Basics of Copper Wire

Basics of Copper Wire

Copper wire performance differentiation overview

According to the resistivity (the size of the resistance value of the material with a length of 1m and a cross-sectional area of 1mm2), we generally divide the material into three categories:

Conductors: Resistivity below 102Ω-mm2/m

Semiconductors: Resistivity of 103~108Ω-mm2/m; and

Insulators: Resistivity of 108Ω-mm2/m or more.

At present, the commonly used metal conductors are gold, silver, copper, etc. (the following table), taking into account the price and conductivity of the conductor, the most commonly used for the copper conductor.

Copper conductivity is better, suitable for a wide range of performance, lower cost, but also in its surface tin plating, conducive to welding, and antioxidant effect (refers to the combination of oxidation and oxygen in the air.).

Various properties of copper wire

Conductor resistance - A conductor's resistance is proportional to its length and inversely proportional to its cross-sectional area.

Conductivity - 20 °C when the length of 1 m, cross-sectional area of 1 mm2 of standard soft copper wire resistance 1/58ohm (0.017241 ohm) as a benchmark, known as 100% conductivity. The greater the resistance, the lower the conductivity, the two are inversely proportional.

Bending resistance - one end of a single line is fixed, the other end plus the weight to make the vertical down, and then back and forth 180 bending until the line breaks, the more the number of times of bending, said the stronger the bending resistance.

Tensile Strength-The maximum load or force applied to a specimen to make it break during the tensile test.

Tensile Strength - The tensile strength of a specimen that is subjected to a breaking force per unit area during the tensile test to make the specimen break.

Elongation - the ratio of the increased length of a specimen to its original length at a specified standard distance after elongation to rupture.

Conductor at different temperatures will have different impedance, generally often 20 °C or 25 °C as a standard, the higher the temperature, the greater the impedance will be.

Important High Frequency Parameters of Copper Wire

High-frequency current passes through the conductor; the current tends to be dispersed over the conductor's surface; the closer to the conductor's surface, the greater the current density.

This is known as the skin effect.The higher the frequency, the more the current is concentrated on the conductor's surface; when the frequency is high enough, the current is almost exclusively distributed on the conductor's surface in a thin layer, with almost no current flowing inside the conductor.

For good conductors like copper, conductivity is extremely high, so as the frequency rises, it will soon show a significant skin effect, generally more than 6MHz a little skin depth of approximately 1mil, about 55MHz when the skin depth of about 0.35mil, 1GHz about 0.1mil, the skin effect will inevitably have a great impact on high-speed signals. The following picture is enlarged to see, the surface of the copper is not as smooth as it seems, the skin effect leads to an increase in signal loss.