One Material, Several Designations
C10200 copper alloy and TU2 oxygen-free copper refer to the same material. In the UNS system it is C10200, in the European system CW008A under EN 1412, in the Japanese system C1020, and in the Chinese system TU2 under GB/T 5231. Where a purchase order names only one designation, the others provide the cross reference needed for incoming inspection.
The defining characteristic of the grade is not an alloying addition but the removal of oxygen. Wrought oxygen-free copper is required to contain 99.95% minimum copper with oxygen held to 0.001% maximum, so the structure contains no dispersed cuprous oxide. That single fact explains nearly every advantage the material offers over ordinary tough pitch copper.
Composition and Property Data
| Item | Specified value | Notes |
|---|---|---|
| Copper (Cu), including silver | 99.95% minimum | Purity is the property source |
| Oxygen (O) | 0.001% maximum | No cuprous oxide network |
| Total impurities | 0.05% maximum | Excluding copper and silver |
| Electrical conductivity | 100% IACS minimum (58 MS/m) | Some tempers measure slightly above |
| Thermal conductivity | about 390 W/(m K) | Used for heat sink and coil design |
| Density | 8.94 g/cm³ | Constant for the wrought grade |
| Melting range | about 1083 C | Essentially a single melting point |
| Annealed tensile strength | typically 200-250 MPa | O60/O61 soft temper |
| Annealed elongation | typically 40% or more | Supports deep drawing and fine drawing |
Why "Hydrogen Disease" Does Not Occur
Tough pitch copper contains oxygen in the form of cuprous oxide particles distributed through the grains. When such material is heated in a hydrogen-bearing atmosphere, for example during bright annealing or a brazing cycle, the hydrogen diffuses inward and reacts with the oxide to form steam. Because steam cannot escape from the solid metal, pressure builds at the grain boundaries and the material cracks internally.
In C10200 the oxygen level is so low that there is effectively nothing for the hydrogen to react with, so bright annealing and reducing-atmosphere brazing can be carried out without the risk of intergranular cracking. This is the reason the grade is mandatory for vacuum interrupters, transmitter tubes and other sealed devices where a microscopic internal crack would destroy a vacuum seal.
Production Route and Technical Control Points
Reproducible oxygen control depends on the whole melt-to-finish chain rather than on a single step.
Charge preparation. High purity cathode copper is used as the base charge, and scrap is either excluded or very carefully graded so that impurity levels stay inside the 0.05% total limit.
Melting and casting. Melting is carried out under vacuum or inert gas protection with a graphite crucible and argon cover, followed by continuous or semi-continuous casting of the billet.
Plastic working. Hot rolling, cold rolling, drawing and finishing operations convert the billet into strip, bar, tube or wire. Cold reductions above 80% are achievable with intermediate annealing.
Oxygen monitoring. Oxygen content is measured by inert gas fusion on samples taken from the cast structure and from the finished product, since the value must be demonstrated rather than assumed.
Surface control. Roll cleanliness and lubrication are managed closely because soft copper marks easily, and scratches become rejectable surface defects after bright annealing.
Typical Applications
Electronics is the largest outlet. Lead frames and substrate material benefit from the absence of oxide particles, which otherwise promote blistering and gas expansion during high-temperature assembly. High-frequency coaxial cable relies on C10200 inner conductors for the low attenuation that 5G and broadcast equipment require. Power equipment uses the grade for busbars, vacuum switch tubes and magnet windings, where low outgassing and stable conductivity both matter. Thermal management hardware, including heat sinks, cold plates and heat exchanger components, uses the thermal conductivity of 390 W/(m K). Aerospace and research applications include vacuum seals, cooling passages and cryogenic coil components.
Market and Technical Outlook
Demand growth for oxygen-free copper is driven mainly by battery interconnects in electric vehicles, busbar and inverter hardware in photovoltaic systems, and increasing data throughput in communications equipment. On the technical side, research is concentrated on grain refinement to raise strength while preserving conductivity, and on composite approaches that combine copper with conductive carbon phases. Both directions share the same constraint: anything added to increase strength tends to reduce conductivity, so the balance between purity and mechanical performance remains the central engineering question for this grade.
FAQ
Q: Is TU2 identical to C10200?
The two designations describe the same oxygen-free copper material. TU2 is defined in GB/T 5231 and C10200 in the UNS system, with CW008A under EN 1412 as the European equivalent.
Q: What is hydrogen embrittlement?
It is internal cracking caused by steam forming when hydrogen reacts with cuprous oxide particles at high temperature. Because C10200 contains almost no oxygen, the reaction cannot take place.
Q: What oxygen level is acceptable?
The wrought product specification requires 0.001% maximum oxygen, verified by inert gas fusion testing on samples from each heat.
Q: Can C10200 be deeply drawn?
Yes. Soft tempers show elongation of 40% and above, and cold reductions beyond 80% are normal practice with inter-annealing between passes.
Q: Which industries use this grade most?
Electrical power, electronics and vacuum device manufacturing, followed by aerospace, thermal management and high-end instrument making.
Q: Is a lower-oxygen grade necessary for vacuum service?
For the most demanding sealed devices a higher-purity oxygen-free grade is sometimes specified, but C10200 satisfies the great majority of vacuum and reducing-atmosphere applications.
