{ "spore": "profile", "id": "tin-zinc", "spore_version": "0.2", "family": "low-melting-metals-and-solders", "name": "Tin-zinc (Sn91Zn9 eutectic) and tin-bismuth (Sn42Bi58) low-temperature solders", "abbreviation": "SnZn and SnBi", "role": "lead-free low-melting solder alloys", "category": "metals", "type": "heavy-metals", "summary": "Two lead-free low-temperature solders are covered here. The first is the tin-zinc eutectic Sn91Zn9 (91 % tin and 9 % zinc by weight), sold by Kapp Alloy as KappAloy9 for soldering aluminium to aluminium and to copper. Kapp prints a eutectic melting point of 199 °C, a density of 7.27 g/cc, a tensile strength of 54.7 MPa and an elongation at break of 32.50 %. The second is the tin-bismuth eutectic Sn42Bi58 (42 % tin and 58 % bismuth), which AIM Solder gives a eutectic melting point of 138 °C, a density of 8.72 g/cc and a tensile strength of 8,000 psi. Both sit below the 217 to 220 °C of SAC305, and Sn-Bi is also below the 183 °C of tin-lead eutectic (Sn-Zn, at 199 °C, sits above tin-lead). Sn-Bi is brittle under shock and drop, according to an iNEMI project page. Sn-Zn corrodes in chloride, and a 0.5 M NaCl study of Sn-3Zn-xBi alloys gives corrosion current densities of 8.7 to 17.4 uA.cm-2. No corrosion number for the Sn91Zn9 eutectic itself was found.\n", "best_for": "Low-temperature soldering of heat-sensitive electronics. Sn-Bi suits second-solder reflow at 138 °C, and Sn-Zn suits aluminium-to-copper joints that need a 199 °C eutectic (Kapp, AIM)", "weakest_at": "Sn-Bi is brittle under mechanical shock and drop, and Sn-Zn corrodes in chloride and leaves flux residue that is slightly corrosive (iNEMI, Brunel, Kapp)", "identity": { "formula": "Sn91Zn9 (91 % tin and 9 % zinc by weight; eutectic) and Sn42Bi58 (42 % tin and 58 % bismuth by weight; eutectic). Both are alloys, not compounds.", "designations": [ { "system": "Trade name", "code": "KappAloy9", "source": "kapp-kappaloy9", "where": "Product page title, 91Sn/9Zn Tin-Zinc Lead-Free Solder" } ], "source": "aim-sn42bi58-tds", "where": "Major alloy ingredients table, Sn 42 +/- 0.5 and Bi 58 +/- 0.5 (AIM TDS). The Sn 91 % and Zn 9 % composition is in the Composition block of kapp-kappaloy9." }, "tags": { "environments": [], "stresses": [], "applications": [ "electronics-and-chips" ] }, "properties": [ { "benchmark": "melting_point", "label": "Eutectic melting point, Sn91Zn9 (KappAloy9)", "value": 199, "bound": "exact", "unit": "°C", "scope": "material", "conditions": { "alloy": "Sn91Zn9 eutectic (91 % Sn, 9 % Zn)", "basis": "Melting Range row printed as Eutectic at 199°C (390°F)" }, "method": "Value printed on the manufacturer product page", "status": "ground", "source": "kapp-kappaloy9", "where": "Properties table, Melting Range row (Eutectic @ 199°C (390°F))", "source_detail": { "title": "KappAloy9 (91Sn/9Zn) Tin-Zinc Lead-Free Solder, Kapp Alloy product page", "id": "Kapp Alloy and Wire, Inc., product page (collection kappaloy9)", "url": "https://kappalloy.com/collections/kappaloy9", "year": 2026, "kind": "datasheet", "license": "manufacturer web page, cited not reproduced" } }, { "benchmark": "density", "label": "Density, Sn91Zn9 (KappAloy9)", "value": 7.27, "bound": "exact", "unit": "g/cc", "scope": "material", "conditions": { "alloy": "Sn91Zn9", "temperature": "not stated on the page" }, "method": "Value printed on the manufacturer product page (the SDS also prints a specific gravity of 7.27)", "status": "ground", "source": "kapp-kappaloy9", "where": "Properties table, Density row (7.27 g/cc (0.263 lb/in3))", "source_detail": { "title": "KappAloy9 (91Sn/9Zn) Tin-Zinc Lead-Free Solder, Kapp Alloy product page", "id": "Kapp Alloy and Wire, Inc., product page (collection kappaloy9)", "url": "https://kappalloy.com/collections/kappaloy9", "year": 2026, "kind": "datasheet", "license": "manufacturer web page, cited not reproduced" } }, { "benchmark": "ultimate_tensile_strength", "label": "Ultimate tensile strength, Sn91Zn9 (KappAloy9)", "value": 54.7, "bound": "exact", "unit": "MPa", "scope": "material", "conditions": { "alloy": "Sn91Zn9", "product_form": "solid wire, ribbon and spool, as sold", "test_method": "not stated on the page" }, "method": "Value printed on the manufacturer product page, shown in parentheses after 7930 psi", "status": "ground", "note": "The page prints 7930 psi (54.7 MPa). No test method or standard is named, so treat it as indicative.", "source": "kapp-kappaloy9", "where": "Technical Data table, Tensile Strength, Ultimate row (7930 psi (54.7 MPa))", "source_detail": { "title": "KappAloy9 (91Sn/9Zn) Tin-Zinc Lead-Free Solder, Kapp Alloy product page", "id": "Kapp Alloy and Wire, Inc., product page (collection kappaloy9)", "url": "https://kappalloy.com/collections/kappaloy9", "year": 2026, "kind": "datasheet", "license": "manufacturer web page, cited not reproduced" } }, { "benchmark": "elongation", "label": "Elongation at break, Sn91Zn9 (KappAloy9)", "value": 32.5, "bound": "exact", "unit": "%", "scope": "material", "conditions": { "alloy": "Sn91Zn9", "test_method": "not stated on the page" }, "method": "Value printed on the manufacturer product page", "status": "ground", "source": "kapp-kappaloy9", "where": "Technical Data table, Elongation at Break row (32.50%)", "source_detail": { "title": "KappAloy9 (91Sn/9Zn) Tin-Zinc Lead-Free Solder, Kapp Alloy product page", "id": "Kapp Alloy and Wire, Inc., product page (collection kappaloy9)", "url": "https://kappalloy.com/collections/kappaloy9", "year": 2026, "kind": "datasheet", "license": "manufacturer web page, cited not reproduced" } }, { "benchmark": "thermal_conductivity", "label": "Thermal conductivity, Sn91Zn9 (KappAloy9)", "value": 61, "bound": "exact", "unit": "W/m-K", "scope": "material", "conditions": { "temperature": "85 °C, as printed in the table", "alloy": "Sn91Zn9" }, "method": "Value printed on the manufacturer product page", "status": "ground", "source": "kapp-kappaloy9", "where": "Technical Data table, Thermal Conductivity row (61.0 W/m-K at 85.0 °C)", "source_detail": { "title": "KappAloy9 (91Sn/9Zn) Tin-Zinc Lead-Free Solder, Kapp Alloy product page", "id": "Kapp Alloy and Wire, Inc., product page (collection kappaloy9)", "url": "https://kappalloy.com/collections/kappaloy9", "year": 2026, "kind": "datasheet", "license": "manufacturer web page, cited not reproduced" } }, { "benchmark": "specific_heat", "label": "Specific heat, Sn91Zn9 (solid)", "value": 0.239, "bound": "exact", "unit": "J/g-°C", "scope": "material", "conditions": { "phase": "solid (liquid value is 0.272 J/g-°C as printed)", "alloy": "Sn91Zn9" }, "method": "Value printed on the manufacturer product page", "status": "ground", "source": "kapp-kappaloy9", "where": "Technical Data table, Specific Heat Capacity row (0.239 J/g-°C solid; 0.272 J/g-°C liquid)", "source_detail": { "title": "KappAloy9 (91Sn/9Zn) Tin-Zinc Lead-Free Solder, Kapp Alloy product page", "id": "Kapp Alloy and Wire, Inc., product page (collection kappaloy9)", "url": "https://kappalloy.com/collections/kappaloy9", "year": 2026, "kind": "datasheet", "license": "manufacturer web page, cited not reproduced" } }, { "benchmark": "electrical_resistivity", "label": "Electrical resistivity, Sn91Zn9 (KappAloy9)", "value": 0.000011, "bound": "exact", "unit": "ohm-cm", "scope": "material", "conditions": { "alloy": "Sn91Zn9", "temperature": "not stated on the page" }, "method": "Value printed on the manufacturer product page, copied as printed", "status": "ground", "source": "kapp-kappaloy9", "where": "Technical Data table, Electrical Resistivity row (0.0000110 ohm-cm)", "source_detail": { "title": "KappAloy9 (91Sn/9Zn) Tin-Zinc Lead-Free Solder, Kapp Alloy product page", "id": "Kapp Alloy and Wire, Inc., product page (collection kappaloy9)", "url": "https://kappalloy.com/collections/kappaloy9", "year": 2026, "kind": "datasheet", "license": "manufacturer web page, cited not reproduced" } }, { "benchmark": "melting_point", "label": "Eutectic melting point, Sn42Bi58", "value": 138, "bound": "exact", "unit": "°C", "scope": "material", "conditions": { "alloy": "Sn42Bi58 eutectic (42 % Sn, 58 % Bi)", "basis": "AIM gives one eutectic value, both solidus and liquidus" }, "method": "Value printed on the AIM data sheet (Document Rev NF4)", "status": "ground", "source": "aim-sn42bi58-tds", "where": "Features list and Description, eutectic melting point of 138°C (280°F)", "source_detail": { "title": "Sn42/Bi58 lead-free solder alloy, AIM technical data sheet", "id": "AIM Solder, Document Rev NF4", "url": "https://aimsolder.com/wp-content/uploads/alloy_sn42-bi58_tds.pdf", "year": 2024, "kind": "datasheet", "license": "supplier technical data sheet, cited not reproduced" } }, { "benchmark": "density", "label": "Density, Sn42Bi58", "value": 8.72, "bound": "exact", "unit": "g/cc", "scope": "material", "conditions": { "alloy": "Sn42Bi58", "temperature": "not stated on the sheet" }, "method": "Value printed on the AIM data sheet, Properties table", "status": "ground", "source": "aim-sn42bi58-tds", "where": "Properties table, Density g/cc row (8.72)", "source_detail": { "title": "Sn42/Bi58 lead-free solder alloy, AIM technical data sheet", "id": "AIM Solder, Document Rev NF4", "url": "https://aimsolder.com/wp-content/uploads/alloy_sn42-bi58_tds.pdf", "year": 2024, "kind": "datasheet", "license": "supplier technical data sheet, cited not reproduced" } }, { "benchmark": "ultimate_tensile_strength", "label": "Tensile strength, Sn42Bi58", "value": 8000, "bound": "exact", "unit": "psi", "scope": "material", "conditions": { "alloy": "Sn42Bi58", "product_form": "not stated on the sheet", "test_method": "not stated on the sheet" }, "method": "Value printed on the AIM data sheet, Properties table (no MPa figure is printed)", "status": "ground", "note": "The sheet prints 8,000 psi with no test method or product form, so it is not comparable with the MPa figures for SAC305 and Sn-Zn without conversion.", "source": "aim-sn42bi58-tds", "where": "Properties table, Tensile Strength PSI row (8,000)", "source_detail": { "title": "Sn42/Bi58 lead-free solder alloy, AIM technical data sheet", "id": "AIM Solder, Document Rev NF4", "url": "https://aimsolder.com/wp-content/uploads/alloy_sn42-bi58_tds.pdf", "year": 2024, "kind": "datasheet", "license": "supplier technical data sheet, cited not reproduced" } }, { "benchmark": "elongation", "label": "Elongation, Sn42Bi58", "value": 55, "bound": "exact", "unit": "%", "scope": "material", "conditions": { "alloy": "Sn42Bi58", "test_method": "not stated on the sheet" }, "method": "Value printed on the AIM data sheet, Properties table", "status": "ground", "source": "aim-sn42bi58-tds", "where": "Properties table, Elongation % row (55)", "source_detail": { "title": "Sn42/Bi58 lead-free solder alloy, AIM technical data sheet", "id": "AIM Solder, Document Rev NF4", "url": "https://aimsolder.com/wp-content/uploads/alloy_sn42-bi58_tds.pdf", "year": 2024, "kind": "datasheet", "license": "supplier technical data sheet, cited not reproduced" } }, { "benchmark": "cte", "label": "Coefficient of thermal expansion, Sn42Bi58", "value": 15, "bound": "exact", "unit": "ppm/°C", "scope": "material", "conditions": { "temperature": "20 °C, as printed in the table", "alloy": "Sn42Bi58" }, "method": "Value printed on the AIM data sheet, Properties table", "status": "ground", "source": "aim-sn42bi58-tds", "where": "Properties table, Coefficient of Thermal Expansion @ 20° C row (15 PPM/° C)", "source_detail": { "title": "Sn42/Bi58 lead-free solder alloy, AIM technical data sheet", "id": "AIM Solder, Document Rev NF4", "url": "https://aimsolder.com/wp-content/uploads/alloy_sn42-bi58_tds.pdf", "year": 2024, "kind": "datasheet", "license": "supplier technical data sheet, cited not reproduced" } }, { "benchmark": "thermal_conductivity", "label": "Thermal conductivity, Sn42Bi58", "value": 0.19, "bound": "exact", "unit": "W/cm-°C", "scope": "material", "conditions": { "temperature": "85 °C, as printed in the table", "alloy": "Sn42Bi58" }, "method": "Value printed on the AIM data sheet, Properties table. The printed unit is W/cm-°C; in SI units this is 19 W/m-K, converted only for comparison in the story.", "status": "ground", "source": "aim-sn42bi58-tds", "where": "Properties table, Thermal Conductivity @ 85° C row (0.19 W/cm-° C)", "source_detail": { "title": "Sn42/Bi58 lead-free solder alloy, AIM technical data sheet", "id": "AIM Solder, Document Rev NF4", "url": "https://aimsolder.com/wp-content/uploads/alloy_sn42-bi58_tds.pdf", "year": 2024, "kind": "datasheet", "license": "supplier technical data sheet, cited not reproduced" } }, { "benchmark": "latent_heat_of_fusion", "label": "Latent heat of fusion, Sn42Bi58", "value": 44.8, "bound": "exact", "unit": "J/g", "scope": "material", "conditions": { "alloy": "Sn42Bi58" }, "method": "Value printed on the AIM data sheet, Properties table", "status": "ground", "note": "latent_heat_of_fusion is not a name in property-canon.yaml; used as written.", "source": "aim-sn42bi58-tds", "where": "Properties table, Latent Heat of Fusion J/g row (44.8)", "source_detail": { "title": "Sn42/Bi58 lead-free solder alloy, AIM technical data sheet", "id": "AIM Solder, Document Rev NF4", "url": "https://aimsolder.com/wp-content/uploads/alloy_sn42-bi58_tds.pdf", "year": 2024, "kind": "datasheet", "license": "supplier technical data sheet, cited not reproduced" } }, { "benchmark": "melting_point", "label": "Melting point, Sn63/Pb37 eutectic (comparison)", "value": 183, "bound": "exact", "unit": "°C", "scope": "material", "conditions": { "alloy": "Sn63/Pb37 eutectic", "basis": "Liquidus printed as 183 °C (361 °F), eutectic" }, "method": "Value printed on the AIM Sn63/Pb37 data sheet (Document Rev NF5)", "status": "ground", "source": "aim-sn63-tds", "where": "Features list (Liquidus 183°C (361°F)) and Typical Melting Temperature block (183°C (361°F) Eutectic)", "source_detail": { "title": "Sn63/Pb37 Electropure solder alloy, AIM technical data sheet", "id": "AIM Solder, Document Rev NF5", "url": "https://www.aimsolder.com/wp-content/uploads/alloy_sn63-pb37_tds.pdf", "year": 2024, "kind": "datasheet", "license": "supplier technical data sheet, cited not reproduced" } }, { "benchmark": "melting_point", "label": "Melting range, SAC305 (comparison)", "value": 217, "value_high": 220, "bound": "range", "unit": "°C", "scope": "material", "conditions": { "alloy": "SAC305, Sn-3.0Ag-0.5Cu", "basis": "solidus 217 °C and liquidus 220 °C as printed" }, "method": "Values printed in the Selected Properties table of the Indium data sheet", "status": "ground", "source": "indium-256", "where": "Indalloy 256 Properties table, Solidus 217 °C and Liquidus 220 °C rows", "source_detail": { "title": "Indalloy 256 (SAC305) for Preforms, product data sheet", "id": "Indium Corporation, Form No. 100346 R0", "url": "https://www.indium.com/wp-content/uploads/2025/03/Indalloy256-for-Preforms-PDS-100346-R0-1.pdf", "year": 2025, "kind": "datasheet", "license": "supplier product data sheet, cited not reproduced" } }, { "benchmark": "density", "label": "Density, SAC305 (comparison)", "value": 7.35, "bound": "exact", "unit": "g/cc", "scope": "material", "conditions": { "alloy": "SAC305", "temperature": "not stated in the datasheet" }, "method": "Value printed in the Selected Properties table of the Indium data sheet", "status": "ground", "source": "indium-256", "where": "Indalloy 256 Properties table, Density row (7.35 g/cc)", "source_detail": { "title": "Indalloy 256 (SAC305) for Preforms, product data sheet", "id": "Indium Corporation, Form No. 100346 R0", "url": "https://www.indium.com/wp-content/uploads/2025/03/Indalloy256-for-Preforms-PDS-100346-R0-1.pdf", "year": 2025, "kind": "datasheet", "license": "supplier product data sheet, cited not reproduced" } }, { "benchmark": "thermal_conductivity", "label": "Thermal conductivity, SAC305 (comparison)", "value": 61, "bound": "exact", "unit": "W/mK", "scope": "material", "conditions": { "alloy": "SAC305", "temperature": "not stated in the datasheet" }, "method": "Value printed in the Selected Properties table of the Indium data sheet", "status": "ground", "source": "indium-256", "where": "Indalloy 256 Properties table, Thermal Conductivity row (61 W/mK)", "source_detail": { "title": "Indalloy 256 (SAC305) for Preforms, product data sheet", "id": "Indium Corporation, Form No. 100346 R0", "url": "https://www.indium.com/wp-content/uploads/2025/03/Indalloy256-for-Preforms-PDS-100346-R0-1.pdf", "year": 2025, "kind": "datasheet", "license": "supplier product data sheet, cited not reproduced" } }, { "benchmark": "cte", "label": "Coefficient of thermal expansion, SAC305 (comparison)", "value": 21, "bound": "exact", "unit": "ppm/°C", "scope": "material", "conditions": { "alloy": "SAC305", "temperature": "range not stated in the datasheet" }, "method": "Value printed in the Selected Properties table of the Indium data sheet", "status": "ground", "source": "indium-256", "where": "Indalloy 256 Properties table, CTE row (21 ppm/°C)", "source_detail": { "title": "Indalloy 256 (SAC305) for Preforms, product data sheet", "id": "Indium Corporation, Form No. 100346 R0", "url": "https://www.indium.com/wp-content/uploads/2025/03/Indalloy256-for-Preforms-PDS-100346-R0-1.pdf", "year": 2025, "kind": "datasheet", "license": "supplier product data sheet, cited not reproduced" } } ], "corrosion": [ { "environment": "0.5 M NaCl solution at 20 °C, potentiodynamic polarization (Sn-3Zn with 0 to 7 wt % Bi, Sn-Zn family, not the eutectic)", "headline": "In 0.5 M NaCl the Sn-3Zn alloy has a corrosion current density of 13.5 uA.cm-2, and adding 1 wt % Bi raises it to 17.4 uA.cm-2.", "effect": "The Brunel study reports icorr of 13.5 uA.cm-2 for Sn-3Zn, 17.4 uA.cm-2 for Sn-3Zn-1Bi, 13.4 uA.cm-2 for Sn-3Zn-5Bi and 8.7 uA.cm-2 for Sn-3Zn-7Bi. The authors link the 1 wt % Bi result to coarser and more evenly spread Zn-rich precipitates. Corrosion products were mainly Cl, O and Zn, and pits were found on the surface. The paper gives no mm/y rate, so no rating is given.", "rating": "unknown", "conditions": { "electrolyte": "0.5 M NaCl, aerated, room temperature 20 +/- 2 oC", "alloy_family": "Sn-3Zn-xBi, x = 0, 1, 3, 5, 7 wt %, not the Sn91Zn9 eutectic", "method": "Tafel extrapolation to Ecorr" }, "source": "brunel-sn-zn-bi", "where": "Table 2 and the results paragraph (icorr values in uA.cm-2); Figure 5 and surface element mapping" }, { "environment": "Residue of the Kapp Golden Flux used with KappAloy solders on aluminium joints", "headline": "Kapp says the flux residue is electrically conductive and slightly corrosive.", "effect": "The manufacturer says Golden Flux residue should be removed with warm water or alcohol and a clean rag. It is designed for aluminium-to-aluminium and aluminium-to-copper joints. Kapp gives no corrosion rate for the solder itself.", "rating": "low", "conditions": { "basis": "manufacturer product-page statement about the matching flux residue", "material": "flux residue, not the bare solder" }, "source": "kapp-kappaloy9", "where": "Matching Kapp Golden Flux paragraph (Residue is electrically conductive and slightly corrosive)" } ], "risks": { "hazards": [ { "text": "The Kapp safety data sheet (SDS 121 GHS, dated 01/01/2025) says the tin-zinc solder is not considered hazardous under Regulation (EC) 1272/2008 or the OSHA Hazard Communication Standard, and has no signal word.", "ghs": [], "source": "kapp-sds-121", "where": "Section II, Hazard information (No signal word; Not considered hazardous)" }, { "text": "Excessive inhalation of zinc oxide fumes may cause zinc shakes, a flu-like illness that usually stops when the person leaves the source. The SDS says the product should be used with NIOSH-approved breathing protection against dusts and fumes.", "ghs": [], "source": "kapp-sds-121", "where": "Section XI, Toxicology information (Zinc entry); Section VIII, Respiratory Protection" }, { "text": "Finely divided dust of the tin-zinc alloy may form an explosive mixture with air. The SDS also warns that wet or moist ingots present an explosion hazard when submerged in molten solder.", "ghs": [], "source": "kapp-sds-121", "where": "Section V, Unusual Fire and Explosion Hazards; Section VII, Handling and storage (ingot warning)" }, { "text": "PubChem's zinc record aggregates ECHA notifications. H250 (catches fire spontaneously if exposed to air) is reported for 26.7 % of company reports, and H400 and H410 (very toxic to aquatic life) for 84.9 % and 79 %. The record does not say which zinc form each notification covers, so these codes are not a classification of the tin-zinc solder.", "ghs": [ "H250", "H260", "H400", "H410" ], "source": "pubchem-zinc", "where": "GHS Classification section, ECHA aggregated notifications (CID 23994)" }, { "text": "The AIM SDS for Sn42-Bi58 NC 273LT (EU, version 1.07, issued 5/17/2024) classifies the product as Aquatic Chronic 1, H410, with signal word Warning. This SDS covers the NC 273LT product, which contains flux components, not the bare Sn42Bi58 alloy.", "ghs": [ "H410" ], "source": "aim-sn42bi58-sds-eu", "where": "Section 2.1 Classification (Aquatic Chronic 1, H410) and Section 2.2 signal word" }, { "text": "The AIM Asia GHS SDS for Sn42-Bi58 NC 273LT (version 0.15, issued 5/6/2024) lists skin corrosion or irritation Category 3 (causes mild skin irritation) and skin sensitisation Category 1 (may cause an allergic skin reaction). Signal word Warning. It is for the same flux-containing product, not the bare alloy.", "ghs": [], "source": "aim-sn42bi58-sds-asia", "where": "Section 2 Classification (Skin Corrosion/Irritation Category 3; Skin Sensitization Category 1) and Hazard statements" }, { "text": "PubChem's bismuth record shows 'Not Classified' from 324 of 382 company reports. Four notifications, from 58 of 382 reports, carry H370 (damage to organs, single exposure) and H372 (damage to organs through prolonged or repeated exposure). The record does not say which bismuth substance is covered.", "ghs": [ "H370", "H372" ], "source": "pubchem-bismuth", "where": "GHS Classification section, ECHA aggregated notifications (CID 5359367)" } ], "failure_risks": [ { "mode": "Brittle fracture of Sn-Bi joints under shock and drop", "trigger": "Mechanical shock or drop at high strain rate, for compositions close to the eutectic (about 58 wt % Bi)", "consequence": "iNEMI says BiSn-based joints near 58 wt % Bi are prone to brittle fracture at high strain rates and carry a high risk under mechanical shock and drop conditions in consumer electronics.", "severity": "high", "source": "inemi-bisn", "where": "Project background text on BiSn brittle fracture (no numbers given)" }, { "mode": "Chloride corrosion of the Zn-rich phase in Sn-Zn alloys", "trigger": "Immersion in aerated 0.5 M NaCl at 20 °C (tested on Sn-3Zn-xBi, not on the eutectic)", "consequence": "The Brunel study reports corrosion current densities of 8.7 to 17.4 uA.cm-2 across the Sn-3Zn-xBi series and pits in the surface, with Cl, O and Zn in the corrosion products. No service rate is given.", "severity": "moderate", "source": "brunel-sn-zn-bi", "where": "Table 2 (icorr values) and the surface and pit analysis paragraphs" }, { "mode": "Residual flux corrosion on aluminium joints", "trigger": "Golden Flux residue left on the joint after soldering aluminium", "consequence": "The residue is electrically conductive and slightly corrosive, according to Kapp. The residue should be removed with warm water or alcohol.", "severity": "low", "source": "kapp-kappaloy9", "where": "Matching Kapp Golden Flux paragraph" } ], "side_effects": [], "handling": [ { "text": "Wash thoroughly before smoking or eating, as the Kapp SDS states in capitals.", "source": "kapp-sds-121", "where": "Section XVI, Other information (PERSONNEL SHOULD WASH THOROUGHLY BEFORE SMOKING OR EATING)" }, { "text": "Use NIOSH-approved breathing apparatus against dusts and fumes, and approved safety glasses or goggles, as the SDS states.", "source": "kapp-sds-121", "where": "Section VIII, Exposure controls (Respiratory Protection; Eye Protection)" }, { "text": "Use with adequate ventilation and proper personal protective equipment, and refer to the SDS for emergency information. The AIM sheet is for the Sn42Bi58 alloy.", "source": "aim-sn42bi58-tds", "where": "Safety paragraph" }, { "text": "Do not overheat the Golden Flux. It chars above 550 °F (288 °C), as the Kapp product page states in capitals.", "source": "kapp-kappaloy9", "where": "Matching Kapp Golden Flux paragraph (DO NOT OVERHEAT FLUX)" } ], "mitigations": [] }, "uses": [ { "application": "electronics-and-chips", "device": "Second-solder reflow for circuit board assembly, Sn42Bi58", "example": "AIM says Sn42/Bi58 is used for second-solder reflow for circuit board assembly, and for other low temperature soldering requirements. It is available as paste, solid and cored wire, foil, powder, bar, ingot and anode.", "source": "aim-sn42bi58-tds", "where": "Description section (Typical applications) and the product forms list" }, { "application": "electronics-and-chips", "device": "Aluminium-to-copper electrical joints and bus contacts, Sn91Zn9", "example": "Kapp describes KappAloy9 for joining aluminium wire to copper busses or contacts, copper wire to aluminium busses, and electronic wires to aluminium fittings, heating panels and high-voltage components. Kapp says the low melting point limits heat damage to nearby electrical and electronic components.", "source": "kapp-kappaloy9", "where": "Applications list and the product description paragraph" }, { "application": "electronics-and-chips", "device": "Bismuth-containing solders", "example": "The USGS says bismuth is a nontoxic replacement for lead in brass, free-machining aluminium alloys, steels and solders, and that bismuth alloys are used for low melting point uses such as fusible alloys.", "source": "usgs-bismuth-2026", "where": "Domestic Production and Use paragraph (metallurgical applications)" } ], "supply": [ { "subject": "Tin (mine production, world), for both alloys", "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 recycled in 2025, which is 22 % of apparent consumption.", "substitutes": [ "USGS: epoxy resins are listed as a substitute 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; Substitutes" }, { "subject": "Zinc (mine production, world), for Sn91Zn9", "producers": [ { "country": "China", "share_percent": 31.5, "year": 2025 }, { "country": "Peru", "share_percent": 11.5, "year": 2025 }, { "country": "Australia", "share_percent": 8.5, "year": 2025 }, { "country": "India", "share_percent": 6.7, "year": 2025 }, { "country": "Mexico", "share_percent": 6, "year": 2025 } ], "critical_lists": [], "recycling": "USGS: refined zinc produced in the United States was recovered from secondary materials, including galvanizing residues and crude zinc oxide from electric arc furnace dust. No percentage is printed in the text read.", "substitutes": [ "USGS: aluminium and plastics substitute for galvanized sheet in automobiles. Many elements are substitutes for zinc in chemical, electronic and pigment uses." ], "source": "usgs-zinc-2026", "where": "World Mine Production and Reserves table, 2025e column (world total 13,000, thousand metric tons zinc content; shares calculated by Space Mushroom from China 4,100, Peru 1,500, Australia 1,100, India 870 and Mexico 780); Recycling; Substitutes" }, { "subject": "Bismuth (refinery production, world), for Sn42Bi58", "producers": [ { "country": "China", "share_percent": 88, "year": 2025 }, { "country": "Korea, Republic of", "share_percent": 6.3, "year": 2025 }, { "country": "Laos", "share_percent": 3.1, "year": 2025 }, { "country": "Japan", "share_percent": 3.1, "year": 2025 } ], "critical_lists": [], "recycling": "USGS: recycled bismuth-containing alloy scrap was estimated to make 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 (China 88% of world production in 2025); World Refinery Production table, 2025 column (world total 16,000 t; Korea 1,000, Laos 500, Japan 500 with shares calculated by Space Mushroom); Recycling; Substitutes" } ], "media": [], "documents": [ { "title": "Kapp Alloy: KappAloy9 (91Sn/9Zn) product page, Properties and Technical Data", "type": "datasheet", "url": "https://kappalloy.com/collections/kappaloy9", "year": 2026 }, { "title": "Kapp Alloy and Wire: Safety Data Sheet SDS 121 GHS, KappAloy Tin-Zinc Solders for Aluminum Soldering (dated 01/01/2025)", "type": "sds", "url": "https://cdn.shopify.com/s/files/1/0809/8686/5687/files/SDS_121_GHS_KappAloy_Tin_Zinc.pdf", "year": 2025 }, { "title": "AIM: Alloy Sn42/Bi58 (NC 273LT) technical data sheet, Document Rev NF4", "type": "datasheet", "url": "https://aimsolder.com/wp-content/uploads/alloy_sn42-bi58_tds.pdf", "year": 2024 }, { "title": "AIM: Alloy Sn42-Bi58 NC 273LT safety data sheet, EU CLP (version 1.07, issued 5/17/2024)", "type": "sds", "url": "https://aimsolder.com/wp-content/uploads/alloy_sn42-bi58_nc273lt-clp_europe-english.pdf", "year": 2024 }, { "title": "AIM: Alloy Sn42-Bi58 NC 273LT GHS safety data sheet, Asia (version 0.15, issued 5/6/2024)", "type": "sds", "url": "https://www.aimsolder.com/wp-content/uploads/Alloy_Sn42-Bi58_NC273LT-GHS_Asia-English.pdf", "year": 2024 }, { "title": "AIM: Alloy Sn63/Pb37 Electropure technical data sheet, Document Rev NF5", "type": "datasheet", "url": "https://www.aimsolder.com/wp-content/uploads/alloy_sn63-pb37_tds.pdf", "year": 2024 }, { "title": "Indium Corporation: Indalloy 256 (SAC305) for preforms, product data sheet (form 100346 R0)", "type": "datasheet", "url": "https://www.indium.com/wp-content/uploads/2025/03/Indalloy256-for-Preforms-PDS-100346-R0-1.pdf", "year": 2025 }, { "title": "Liu, Khorsand and Ji (Brunel University London): Electrochemical corrosion behaviour of Sn-Zn-xBi lead-free solder alloys in 0.5 M NaCl solution", "type": "paper", "url": "https://bura.brunel.ac.uk/bitstream/2438/18088/1/FullText.pdf" }, { "title": "iNEMI project page: BiSn-Based Low-Temperature Soldering Process and Reliability, Phases 1-3a", "type": "report", "url": "https://www.inemi.org/iNEMI/Projects/BiSn-Based%20Low-Temperature%20Soldering%20Process%20and%20Reliability,%20Phases%201-3a", "year": 2026 }, { "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: Zinc", "type": "report", "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-zinc.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 compound record: Zinc (CID 23994), GHS classification", "type": "database", "url": "https://pubchem.ncbi.nlm.nih.gov/compound/Zinc", "year": 2026 }, { "title": "PubChem compound record: Bismuth (CID 5359367), GHS classification", "type": "database", "url": "https://pubchem.ncbi.nlm.nih.gov/compound/Bismuth", "year": 2026 } ], "gaps": [ "No corrosion rate or corrosion potential for the Sn91Zn9 eutectic was found. The Brunel study tested Sn-3Zn-xBi in 0.5 M NaCl, and the two open MDPI Sn-Zn corrosion papers returned HTTP 403 to every fetch attempt, so their numbers are not used.", "No corrosion data of any kind for Sn42Bi58 were found in the sources read.", "Sn91Zn9 properties rest on one manufacturer product page (Kapp). No AIM or Indium Sn91Zn9 technical data sheet was found, and the AIM Prospector entry needs an account. Kapp prints no test method for the tensile or elongation values.", "The Kapp SDS lists composition ranges for tin and zinc, but the PDF text is garbled in that section, so no range is recorded.", "The AIM SDS for Sn42Bi58 covers NC 273LT, a flux-containing product, not the bare alloy. No bare-alloy SDS was found, so the bare Sn-Bi alloy has no SDS-based hazard classification here.", "The Sn42Bi58 tensile figure is printed in psi only (8,000 psi). It is recorded as printed and not converted. The sheet gives no test method.", "AIM prints Sn42Bi58 Brinell hardness as 23 with no unit, and an electrical conductivity line with a label that conflicts with its value (4.5 % IACS). Neither is recorded.", "The Kapp SDS prints a melting range of 198 to 343 C. The upper figure is not a melting point for the eutectic, so only the page value of 199 C is recorded.", "The Sn63/Pb37 data sheet read in this run gives only the melting point. Density and CTE for tin-lead are not recorded here, so the comparison table has no tin-lead density or thermal conductivity.", "The Sn42Bi58 thermal conductivity is printed as 0.19 W/cm-°C. The SI equivalent (19 W/m-K) is used only for the comparison paragraph.", "The iNEMI page gives qualitative brittleness statements only. No strain rate, impact energy or joint strength numbers were read for Sn-Bi.", "The Brunel paper gives no year in the text read, so no year is recorded for it. Its results apply to Sn-3Zn-xBi, which is not the eutectic.", "USGS 2026 text read for tin, zinc and bismuth contains no critical-mineral list statement. The USGS critical list and the EU critical raw materials list were not read for these three metals, so critical_lists is empty.", "The USGS zinc summary does not print a recycling percentage, so none is recorded.", "Mine and refinery shares are calculated from the USGS 2025e values, except the bismuth China share (88 %), which USGS prints.", "Space-exposure data (outgassing, atomic oxygen, radiation, thermal cycling of Sn-Zn or Sn-Bi joints) were not searched in this run. Tin whisker data for these alloys were not read.", "No UNS, JIS, ASTM or EN designation was found for Sn91Zn9 or Sn42Bi58 in the sources read. Only the Kapp trade name KappAloy9 is recorded." ], "story": { "why": "Both alloys melt below SAC305 (217 to 220 °C), and Sn-Bi also melts below tin-lead (183 °C). Sn-Bi at 138 °C is for second-solder reflow that must not remelt the first joints, and Sn-Zn at 199 °C is for aluminium joints where heat must stay low to protect nearby parts (Kapp, AIM).", "uses": [ { "where": "Second-solder reflow, Sn42Bi58", "line": "AIM says Sn42/Bi58 is used for second-solder reflow for circuit board assembly, and for other low temperature soldering requirements." }, { "where": "Aluminium-to-copper joints, Sn91Zn9", "line": "Kapp describes KappAloy9 for aluminium wire to copper busses, copper wire to aluminium busses, and electronic wires to aluminium fittings and high-voltage components." }, { "where": "Bismuth in solders", "line": "The USGS calls bismuth a nontoxic replacement for lead in solders and fusible alloys." } ], "can_do": [ { "label": "Melt low", "line": "AIM gives a Sn42Bi58 eutectic melting point of 138 °C (280 °F).", "benchmark": "melting_point", "scope": "material", "value": "138 °C" }, { "label": "Melt low for aluminium", "line": "Kapp gives the Sn91Zn9 eutectic at 199 °C (390 °F) for aluminium soldering.", "benchmark": "melting_point", "scope": "material", "value": "199 °C" }, { "label": "Weight", "line": "AIM gives a Sn42Bi58 density of 8.72 g/cc. Kapp gives 7.27 g/cc for Sn91Zn9.", "benchmark": "density", "scope": "material", "value": "8.72 g/cc" }, { "label": "Carry heat", "line": "Kapp gives a thermal conductivity of 61.0 W/m-K at 85 °C for Sn91Zn9. AIM gives 0.19 W/cm-°C at 85 °C for Sn42Bi58.", "benchmark": "thermal_conductivity", "scope": "material", "value": "61.0 W/m-K" } ], "compare": "Both alloys melt below SAC305, which is their reason for use. Sn-Bi melts at 138 °C, well below tin-lead's 183 °C and SAC305's 217 °C. Sn-Zn melts at 199 °C, which is still below SAC305. Sn-Zn has a density of 7.27 g/cc, close to SAC305's 7.35 g/cc, and both print a thermal conductivity of about 61 W/m-K. Sn-Bi is much denser (8.72 g/cc) and has a conductivity of 0.19 W/cm-°C, about 19 W/m-K, roughly one third of the others. The Sn-Bi weak point is brittleness under shock, and the Sn-Zn weak point is corrosion in chloride. Tin-lead density was not read in this run, so the comparison table has no tin-lead density row.", "compare_rows": [ { "label": "Melting point", "benchmark": "melting_point", "scope": "material" }, { "label": "Density", "benchmark": "density", "scope": "material" }, { "label": "Thermal conductivity", "benchmark": "thermal_conductivity", "scope": "material" } ], "handling": [ "Check the SDS for the exact product. The bare Sn-Zn alloy is not classified by Kapp, but the Sn-Bi flux product is classified H410 in the EU.", "Wash hands before eating, and do not overheat the Golden Flux for Sn-Zn (it chars above 550 °F).", "Keep wet or moist ingots away from molten solder.", "Ventilate the work area and wear NIOSH-approved respiratory protection against dust and fume." ], "good_for": [ "Low-temperature second-solder reflow of Sn42Bi58 (AIM), where the first joints must not remelt.", "Aluminium-to-copper electrical joints with Sn91Zn9 and Kapp Golden Flux (Kapp)." ], "watch_out": [ "Sn-Bi is brittle under shock and drop at high strain rate (iNEMI).", "Sn-Zn corrodes in chloride (Brunel, icorr 8.7 to 17.4 uA.cm-2 for the Sn-3Zn-xBi series; the eutectic itself was not tested).", "Flux residue on aluminium joints is slightly corrosive (Kapp).", "The Sn-Bi SDS covers a flux-containing product, not the bare alloy." ], "verdict": "Sn91Zn9 (199 °C) and Sn42Bi58 (138 °C) are the two low-melting lead-free options in this profile. Sn-Bi is best for second-solder reflow where its shock brittleness is acceptable; Sn-Zn is best for aluminium joints with its matching flux. Neither has a corrosion rate for the eutectic, and both have their data from one or two vendor sheets, so the values are indicative.", "recipe": { "line": "Two eutectic alloys. Sn91Zn9 is tin with 9 % zinc by weight, and Sn42Bi58 is tin with 58 % bismuth by weight. No intermetallic phase is described for either alloy in the sources read, and no process route is given for either alloy.", "parts": [ { "name": "Tin (in Sn91Zn9)", "symbol": "Sn", "role": "The matrix of the tin-zinc eutectic. Kapp describes the alloy as a soft, lower melting point tin-zinc eutectic.", "share_percent": 91 }, { "name": "Zinc (in Sn91Zn9)", "symbol": "Zn", "role": "Sets the eutectic at 199 °C (Kapp). Zinc oxidises easily, so Kapp recommends a matching flux for aluminium joints.", "share_percent": 9 }, { "name": "Tin (in Sn42Bi58)", "symbol": "Sn", "role": "The tin share of the tin-bismuth eutectic, which melts at 138 °C (AIM).", "share_percent": 42 }, { "name": "Bismuth (in Sn42Bi58)", "symbol": "Bi", "role": "Sets the 138 °C eutectic. The iNEMI page says compositions near 58 wt % Bi are prone to brittle fracture at high strain rates.", "share_percent": 58 } ] }, "risk_groups": [ { "title": "For people", "lead": "The Kapp SDS does not classify the tin-zinc solder. The AIM SDS for the Sn-Bi flux product is classified H410 in the EU and carries skin-irritant and sensitiser classes in Asia. The bare Sn-Bi alloy SDS was not found.", "points": [ { "label": "Sn-Zn alloy", "line": "Kapp SDS 121 GHS (2025): not hazardous under Regulation (EC) 1272/2008, no signal word. Zinc oxide fumes can cause zinc shakes." }, { "label": "Zinc record", "line": "PubChem's zinc record shows H250 (pyrophoric) for 26.7 % of company reports, and H400 and H410 for most. The record does not say which zinc form each report covers." }, { "label": "Sn-Bi flux product", "line": "AIM SDS for NC 273LT: EU classification Aquatic Chronic 1, H410, signal word Warning. Asia SDS lists mild skin irritation and possible allergic skin reaction." } ], "level": 0, "verdict": "Bare alloys: not hazardous. Flux products: check" }, { "title": "If a joint fails", "lead": "The sources read give a brittle-fracture risk for Sn-Bi, and a chloride corrosion risk for the Sn-Zn family. Neither has a service rate for the eutectic.", "points": [ { "label": "Sn-Bi brittle", "line": "iNEMI says BiSn compositions near 58 wt % Bi are prone to brittle fracture at high strain rates and carry a high risk under shock and drop." }, { "label": "Sn-Zn chloride", "line": "In 0.5 M NaCl, Sn-3Zn has an icorr of 13.5 uA.cm-2. Adding 1 wt % Bi raises it to 17.4 uA.cm-2, and 7 wt % Bi lowers it to 8.7 uA.cm-2 (Brunel)." }, { "label": "Flux residue", "line": "Kapp says Golden Flux residue is electrically conductive and slightly corrosive, and should be removed with warm water or alcohol." } ], "verdict": "Sn-Bi: brittle under shock. Sn-Zn: corrodes in chloride" }, { "title": "Handling and storage", "points": [ { "label": "Hygiene", "line": "Wash thoroughly before smoking or eating (Kapp SDS, Section XVI)." }, { "label": "Dust and fume", "line": "Finely divided dust may form an explosive mixture with air, and zinc oxide fumes can cause zinc shakes. Use NIOSH-approved breathing protection (Kapp SDS, Sections V, VIII and XI)." }, { "label": "Wet ingots", "line": "Wet or moist ingots present an explosion hazard when submerged in molten solder (Kapp SDS, Section VII)." } ], "verdict": "Ventilate, wash before eating, keep ingots dry" } ] }, "updated": "2026-10-26", "review": { "status": "draft", "method": "assistant", "checked_values": 19, "unreachable": 4, "caveats": 4, "note": "Read by an AI assistant on 2026-10-26 from the Kapp product page and SDS, the AIM Sn42Bi58 data sheet and two SDS versions, the AIM Sn63/Pb37 data sheet, the Indium SAC305 data sheet, the Brunel paper, the iNEMI page, the USGS 2026 summaries and the PubChem pug_view records. Unreachable: the two MDPI Sn-Zn corrosion papers (HTTP 403), MakeItFrom and American Elements (HTTP 403), and the AIM Prospector Sn91Zn9 sheet (account needed). Caveats: the Sn-Zn corrosion data are for Sn-3Zn-xBi, not the eutectic; the Sn-Bi SDS covers a flux-containing product; the tensile values carry no test method; the GHS notifications cover the element, not the alloy." }, "sources": { "kapp-kappaloy9": { "title": "KappAloy9 (91Sn/9Zn) Tin-Zinc Lead-Free Solder, Kapp Alloy product page", "id": "Kapp Alloy and Wire, Inc., product page (collection kappaloy9)", "url": "https://kappalloy.com/collections/kappaloy9", "year": 2026, "kind": "datasheet", "license": "manufacturer web page, cited not reproduced" }, "kapp-sds-121": { "title": "Safety Data Sheet, KappAloy Tin-Zinc Solders for Aluminum Soldering (SDS 121 GHS R13)", "id": "Kapp Alloy and Wire, Inc., dated 01/01/2025", "url": "https://cdn.shopify.com/s/files/1/0809/8686/5687/files/SDS_121_GHS_KappAloy_Tin_Zinc.pdf", "year": 2025, "kind": "datasheet", "license": "supplier safety data sheet, cited not reproduced" }, "aim-sn42bi58-tds": { "title": "Sn42/Bi58 lead-free solder alloy, AIM technical data sheet", "id": "AIM Solder, Document Rev NF4", "url": "https://aimsolder.com/wp-content/uploads/alloy_sn42-bi58_tds.pdf", "year": 2024, "kind": "datasheet", "license": "supplier technical data sheet, cited not reproduced" }, "aim-sn42bi58-sds-eu": { "title": "Safety Data Sheet, Alloy Sn42-Bi58 NC 273LT (EU CLP, REACH 2020/878)", "id": "AIM Solder, version 1.07, issued 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" }, "aim-sn42bi58-sds-asia": { "title": "GHS Safety Data Sheet, Alloy Sn42-Bi58 NC 273LT (Asia)", "id": "AIM Solder, version 0.15, issued 5/6/2024", "url": "https://www.aimsolder.com/wp-content/uploads/Alloy_Sn42-Bi58_NC273LT-GHS_Asia-English.pdf", "year": 2024, "kind": "datasheet", "license": "supplier safety data sheet, cited not reproduced" }, "aim-sn63-tds": { "title": "Sn63/Pb37 Electropure solder alloy, AIM technical data sheet", "id": "AIM Solder, Document Rev NF5", "url": "https://www.aimsolder.com/wp-content/uploads/alloy_sn63-pb37_tds.pdf", "year": 2024, "kind": "datasheet", "license": "supplier technical data sheet, cited not reproduced" }, "indium-256": { "title": "Indalloy 256 (SAC305) for Preforms, product data sheet", "id": "Indium Corporation, Form No. 100346 R0", "url": "https://www.indium.com/wp-content/uploads/2025/03/Indalloy256-for-Preforms-PDS-100346-R0-1.pdf", "year": 2025, "kind": "datasheet", "license": "supplier product data sheet, cited not reproduced" }, "brunel-sn-zn-bi": { "title": "Electrochemical corrosion behaviour of Sn-Zn-xBi lead-free solder alloys in 0.5 M NaCl solution", "id": "Liu G, Khorsand S, Ji S; Brunel Centre for Advanced Solidification Technology, Brunel University London", "url": "https://bura.brunel.ac.uk/bitstream/2438/18088/1/FullText.pdf", "kind": "paper", "license": "author-hosted full text, cited not reproduced" }, "inemi-bisn": { "title": "iNEMI project: BiSn-Based Low-Temperature Soldering Process and Reliability, Phases 1-3a", "id": "iNEMI project page", "url": "https://www.inemi.org/iNEMI/Projects/BiSn-Based%20Low-Temperature%20Soldering%20Process%20and%20Reliability,%20Phases%201-3a", "year": 2026, "kind": "web", "license": "public project web page, cited not reproduced" }, "usgs-tin-2026": { "title": "Mineral Commodity Summaries 2026: Tin (U.S. Geological Survey)", "id": "USGS MCS 2026", "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-tin.pdf", "year": 2026, "kind": "report", "license": "public domain (USGS)" }, "usgs-zinc-2026": { "title": "Mineral Commodity Summaries 2026: Zinc (U.S. Geological Survey)", "id": "USGS MCS 2026", "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-zinc.pdf", "year": 2026, "kind": "report", "license": "public domain (USGS)" }, "usgs-bismuth-2026": { "title": "Mineral Commodity Summaries 2026: Bismuth (U.S. Geological Survey)", "id": "USGS MCS 2026", "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-bismuth.pdf", "year": 2026, "kind": "report", "license": "public domain (USGS)" }, "pubchem-zinc": { "title": "PubChem compound record: Zinc, GHS classification", "id": "CID 23994; PubChem pug_view JSON", "url": "https://pubchem.ncbi.nlm.nih.gov/compound/Zinc", "year": 2026, "kind": "database", "license": "public domain (NCBI); notifications attributed to ECHA" }, "pubchem-bismuth": { "title": "PubChem compound record: Bismuth, GHS classification", "id": "CID 5359367; PubChem pug_view JSON", "url": "https://pubchem.ncbi.nlm.nih.gov/compound/Bismuth", "year": 2026, "kind": "database", "license": "public domain (NCBI); notifications attributed to ECHA" } }, "license": "CC-BY-4.0", "url": "https://spacemushroom.com/profiles/tin-zinc/" }