5G brings us beyond the transmission speed of optical fiber (Mobile Beyond Giga), beyond the real-time capabilities of industrial buses (Real-Time World) and all-space connection (All-Online Everywhere), 5G will open an era of opportunities.
From the perspective of 5G construction needs, 5G will adopt the "macro station + small station" network coverage model. The upgrade of base stations will bring a wave of renovation of the original base station and the construction of new base stations. The massive growth of 5G base stations will simultaneously drive the substantial growth of components such as PCBs, antenna elements and filters.
In 5G base stations, Printed Circuit Board (PCB) as the most basic connection device will be widely used.
The widely used substrate material in the PCB industry is a glass fiber cloth reinforced epoxy substrate FR-4 (epoxy glass fiber cloth copper clad), which is made of one or more layers of glass fiber impregnated with epoxy resin Cloth composition.
Glass fiber cloth and special resin are one of the important raw materials for PCB. Glass fiber cloth as a reinforcing material plays the role of insulation and strength; special resin as a filling material plays a role of bonding and improving the performance of the board.
In order to meet the requirements of reliability, complexity, electrical performance and assembly performance of high-frequency high-speed PCB products, many manufacturers of PCB substrate materials have made different improvements to special resins.
In the current trend of high speed and high frequency, more mainstream PCB materials include polytetrafluoroethylene resin (PTFE), epoxy resin (EP), bismaleimide triazine resin (BT), thermosetting cyanate resin (CE), thermosetting polyphenylene ether resin (PPE) and polyimide resin (PI), and more than 130 kinds of copper clad laminates derived therefrom.
For the base station PCB, the most important indicators are dielectric characteristics, signal transmission speed and heat resistance. The PTFE substrate on the first two points has good performance.
It is the organic material with the best dielectric properties found so far. The excellent dielectric properties are conducive to the complete and rapid transmission of signals. From this perspective, PTFE is the preferred resin material for base station PCBs in the 5G era.
Plastic antenna elements are promising
The antenna element is the core component of the antenna. As the main component of the antenna, the antenna element is mainly responsible for amplifying the signal and controlling the radiation direction of the signal, which can also make the electromagnetic signal received by the antenna stronger.
In the 5G era, due to the higher frequency band and the use of Massive-MIMO technology, the size of the antenna element has become smaller and the number has increased significantly. Considering the antenna performance and AAU installation issues, the plastic antenna element solution has certain comprehensive advantages.
In order to cope with the changes of the new 5G antenna, a new process appeared on the market-3D selective plating plastic vibrator solution.
The so-called plastic antenna element is a modified plastic material containing an organic metal compound. The complex 3D three-dimensional shape is manufactured at one time by injection molding, and then the plastic surface is metalized using special technology. While ensuring that the antenna meets the performance of 5G electrical appliances, the plastic vibrator greatly reduces the weight of the product, reduces dangerous process steps, and saves costs.
In addition to being very light, the 3D plastic vibrator can also meet the precision requirements that cannot be achieved by sheet metal and die casting processes. Both injection molding and selective plating are very high-precision processes. Combining them together can ensure that the accuracy of the antenna element meets the requirements of high frequency scenes above 3.5G.
Ceramic dielectric filters have many advantages
In the 4G era, communication base stations mainly use metal cavity filter solutions. In the 5G era, the number of base station channels has expanded by 16 times, and the miniaturization of devices has become a trend. Ceramic dielectric filters have the advantages of light weight and miniaturization. At the same time, they have a reliable mechanical structure and a vibration-free structure, which facilitates automated assembly. In the long run, it will become 5G. Mainstream components of base stations.
Composite material communication tower and radome
The tall communication towers are mostly steel structures, but corrosion is a big problem, and composite materials can solve this problem. The composite material is relatively light, using the fastenerless connection technology, the individual components of the tower structure can be quickly assembled, no metal bolts are required during the assembly process, the installation is convenient, and the weight of the entire tower body is reduced.
The radome must have good electromagnetic wave penetration characteristics, and the mechanical properties must be able to withstand the erosion of external harsh environments such as storms, ice, snow, dust, and solar radiation. In terms of material requirements, the dielectric constant and loss tangent at the operating frequency are required to be low, and sufficient mechanical strength is required.
In general, inflatable radomes are commonly coated with polyester fiber film coated with Hypalon rubber or neoprene; glass fiber reinforced plastics are used for rigid radomes; honeycomb cores or foam plastics are often used for the sandwich in the sandwich structure.
In the 5G trend, composite materials with superior performance have become popular antenna cover materials. Composite materials can play the role of insulation and anti-corrosion, lightning protection, anti-jamming, durable, etc., and the effect of wave transmission is very good.
Mobile phone back cover: preferred PC / PMMA plastic composite material
In the 5G era, new requirements for the structure and shape of mobile phones, such as miniaturization, ultra-thinness, and full-screen, all require new technology and material support. The demand for functions such as wireless charging and NFC has accelerated the demetallization of the back cover of mobile phones, driving the PC / PMMA co-extruded composite sheet market to rise significantly.
In the 5G era, stricter requirements have been put on the materials of 5G application equipment. Since 5G is taking millimeter waves sensitive to metal, using a metal case will shield the signal. Plastic composite materials have become the trend of choice for mobile phone back cover due to their superior performance.
Among them, the most popular is PC / PMMA composite sheet. This material is made by co-extrusion (non-alloy material) of PMMA and PC, including PMMA layer and PC layer.
After the MMA layer is hardened, it can reach a pencil hardness of more than 4H, ensuring the scratch resistance of the product, while the PC layer can ensure that it has sufficient toughness to ensure the overall impact strength.
Graphene: the ideal heat dissipation material for 5G devices
High frequency, the upgrading of hardware components and the exponential growth of the number of networked devices and antennas, electromagnetic interference between devices and within the device itself is ubiquitous, and electromagnetic interference and electromagnetic radiation are also increasingly harmful to electronic equipment.
At the same time, with the updating and upgrading of electronic products, the power consumption of the equipment continues to increase, and the heat generation also rises rapidly.
In the future, high-frequency and high-power electronic products should focus on solving the electromagnetic radiation and heat generated by them.
For this reason, more and more electromagnetic shielding and heat conduction devices will be added to the design of electronic products. Therefore, the role of electromagnetic shielding and heat dissipation materials and devices will become increasingly important, and future demand will continue to grow.
Taking thermal conductive graphene as an example, 5G mobile phones are expected to adopt customized thermal conductive graphene solutions in more key parts. At the same time, composite and multi-layer high thermal conductive films will be more used due to better heat dissipation.
5G composite material related news
Covestro develops 5G base station housing materials
In mid-2019, Shi Marco, vice president of innovation for Covestro Asia Pacific, said that the company has successfully developed a housing material suitable for 5G base stations.
Shima Ke said that 5G technology has the characteristics of high frequency and short wavelength, resulting in a large degree of signal attenuation, which means that a large number of 5G micro base stations must be deployed to continuously amplify the signal to ensure signal coverage. Compared with the 4G era, the number of 5G micro base stations is expected to increase by about 20 times.
In the process of developing 5G base stations, it is necessary to ensure that 5G high-frequency signals can successfully penetrate the shell, which places high requirements on the materials. More than a year ago, Covestro's polymer research and development center in Shanghai launched this experiment for 5G base station housing materials.
BASF's innovative polyurethane solution provides solid support for China's 5G communication tower
BASF's innovative material solutions for Elastolit® polyurethane (PU) help China deploy 5G networks. Anhui Huike Hengyuan Composite Materials Co., Ltd. (Huike) uses Elastolit to make 60 communication towers, which are distributed in Beijing, Suzhou and many cities in Heilongjiang and Jiangxi.
Compared with traditional concrete or steel-based materials, the communication tower made of Elastolit® is lighter in weight and can be quickly installed even in remote areas, while being able to withstand severe weather such as heavy snow and strong winds.
Andy Postlethwaite, Global Senior Vice President of BASF's Asia Pacific Performance Materials Division, said: "5G base stations carrying transmission equipment and antennas must remain strong in severe weather conditions. The 35-meter-high communication tower made of BASF's PU composite material weighs About 1,500 to 1,800 kilograms, its breaking strength is ten times its own weight. "
Not only that, communication towers made of Elastolit® are more cost-effective than traditional steel towers. Elastolit® has rust and corrosion resistance and requires less maintenance. The surface is covered with a specially formulated UV-resistant coating, which can extend its service life. At the same time, it is fireproof and can quickly extinguish itself.
Russian physicists carry out composite material performance research for 5G equipment
Radiation physicists at Tomsk State University (TSU) in Russia are building a composite material performance database that can assist in the creation of 5G and space communications equipment operating in the terahertz range. Scientists are developing composite materials using acrylonitrile-butadiene-styrene (ABS) engineering plastics and carbon nanotubes, and measuring their performance in the frequency range of 10 MHz to 1 THz.
To develop this raw material, radiation physicists are using polymers and filling them with carbon nanotubes, aided by chemical processes. These materials are currently being produced by the Poleskov Institute of Catalysis of the Siberian Branch of the Russian Academy of Sciences for the Terahertz Laboratory of the School of Radiophysics.
"By adding different amounts of carbon nanotubes, we changed the dielectric properties of the material. For example, we can increase the dielectric constant." Alexander Badyin, associate professor and project manager of the School of Radiological Physics, explained, "Then we use 3D printing technology, A printed circuit board with components (conductors, resistors, etc.) can be obtained. We control the parameters of the device to print a control sample (board or ring) and check the performance of the composite material in the terahertz range. "
The researchers said that the previous scientific research mainly focused on 4-5 gigahertz household radiation bands. The TSU team of scientists has a wider scope of work-up to 1 terahertz. The researchers said that the current study is not sufficient. As of December 2019, researchers have studied the characteristics of nearly 50 samples.
Shin-Etsu Chemical Co., Ltd. of Japan launched products such as "quartz cloth" to meet the needs of the 5G era
According to the needs of the 5G era, Japan ’s Shin-Etsu Chemical Industry has launched “quartz glass fiber cloth” and “thermosetting low-dielectric resin”, which can be used in 5G high-band electronic devices and circuit boards, antennas, and radomes. In addition, Shin-Etsu Chemical Industry has also increased the variety of heat sinks.
The dielectric constant of quartz glass fiber cloth is lower than 3.7, the dissipation factor is lower than 0.001, the coefficient of linear expansion is lower than 1ppm / ℃, and the characteristics of transmission loss (the degree of deterioration of electrical signals) are extremely excellent. This product is most suitable as the core material of 5G ultra-high-speed wiring boards, fiber-reinforced resin parts for antennas and radomes, etc.
Thermosetting low-dielectric resin is a kind of low-elastic resin with low dielectric constant and high strength close to fluororesin. Its high frequency band (10 ~ 80GHz) has a dielectric constant below 2.5 and a dissipation factor below 0.00025. This is the lowest level of thermosetting resin. Due to the low hygroscopicity of the product and its high adhesion to low-thickness copper foil, it can also be used for FCCL (soft copper foil substrate).