A comparison between oxygen-free copper network cables and all-copper network cables

The internal cable material of Ethernet cables varies depending on different prices and applications. Generally, we call network cables oxygen-free copper network cables. However, there are also other names for network cables, such as copper-clad copper, copper-clad silver, copper-clad steel, etc. In this issue, we will analyze these materials of network cables.

I. Types of Network Cables

Copper-clad steel: The center is steel and the surface is coated with a layer of copper. It has high electrical conductivity, strong rigidity, is relatively hard and not easy to bend or deform. The melting point of steel is higher than that of copper (the melting point of copper is around 1000℃, while that of steel is around 1500℃). Therefore, when burning copper with a lighter, it will melt steel first and then steel, resulting in sparks and a darkening of the color of steel (steel is prone to oxidation and turns black). Furthermore, when using a magnet to attract, the copper-clad steel will adhere to the magnet.

2. Copper-clad aluminum: The center is aluminum and the surface is coated with a layer of copper. When burned with a lighter, it immediately drosses and turns gray. After the copper-clad aluminum burns, the conductor will break easily when pinched with a finger and is relatively brittle, often breaking into multiple sections. Furthermore, the specific gravity of copper-clad aluminum is light, only one-third that of copper (the specific gravity of copper-clad aluminum is about 3.0g/cm ³, while that of pure copper is 8.9g/cm ³).

3. Copper-clad copper: The center is brass, and the surface is coated with a layer of pure copper. Brass is an alloy composed of copper and zinc, and its surface color is dull and not very bright. Look at the cut end face. Cut the end face of the wire open. If the outside of the end face is red and the center is yellow, it is copper-clad copper. Use a knife to scrape the copper wire to a certain extent. If it shows red, it is pure copper, and if it shows yellow inside, it is brass.

4. Pure copper (oxygen-free copper OFC 4N) : OFC 4N is pure copper with a purity of 99.99%, free of oxygen and any deoxidizer residues. It features excellent electrical conductivity, thermal conductivity, ductility and corrosion resistance. The method to identify pure copper (oxygen-free copper OFC 4N) is as follows: The surface color is bright and reddish red. When burned with a lighter, it slowly melts into a small dot. If not burned, it turns red and black. After cooling, it returns to its original color. It should be noted that if the surface color changes, it is because of oxidation during burning. If the surface is scraped off, the inside will still be reddish red.

Why is a layer of oxygen-free copper plated on the core of the network cable conductor?

Since oxygen-free copper is pure copper that contains neither oxygen nor any residual deoxidizers (but still contains very trace amounts of oxygen and some impurities), according to the standard, the oxygen content should not exceed 0.003%, the total impurity content should not exceed 0.05%, and the purity of copper should be greater than 99.95%.

Oxygen-free copper features high purity, excellent electrical conductivity, thermal conductivity, cold and hot working performance, as well as good welding and corrosion resistance, making it suitable as a high-quality material for network cables. Besides the oxygen-free copper network cables commonly available on the market now, there are also bronze network cables, also known as all-copper network cables or copper-clad copper network cables.

In general small-scale projects with a long service life, bronze network cables are often chosen. However, for larger projects, oxygen-free copper network cables are selected as the medium for transmitting network signals. During network signal transmission, both the transmission effect and distance are related to the material of the network cable. The better the material of the conductor, the smaller the resistance of the network cable, the better the transmission effect, and the longer the transmission distance.

Because the purity of oxygen-free copper is higher than that of bronze, the resistance of oxygen-free copper network cables is much lower than that of bronze network cables. Within 300 meters, the resistance of bronze network cables is approximately 110 ohms, while that of oxygen-free copper network cables is only about 30 ohms.

The effective transmission distance of network cables is also related to the size of their resistance. Under normal circumstances, oxygen-free copper network cables can transmit about 120 to 150 meters, while bronze network cables can only transmit about 70 meters. The physical properties of oxygen-free copper network cables and bronze network cables are both relatively stable, with high oxidation resistance. Moreover, their colors are basically the same. The conductors of bronze network cables are coated with a layer of oxygen-free copper, which cannot be distinguished on the surface. When it is impossible to distinguish the conductors of oxygen-free copper and bronze network cables, the surface or cross-section can be scraped open with a knife.