Copper 101 and 110 are two of the most commonly used pure copper grades, and while they appear similar, their subtle differences in purity, conductivity, and workability can significantly impact your material choice. In this article, I’ll guide you through the key differences, help you understand which alloy is more suitable for which application, and share real examples from projects I’ve worked on.
What Is Copper 101
Copper 101 is commonly used in applications requiring ultra-high conductivity and purity. With 99.99% copper and virtually zero oxygen, it offers electrical conductivity exceeding 101% IACS, making it ideal for RF components and aerospace systems. However, its softness presents challenges during machining and requires specialized cutting strategies.
Copper 101, also known as C101 or OFE (Oxygen-Free Electronic) copper, is a highly pure grade with a minimum purity of 99.99% and virtually zero oxygen content. It’s often used in applications where high electrical conductivity and low oxidation risk are critical.
The ultra-high purity makes it ideal for high-frequency or high-voltage components, such as RF connectors and aerospace-grade wiring.
Its electrical conductivity can exceed 101% IACS, making it one of the most conductive materials available.
In my experience working with telecom hardware clients, Copper 101 was always chosen when signal clarity and low resistance were a must.
It’s not the easiest material to machine due to its softness and lack of oxygen, which can lead to smearing during cutting. with a minimum purity of 99.99% and virtually zero oxygen content. It’s often used in applications where high electrical conductivity and low oxidation risk are critical.
What Is Copper 110
Copper 110, or C110 (also called Electrolytic Tough Pitch, ETP copper), is about 99.90% pure and contains a small amount of oxygen (0.02–0.04%). It’s the most widely used copper grade due to its balance of conductivity, cost, and machinability.
It has excellent electrical conductivity (approximately 100% IACS) and is ideal for power distribution, plumbing, and bus bars.
That trace oxygen content helps form a stable oxide layer, which actually improves surface finish in some machining processes.
When I managed a custom busbar project for an EV charging system, we chose C110 because of its cost efficiency and ease of fabrication.
It’s easier to weld, braze, and machine than Copper 101, especially in medium-to-high production volumes.
Performance Comparison Between Copper 101 And 110
C101 exceeds 101% IACS, reaches 350 MPa in strength and 90 HB in hardness. C110, while slightly lower in performance, provides greater ductility—which I relied on in a tight-bend EV busbar design.
Electrical Conductivity: Copper 101 has slightly higher conductivity (>101% IACS) compared to Copper 110 (~100% IACS). This makes it more suitable for precision electronics.
Thermal Conductivity: Both grades are excellent, but C101 has marginally better thermal conductivity, ideal for heat sinks or RF enclosures.
Mechanical Strength: C101 is harder (70–90 HB) and stronger (250–350 MPa) than C110 (45–60 HB, 150–220 MPa), which gives it an edge in structural applications.
Ductility: C110 is more ductile, which means it’s better suited for forming and bending without cracking. I once had to switch from C101 to C110 during a project involving tight-radius bends in high-current components.
Corrosion Resistance: Both perform well, but C110 forms a protective oxide film, enhancing resistance in exposed environments.
Machining And Processing Methods For Copper 101 And 110
Copper 101 and 110 require different machining and processing methods due to differences in purity, oxygen content, and mechanical properties. These differences affect their behavior in CNC machining, forming, welding, heat treatment, and surface finishing.
1. CNC Machining
Copper 101:
Due to its 99.99% purity and lack of oxygen, Copper 101 is soft and prone to smearing during milling. This results in poor chip formation and rapid tool wear.
I typically use carbide tools with TiAlN coating, low cutting speeds (120–180 m/min), and coolant flow >10 L/min.
Best results come from shallow passes and feed rates <0.05 mm/rev in turning.
For example, on a set of high-frequency antenna connectors, we achieved Ra < 0.3 µm with single-point diamond turning but had to regrind tools after every 20 parts.
Copper 110:
With 99.9% purity and 0.02–0.04% oxygen, it machines much more easily.
Feed rates can be increased by 30–50% compared to C101.
I often use 3-flute end mills at 250–400 m/min cutting speed. Chips break more cleanly, surface burrs are fewer.
We once produced 500 copper busbar bases using C110 with a tool change interval of 150 parts—3× longer than C101.
2. Forming & Bending
Copper 101:
Poor cold formability. Needs frequent intermediate annealing at 400°C for 30 minutes to avoid cracking.
On an RF shielding case, we had to redesign the geometry because C101 cracked during a 90° bend with 2 mm wall thickness.
Copper 110:
Excellent for deep drawing, stamping, and bending.
In HVAC applications, we used C110 to form finned tubing with multiple folds at <1.2 mm wall thickness without annealing.
Recommended minimum bend radius = 1.5× thickness. Dies must be smooth to prevent surface scoring.
3. Welding & Brazing
Copper 101:
Extremely sensitive to hydrogen. TIG or laser welding only recommended under argon shield or vacuum.
I once used C101 in a vacuum chamber component—the welds failed under 2 bar helium leak testing due to trace porosity.
Copper 110:
Much easier to weld and braze. The oxygen content allows it to form a protective Cu₂O layer, enhancing arc stability.
Phosphor bronze filler rods (AWS BCuP-5) are commonly used in brazing.
MIG/TIG welding works well for busbars, coil brackets, electrical terminals.
Preheat to 150–200°C to reduce thermal stress.
4. Heat Treatment
Copper 101:
Can be annealed at 370–650°C but requires inert gas or vacuum atmosphere to prevent oxidation.
After annealing, mechanical strength drops significantly (yield < 50 MPa), but electrical conductivity improves slightly.
Copper 110:
Tolerates air atmosphere during annealing. Typically soft annealed at 400–600°C, held for 30–60 minutes.
Used to restore ductility before secondary forming.
Avoid over-annealing, which can cause grain coarsening and reduced dimensional stability.
5. Surface Finishing
Copper 101:
Accepts electropolishing (Ra < 0.2 µm), mechanical polishing, and vacuum plating.
Common in optics, sensors, vacuum systems.
Easily oxidizes when exposed to air after finishing—must be packaged immediately with anti-oxidation film or argon flush.
Copper 110:
Supports a wider range of finishing:
Nickel/silver/gold plating for electrical parts
Sandblasting or brushing for industrial hardware
In one EV power module, we plated C110 terminals with 8 µm of silver to reduce contact resistance below 0.2 mΩ.
Typical Applications Of Copper 101 And 110
In practical applications, the choice between Copper 101 and 110 depends on performance requirements, material purity, cost constraints, and processing conditions. Copper 101 is preferred for high-conductivity electronic systems, while Copper 110 is more suitable for cost-sensitive, high-volume manufacturing environments.
| Feature / Use Case | Copper 101 (C101) | Copper 110 (C110) |
| Electrical Conductivity | >101% IACS – ideal for precision electronics | ~100% IACS – sufficient for general systems |
| Target Industry | Aerospace, RF, telecom, scientific research | Industrial, construction, energy infrastructure |
| Typical Applications | RF connectors, vacuum devices, signal cables | Busbars, power cables, plumbing fittings |
| Thermal Applications | High-efficiency heat sinks, superconductors | HVAC heat exchangers, general heat plates |
| Cost Consideration | Expensive due to high purity | More affordable and widely available |
| Elaborazione | Harder to machine, softer and purer | Easier to form, weld, and machine |
| Example from my projects | Used C101 in a telecom prototype (low signal loss) | Used C110 in HVAC control enclosures (cost win) |
Domande frequenti
What Is The Difference Between Copper 101 And Copper 110?
In my experience, Copper 101 offers higher purity (99.99%) and slightly better electrical conductivity, making it ideal for precision applications. Copper 110, though slightly less pure (99.9%), is more machinable and cost-effective, which makes it my go-to choice for large-volume or formed parts.
What Is 110 Copper Used For?
I often use Copper 110 for electrical busbars, switchgear, industrial plumbing, and structural components. Its good conductivity and excellent formability make it suitable for both electrical and mechanical uses.
What Is CDA 110 Copper?
CDA 110 is the Copper Development Association’s designation for Electrolytic Tough Pitch (ETP) copper. When I see “CDA 110,” I know I’m working with 99.9% pure copper that’s widely used in the electrical industry.
Is C110 Copper Full Hard?
C110 copper is available in different tempers. While full hard is possible, I usually work with half-hard (H02) or quarter-hard (H01), depending on whether the part needs more strength or better formability.
Is 101 Copper Oxygen Free?
Yes, Copper 101 is completely oxygen-free—this is why it’s called OFE (Oxygen-Free Electronic) copper. I use it when even tiny amounts of oxygen could affect conductivity or performance, especially in vacuum or high-frequency environments.
What Is The Difference Between C101 And C102 Copper?
C101 is purer than C102, both in terms of copper content and oxygen levels. I’ve found C101 more suitable for ultra-sensitive applications, while C102 is still excellent for most high-conductivity needs but may be slightly easier to process.
Conclusion
In my experience, choosing between Copper 101 and 110 isn’t just about specs—it’s about context. If you’re building ultra-sensitive electronics, go with Copper 101. If you’re balancing budget and performance in structural or power-related components, Copper 110 is the go-to. Both materials are exceptional, but knowing when and why to use each can make all the difference in performance, cost, and manufacturability.
