Why should the inner core conductor of HDMI cable use oxygen-free copper?

The factors that affect the quality of the HDMI cable are nothing more than craftsmanship and material, and what kind of inner core conductor the HDMI cable uses directly determines the quality of the HDMI cable. Generally, HDMI cable manufacturers that attach importance to quality will use oxygen-free copper as the inner core conductor. core conductor, what are the advantages of using oxygen-free copper as the inner core conductor?


As we all know, the commonly used materials of the inner core conductor of HDMI cable can be generally divided into: iron core, alloy core, gold core, silver core, pure copper and so on. Among the metals, gold and silver have the smallest resistivity and the best electrical conductivity, but the cost of gold and silver materials is expensive, which is not acceptable to most consumers. HDMI cables with iron cores or other alloy materials are mostly inferior quality cables, with low production costs and poor electrical conductivity. High quality transmission of the signal. As a commonly used metal material, copper has good electrical conductivity and is cheaper than gold and silver. At present, the mainstream HDMI cables all use copper as the conductor, but due to the traditional smelting process of copper, copper contains many impurities. , and most of the impurities are oxides, which affect the electrical conductivity of copper. In order to change this deficiency, manufacturers have produced copper of different purities by changing the copper smelting process to meet the needs of different scenarios. Copper wires also have low and high grades, which can generally be divided into the following types:

1. TPC (electrolytic copper): It is the raw material for common copper materials, and the general purity is 99.95%.

2. OFC (Oxygen-Free Copper): It removes some oxygen molecules and impurities in electrolytic copper. The general purity is 99.995%, commonly known as 4N copper (4N represents 99.99%).

3. LC-OFC (Linear Crystalline Oxygen-Free Copper or Crystalline Oxygen-Free Copper): By further removing oxides in copper and removing other impurities, the grains of high-conductivity oxygen-free copper are grown by mechanical processing and heat treatment methods to make The purity of copper is increased to more than 99.995%.

4.OCC (single crystal oxygen-free copper, divided into PC-OCC and UP-OCC): when smelting copper, the method of directional growth and rapid solidification is used to make the crystal growth of copper elongated, and the longest can reach 125 meters. , make the grain boundary in the wire disappear, fundamentally eliminate the influence of grain boundary and oxide on signal distortion, and increase the purity of copper to more than 99.996%.

It is worth noting that the cost of ordinary copper wire is lower, the more impurities contained in it, the lower the purity and the cheaper the price. In order to remove impurities in the copper material, the more cost is spent on the process, so the higher the purity, the more expensive the price. For example, the price of 6N copper wire is equivalent to the price of pure silver, and the price of 8N copper wire is equivalent to the price of gold. In this explanation, "N" is the abbreviation of English "NINE", 8N" means that the purity is 99.999999%, "4N" means that the purity is 99.99%, and 5N, 6N, 7N are also expressed in the same way.




Combining various factors, the inner core conductor of mainstream HDMI cables generally uses the second type of OFC (oxygen-free copper) as the inner core conductor. Let me introduce the transmission characteristics and advantages of OFC (oxygen-free copper):

1. First understand the skin effect (or skin effect) of copper wire: the current inside the copper wire is actually very small, and the current is concentrated in a thin layer adjacent to the surface of the wire. As a result, its resistance increases. The increase of wire resistance increases its power loss, a phenomenon known as the skin effect. This is mainly due to the fact that OFC has changed the metal structure of copper through high-tech methods such as electrochemical method, PN junction implantation method, and isotope irradiation modification method. The surface is suitable for transmitting frequency signals above 5000Hz, while its center is only suitable for transmitting frequency signals below 5000Hz, so that the high and low frequencies do not interfere with each other, which is beneficial to improve the clarity of the playback sound and improve the playback sound when transmitting large signals. sound quality.

2. The advantages of OFC (oxygen-free copper):
Oxygen-free copper has low resistance, good conductivity, small transmission loss, small signal distortion, clear image, high oxidation resistance, good softness, and long service life. In addition, oxygen-free copper conductors have good sound quality, stable sound, medium The low frequency is thick and audible.


Based on the above understanding, STC-Cable, as a member of the International HDMI Cable Association, has been focusing on HDMI cables for 14 years, and has always adhered to the industry material standards, using oxygen-free copper as the inner core conductor, and has established a good benchmark in the industry. Demonstration role, at the same time It also established the reputation and status of STC in the industry!


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Post time: Oct-20-2022
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