Classification and advantages of copper foil
Classification of copper foil
Industrial copper foil can be generally 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, and was the copper used in the early soft board manufacturing process. Foil, while electrolytic copper foil has the advantage of lower manufacturing cost than rolled copper foil.
(1) Rolled copper foil
Rolled copper foil is a raw foil (also called rough foil) made by rolling a copper plate multiple times, and is roughened according to requirements.
Due to the limited processing technology of rolled copper foil, its width is difficult to meet the requirements of rigid copper clad laminates, so rolled copper foil is rarely used on rigid copper clad laminates. Since the folding resistance and elasticity coefficient of rolled copper foil are greater than those of electrolytic copper foil, it is suitable for flexible copper clad laminates.
The copper purity of rolled copper foil (99.9%) is higher than that of electrolytic copper foil (99.8%), and the rough surface is smoother than that of electrolytic copper foil. These are all conducive to the rapid transmission of electrical signals. Therefore, in recent years, foreign countries have used rolled copper foil as the base material for high-frequency and high-speed signal transmission and fine-wire printed boards.
It is used as the printed board base material in audio equipment and can also improve the sound quality. It is also used in "metal sandwich boards" made to reduce the thermal expansion coefficient (TCE) of multi-layer circuit boards with thin wires and high-layer count.
(2)Electrolytic copper foil
Electrolytic copper foil is made by first dissolving copper into a solution, and then electrodepositing the copper sulfate electrolyte under the action of direct current in a special electrolytic equipment to make the original foil. The original foil is then surface treated and resistant to corrosion as required. A series of surface treatments such as thermal layer treatment and anti-oxidation treatment.
Electrolytic copper foil is different from rolled copper foil. The surface crystal forms of electrolytic copper foil on both sides are different. The side close to the cathode roller is relatively smooth and is called the smooth side; the other side has a concave and convex crystal structure and is relatively rough, called the matte side.
Since electrolytic copper foil has a columnar crystal structure and its strength, toughness and other properties are inferior to those of rolled copper foil, 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 usage and significantly reduce battery pack costs.
Significantly reduce the increase in dynamic internal resistance of the battery cell;
Improve the pressure difference consistency of the battery pack;
Extend battery pack life.
2. Improve the bonding adhesion between active materials and current collectors and reduce the manufacturing cost of pole pieces. like:
Improve the adhesion of cathode materials and collectors using water-based systems;
Improve the adhesion between nanoscale or submicron cathode materials and collectors;
Improve the adhesion of lithium titanate or other high-capacity anode materials and collectors;
Improve the pole piece manufacturing qualification rate and reduce pole piece manufacturing costs.
3. Reduce polarization, increase rate and gram capacity, and improve battery performance. like:
Partially reduce the proportion of binder in the active material and increase the gram capacity;
Improve electrical contact between active material and current collector;
Reduce polarization and improve power performance.
4. Protect current collector and extend battery life. like:
Prevent collector corrosion and oxidation;
Improve the surface tension of the collector and enhance the easy coating performance of the collector;
Can replace more expensive etched foils or replace standard foils with thinner foils.
