 and H372. The record is for bismuth, not this alloy."
          }
        ],
        "level": 0,
        "verdict": "Hazard data limited"
      },
      {
        "title": "If a joint fails",
        "lead": "These are failure routes from the AIM ratings and the printed melting point. No field or space failure data were found.",
        "points": [
          {
            "label": "Melting",
            "line": "The alloy melts at 138 °C as printed. No service temperature limit is printed in either AIM sheet."
          },
          {
            "label": "Thermal fatigue",
            "line": "AIM rates thermal fatigue resistance Poor for this alloy, the same as Sn63/Pb37, against Excellent for SAC305."
          }
        ]
      },
      {
        "title": "Handling and storage",
        "points": [
          {
            "label": "Shelf life",
            "line": "Water-soluble cored wire with this alloy has a shelf life of 3 years. Other cored wire, solid wire and bar have an indefinite shelf life, per AIM."
          },
          {
            "label": "Flux",
            "line": "The alloy is compatible with most electronic grade fluxes. Cleaning follows the flux maker's data sheets."
          }
        ]
      }
    ]
  },
  "updated": "2026-11-01",
  "review": {
    "status": "draft",
    "method": "assistant",
    "checked_values": 23,
    "unreachable": 0,
    "caveats": 3,
    "note": "Read by an AI assistant on 2026-11-01 from the AIM datasheet and information sheet, USGS Mineral Commodity Summaries 2026 (tin, bismuth), and PubChem. Two AIM values disagree (tensile strength); both are recorded."
  },
  "sources": {
    "aim-tds": {
      "title": "Sn42/Bi58 lead-free solder alloy, technical data sheet",
      "id": "AIM, Document Rev # NF4",
      "url": "https://aimsolder.com/wp-content/uploads/alloy_sn42-bi58_tds.pdf",
      "year": 2026,
      "kind": "datasheet",
      "license": "supplier technical data sheet, cited not reproduced"
    },
    "aim-info": {
      "title": "Alloy Information: common solder alloys, specialty solder alloys and technical information",
      "id": "AIM alloy information sheet (legacy file)",
      "url": "https://aimsolder.com/wp-content/uploads/legacy-files/alloy_information.pdf",
      "year": 2026,
      "kind": "datasheet",
      "license": "supplier information sheet, cited not reproduced"
    },
    "usgs-tin-2026": {
      "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-bismuth-2026": {
      "title": "Mineral Commodity Summaries 2026: Bismuth",
      "id": "USGS MCS 2026, February 2026",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-bismuth.pdf",
      "year": 2026,
      "kind": "report",
      "license": "public domain (USGS)"
    },
    "pubchem-bismuth": {
      "title": "PubChem compound record, Bismuth (CID 5359367), GHS classification",
      "id": "CID 5359367",
      "url": "https://pubchem.ncbi.nlm.nih.gov/compound/5359367",
      "year": 2026,
      "kind": "database",
      "license": "public domain (NCBI)"
    },
    "aim-sds-nc273lt": {
      "title": "Safety data sheet: Alloy Sn42-Bi58 NC 273LT (solder paste), version 1.07",
      "id": "AIM Solder Europe, product code GHS049, revised 5/17/2024",
      "url": "https://aimsolder.com/wp-content/uploads/alloy_sn42-bi58_nc273lt-clp_europe-english.pdf",
      "year": 2024,
      "kind": "datasheet",
      "license": "supplier safety data sheet, cited not reproduced"
    },
    "kang2021": {
      "title": "Low Melting Temperature Sn-Bi Solder: Effect of Alloying and Nanoparticle Addition on the Microstructural, Thermal, Interfacial Bonding, and Mechanical Characteristics",
      "id": "Kang, Rajendran and Jung, Metals 2021, 11, 364, doi:10.3390/met11020364",
      "url": "https://mdpi-res.com/d_attachment/metals/metals-11-00364/article_deploy/metals-11-00364-v2.pdf",
      "year": 2021,
      "kind": "paper",
      "license": "CC BY 4.0"
    },
    "nist-solder-db": {
      "title": "Database for Solder Properties with Emphasis on New Lead-free Solders: Properties of Lead-Free Solders, Release 4.0",
      "id": "NIST and Colorado School of Mines, Release 4.0, dated 11 February 2002",
      "url": "https://www.metallurgy.nist.gov/solder/NIST_LeadfreeSolder_v4.pdf",
      "year": 2002,
      "kind": "database",
      "license": "NIST database, cited not reproduced"
    }
  },
  "license": "CC-BY-4.0",
  "url": "https://spacemushroom.com/profiles/solder-sn42bi58/"
}