Processing foil is not only an important basic material for manufacturing CCL and PCB, but also in other fields

Electrolytic copper production process: electrolysis is completed by electroplating process. Electrolytic copper is formed by separating copper ions from copper sulfate solution with electric current, and then it is completed after processes such as oxidation resistance and roughening treatment

Manufacturing process of calendered copper: calendered copper is produced by coating. Calendered copper is rolled from copper ingots, and then processed by forging, oxidation resistance, roughening, etc., with the thickness generally between 5um and 135um.

In terms of cost, Calendered copper foil The fixed assets of, Electrolytic copper foil It has advantages in cost. In terms of production technology, the production technology of calendered copper foil has high requirements, complex process and long process. At the same time, the production technology is mostly in the hands of Japanese and American enterprises, and the production is mostly limited by patents.

High precision calendered copper foil is mainly produced by foreign manufacturers. Due to the high technical threshold of high-precision rolled copper foil, the main rolled copper foil in the book is concentrated in several manufacturers: NipponMining, Fukuda, Olibrass and Hitachi Cable. It can be seen that Japanese enterprises are in the leading position in the field of rolled copper foil.

Lithium copper foil Its performance also determines the quality of lithium battery, which is crucial to lithium battery. Lithium batteries are mainly used in 3C products, new energy vehicles, energy storage industry, etc

The microstructure of copper foil materials is different due to different processing technologies. The cross section of the material is observed under a 1000 times microscope, and the atomic structure of the calendered copper is irregular layered strong crystal. For the recrystallization after heat treatment, it is not easy to form cracks, and the bending property is good; The electrolytic copper material presents columnar crystal structure in the thickness direction, which is easy to crack and fracture when bending.

In view of the shortcomings of electrolytic materials, some material suppliers have developed high elongation electrolytic materials, that is, after conventional processing, the materials are heat treated again to recrystallize copper atoms, but its columnar structure still remains. Therefore, there is still a big gap between the flexibility and calendered copper foil.

2. Performance

Conductivity: the conductivity of rolled copper is weaker than that of electrolytic copper.

Ductility: The compressibility of rolled copper material is better than that of electrolytic copper material. The elongation of rolled copper material reaches 20-45%, while that of electrolytic copper material is only 4-40%

Bending: after the determination of bending and bending (the samples are all 35 µ m thick and heat treated at 200 ℃/30 min, the radius of curvature is 2.5nn, and the stroke is 25mm), the rolling copper foil is 11600 times, the special electrolytic copper foil is 5233 times, and the standard electrolytic copper foil is 2560 times. It can be seen from the test and evaluation results of flexibility that the flexibility of rolled copper foil is about 4 times higher than that of ordinary electrolytic copper foil. Its flexural reliability has an overwhelming advantage.

Manufacturability: electrolytic copper material is formed by electroplating. Its copper particle crystal structure is easy to form vertical line edges when etching, which is very conducive to the production of fine wires.

Flatness: due to the high density of rolled copper foil, its production mode determines that its surface has uniform smoothness. The surface roughness (Rz) of the raw rolled copper foil produced is only 1 μ m. However, the surface roughness Rz of ordinary raw electrolytic copper foil is 5 μ m。