In 1919, the initial commercial use of 5G. The upstream materials of core materials such as high-frequency copper clad laminates are basically similar to traditional CCL. After being produced by downstream PCB manufacturers as high-frequency circuit boards suitable for high-frequency environments, they are used in base station antenna modules and power amplifiers. Modules and other equipment components, and eventually widely used in high-frequency communication fields such as communication base stations (antennas, power amplifiers, low-noise amplifiers, filters, etc.), automotive auxiliary systems, aerospace technology, satellite communications, satellite TV, military radar, etc.
5G high-frequency technology places higher demands on circuits. Radio frequency circuits with operating frequencies above 1 GHz are generally called high-frequency circuits. In the process of mobile communication from 2G to 3G and 4G, the communication frequency band has developed from 800 MHz to 2.5 GHz. In the 5G era, the communication frequency band will be further improved. The PCB board will be equipped with antenna elements, filters and other devices in the 5G radio frequency. According to the requirements of the Ministry of Industry and Information Technology, the early 5G deployment is expected to use the 3.5GHz frequency band, and the 4G frequency band is mainly around 2GHz. Generally, electromagnetic waves with a wavelength of 1-10 mm in the 30-300 GHz frequency band are millimeter waves.
In 5G large-scale commercial use, millimeter wave technology ensures better performance: the bandwidth is extremely wide, the available spectrum bandwidth of the 28GHz band can reach 1GHz, and the available signal bandwidth of each channel of the 60GHz band can reach 2GHz; the corresponding antenna has high resolution and anti-interference performance Good, miniaturization can be achieved; the propagation attenuation in the atmosphere is faster, and close-range confidential communication can be achieved.
In order to solve the needs of high frequency and high speed, as well as to deal with the problems of poor millimeter wave penetration and fast attenuation, 5G communication equipment has the following three performance requirements for PCB:1. Low transmission loss;
2. Low transmission delay；
3. Precision control of high characteristic impedance.
There are two ways to increase the frequency of PCBs. One is that the PCB manufacturing process requires more, and the other is to use high-frequency CCL-the substrate material that meets the high-frequency application environment is called high-frequency copper clad.
There are mainly two indicators of dielectric constant (Dk) and dielectric loss factor (Df) to measure the performance of high frequency copper clad laminate materials. The smaller the Dk and Df, the more stable, the better the performance of the high-frequency high-speed substrate. In addition, for the RF board, the PCB board has a larger area and more layers, which requires the substrate to have higher heat resistance (Tg, high temperature modulus retention rate) and stricter thickness tolerances.
There are several main high-frequency & high-speed materials for common printed circuit boards: hydrocarbon resin, PTFE, LCP liquid crystal polymer, PPE/PPO, etc.