Solder & Low-Melting Alloy Sn99.3Cu0.7
also SAC0307-precursor
Sn99.3Cu0.7 is the low-cost lead-free eutectic tin-copper solder, melting near 227 °C and listed as the precursor composition to SAC0307.
Reference datasheet — Sn99.3Cu0.7 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.
Sn99.3Cu0.7 tempers and conditions
Sn99.3Cu0.7 is supplied in 2 conditions, soft to hard.
Compare all 2 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Isothermally aged (e.g. 125-150 °C, 500-1000 h) / creep-softened joint | End-of-life design case: coarsened Cu6Sn5 and thick Cu3Sn IMC give lower strength and higher ductility. | 11 | 22 | 45 | 11 HB | 15 % IACS |
thin joint, as reflowed/wave-soldered (fine as-cast microstructure) | Use these values for joint-level strength predictions immediately after soldering, before thermal aging. | 23 | 38 | 28 | 16 HB | 14 % IACS |
Supply forms, finishes and certifications
Ways Sn99.3Cu0.7 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
BARDefault | Cast solder bar / ingot for wave and pot soldering | Supply form |
FOIL | Rolled ribbon / foil / tape | Supply form |
PREFORM | Stamped preforms, washers, discs and rings | Supply form |
SPHERE | BGA/CSP solder spheres and micro-balls | Supply form |
WIRE | Solid drawn/extruded solder wire | Supply form |
WIRE-FC | Flux-cored wire | Supply form |
PASTE | Solder paste | Printing process |
What is Sn99.3Cu0.7?
Sn99.3Cu0.7 is the low-cost lead-free eutectic tin-copper solder, melting near 227 °C and listed as the precursor composition to SAC0307. It is supplied as bar, solid and flux-cored wire, paste, spheres, preforms and foil, and is the default wave-solder alloy where silver-bearing SAC cost is not justified. Properties are 15 MPa yield, 28 MPa tensile, 40 % elongation, 14 HB, 65 W/m·K thermal conductivity and 14 % IACS, with service to about 100 °C. Wetting and strength are lower than SAC305, so silver-microalloyed Sn99Cu0.7Ag0.3 is the nearest upgrade. Sn99.3Cu0.7 has a density of 7.31 g/cm³ (0.264 lb/in³), lighter than 90% of solder & low-melting alloy grades. It melts at 227°C (441 °F). Sn99.3Cu0.7 has a yield strength of 15 MPa (2.18 ksi) and a tensile strength of 28 MPa (4.06 ksi) — weaker than 82% of solder & low-melting alloy grades. Elongation at break is 40% and the elastic modulus is 43 GPa (6.24 Msi).
What is Sn99.3Cu0.7 used for?
- lead-free wave soldering
- cost-sensitive consumer electronics
- general plumbing/HVAC (lead-free)
Advantages
- Conducts heat well — 65 W/m·K (37.6 BTU/hr·ft·°F), better than 96% of solder & low-melting alloy grades
- High electrical conductivity — 14 % IACS, better than 94% of solder & low-melting alloy grades
- Lightweight — 7.31 g/cm³ (0.264 lb/in³), better than 90% of solder & low-melting alloy grades
Limitations
- Difficult to machine — 20/100, worse than 94% of solder & low-melting alloy grades
- Low strength — 15 MPa (2.18 ksi), worse than 82% of solder & low-melting alloy grades
- High embodied carbon — 18 kg CO₂/kg, worse than 76% of solder & low-melting alloy grades
Sn99.3Cu0.7 properties
Typical room-temperature values; bars are the position among solder & low-melting alloy grades.
Physical3
Sn99.3Cu0.7 has a density of 7.31 g/cm³ (0.264 lb/in³), lighter than 90% of solder & low-melting alloy grades. It melts at 227°C (441 °F).
Mechanical11
Sn99.3Cu0.7 has a yield strength of 15 MPa (2.18 ksi) and a tensile strength of 28 MPa (4.06 ksi) — weaker than 82% of solder & low-melting alloy grades. Elongation at break is 40% and the elastic modulus is 43 GPa (6.24 Msi).
Thermal6
Sn99.3Cu0.7 is rated for continuous service to 100°C (212 °F). It conducts heat at 65 W/m·K (37.6 BTU/hr·ft·°F), better than 96% of solder & low-melting alloy grades. Thermal expansion is 22 µm/m·K (12.2 µin/in·°F).
Electrical3
Sn99.3Cu0.7 conducts electricity at 14 % IACS, better than 94% of solder & low-melting alloy grades.
Chemical & Environmental3
Corrosion resistance is fair (45/100), worse than 52% of solder & low-melting alloy grades.
Sustainability4
Producing a kilogram of Sn99.3Cu0.7 takes about 320 MJ of energy and emits 18 kg of CO₂ — more than 81% of solder & low-melting alloy grades. Typical recycled content is 30%.
Manufacturability6
Sn99.3Cu0.7's machinability is poor (20/100, worse than 94% of solder & low-melting alloy grades); formability excellent (90/100).
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. Sn99.3Cu0.7 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Sn99.3Cu0.7
Is Sn99.3Cu0.7 easy to machine?
Rarely machined — extremely soft and gummy; if trimming preforms use sharp high-rake tools, low speed, no coolant carry-over into the flux.
Can Sn99.3Cu0.7 be welded?
Not arc-welded; it is the filler itself — process at 250-270 °C pot / 245-260 °C reflow peak with N2 or active no-clean flux, and expect ~15-25 °C more heat than SnPb37.
Can Sn99.3Cu0.7 be formed, bent or molded?
Extrudes and rolls easily to wire, ribbon and stamped preforms; atomized into Type 3/4 powder for paste; anneals at room temperature so cold work does not persist.
Sn99.3Cu0.7 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 |
|---|---|---|
| CuISO 9453 alloy 401 / J-STD-006 Sn99.3Cu0.7 | 0.6 – 0.9 | 0.7 |
| PbRoHS limit 0.1 % max; premium bar often <0.05 % | ≤ 0.07 | |
| Sb | ≤ 0.05 | |
| Bi | ≤ 0.1 | |
| Agresidual only | ≤ 0.1 | |
| As | ≤ 0.03 | |
| Fe | ≤ 0.02 | |
| Niintentional 0.05-0.06 % Ni in micro-alloyed SN100C-type variants | ≤ 0.01 | |
| Zn | ≤ 0 | |
| Al | ≤ 0 | |
| Cd | ≤ 0 | |
| Sn≈99.3 % nominal | balance |
What surface finishes work on Sn99.3Cu0.7?
Used as-soldered; keep flux residues cleaned or fully no-clean, avoid bright-Sn-like whisker conditions, and do not plate or anodize the joint.
Equivalent designations
Standards and trade names that resolve to Solder & Low-Melting Alloy Sn99.3Cu0.7 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Trade names
- SAC0307-precursor
- Also called
- IEC C7SnCu0.7
How much does Sn99.3Cu0.7 cost?
Sn99.3Cu0.7 is a high-cost solder & low-melting alloy ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sn99.3Cu0.7 — frequently asked
What is Sn99.3Cu0.7 used for?
Sn99.3Cu0.7 is typically used for lead-free wave soldering, cost-sensitive consumer electronics and general plumbing/HVAC (lead-free). In short: cheapest lead-free solder; silver-free wave alloy; SAC0307 precursor composition.
What is the yield strength of Sn99.3Cu0.7?
Sn99.3Cu0.7 has a typical yield strength of 15 MPa (2.18 ksi) and a tensile strength of 28 MPa (4.06 ksi) — weaker than 82% of solder & low-melting alloy grades. Strength varies by condition: see the 2 listed tempers.
Is Sn99.3Cu0.7 easy to machine?
Not especially — machinability is rated poor (20/100, worse than 94% of solder & low-melting alloy grades). Rarely machined — extremely soft and gummy; if trimming preforms use sharp high-rake tools, low speed, no coolant carry-over into the flux.
Can Sn99.3Cu0.7 be welded?
Not arc-welded; it is the filler itself — process at 250-270 °C pot / 245-260 °C reflow peak with N2 or active no-clean flux, and expect ~15-25 °C more heat than SnPb37.
What surface finishes work on Sn99.3Cu0.7?
Used as-soldered; keep flux residues cleaned or fully no-clean, avoid bright-Sn-like whisker conditions, and do not plate or anodize the joint.
Can Sn99.3Cu0.7 be formed, bent or molded?
Extrudes and rolls easily to wire, ribbon and stamped preforms; atomized into Type 3/4 powder for paste; anneals at room temperature so cold work does not persist.
What is the maximum service temperature of Sn99.3Cu0.7?
Sn99.3Cu0.7 is rated for continuous use to about 100°C (212 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does Sn99.3Cu0.7 cost?
Sn99.3Cu0.7 is a high-cost solder & low-melting alloy ($$$$), 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
- ISO 9453 — Soft solder alloys, chemical composition and forms (alloy 401, Sn99.3Cu0.7) — ISO (2020)
- J-STD-006 — Requirements for Electronic Grade Solder Alloys and Fluxed/Non-Fluxed Solid Solders — IPC (2013)
- Properties of Lead-Free Solders / Solder Property Database — NIST (2002)
- ASM Handbook Vol. 6 — Welding, Brazing and Soldering (soldering section) — ASM International (1993)
- Lead-free alloy data sheets (Sn100 / SnCu0.7, SN100C) — Indium Corporation / AIM Solder / Nihon Superior (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.