For industrial applications, oxygen-free copper is valued more for its chemical purity than its electrical conductivity.
Oxygen-Free copper, abbreviated OFC (or OFHC) is a grade of copper free of oxygen, containing no deoxidants. It is distinguished by its high degree of purity compared to other available grades of copper. The content of permissible impurities is limited to only a maximum of 74ppm. (1ppm = 0.0001%)
This is the purest form of copper available in the market, containing up to a minimum of 99.99% purity. The OFC is removed of oxygen and manufactured from electrolytic copper, and can be considered a top grade copper in terms of electrical conductivity.
OFC is used in applications such as plasma deposition (sputtering) processes, the manufacture of semiconductors, and accelerators. In any of these applications, the release of oxygen or other impurities can cause undesirable chemical reactions with the materials in the local environment.