Solder & Low-Melting Alloy SAC387
ISO 713 · also IEC A38C7
SAC387 (IEC A38C7) is a near-eutectic tin-silver-copper solder for wave and reflow assembly, combining good wetting with higher strength than lower-silver SAC grades.
Reference datasheet — SAC387 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.
What is SAC387?
SAC387 (IEC A38C7) is a near-eutectic tin-silver-copper solder for wave and reflow assembly, combining good wetting with higher strength than lower-silver SAC grades. It is supplied as bar, solid and cored wire, paste, spheres, powder and preforms, with reflow peaks of 235–250 °C and wave pots at 255–265 °C. Bulk properties are 38 MPa yield, 50 MPa tensile, 33% elongation and 15 HB, with service to about 125 °C. The higher silver content raises cost relative to SAC305, which is the usual lower-cost alternative for general consumer assembly. SAC387 has a density of 7.44 g/cm³ (0.269 lb/in³), lighter than 63% of solder & low-melting alloy grades. It melts at 217°C (423 °F). SAC387 has a yield strength of 38 MPa (5.51 ksi) and a tensile strength of 50 MPa (7.25 ksi) — stronger than 85% of solder & low-melting alloy grades. Elongation at break is 33% and the elastic modulus is 50 GPa (7.25 Msi).
What is SAC387 used for?
- Wave soldering
- Reflow soldering
- Through-hole assembly
Advantages
- High electrical conductivity — 13 % IACS, better than 87% of solder & low-melting alloy grades
- Stiff — 50 GPa (7.25 Msi), better than 86% of solder & low-melting alloy grades
- High strength — 38 MPa (5.51 ksi), better than 85% of solder & low-melting alloy grades
- Conducts heat well — 58 W/m·K (33.5 BTU/hr·ft·°F), better than 85% of solder & low-melting alloy grades
- Readily welded — 30/100, better than 83% of solder & low-melting alloy grades
Limitations
- Difficult to machine — 20/100, worse than 94% of solder & low-melting alloy grades
- High embodied carbon — 24 kg CO₂/kg, worse than 94% of solder & low-melting alloy grades
SAC387 properties
Typical room-temperature values; bars are the position among solder & low-melting alloy grades.
Physical3
SAC387 has a density of 7.44 g/cm³ (0.269 lb/in³), lighter than 63% of solder & low-melting alloy grades. It melts at 217°C (423 °F).
Mechanical11
SAC387 has a yield strength of 38 MPa (5.51 ksi) and a tensile strength of 50 MPa (7.25 ksi) — stronger than 85% of solder & low-melting alloy grades. Elongation at break is 33% and the elastic modulus is 50 GPa (7.25 Msi).
Thermal6
SAC387 is rated for continuous service to 125°C (257 °F). It conducts heat at 58 W/m·K (33.5 BTU/hr·ft·°F), better than 85% of solder & low-melting alloy grades. Thermal expansion is 22 µm/m·K (12.2 µin/in·°F).
Electrical3
SAC387 conducts electricity at 13 % IACS, better than 87% 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 SAC387 takes about 350 MJ of energy and emits 24 kg of CO₂ — more than 92% of solder & low-melting alloy grades. Typical recycled content is 30%.
Manufacturability7
SAC387's machinability is poor (20/100, worse than 94% of solder & low-melting alloy grades); weldability poor (30/100); 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. SAC387 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with SAC387
Is SAC387 easy to machine?
Rarely machined — the alloy is soft and gummy, smears and loads tooling; cut with sharp positive-rake tools and lubricant if required.
Can SAC387 be welded?
Not welded; it is the filler metal itself — reflow peak 235–250 °C or a 255–265 °C wave pot with nitrogen preferred to limit dross.
Can SAC387 be formed, bent or molded?
Cast to bar, extruded/drawn to wire, atomized to Type 3–5 powder or stamped to preforms; all forming is done near room temperature at high homologous temperature so it work-softens rather than hardens.
SAC387 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 |
|---|---|---|
| Agnear-eutectic silver level | 3.5 – 4 | 3.8 |
| Cu | 0.5 – 0.9 | 0.7 |
| PbRoHS lead-free limit; many suppliers hold ≤0.05 | ≤ 0.07 | |
| Sbimpurity | ≤ 0.1 | |
| Biimpurity | ≤ 0.1 | |
| Feimpurity | ≤ 0.02 | |
| Asimpurity | ≤ 0.03 | |
| CdRoHS restricted | ≤ 0 | |
| Znimpurity | ≤ 0 | |
| Alimpurity | ≤ 0.01 | |
| Snbalance, ~95.5 % | balance |
What surface finishes work on SAC387?
Joints are cleaned of flux residue (or left with no-clean flux); no plating or anodizing — protect against humidity plus bias to avoid dendritic migration.
Equivalent designations
Standards and trade names that resolve to Solder & Low-Melting Alloy SAC387 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- ISO
- 713
- Trade names
- IEC A38C7
How much does SAC387 cost?
SAC387 is a high-cost solder & low-melting alloy ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
SAC387 — frequently asked
What is SAC387 used for?
SAC387 is typically used for wave soldering, reflow soldering and through-hole assembly. In short: near-eutectic SAC solder; stronger than SAC305; good wetting on copper.
What is the yield strength of SAC387?
SAC387 has a typical yield strength of 38 MPa (5.51 ksi) and a tensile strength of 50 MPa (7.25 ksi) — stronger than 85% of solder & low-melting alloy grades.
Is SAC387 easy to machine?
Not especially — machinability is rated poor (20/100, worse than 94% of solder & low-melting alloy grades). Rarely machined — the alloy is soft and gummy, smears and loads tooling; cut with sharp positive-rake tools and lubricant if required.
Can SAC387 be welded?
Not readily — weldability is rated poor (30/100). Not welded; it is the filler metal itself — reflow peak 235–250 °C or a 255–265 °C wave pot with nitrogen preferred to limit dross.
What surface finishes work on SAC387?
Joints are cleaned of flux residue (or left with no-clean flux); no plating or anodizing — protect against humidity plus bias to avoid dendritic migration.
Can SAC387 be formed, bent or molded?
Cast to bar, extruded/drawn to wire, atomized to Type 3–5 powder or stamped to preforms; all forming is done near room temperature at high homologous temperature so it work-softens rather than hardens.
What is the maximum service temperature of SAC387?
SAC387 is rated for continuous use to about 125°C (257 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does SAC387 cost?
SAC387 is a high-cost solder & low-melting alloy ($$$$), 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
- IEC 61190-1-3 Attachment materials for electronic assembly — requirements for electronic grade solder alloys — IEC (2007)
- J-STD-006 Requirements for Electronic Grade Solder Alloys and Fluxed/Non-Fluxed Solid Solders — IPC/JEDEC (2013)
- Properties of Lead-Free Solders (solder alloy property database) — NIST (2002)
- Solder property measurements and lead-free alloy data reports — National Physical Laboratory (NPL) (2008)
- Lead-free SAC alloy bar, wire, paste and sphere datasheets — Indium Corporation / Alpha Assembly Solutions (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.