signal cable copper conductor

         With the rise of AI, transmission rate requirements are getting higher and higher. High-speed interconnection is the main bottleneck for communication between electronic components. 25-30Gbps per serial channel is becoming mainstream. Such data rates and even higher data rates can Generated and transmitted on a small scale on a chip, but for transmission cables a good conductor like copper , the conductivity is extremely high, so as the frequency increases, it quickly shows an obvious skin effect. Generally, the skin depth is a little more than 6MHz and is approximately 1mil. At about 55MHz, the skin depth is about 0.35mil. At 1GHz, it is about 0.1mil, the skin effect will inevitably have a great impact on high-speed signals.When the copper core is enlarged, the surface of the copper is not as smooth as it looks, and the skin effect causes increased signal loss. When high-frequency current flows through a conductor, the current will tend to be distributed on the surface of the conductor, and the closer to the surface of the conductor, the greater the current density. This phenomenon is the skin effect. The higher the frequency, the more concentrated the current is on the surface of the conductor. It can be imagined that when the frequency is high enough, the current is almost only distributed in a thin layer on the surface of the conductor, and there is almost no current inside the conductor.