What kind of electromagnetic shielding materials are needed for 5G base stations

electromagnetic shielding materialApplication on base station

There are many types of base stations, including macro base stations with high transmission power, micro base stations used in urban and rural areas, picobase stations used in public places, and indoor flying base stations with low transmission power. As of now, the number of 5G base stations in China has reached nearly 2 million, making it the first country in the world to build a 5G network based on an independent networking model.

The communication base station is usually made of aluminum alloy die-casting parts. As is well known, metal is a good electromagnetic shielding material. However, the overall electromagnetic radiation protection still requires the use of conductive silicone strips at various joints, only in this way can the entire base station form a continuous conductive body. It can be assumed that a continuous conductor can confine electromagnetic waves within the base station (eddy current and reflection effects, positively correlated with conductivity), preventing leakage. However, in practical applications, base stations are exposed to environmental factors such as ultraviolet radiation, high temperature, severe cold, and humidity for a long time. The design of conductive materials requires multidimensional consideration and is not a simple task.

Communication base stations are strategic infrastructure for achieving informatization, and their transmitting antennas send electromagnetic wave signals into space during operation. According to Chinese laws, the construction of mobile communication base stations must comply with the requirements of the "Regulations on Electromagnetic Radiation Protection" and the "Environmental Electromagnetic Wave Health Standards". Only when the electric field strength meets the upper limit requirements of less than 12V/m or the power density is less than 40mW/cm2, can it be considered as meeting safety standards. On January 1, 2019, the "Monitoring Method for Electromagnetic Radiation Protection of Mobile Communication Base Stations" issued by the Ministry of Ecology and Environment officially came into effect, highlighting the high importance that the country attaches to electromagnetic protection of base stations.
At present, the world is accelerating the deployment of 5G mobile communication for commercial use, and the electromagnetic shielding treatment of mobile communication base stations and application terminals is particularly urgent.

The casing of communication base stations is usually made of aluminum alloy die-casting parts. In order to achieve overall electromagnetic radiation protection, conductive silicone strips need to be connected at the joints of the die-casting parts (as shown in the figure below).Conductive silicone stripMake the aluminum alloy base station shell form a continuous conductive body, and restrict electromagnetic waves inside the base station through the eddy current effect and reflection effect of the conductive body, thereby preventing electromagnetic wave leakage and radiation. For 5G high-frequency communication, the electromagnetic shielding effectiveness of conductive silicone strips is mainly achieved through eddy current effect. The stronger the conductivity of the material, the more obvious the eddy current effect. Therefore, in order to improve the electromagnetic shielding effectiveness, the base station housing material needs to have higher conductivity. In addition to conductivity, conductive silicone strips can only meet practical application needs if they meet specific mechanical properties. For example, base station integrators have strict requirements for tensile strength, tear strength, elongation at break, compression permanent deformation, etc. The working environment of outdoor base stations is relatively harsh, such as prolonged high temperature, severe cold, humidity, and corrosive environment, which may cause deterioration of the performance of conductive materials. Therefore, conductive silicone strips must be able to withstand strict environmental aging tests.

Market and Development

Required in the base stationelectromagnetic shielding materialMainly including sealing strips, conductive adhesives, gaskets, etc., the high-performance materials of such products have been monopolized by foreign countries in the past, such as Laird from the United States, Norland from Sweden, Gomel from the United States, 3M, etc. However, in recent years, domestic enterprises have also achieved great success, with product performance comparable to foreign enterprises. Representative enterprises include Shenzhen Feirongda, Shenzhen Hongfucheng, Beijing Zhongshi Weiye, Longyang Electronics, etc. In the past five years, the market for electromagnetic shielding materials alone in China has risen to over 20 billion yuan.

Electromagnetic shielding has been developed for many years. To cope with high-frequency radio waves, all development routes are focused on improving conductivity, such as adding conductors or powders. However, many inherent materials have upper limits, so various materials have also been developed to cope with different scenarios, such as smart connected vehicles, flexible circuits, smart wearable devices, etc. Even once 6G communication transitions to THz in the future, many existing electromagnetic shielding materials will simply not be able to meet the requirements. The electromagnetic shielding industry is about to usher in a new round of revolution, with challenges and opportunities coexisting!