Solder & Low-Melting Alloy Bi57Sn42Ag1
Bi57Sn42Ag1 is a lead-free bismuth-tin-silver solder alloy melting near 137–139 °C, supplied as T3 and T4 paste, cored and solid wire, bar, preforms, foil and spheres.
Reference datasheet — Bi57Sn42Ag1 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Bi57Sn42Ag1 tempers and conditions
Bi57Sn42Ag1 is supplied in one standard condition, AS-REFLOWED.
Supply forms, finishes and certifications
Ways Bi57Sn42Ag1 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
BAR | Solder bar / ingot for wave, dip and pot use | Supply form |
FOIL | Rolled foil / ribbon | Supply form |
PASTE-T3 | Solder paste, Type 3 powder | Supply form |
PASTE-T4Default | Solder paste, Type 4 powder (20–38 µm), no-clean flux | Supply form |
PREFORM | Stamped preforms / washers / discs | Supply form |
SPHERE | Solder spheres / BGA balls | Supply form |
WIRE-CORED | Flux-cored solder wire | Supply form |
WIRE-SOLID | Solid solder wire | Supply form |
What is Bi57Sn42Ag1?
Bi57Sn42Ag1 is a lead-free bismuth-tin-silver solder alloy melting near 137–139 °C, supplied as T3 and T4 paste, cored and solid wire, bar, preforms, foil and spheres. Electronics assemblers choose it for low-temperature reflow and step soldering under higher-melting joints where RoHS compliance and reduced thermal stress on components matter; as-reflowed joints show 62 MPa tensile strength and 35% elongation. Maximum service temperature is about 80 °C and the Bi-rich phase is notch sensitive, so it is not a substitute for SnAgCu in high-temperature or high-shock service. Bi57Sn42Ag1 has a density of 8.57 g/cm³ (0.31 lb/in³), heavier than 53% of solder & low-melting alloy grades. It melts at 137°C (279 °F). Bi57Sn42Ag1 has a yield strength of 40 MPa (5.8 ksi) and a tensile strength of 62 MPa (8.99 ksi) — stronger than 88% of solder & low-melting alloy grades. Elongation at break is 35% and the elastic modulus is 42 GPa (6.09 Msi).
What is Bi57Sn42Ag1 used for?
- low-temp SMT reflow
- step soldering below higher-melt joints
- temperature-sensitive component assembly
- LED module soldering
Advantages
- High strength — 40 MPa (5.8 ksi), better than 88% of solder & low-melting alloy grades
- Good corrosion resistance — 55/100, better than 78% of solder & low-melting alloy grades
Limitations
- Poor heat conductor — 19 W/m·K (11 BTU/hr·ft·°F), worse than 92% of solder & low-melting alloy grades
- Low electrical conductivity — 5 % IACS, worse than 90% of solder & low-melting alloy grades
- Limited service temperature — 80°C (176 °F), worse than 88% of solder & low-melting alloy grades
- Limited formability — 65/100, worse than 75% of solder & low-melting alloy grades
Bi57Sn42Ag1 properties
Typical room-temperature values; bars are the position among solder & low-melting alloy grades.
Physical3
Bi57Sn42Ag1 has a density of 8.57 g/cm³ (0.31 lb/in³), heavier than 53% of solder & low-melting alloy grades. It melts at 137°C (279 °F).
Mechanical11
Bi57Sn42Ag1 has a yield strength of 40 MPa (5.8 ksi) and a tensile strength of 62 MPa (8.99 ksi) — stronger than 88% of solder & low-melting alloy grades. Elongation at break is 35% and the elastic modulus is 42 GPa (6.09 Msi).
Thermal6
Bi57Sn42Ag1 is rated for continuous service to 80°C (176 °F). It conducts heat at 19 W/m·K (11 BTU/hr·ft·°F), worse than 92% of solder & low-melting alloy grades. Thermal expansion is 15 µm/m·K (8.33 µin/in·°F).
Electrical3
Bi57Sn42Ag1 conducts electricity at 5 % IACS, worse than 90% of solder & low-melting alloy grades.
Chemical & Environmental3
Corrosion resistance is good (55/100), better than 78% of solder & low-melting alloy grades.
Sustainability4
Producing a kilogram of Bi57Sn42Ag1 takes about 170 MJ of energy and emits 12 kg of CO₂ — less than 56% of solder & low-melting alloy grades. Typical recycled content is 20%.
Manufacturability7
Bi57Sn42Ag1's machinability is fair (35/100, better than 58% of solder & low-melting alloy grades); weldability poor (20/100); formability good (65/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the solder & low-melting alloy family
Yield strength against density for every solder & low-melting alloy grade FabDigit runs. Bi57Sn42Ag1 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Bi57Sn42Ag1
Is Bi57Sn42Ag1 easy to machine?
Very soft and gummy — use sharp positive-rake tools, high rake, light cuts and coolant; usually cast/stamped to size rather than machined.
Can Bi57Sn42Ag1 be welded?
Not fusion-welded; it is the filler itself — reflow at 170–190 °C peak, keep pot temperature ≤200 °C to limit dross and Bi segregation.
Can Bi57Sn42Ag1 be formed, bent or molded?
Readily extruded to wire and rolled to foil/preforms; avoid high strain-rate bending of finished joints because Bi-rich phase is notch sensitive.
Bi57Sn42Ag1 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Biprimary constituent, near Bi-Sn eutectic | 56 – 58 | 57 |
| Aggrain refinement, improves ductility/wetting | 0.8 – 1.2 | 1 |
| PbRoHS limit <0.1 wt%; low Pb critical to avoid 96 °C ternary | ≤ 0.07 | |
| Cuimpurity | ≤ 0.05 | |
| Feimpurity | ≤ 0.02 | |
| Znimpurity, degrades wetting | ≤ 0 | |
| CdRoHS-restricted impurity | ≤ 0 | |
| Sbimpurity | ≤ 0.05 | |
| Asimpurity | ≤ 0.03 | |
| Sn | balance |
What surface finishes work on Bi57Sn42Ag1?
Wets Cu, Ni/Au (ENIG) and OSP finishes well with mild no-clean flux; never solder to Pb-containing finishes (96 °C ternary); clean halide residues to avoid dendrite growth.
How much does Bi57Sn42Ag1 cost?
Bi57Sn42Ag1 is a high-cost solder & low-melting alloy ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Bi57Sn42Ag1 — frequently asked
What is Bi57Sn42Ag1 used for?
Bi57Sn42Ag1 is typically used for low-temp SMT reflow, step soldering below higher-melt joints, temperature-sensitive component assembly and LED module soldering. In short: low-temperature RoHS solder; reflows at 170–190 °C; strongest alloy in family.
What is the yield strength of Bi57Sn42Ag1?
Bi57Sn42Ag1 has a typical yield strength of 40 MPa (5.8 ksi) and a tensile strength of 62 MPa (8.99 ksi) — stronger than 88% of solder & low-melting alloy grades.
Is Bi57Sn42Ag1 easy to machine?
Not especially — machinability is rated fair (35/100, better than 58% of solder & low-melting alloy grades). Very soft and gummy — use sharp positive-rake tools, high rake, light cuts and coolant; usually cast/stamped to size rather than machined.
Can Bi57Sn42Ag1 be welded?
Not readily — weldability is rated poor (20/100). Not fusion-welded; it is the filler itself — reflow at 170–190 °C peak, keep pot temperature ≤200 °C to limit dross and Bi segregation.
What surface finishes work on Bi57Sn42Ag1?
Wets Cu, Ni/Au (ENIG) and OSP finishes well with mild no-clean flux; never solder to Pb-containing finishes (96 °C ternary); clean halide residues to avoid dendrite growth.
Can Bi57Sn42Ag1 be formed, bent or molded?
Readily extruded to wire and rolled to foil/preforms; avoid high strain-rate bending of finished joints because Bi-rich phase is notch sensitive.
What is the maximum service temperature of Bi57Sn42Ag1?
Bi57Sn42Ag1 is rated for continuous use to about 80°C (176 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does Bi57Sn42Ag1 cost?
Bi57Sn42Ag1 is a high-cost solder & low-melting alloy ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- J-STD-006 Requirements for Electronic Grade Solder Alloys — IPC/JEDEC (2013)
- GB/T 20422 (2018)
- NIST Solder Alloy Property Database (Bi-Sn systems) — NIST (2002)
- ASM Handbook Vol. 3 — Alloy Phase Diagrams (Bi-Sn, Bi-Sn-Ag) — ASM International (2016)
- Low-temperature Bi-Sn-Ag solder paste and preform datasheets — Indium Corporation / AIM Solder / Alpha Assembly (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.