What is the annealing process of copper foil and what characteristics does the annealed copper foil have?

The annealing process of copper foil is an important step in the production of copper foil. It involves heating the copper foil to a certain temperature, holding it for a period, and then cooling it to improve the crystal structure and properties of the copper foil. The main purpose of annealing is to relieve stress, improve crystal structure, enhance the ductility and toughness of the copper foil, reduce resistivity, and improve electrical conductivity.

In the production process of rolled copper foil, annealing is a key step that usually occurs after cold rolling. The production process of rolled copper foil includes melting, casting, hot rolling, cold rolling, annealing, further cold rolling, degreasing, surface treatment, inspection, and slitting and packaging. The annealing process of rolled copper foil can improve its resistance to bending because it has a flaky crystalline structure with high orientation on the (200) crystal plane, which generates slip bands after bending, alleviating the passive accumulation inside during bending.

The characteristics of annealed copper foil include:

Improved Crystal Structure: Annealing can rearrange the crystals in the copper foil, relieving or eliminating stress.

Enhanced Ductility and Toughness: Due to the reduction of stress, the copper foil becomes more workable and moldable.

Reduced Resistivity: Annealing helps to decrease grain boundaries and stacking faults caused by cold processing, thereby reducing resistivity and improving electrical conductivity.

Enhanced Corrosion Resistance: Annealing can remove the oxide layers formed on the surface of the copper foil during cold processing, restoring the smooth metallic surface and improving corrosion resistance.

In addition, the lubrication during the copper foil rolling process, the surface quality of the rollers, and the filtration precision of the rolling oil and the external environment are also important factors affecting the surface quality of the copper foil, which indirectly affects the performance of the annealed copper foil.