The Strip and Bar Forms of a Single Grade
C10200 oxygen-free copper is a single metallurgical grade that reaches the market in several product forms. Strip is the flat rolled form used in high-speed stamping and coil-fed assembly; bar is the solid section used for machined electrodes, terminals and busbar stock. Both come from the same melt, so both share the same 99.95% minimum copper content and the same 0.001% maximum oxygen limit.
The grade is specified in ASTM B152 for flat rolled products and in ASTM B124 for rod and bar, and it is equivalent to CW008A under EN 1412 and TU2 under GB/T 5231. What changes between forms is not the chemistry but the dimensional tolerance, the temper and the surface condition.
Composition and Physical Data
| Item | Specified value | Notes |
|---|---|---|
| Copper (Cu), including silver | 99.95% minimum | Purity is the performance driver |
| Oxygen (O) | 0.001% maximum | Eliminates cuprous oxide precipitation |
| Total impurities excluding Cu and Ag | 0.05% maximum | Includes sulphur and phosphorus residuals |
| Electrical conductivity | 100% IACS minimum (58 MS/m) | Higher values are seen in some tempers |
| Thermal conductivity | about 390 W/(m K) | Supports heat sink and electrode design |
| Density | 8.94 g/cm³ | Used for weight calculation |
| Melting point | 1083 C | Narrow melting range |
| Annealed tensile strength | about 200-250 MPa | Temper dependent |
| Annealed yield strength | about 60-100 MPa | Proof stress at 0.2% offset |
| Annealed elongation | about 35-45% | Confirms forming capability |
Product Forms and Dimensional Ranges
| Form | Dimensional range | Temper availability |
|---|---|---|
| Strip and foil | from very thin foil gauges up to about 3 mm thick | O60/O61, H01, H02, H04 |
| Sheet and plate | sheet up to about 4.8 mm; plate above that | O60/O61, H02, H04 |
| Round bar | roughly 1 mm to 150 mm diameter | Soft, half-hard, hard, as drawn |
| Section bar | square, hexagonal and flat sections on request | Soft to hard |
Strip is usually supplied with a bright rolled or bright annealed surface, in coils matched to the customer's press feed. Bar is delivered in straight lengths, either drawn bright or turned and polished, with end faces cut square. Tolerances follow the applicable product standard, and the temper must always be named on the order because it controls the mechanical figures far more than the chemistry does.
Melt Practice and Oxygen Control
Achieving a genuine 0.001% oxygen level is a process result, not an inspection result. The usual route starts with high purity cathode copper, melts it under vacuum or inert gas protection, and casts the billet in a closed or semi-closed system so that oxygen pickup between furnace and mould is prevented. Vacuum induction melting followed by an upward or horizontal continuous casting line is common practice for the strip and bar forms.
Charge selection keeps impurity-bearing scrap out of the melt, protecting the 0.05% total impurity limit.
Graphite crucibles and an argon cover are used to avoid reaction between the melt and refractory oxides.
Oxygen content is monitored by inert gas fusion, and the level is controlled within a few parts per million around the specified value.
Roll and die surfaces are kept clean and well lubricated, because soft copper marks easily and surface defects survive into the finished product.
Applications by Form
Strip serves electrical and electronic manufacturing: printed circuit substrate stock, connectors, relays, terminals, shielding and flexible busbar laminations. Bar serves machined and current-carrying parts: electrode holders, high-frequency conductive components, vacuum tube electrodes, transformer hardware and switchgear contacts. Both forms appear in thermal management hardware such as heat sinks and cold plates, and in aerospace components where vacuum seals and cooling passages must remain sound. Chemical and process industry equipment uses the same material for gaskets, liners and high temperature fittings.
FAQ
Q: Are the strip and bar forms the same alloy?
Yes. Both are C10200 oxygen-free copper with 99.95% minimum copper and 0.001% maximum oxygen; only the product standard, tolerances and temper differ.
Q: Why is the oxygen limit so strict?
Any cuprous oxide present can react with hydrogen at high temperature and crack the metal from the inside, so the limit protects both joining processes and sealed-device service.
Q: What bar tempers are available?
Soft, half-hard, hard and as-drawn conditions are all produced, with the choice governed by the machining operation and the strength the finished part requires.
Q: Can strip be supplied for automatic stamping?
Yes. Coil gauge consistency, edge condition and temper uniformity are controlled for high-speed press feeds, and tinned or bright annealed finishes are available.
Q: How is purity verified on delivery?
Chemical analysis of the heat plus inert gas fusion testing for oxygen, together with mechanical and electrical testing appropriate to the temper supplied.
Q: Is the material suitable for vacuum furnaces?
Yes. With essentially no oxygen and no volatile additions, outgassing behaviour in vacuum is favourable.
