spore: profile id: solder-sn-pb spore_version: 0.2 family: low-melting-metals-and-solders name: Tin-lead solder (Sn63/Pb37 eutectic and Sn60/Pb40) abbreviation: SnPb role: low-melting solder alloy for electronics assembly category: metals type: heavy-metals summary: | Tin-lead solder is a metal alloy of tin and lead. The 63/37 composition is a eutectic: it has one melting point, 183 °C, with no pasty range. The Sn60/Pb40 composition melts over a short range, from 183 °C to about 190 °C. The datasheets read for this profile put the density at about 8.4 to 8.5 g/cm3, the tensile strength of the 63/37 alloy at 43 MPa. A maker of 60/40 wire gives its thermal conductivity as 49 W/m·K and its elongation at break as 40 %. The US Aerospace Corporation review says tin whiskers were avoided for decades by adding a small amount of lead to the solder. best_for: Soldering of electronic assemblies where a single, low melting point and a long track record matter more than RoHS compliance (the Sn60/Pb40 sheet says it is restricted to professional use) weakest_at: Lead toxicity and regulatory limits (the Sn60/Pb40 sheet says it cannot be sold to private consumers), and low tensile strength and creep resistance compared with lead-free alloys identity: formula: Sn63/Pb37 eutectic (63 % tin and 37 % lead by weight) and Sn60/Pb40 (59.5 to 60.5 % tin, remainder lead, by weight); an alloy, not a compound source: aimtek-6337 where: Nominal Composition line (Sn 63 %, Pb 37 % remainder) of the Aimtek 63/37 data sheet; Sn content of the Sn60Pb40 range from section 2.2 of the Cynel-Unipress data sheet designations: - system: ASTM code: B32 note: solder grade Sn63 source: aimtek-6337 where: Industry Specifications line (ASTM B32 Sn63) - system: ISO code: '9453' note: alloy designation Sn60Pb40 in ISO 9453:2014 source: cynel-sn60pb40 where: 'Header block: Alloy designation according to ISO 9453:2014, Sn60Pb40' tags: environments: [] stresses: [] applications: - electronics-and-chips properties: - benchmark: melting_point label: Melting point, Sn63/Pb37 eutectic value: 183 unit: °C scope: material conditions: alloy: Sn63/Pb37 eutectic basis: solidus and liquidus both printed as 183 °C (361 °F); the sheet gives one value for both method: Value printed on a manufacturer data sheet status: ground source: aimtek-6337 where: 'Melting Temperature block: Solidus (Flow point) and Liquidus (Melt point), both 361°F (183°C)' - benchmark: density label: Density, Sn63/Pb37 eutectic value: 8.4 unit: g/cm3 scope: material conditions: alloy: Sn63/Pb37 eutectic temperature: not stated on the sheet method: Value printed on a manufacturer data sheet (the sheet also prints 0.303 lb/in3) status: ground source: aimtek-6337 where: 'Density line: 0.303 lb./in³ (8.40 g/cm³)' - benchmark: ultimate_tensile_strength label: Tensile strength, Sn63/Pb37 eutectic value: 43 unit: MPa scope: material conditions: alloy: Sn63/Pb37 eutectic product_form: not stated on the sheet test_method: not stated on the sheet method: Value printed on a manufacturer data sheet (the sheet prints 6240 psi) status: ground note: The sheet does not name the test standard, product form or temper, so treat it as indicative. source: aimtek-6337 where: 'Tensile Strength line: 6240 psi (43 MPa)' - benchmark: electrical_resistivity label: Electrical resistivity, Sn63/Pb37 eutectic value: 0.0000145 unit: ohm-cm scope: material conditions: alloy: Sn63/Pb37 eutectic temperature: not stated on the sheet method: Value printed on a manufacturer data sheet (printed as 1.45 x 10 to the power -5) status: ground source: aimtek-6337 where: 'Electrical Resistivity line: 1.45 x 10 -5 ohm-cm' - benchmark: melting_point label: Melting range, Sn60/Pb40 (cored wire data sheet) value: 183 value_high: 190 bound: range unit: °C scope: material conditions: alloy: Sn60Pb40, ISO 9453 designation product_form: cored solder wire method: Range printed on a manufacturer data sheet (solidus/liquidus) status: ground source: cynel-sn60pb40 where: 'Section 2.5: Melting point (solidus/liquidus) 183/190 °C' - benchmark: melting_point label: Melting range, Sn60/Pb40 (bar and wire data sheet) value: 183 value_high: 191 bound: range unit: °C scope: material conditions: alloy: Sn60Pb40, nominal composition method: Range printed on a manufacturer data sheet (solidus and liquidus) status: ground source: aimtek-6040 where: 'Melting Temperature block: Solidus (Flow point) 361°F (183°C); Liquidus (Melt point) 376°F (191°C)' - benchmark: density label: Density, Sn60/Pb40 (cored wire data sheet) value: 8.5 unit: g/cm3 scope: material conditions: alloy: Sn60Pb40 basis: printed as approximately 8,50 g/cm3 (the sheet uses a decimal comma) method: Value printed on a manufacturer data sheet status: ground source: cynel-sn60pb40 where: 'Section 2.6: Specific weight ~8,50 g/cm3' - benchmark: density label: Density, Sn60/Pb40 (bar and wire data sheet) value: 8.49 unit: g/cm3 scope: material conditions: alloy: Sn60Pb40, nominal composition method: Value printed on a manufacturer data sheet (the sheet also prints 0.3068 lb/in3) status: ground source: aimtek-6040 where: 'Density line: 0.3068 lb./in³ (8.49 g/cm³)' - benchmark: ultimate_tensile_strength label: Tensile strength at break, Sn60/Pb40 (bar and wire data sheet) value: 44.13 unit: MPa scope: material conditions: alloy: Sn60Pb40, nominal composition product_form: not stated on the sheet test_method: not stated on the sheet method: Value printed on a manufacturer data sheet (the sheet prints 6400 psi) status: ground note: The Cynel sheet gives a different figure for the same alloy (535 kg/cm2). The two sheets do not state the test method, so the difference cannot be resolved here. source: aimtek-6040 where: 'Tensile Strength line: 6400 psi (44.13 MPa)' - benchmark: ultimate_tensile_strength label: Tensile strength at break, Sn60/Pb40 (cored wire data sheet) value: 535 unit: kg/cm2 scope: material conditions: alloy: Sn60Pb40, ISO 9453 designation product_form: cored solder wire test_method: not stated on the sheet method: Value printed on a manufacturer data sheet in the unit the sheet uses status: ground source: cynel-sn60pb40 where: 'Section 2.9: Tensile strength at break 535 kg/cm2' - benchmark: elongation label: Elongation at break, Sn60/Pb40 (cored wire data sheet) value: 40 unit: '%' scope: material conditions: alloy: Sn60Pb40, ISO 9453 designation product_form: cored solder wire test_method: not stated on the sheet method: Value printed on a manufacturer data sheet status: ground source: cynel-sn60pb40 where: 'Section 2.10: Elongation at break 40%' - benchmark: thermal_conductivity label: Thermal conductivity, Sn60/Pb40 (cored wire data sheet) value: 49 unit: W/m·K scope: material conditions: alloy: Sn60Pb40, ISO 9453 designation temperature: not stated on the sheet method: Value printed on a manufacturer data sheet status: ground source: cynel-sn60pb40 where: 'Section 2.8: Thermal conductivity 49 W/m·K' corrosion: - environment: Humid heat, 85 °C and 85 % relative humidity, no applied voltage, up to 1000 hours (tin corrosion under QFN packages on solder-paste boards) headline: In an 85 °C and 85 % humidity test, the 63/37 paste showed no tin-corrosion failure, and it corroded more slowly than SAC305. effect: A Cookson Electronics and MSLCircuits study found tin corrosion products under QFN and large passive parts after 500 hours or more. The authors say flux chemistry had the largest effect, and that SAC305 corroded faster than 63Sn37Pb. They say the failure was not seen with the 63/37 paste used. Reflow conditions had almost no effect. rating: low conditions: exposure: 85 °C and 85 % RH, no applied voltage, readings at 250, 500, 750 and 1000 hours comparison: SAC305 paste on the same boards flux: three solder-paste flux chemistries source: cookson-2010 where: Executive Summary; Introduction (63/37 paste bullet); Summary of MSLCircuits failure analysis - environment: Tin-plated surfaces that carry no lead, such as pure tin plating on connector pins and relays headline: Tin-lead is the only method the Aerospace Corporation review found to stop tin whiskers consistently. effect: The review states that the only consistently demonstrated method of precluding tin whiskers is a minimum percentage of lead in the solder. Figure 7 shows whiskers on a tin-plated Kovar terminal in the region that was not covered by Sn-Pb solder during a hot solder dip, so the solder protects only where it covers the surface. rating: low conditions: basis: literature review of tin-whisker mechanisms and mitigation; not a corrosion test of the solder itself source: barr2007 where: Section 1 (What are tin whiskers) and Figure 7 caption risks: hazards: - text: Contains lead, a toxic element. The Sn63/Pb37 data sheet asks users to consult the material safety data sheet before handling and to use adequate ventilation and personal protective equipment. ghs: [] source: aim-electropure where: Handling and Safety sections - text: The NIOSH pocket guide sets the lead exposure limit at a time-weighted average of 0.050 mg/m3 (8 hours), and an IDLH of 100 mg/m3 (as Pb). Exposure can be by inhalation, ingestion, and skin or eye contact. ghs: [] source: niosh-lead where: 'Lead pocket guide entry: OSHA PEL, NIOSH REL, IDLH and exposure routes' - text: The Sn60/Pb40 wire is classed as a professional-use product because of its lead content and cannot be sold to private consumers. The sheet does not state a GHS classification. ghs: [] source: cynel-sn60pb40 where: Section 1 (General characteristics) failure_risks: - mode: Tin whisker short circuit on pure tin plating (the failure that lead in solder prevents) trigger: Pure tin plating with no lead, over time, with stress or in close-spaced circuits consequence: Whiskers can grow tens of millimetres and short neighbouring conductors. The review says a short can stay in place indefinitely unless the current is high enough to fuse the whisker, generally above 50 mA. severity: moderate source: barr2007 where: Section 2 (Problems metal whiskers can cause) side_effects: - text: Flux residues from the cored wire may remain on the joint after soldering. The sheet says they need not be removed, and recommends alcohol-based solvents if washing is needed. affects: The soldered surface source: cynel-sn60pb40 where: Section 3 (SW26 flux) handling: - text: Store at room temperature in a dry place, out of reach of children. source: cynel-sn60pb40 where: Section 4.5 (Storage) - text: Use with adequate ventilation and proper personal protective equipment. Do not dispose of hazardous materials in non-approved containers. source: aim-electropure where: Safety section - text: Recommended soldering tip temperature is 340 to 400 °C for the Sn60/Pb40 cored wire. source: cynel-sn60pb40 where: Section 2.12 mitigations: - text: Specify a tin-lead alloy rather than pure tin plating where whisker growth matters. The Aerospace Corporation review calls a minimum lead content the only consistently demonstrated whisker preventer. source: barr2007 where: Abstract and Section 1 uses: - application: electronics-and-chips device: Wave soldering and printed-circuit assembly example: The maker says 63Sn/37Pb is typically used in wave soldering and plating, primarily as a corrosion-protection coating and as a base for soldering. It is sold as bar, wire, foil, spheres, preforms, paste and powder. source: aim-electropure where: Description paragraph and product-form list - application: electronics-and-chips device: Spacecraft and high-reliability electronics example: A 2005 NASA review of lead-free soldering says that exemptions written for high-reliability aerospace electronics will not protect those assemblies from lead-free parts entering the supply chain. source: nasa-bok-2005 where: Introduction, paragraph on exemptions (lines on aerospace electronics) - application: electronics-and-chips device: Connector pins and relays in space hardware example: The Aerospace Corporation review notes that most space systems generally prohibit pure tin plating, and that tin whiskers grew in a hermetically sealed relay that had been pure tin plated. source: barr2007 where: Abstract and Figure 3 caption supply: - subject: Tin producers: - country: China share_percent: 24.5 year: 2025 - country: Indonesia share_percent: 21 year: 2025 - country: Peru share_percent: 11.4 year: 2025 - country: Brazil share_percent: 9.7 year: 2025 - 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 the survey says is 22 % of apparent consumption. Tin has not been mined or smelted in the United States since 1993 or 1989.' substitutes: - 'USGS: epoxy resins for solder; other substitutes listed are for cans, bronze, bearing metals and some chemicals.' source: usgs-mcs2026-tin where: Domestic Production and Use; Events, Trends and Issues; World Mine Production table (2025e, shares calculated by Space Mushroom against the 290,000 t world total); Substitutes - subject: Lead producers: - country: China share_percent: 42.2 year: 2025 - country: Australia share_percent: 10.7 year: 2025 - country: Peru share_percent: 6.4 year: 2025 - country: Russia share_percent: 5.8 year: 2025 - country: India share_percent: 4.9 year: 2025 critical_lists: - list: USGS 2025 List of Critical Minerals (lead added in the 2025 list) listed: true recycling: 'USGS: an estimated 1 million tons of secondary lead was produced in 2025, equal to 70 % of apparent domestic consumption. Nearly all of it came from old scrap, mostly lead-acid batteries.' substitutes: - 'USGS: tin has replaced lead in solder for potable water systems, and the electronics industry has moved toward lead-free solders.' source: usgs-mcs2026-lead where: Events, Trends and Issues (critical-list paragraph); World Mine Production table (2025e, shares calculated by Space Mushroom against the 4,500 thousand t world total); Recycling; Substitutes media: [] documents: - title: Aimtek 63/37 tin-lead solder technical data sheet type: datasheet url: https://aimtek.com/wp-content/uploads/2022/08/Aimtek-63-37-Tin-Lead-Solder-Technical-Data-Sheet.pdf year: 2022 - title: Aimtek 60/40 tin-lead solder technical data sheet type: datasheet url: https://aimtek.com/wp-content/uploads/2022/08/Aimtek-60-40-Tin-Lead-Solder-Technical-Data-Sheet.pdf year: 2022 - title: Cynel-Unipress technical data sheet, Sn60Pb40 cored solder wire (ISO 9453) type: datasheet url: https://ormix.lv/lv/catalog/showpdf/name/68ac979d42cb80508f9a5c4e8896ef9c.pdf year: 2022 - title: AIM Electropure 63Sn/37Pb technical data sheet type: datasheet url: https://assets.rs-online.com/v1698743561/Datasheets/77c922b68bf764517b10fb2353c292d5.pdf year: 2004 - title: Mitigating and preventing the growth of tin and other metal whiskers on critical hardware (The Aerospace Corporation) type: paper url: https://nepp.nasa.gov/whisker./reference/tech_papers/2007-barr-paper-mitigating-whiskers.pdf year: 2007 - title: 'Lead-free soldering for space applications: Lead-Free Solder Body of Knowledge (NASA, Kennedy Space Center)' type: report url: https://xdevs.com/doc/NASA/lead-free%20solder%20bok%20report%206-21-%202005.pdf year: 2005 - title: Tin corrosion under QFN packages at elevated temperature and humidity (IPC Midwest 2010) type: paper url: https://www.electronics.org/system/files/technical_resource/E11%26S04_02.pdf year: 2010 - 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: Lead' type: report url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-lead.pdf year: 2026 gaps: - The 63/37 Caplinq data sheet returned a server error on download, so its thermal conductivity, elongation and hardness values for Sn63/Pb37 are not in this file. - PubChem's GHS summary for lead returned a verification page, so the lead GHS hazard statements (H-codes) are not recorded. Hazard data for lead rest on the NIOSH pocket guide and the manufacturer sheets. - No safety data sheet for a tin-lead solder wire was read in this run; handling data come from the manufacturer sheets. - The USGS tin text read in this run does not state whether tin is on the 2025 US critical-minerals list. EU critical-raw-materials status of tin and lead was not checked. - Supply shares are calculated by Space Mushroom from USGS 2025e mine production (lead world total 4,500 thousand t; tin world total 290,000 t), not printed by USGS. - No quantitative corrosion rate for Sn63/Pb37 in humid air was found. The IBM report on SnO and SnO2 growth in humid aging could not be downloaded. - No vacuum, radiation, thermal-cycling or flight test result for tin-lead solder was read in this run. The space-related sources are a 2005 NASA review and a 2007 Aerospace Corporation review. - Hardness of the Sn60/Pb40 wire (16 HB in the cored wire sheet) is not included, because hardness is not in the canonical property list. - The Sn63/Pb37 wire datasheet does not give tensile test conditions, and the two Sn60/Pb40 sheets give tensile figures that differ (44.13 MPa and 535 kg/cm2). Both are kept as printed. - Atomic weights were not added to the recipe, because no fetched source prints them for this alloy. The recipe uses mass shares from the data sheets. - No image was checked for licence, so the media list is empty. - The NASA-STD-8739.3 soldering standard status could not be confirmed (sources conflict on whether it is cancelled), so it is not cited. - The 60/40 cored wire sheet prints its electrical resistivity with a decimal comma (0,153 μΩ·m), which the value-check tool cannot match, so that property was left out. The density and tensile values from the same sheet are kept. sources: aimtek-6337: title: AIMTEK High Purity 63% Tin/37% Lead Solder data sheet id: AIMTEK, Inc., Auburn MA url: https://aimtek.com/wp-content/uploads/2022/08/Aimtek-63-37-Tin-Lead-Solder-Technical-Data-Sheet.pdf year: 2022 kind: datasheet license: supplier document, linked not reproduced aimtek-6040: title: AIMTEK 60% Tin/40% Lead Solder data sheet id: AIMTEK, Inc., Auburn MA url: https://aimtek.com/wp-content/uploads/2022/08/Aimtek-60-40-Tin-Lead-Solder-Technical-Data-Sheet.pdf year: 2022 kind: datasheet license: supplier document, linked not reproduced cynel-sn60pb40: title: Cynel-Unipress technical data sheet, Sn60Pb40 cored solder wire with SW26 flux id: Cynel-Unipress Sp. z o.o., Warsaw; ISO 9453:2014 url: https://ormix.lv/lv/catalog/showpdf/name/68ac979d42cb80508f9a5c4e8896ef9c.pdf year: 2022 kind: datasheet license: supplier document, linked not reproduced aim-electropure: title: AIM Electropure 63Sn/37Pb technical data sheet (bar solder) id: AIM, technical data sheet dated 12.17.2004 url: https://assets.rs-online.com/v1698743561/Datasheets/77c922b68bf764517b10fb2353c292d5.pdf year: 2004 kind: datasheet license: supplier document, linked not reproduced barr2007: title: Mitigating and Preventing the Growth of Tin and Other Metal Whiskers on Critical Hardware id: Stephanie Barr, The Aerospace Corporation, 2007 url: https://nepp.nasa.gov/whisker./reference/tech_papers/2007-barr-paper-mitigating-whiskers.pdf year: 2007 kind: paper license: copyright The Aerospace Corporation (cited, not reproduced) nasa-bok-2005: title: 'Lead-Free Soldering for Space Applications: Lead-Free Solder Body of Knowledge (Kurt Kessel, NASA KSC)' id: NASA NEPP, April 2005 state of technology report (copy hosted on xdevs.com) url: https://xdevs.com/doc/NASA/lead-free%20solder%20bok%20report%206-21-%202005.pdf year: 2005 kind: report license: public domain (NASA) cookson-2010: title: Tin Corrosion under QFN Packages at Elevated Temperature and Humidity id: K. Tellefsen et al., Cookson Electronics, IPC Midwest 2010 url: https://www.electronics.org/system/files/technical_resource/E11%26S04_02.pdf year: 2010 kind: paper license: copyright of the authors (cited, not reproduced) niosh-lead: title: 'NIOSH Pocket Guide to Chemical Hazards: Lead' id: NIOSH / CDC, npgd0368 url: https://www.cdc.gov/niosh/npg/npgd0368.html year: 2024 kind: web license: public domain (US government) usgs-mcs2026-tin: title: Mineral Commodity Summaries 2026, Tin id: USGS MCS 2026, February 2026 url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-tin.pdf year: 2026 kind: report license: public domain (USGS) usgs-mcs2026-lead: title: Mineral Commodity Summaries 2026, Lead id: USGS MCS 2026, February 2026 url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-lead.pdf year: 2026 kind: report license: public domain (USGS) license: CC-BY-4.0 updated: '2026-10-26' review: status: draft method: assistant checked_values: 12 unreachable: 2 caveats: 2 note: Read by an AI assistant on 2026-10-26 from the data sheets, USGS and NIOSH pages listed in sources. Two sources could not be opened (Caplinq 63/37 sheet, PubChem lead record); the two Sn60/Pb40 tensile values differ and are kept as printed. story: recipe: line: 'Tin-lead solder is a binary alloy: tin and lead melted together. The eutectic 63/37 composition is the one with a single melting point. The Sn60/Pb40 composition has a short melting range. Both are cast or drawn into bar, wire and preforms, and the wire is usually cored with a rosin flux.' parts: - name: Tin symbol: Sn share_percent: 63 role: The main metal of the alloy. The maker recommends the alloy for soldering copper, copper alloys and ferrous alloys. - name: Lead symbol: Pb share_percent: 37 role: Part of the eutectic composition, which melts at 183 °C. The Aerospace Corporation review says lead in solder is what has kept tin whiskers away. risk_groups: - title: For people level: 0 verdict: Hazardous because of lead lead: Solder contains lead, a toxic element. The NIOSH guide gives an exposure limit and lists health effects. points: - label: Exposure limit line: The NIOSH pocket guide gives a time-weighted average limit of 0.050 mg/m3 for lead over 8 hours, and an IDLH of 100 mg/m3 (as Pb). - label: Routes line: Exposure can be by inhalation, ingestion, and skin or eye contact. Effects listed include anaemia, kidney disease, tremor and effects on the nervous system. - label: Product rule line: The Sn60/Pb40 sheet says the product cannot be sold to private consumers because of its lead content, and is for professional use only. - title: Handling and storage points: - label: Ventilation line: The maker advises adequate ventilation and personal protective equipment, and asks users to consult the safety data sheet before handling. - label: Storage line: Store at room temperature in a dry place, out of reach of children. Do not put hazardous material in non-approved containers for disposal. - label: Soldering temperature line: The Sn60/Pb40 wire is soldered with a tip at 340 to 400 °C. why: 'Tin-lead solder has been the standard joining metal for electronics for decades. The eutectic 63/37 alloy melts at a single temperature, 183 °C, which gives a sharp transition from liquid to solid. The maker names wave soldering as its typical use. Lead also suppresses tin whiskers, which the Aerospace Corporation review calls the only consistently demonstrated method of preventing them. The trade-off is toxicity: the 60/40 maker says its lead-containing wire is for professional use only and is not RoHS compliant.' uses: - where: Wave soldering and circuit assembly line: The maker describes 63Sn/37Pb as the usual alloy for wave soldering and plating, where it protects surfaces against corrosion and serves as a base for soldering. - where: High-reliability and space electronics line: A 2005 NASA review found that exemptions written for high-reliability aerospace electronics would not protect those assemblies from lead-free parts. The Aerospace Corporation review notes that most space systems prohibit pure tin plating. can_do: - label: Melting point benchmark: melting_point value: 183 °C line: The 63/37 eutectic melts and solidifies at one temperature, 183 °C. The 60/40 alloy melts over a short range, from 183 °C to 190 or 191 °C, according to two data sheets. - label: Density benchmark: density value: 8.40 g/cm3 line: The 63/37 alloy has a density of 8.40 g/cm3, and the 60/40 alloy 8.49 g/cm3 in one data sheet. - label: Tin whiskers value: Lead prevents them line: The Aerospace Corporation review says the only consistently demonstrated way to prevent tin whiskers is a minimum percentage of lead in the solder. compare: 'Tin-lead solder melts at 183 °C at the eutectic, and its maker gives a density of 8.40 g/cm3 and a tensile strength of 43 MPa. Its lead content is the trade-off: the datasheets restrict the 60/40 wire to professional use and say it is not RoHS compliant. The compare rows below use the same property names as the other profiles; no lead-free alloy was read in this run, so no side-by-side figures are given here.' compare_rows: - label: Melting point benchmark: melting_point - label: Density benchmark: density - label: Tensile strength benchmark: ultimate_tensile_strength handling: - Store dry, at room temperature, closed and out of reach of children. - Use adequate ventilation and personal protective equipment, as the maker advises. - Solder at 340 to 400 °C with the cored flux; alcohol-based solvents are recommended if residue needs removing. good_for: - Wave soldering and circuit assembly, where the maker names a single melting point (183 °C for 63/37) as the key property. - Joints where lead's whisker suppression matters, as the Aerospace Corporation review describes. watch_out: - Lead is toxic, and the 60/40 wire is restricted to professional use. - Tensile strength is low (about 43 to 44 MPa in the data sheets), and the two 60/40 sheets disagree on the figure. - Pure tin plating, the lead-free alternative, can grow tin whiskers that short neighbouring conductors. verdict: Tin-lead solder is the long-established, low-melting baseline for electronics. It is the only method the Aerospace Corporation review found to prevent tin whiskers consistently, but its lead content limits where it can be used.