Solder & Low-Melting Alloy Sn91Zn9
ISO 801 · also IEC Z90
Sn91Zn9 is the eutectic tin-zinc solder, IEC designation Z90, melting at about 199 °C and containing no silver, which made it a lower-cost lead-free option and a practical choice for soldering aluminium.
Reference datasheet — Sn91Zn9 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.
Sn91Zn9 tempers and conditions
Sn91Zn9 is supplied in one standard condition, AC.
Supply forms, finishes and certifications
Ways Sn91Zn9 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
FOIL | Rolled foil / stamped preform | Supply form |
WIREDefault | Solder wire / rod | Supply form |
PASTE | Solder paste | Printing process |
AS-SOLDERED | As-soldered joint | Supply option |
What is Sn91Zn9?
Sn91Zn9 is the eutectic tin-zinc solder, IEC designation Z90, melting at about 199 °C and containing no silver, which made it a lower-cost lead-free option and a practical choice for soldering aluminium. It gives the highest strength in this group — 42 MPa yield, 70 MPa tensile, 35% elongation, 22 HB — and is supplied as wire, as-cast bar, rolled foil, paste and as-soldered joints. The zinc content limits service temperature to 100 °C and makes joints and flux residues prone to rapid corrosion in humidity, and it requires aggressive fluxes. Sn89Zn8Bi3 wets slightly better; SAC alloys are preferred where corrosion resistance governs. Sn91Zn9 has a density of 7.27 g/cm³ (0.263 lb/in³), lighter than 98% of solder & low-melting alloy grades. It melts at 199°C (390 °F). Sn91Zn9 has a yield strength of 38 MPa (5.51 ksi) and a tensile strength of 65 MPa (9.43 ksi) — stronger than 85% of solder & low-melting alloy grades. Elongation at break is 40% and the elastic modulus is 40 GPa (5.8 Msi).
What is Sn91Zn9 used for?
- Aluminum component soldering
- Low-cost lead-free soldering
- HVAC/refrigeration joints
Advantages
- Lightweight — 7.27 g/cm³ (0.263 lb/in³), better than 98% of solder & low-melting alloy grades
- Conducts heat well — 61 W/m·K (35.2 BTU/hr·ft·°F), better than 92% of solder & low-melting alloy grades
- High strength — 38 MPa (5.51 ksi), better than 85% of solder & low-melting alloy grades
- High electrical conductivity — 12.5 % IACS, better than 82% of solder & low-melting alloy grades
Limitations
- Needs corrosion protection — 25/100, worse than 100% of solder & low-melting alloy grades
- Difficult to weld — 10/100, worse than 94% of solder & low-melting alloy grades
Sn91Zn9 properties
Typical room-temperature values; bars are the position among solder & low-melting alloy grades.
Physical3
Sn91Zn9 has a density of 7.27 g/cm³ (0.263 lb/in³), lighter than 98% of solder & low-melting alloy grades. It melts at 199°C (390 °F).
Mechanical10
Sn91Zn9 has a yield strength of 38 MPa (5.51 ksi) and a tensile strength of 65 MPa (9.43 ksi) — stronger than 85% of solder & low-melting alloy grades. Elongation at break is 40% and the elastic modulus is 40 GPa (5.8 Msi).
Thermal6
Sn91Zn9 is rated for continuous service to 100°C (212 °F). It conducts heat at 61 W/m·K (35.2 BTU/hr·ft·°F), better than 92% of solder & low-melting alloy grades. Thermal expansion is 24 µm/m·K (13.3 µin/in·°F).
Electrical3
Sn91Zn9 conducts electricity at 12.5 % IACS, better than 82% of solder & low-melting alloy grades.
Chemical & Environmental3
Corrosion resistance is poor (25/100), worse than 100% of solder & low-melting alloy grades.
Sustainability4
Producing a kilogram of Sn91Zn9 takes about 295 MJ of energy and emits 16.5 kg of CO₂ — more than 70% of solder & low-melting alloy grades. Typical recycled content is 30%.
Manufacturability6
Sn91Zn9's machinability is poor (30/100, worse than 60% of solder & low-melting alloy grades); weldability not recommended (10/100); formability excellent (85/100).
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. Sn91Zn9 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Sn91Zn9
Is Sn91Zn9 easy to machine?
Rarely machined; extremely soft and gummy — use sharp high-rake tools, kerosene/light oil lubrication and avoid heat build-up near the 199 °C solidus.
Can Sn91Zn9 be welded?
Not a weldable structural alloy; it is the filler itself — apply at 220–260 °C with halide-activated or ZnCl2-based flux, or fluxless in N2/Ar with ultrasonic agitation for aluminium.
Can Sn91Zn9 be formed, bent or molded?
Easily extruded into wire, rolled to foil and cast to bars owing to its eutectic, narrow-freezing-range structure; work at room temperature to limit creep.
Sn91Zn9 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 |
|---|---|---|
| Zneutectic composition ~8.9 % Zn | 8 – 10 | 9 |
| Pbimpurity limit (RoHS lead-free) | ≤ 0.05 | |
| Cuimpurity limit | ≤ 0.05 | |
| Alimpurity limit; higher Al degrades wetting | ≤ 0.01 | |
| Feimpurity limit | ≤ 0.02 | |
| Sbimpurity limit | ≤ 0.05 | |
| Biimpurity limit | ≤ 0.05 | |
| Cdimpurity limit (RoHS) | ≤ 0 | |
| Asimpurity limit | ≤ 0.03 | |
| Snbalance, ~91 % | balance |
What surface finishes work on Sn91Zn9?
Do not anodize or plate; clean flux residues thoroughly (DI water or solvent) and conformally coat joints, since zinc-rich residues drive rapid corrosion in humidity.
Equivalent designations
Standards and trade names that resolve to Solder & Low-Melting Alloy Sn91Zn9 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- ISO
- 801
- Trade names
- IEC Z90
How much does Sn91Zn9 cost?
Sn91Zn9 is a high-cost solder & low-melting alloy ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sn91Zn9 — frequently asked
What is Sn91Zn9 used for?
Sn91Zn9 is typically used for aluminum component soldering, low-cost lead-free soldering and HVAC/refrigeration joints. In short: solders aluminium reliably; silver-free, low cost; corrosion-sensitive joint.
What is the yield strength of Sn91Zn9?
Sn91Zn9 has a typical yield strength of 38 MPa (5.51 ksi) and a tensile strength of 65 MPa (9.43 ksi) — stronger than 85% of solder & low-melting alloy grades.
Is Sn91Zn9 easy to machine?
Not especially — machinability is rated poor (30/100, worse than 60% of solder & low-melting alloy grades). Rarely machined; extremely soft and gummy — use sharp high-rake tools, kerosene/light oil lubrication and avoid heat build-up near the 199 °C solidus.
Can Sn91Zn9 be welded?
Not readily — weldability is rated not recommended (10/100). Not a weldable structural alloy; it is the filler itself — apply at 220–260 °C with halide-activated or ZnCl2-based flux, or fluxless in N2/Ar with ultrasonic agitation for aluminium.
What surface finishes work on Sn91Zn9?
Do not anodize or plate; clean flux residues thoroughly (DI water or solvent) and conformally coat joints, since zinc-rich residues drive rapid corrosion in humidity.
Can Sn91Zn9 be formed, bent or molded?
Easily extruded into wire, rolled to foil and cast to bars owing to its eutectic, narrow-freezing-range structure; work at room temperature to limit creep.
What is the maximum service temperature of Sn91Zn9?
Sn91Zn9 is rated for continuous use to about 100°C (212 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does Sn91Zn9 cost?
Sn91Zn9 is a high-cost solder & low-melting alloy ($$$$), 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 801, S-Sn91Zn9) — ISO (2020)
- IEC 61190-1-3 — Requirements for electronic grade solder alloys — IEC (2017)
- ASM Handbook Vol. 3: Alloy Phase Diagrams (Sn-Zn system) — ASM International (1992)
- NIST Database for Solder Properties with Emphasis on New Lead-Free Solders — NIST / Colorado School of Mines (2002)
- Lead-Free Solder Interconnect Reliability — ASM International (2005)
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.