C11000 vs C10200: Which Pure Copper Grade Fits Your Process?

When selecting pure copper, the comparison almost always comes down to C11000 (ETP) versus C10200 (oxygen-free). Electrically and thermally, they’re nearly identical. The decision hinges on one element — oxygen — and whether the manufacturing process involves hydrogen at elevated temperature.

In most applications, C11000 provides equivalent performance at lower cost. But pick the wrong grade for the wrong environment, and hydrogen embrittlement creates failures that no post-processing can reverse.

What Are C11000 and C10200?

C11000 — Electrolytic Tough Pitch (ETP) Copper

Minimum 99.90% copper, with a controlled oxygen content of 0.02–0.04%. The oxygen is deliberate — it ties up impurity elements as oxides, improving electrical conductivity. ETP copper accounts for the vast majority of copper busbar, wire, and general electrical applications.

C10200 — Oxygen-Free (OF) Copper

Minimum 99.95% copper, with oxygen held below 0.001% (10 ppm). Produced under a controlled atmosphere to prevent oxygen pickup during casting. The near-zero oxygen content is what gives C10200 its resistance to hydrogen embrittlement and its superior performance in high-temperature brazing and welding.

Chemical Composition — The Oxygen Difference

Element	C11000 (ETP)	C10200 (OF)
Cu (min)	99.90%	99.95%
Oxygen	0.02 – 0.04%	≤ 0.001% (10 ppm)
Total impurities	≤ 0.10%	≤ 0.05%

The 0.02–0.04% oxygen in C11000 isn’t an impurity — it’s a deliberate addition. During solidification, oxygen reacts with residual hydrogen to form steam (H₂O), preventing porosity. But that same oxygen becomes a liability in hydrogen-rich service, where it forms internal steam pockets along grain boundaries.

C10200’s oxygen ceiling of 0.001% is the threshold where hydrogen embrittlement ceases to be a practical concern. It’s also why OF copper is specified for vacuum applications — there’s nothing to outgas at high temperature.

Electrical Conductivity Comparison

Grade	% IACS (Annealed)
C11000	100 – 101
C10200	100 – 101

In annealed condition, both grades deliver 100% IACS or slightly above. The practical electrical performance is identical. If a supplier claims C10200 is “more conductive” than C11000, they’re selling oxygen-free on a non-existent electrical advantage.

The conductivity gap only appears in the cold-worked condition. C11000 loses slightly more conductivity after cold working than C10200 due to the oxygen content influencing dislocation density. The difference is typically 1–2% IACS — measurable in a lab but irrelevant for busbar design. In standard busbar and transformer winding applications, conductivity is not the reason to choose C10200 over C11000.

Mechanical Properties

Property	C11000 (Annealed)	C10200 (Annealed)
Tensile Strength (MPa)	220 – 250	220 – 250
Yield Strength (MPa)	69 – 75	69 – 75
Elongation (%)	45 – 50	45 – 50
Hardness (Rockwell F)	40 – 50	40 – 50

Mechanically, the two grades are interchangeable. Both anneal at similar temperatures (370–650°C) and work-harden at similar rates. If the only requirements are formability and strength, there’s no functional difference.

Thermal Conductivity and Heat Performance

Grade	Thermal Conductivity (W/m·K)
C11000	388 – 391
C10200	388 – 391

Same story as electrical conductivity: the gap is a rounding error. Design heat sinks, vapor chambers, or thermal management systems with C11000 unless the manufacturing process itself demands oxygen-free material (e.g., vacuum brazing in a hydrogen atmosphere).

Hydrogen Embrittlement — The Critical Differentiator

This is the single most important reason to choose C10200 over C11000.

The failure mechanism:

When C11000 (with 0.02–0.04% O₂) is heated above roughly 370°C in a hydrogen-containing atmosphere, hydrogen diffuses into the copper and reacts with the internal cuprous oxide (Cu₂O) particles to form steam (H₂O). The steam pressure fractures the copper along grain boundaries. This is called “hydrogen embrittlement” or “steam embrittlement,” and once it happens, the material is scrap. No heat treatment or welding repair can reverse it.

Go/no-go rule:

• If the process involves hydrogen brazing, welding in a hydrogen atmosphere, or extended service above 370°C in hydrogen → C10200 is mandatory.
• If the process uses standard brazing fluxes in air, inert-gas welding, or operates below 370°C → C11000 is sufficient.

OF copper was developed for this reason. It’s not about conductivity — it’s about surviving manufacturing processes that ETP copper cannot.

Weldability and Brazing

Both grades weld well with GTAW (TIG), but for different reasons:

• C10200 gives clean, porosity-free welds in any atmosphere, including hydrogen shielding.
• C11000 welds well in inert gas (argon, helium) but will embrittle if hydrogen is present in the shielding gas or from contaminated filler. Even a 5% hydrogen mix in argon is enough to cause damage.

For furnace brazing with hydrogen atmosphere — common in electronics and vacuum component manufacturing — C10200 is the only acceptable choice. C11000 will fail during the brazing cycle.

Cost, Availability, and Procurement

Factor	C11000 (ETP)	C10200 (OF)
Material cost	Baseline	+10–20%
Stock availability	Excellent	Good
Common forms	Sheet, plate, bar, tube, wire	Sheet, plate, bar, tube
Typical MOQ (mill direct)	100 kg	200 kg

C11000 is the most widely produced copper grade globally. Every service center carries it. C10200 costs more because the oxygen-free production process requires controlled-atmosphere casting, higher-grade cathode selection, and lower production volumes.

When conductivity alone drives the selection, C11000 delivers identical performance at lower cost. The 10–20% premium for C10200 is non-negotiable only when the application genuinely requires OF copper (hydrogen brazing, vacuum service).

Linsy Copper stocks both C11000 and C10200 in sheet, plate, bar, and tube — contact Linsy for current stock availability and project-specific MOQ.

Application Decision Matrix

Application	Recommended Grade	Reason
Electrical busbar	C11000	Same conductivity, lower cost
Transformer winding	C11000	No hydrogen exposure
Hydrogen furnace brazing	C10200	C11000 embrittles
Vacuum components	C10200	No outgassing
Welded pipe (GTAW/argon)	C11000	Welds fine in inert gas
Heat sinks	C11000	Same thermal, lower cost
Semiconductor lead frames	C10200	Brazing + vacuum requirements
Architectural copper	C11000	No technical reason for OF
Cryogenic applications	C10200	Better low-temp ductility
General fabrication	C11000	Covers 80%+ of applications

Conclusion

C11000 and C10200 are functionally identical in conductivity, strength, and thermal performance. The decision hinges on one question: Does the manufacturing process involve hydrogen at elevated temperature? If yes, C10200 is mandatory. If no, C11000 does the job at 10–20% less cost with better availability. Linsy Copper supplies both grades with project-specific MOQ and grade-fit documentation. Send the drawing for a grade-fit review.

FAQ

1. Is C10200 more conductive than C11000?

   No. Both reach 100–101% IACS when annealed. The real difference is oxygen content, not electrical performance.

2. When is C10200 absolutely required?

   When the copper is heated above ~370°C in the presence of hydrogen — typically during hydrogen furnace brazing, hydrogen-atmosphere welding, or vacuum component manufacturing.

3. Can C11000 be welded?

   Yes, using GTAW (TIG) with argon or helium shielding gas. Hydrogen-containing shielding gas or contaminated filler material will cause embrittlement in C11000 welds.

4. What’s the cost difference?

   Generally no. The oxygen content in C11000 can outgas at high vacuum and elevated temperature. C10200 is preferred for vacuum chambers and components.

5. Which grade should be specified for busbar?

   C11000. The electrical conductivity is identical to C10200 at a lower cost. Unless the busbar manufacturing involves hydrogen brazing, there’s no advantage to OF copper.