Classification of copper foil

Industrial copper foil can be commonly divided into two categories: Rolled copper foil (RA copper foil) and electrolytic copper foil (ED copper foil). Among them, rolled copper foil has good ductility and other characteristics, which is the copper foil used in the early soft board manufacturing process, while electrolytic copper foil has the advantage of lower manufacturing cost than rolled copper foil.

(1) Calendered copper foil

Calendered copper foil is the original foil (also known as raw foil) made of copper plate by repeated rolling, which is roughened according to requirements.

Due to the limitation of calendered copper foil processing technology, its width is difficult to meet the requirements of rigid copper clad laminate, so calendered copper foil is rarely used on rigid copper clad laminate. Because the bending resistance and elastic coefficient of calendered copper foil are greater than that of electrolytic copper foil, it is suitable for flexible copper clad laminates.

The copper purity of calendered copper foil (99.9%) is higher than that of electrolytic copper foil (99.8%), and it is smoother than electrolytic copper foil on the rough surface, which is conducive to the rapid transmission of electrical signals. Therefore, in recent years, foreign countries have used calendered copper foil on the substrate of high-frequency high-speed signal transmission and thin wire printed boards.

It can also improve the sound quality effect when used in the printed board substrate of audio equipment. It is also used on the "metal sandwich board" made to reduce the coefficient of thermal expansion (TCE) of multilayer circuit boards with thin wires and high layers.

(2) Electrolytic copper foil

Electrolytic copper foil is made by dissolving copper into solution, then electrodepositing copper sulfate electrolyte under the action of direct current in a special electrolytic equipment to make the original foil, and then carrying out a series of surface treatments such as surface treatment, heat-resistant layer treatment and anti-oxidation treatment on the original foil according to the requirements.

Electrolytic copper foil is different from calendered copper foil. The crystalline morphology of both surfaces of electrolytic copper foil is different, and the surface close to the cathode roll is relatively smooth, which is called smooth surface; On the other side, there is a concave convex crystalline structure, which is relatively rough and called hairy surface.

Because electrolytic copper foil belongs to columnar crystalline structure, its strength and toughness are inferior to those of rolled copper foil, so electrolytic copper foil is mostly used in the production of rigid copper clad laminates, and then made into rigid printed boards.

Performance advantages of carbon coated copper foil

1. Significantly improve the consistency of battery pack use and significantly reduce the cost of battery pack.

Significantly reduce the increase of dynamic internal resistance of the cell;

Improve the differential pressure consistency of the battery pack;

Extend battery life.

2. Improve the adhesion between the active material and the collector, and reduce the manufacturing cost of the electrode. For example:

Improve the adhesion between the cathode material and the collector of the aqueous system;

Improve the adhesion between nano or submicron cathode materials and collectors;

Improve the adhesion between lithium titanate or other high-capacity cathode materials and collectors;

Improve the qualification rate of pole pieces and reduce the manufacturing cost of pole pieces.

3. Reduce polarization, improve magnification and gram capacity, and improve battery performance. For example:

Partially reduce the proportion of adhesive in the active material and increase the gram capacity;

Improve the electrical contact between the active substance and the collector;

Reduce polarization and improve power performance.

4. Protect the current collector and prolong the service life of the battery. For example:

Prevent corrosion and oxidation of current collector;

Improve the surface tension of the collector and enhance the easy coating performance of the collector;

It can replace the etching foil with higher cost or replace the original standard foil with thinner foil.

Source: Changjiang nonferrous metals network