If you work with electrical conductors, busbars, or heat transfer components, you need a material that combines high conductivity with reliable formability. 110 copper—formally designated as C11000 (ETP) copper—meets these demands. With a copper content of 99.95% and conductivity of 45–50% IACS, it is the industry standard for applications ranging from PCB foils to solar PV ribbons. This guide covers its material properties, fabrication methods, joining techniques, and surface treatments, giving you the practical knowledge to specify and work with this versatile alloy.
Introduction
Selecting the right copper alloy often comes down to balancing electrical performance, mechanical properties, and cost. 110 copper, also known as electrolytic tough pitch (ETP) copper, occupies a sweet spot. It offers nearly the conductivity of pure copper but with better consistency and formability. Its oxygen content is tightly controlled (below 0.04%) to prevent embrittlement during processing. Understanding its standards, properties, and fabrication requirements ensures you get reliable performance in your electrical, electronic, or architectural projects.
What Global Standards Define 110 Copper?
110 copper is recognized under multiple international standards. Knowing these designations helps you specify the correct material for compliance and interchangeability.
UNS and ASTM Designations
The most common designation for 110 copper is UNS C11000, where “ETP” stands for electrolytic tough pitch. This grade requires a minimum copper content of 99.95%, with oxygen controlled between 0.02% and 0.04%.
Key ASTM specifications include:
- ASTM B152: Sheets, strips, and plates
- ASTM B187: Bars, rods, and shapes
- MIL-C-12166: Military standard for high-reliability applications like aerospace wiring
International Equivalents
110 copper is produced globally under different names. These grades are functionally interchangeable.
| Standard | Designation | Notes |
|---|---|---|
| ISO | Cu-ETP CW004A | European standard; identical composition |
| JIS | C1100 | Japanese standard; widely used in electronics |
| GB/T | T2 | Chinese equivalent for electrical conductors |
| EN | CW004A | European numbering system for copper |
All compliant grades must meet RoHS requirements (no lead, mercury, or other restricted substances) and maintain oxygen content below 0.04% to avoid hydrogen embrittlement during high-temperature processing.
A solar panel manufacturer in Germany specifies ISO Cu-ETP CW004A for PV ribbon interconnects. A U.S.-based counterpart uses UNS C11000 under ASTM B152. Both receive identical material properties.
What Mechanical and Physical Properties Matter?
110 copper’s combination of electrical, thermal, and mechanical properties makes it suitable for a wide range of applications.
Electrical and Thermal Conductivity
These are the primary reasons engineers choose 110 copper.
| Property | Typical Value | Practical Benefit |
|---|---|---|
| Electrical conductivity | 45–50% IACS | Efficient power transmission with minimal energy loss |
| Thermal conductivity | 385–400 W/(m·K) | Rapid heat dissipation—ideal for heat sinks and cooling fins |
| Resistivity | 1.7 × 10⁻⁸ Ω·m | Low resistance for busbars and power conductors |
While pure copper can achieve 58% IACS, 110 copper offers nearly the same performance at a lower cost and with better formability.
Mechanical Properties
These properties determine how the material behaves during fabrication and in service.
| Property | Typical Value | What It Means for Fabrication |
|---|---|---|
| Tensile strength | 210–250 MPa | Withstands mechanical stress in busbars and connectors |
| Yield strength | 70–110 MPa | Deforms under load rather than fracturing |
| Elongation | 35–55% (in 50 mm) | Excellent ductility—can be bent, rolled, or deep-drawn |
| Hardness | 70–90 HRB | Soft enough for forming; durable enough for structural use |
| Density | 8.89 g/cm³ | Heavy—provides stability for large conductors |
The elongation of 35–55% is critical. It allows 110 copper to be formed into complex shapes without cracking, whether for architectural gutters or deep-drawn electrical enclosures.
Physical Properties
- Melting point: 1083°C. Withstands high temperatures in motor windings and transformer applications.
- Coefficient of thermal expansion: 17 × 10⁻⁶/°C. Compatible with common insulating materials.
- Modulus of elasticity: 115 GPa. Provides stiffness for structural conductors.
How Is 110 Copper Fabricated?
Working with 110 copper requires attention to its softness and tendency to work harden. Proper techniques prevent cracking and ensure consistent results.
Cold Forming and Bending
110 copper handles cold forming well, but work hardening occurs with extensive deformation.
- Bending radius: Use a minimum radius of 1–2× material thickness. For a 2 mm thick sheet, use a 2–4 mm radius to avoid cracking.
- Deep drawing: Suitable for cups, enclosures, and connectors. Multiple draws with intermediate annealing may be required for complex shapes.
- Spinning and hydroforming: Feasible for curved parts like waveguide components.
A manufacturer producing deep-drawn electrical enclosures anneals 110 copper between drawing operations to restore ductility.
Annealing
Annealing softens 110 copper after cold working and relieves internal stresses.
- Annealing temperature: 370–650°C, depending on the degree of cold work.
- Cooling: Air cooling is acceptable. Rapid quenching is not required.
- Atmosphere: Use a reducing or inert atmosphere to prevent oxidation.
For parts that require maximum ductility, anneal at the higher end of the range (600–650°C) and hold for 30–60 minutes.
Machining
110 copper has a machinability rating of 20% compared to free-cutting brass (C36000). This means it machines slowly and requires sharp tools.
- Cutting tools: Use high-speed steel or carbide tools with sharp edges.
- Coolant: Apply generous coolant to prevent overheating and work hardening.
- Speeds and feeds: Use moderate cutting speeds (300–500 SFM for carbide) and light feeds.
Stress Relief After Welding
Welding introduces residual stresses that can cause distortion or cracking in service.
- Stress relief temperature: 200–250°C for 1–2 hours.
- Cooling: Air cool slowly to room temperature.
How Do You Weld, Braze, and Join 110 Copper?
Joining 110 copper requires careful control of heat and filler materials to maintain conductivity and joint integrity.
Gas Tungsten Arc Welding (TIG)
TIG welding is the most reliable method for 110 copper, especially for sections thicker than 1.5 mm.
- Preheat: For sections over 6 mm thick, preheat to 200–540°C to ensure full fusion and prevent cracking.
- Filler metal: Use silicon-bronze ERCuSi-A for general welding. It bonds well and maintains good conductivity.
- Shielding gas: 100% argon or argon-helium mixtures for deeper penetration.
Brazing
Brazing is often preferred for thin sections or when minimal heat input is desired.
- Filler metals: Use phosphorus-deoxidized brazing alloys (BCuP series). These alloys self-flux on copper.
- Joint design: Lap joints are preferred over butt joints for strength.
- Flux: Required for silver-based filler metals; not needed for BCuP alloys.
A refrigeration technician uses BCuP brazing alloys to join 110 copper tubing. The filler flows well and creates leak-free joints without separate flux.
Other Joining Methods
- Electron beam welding (EBW): Used for precision parts like vacuum chamber gaskets where minimal heat-affected zone is critical.
- Resistance spot welding: Requires high current density (10,000–15,000 A/mm²). Used in automotive electrical components.
- Soldering: Common for PCB and electronic applications. Use flux-cored solder with tin-lead or lead-free compositions.
Post-Joining Considerations
After welding or brazing, test joint conductivity. A drop of more than 5% IACS from the base metal indicates poor fusion or contamination. Re-work such joints to avoid performance issues.
What Surface Treatments Work for 110 Copper?
Surface treatments protect 110 copper from tarnish, improve solderability, and enhance appearance.
Plating
Plating is the most common surface treatment for 110 copper in electrical applications.
| Treatment | Purpose | Common Applications |
|---|---|---|
| Tin plating | Improves solderability; protects against oxidation | PCB foils, connector terminals |
| Silver plating | Maintains high conductivity; provides corrosion resistance | RF shielding gaskets, high-frequency connectors |
| Nickel underlayer | Provides corrosion barrier before other plating | Marine electrical components |
| Gold plating | Prevents oxidation; ensures reliable contact | Precision connectors, aerospace |
A PCB manufacturer specifies tin-plated 110 copper foil. The tin layer ensures reliable soldering of components while protecting the copper from oxidation during storage.
Chemical Treatments
- Benzotriazole (BTA) dip: Forms a thin protective layer that prevents tarnishing. Used on coinage stock and decorative items.
- Electropolishing: Creates an ultra-smooth surface finish (Ra < 0.1 µm). Used for vacuum chamber components and decorative pieces.
- Chromate conversion (Alodine): Adds corrosion resistance while maintaining electrical conductivity. Used for outdoor electrical components.
Decorative Finishes
- Hot black oxide: Creates a dark, matte finish for architectural accents and medallions.
- Clear lacquer: Protects polished surfaces from finger prints and tarnish.
What Are the Top Applications for 110 Copper?
110 copper’s combination of properties makes it essential across multiple industries.
Electrical and Power Distribution
- Busbars: Transmit power in switchgear, data centers, and industrial plants.
- PCB foil: Forms the conductive layers on printed circuit boards.
- Solar PV ribbon: Connects solar cells in photovoltaic panels.
- Transformer windings: Efficient energy transfer in power distribution.
Electronics and Telecommunications
- Waveguide components: RF shielding gaskets for 5G equipment.
- Connector terminals: Reliable electrical connections in consumer electronics.
- Heat sinks: Cooling fins for CPUs, power supplies, and LED lighting.
Construction and Architecture
- Lightning protection cables: Channel lightning safely to ground.
- Flashing and gutters: Corrosion-resistant, long-lasting architectural elements.
- Roofing accents: Decorative elements that weather to a distinctive patina.
Specialty Applications
- Vacuum chamber gaskets: Maintain airtight seals in scientific equipment.
- Coinage and medallions: Durable, easy to engrave, and tarnish-resistant with BTA treatment.
- Heat exchanger tubes: Transfer heat efficiently in HVAC systems.
Conclusion
110 copper (C11000 ETP) delivers a practical combination of high conductivity, excellent formability, and reliable mechanical properties. Its 99.95% copper content and controlled oxygen level ensure consistent performance across electrical, electronic, and architectural applications. With clear global standards (ISO Cu-ETP, JIS C1100, GB/T T2) and well-established fabrication methods, it remains a cost-effective choice for projects that require efficient power transmission, heat dissipation, and ease of forming. Proper attention to welding procedures, surface treatments, and annealing ensures you get the full service life this versatile material is designed to provide.
FAQ About 110 Copper
What is the difference between 110 copper and pure copper?
Pure copper (C10200 or C10100) has slightly higher conductivity (approximately 58% IACS vs. 45–50% IACS for 110 copper). However, 110 copper is more affordable, offers better formability, and is more widely available. For most electrical applications, the conductivity difference is negligible.
Can 110 copper be used outdoors?
Yes, but it requires protection. Uncoated 110 copper will develop a natural patina over time but may tarnish. For long-term corrosion resistance, use a nickel underlayer followed by a clear coating or specify chromate conversion treatment. Coated 110 copper is commonly used for gutters, flashing, and outdoor electrical enclosures.
Is 110 copper RoHS compliant?
Most grades are RoHS compliant, meaning they contain no lead, mercury, cadmium, or other restricted substances. However, always verify with your supplier’s documentation. Reputable manufacturers provide RoHS certificates and material test reports confirming compliance.
What welding method works best for 110 copper?
TIG welding with silicon-bronze (ERCuSi-A) filler metal is the most reliable method for sections over 1.5 mm thick. For thin sections or tubing, brazing with BCuP filler alloys is preferred. Preheating thick sections (over 6 mm) to 200–540°C prevents cracking and ensures full fusion.
Why does 110 copper sometimes crack during welding?
Cracking is often caused by hydrogen embrittlement. When copper with oxygen content above 0.04% is heated in a hydrogen-rich atmosphere, hydrogen reacts with oxygen to form steam, creating internal pressure and cracks. Use oxygen-controlled filler metals and avoid hydrogen-containing shielding gases.
How do I prevent 110 copper from tarnishing?
Apply a benzotriazole (BTA) dip for short-term protection during storage. For long-term tarnish resistance, use clear lacquer, tin plating, or a chromate conversion coating. For decorative applications, electropolishing followed by a clear coating provides a bright, protected finish.
Discuss Your Projects with Yigu Rapid Prototyping
Selecting the right copper alloy for electrical, electronic, or architectural applications requires balancing conductivity, formability, and cost. At Yigu Rapid Prototyping, we help engineers and product teams specify 110 copper (C11000) for busbars, PCB foils, and custom formed components. We provide guidance on material selection, fabrication methods, and surface treatments to ensure your project meets performance and compliance requirements. Contact us to discuss your specific application.