Internationally, absorbing materials can absorb 80% of interfering electromagnetic waves throughout the entire 5G communication frequency band. The new absorbing material developed by WHKJ has an average absorption efficiency of 90% in this frequency band.
Wireless communication relies on specific electromagnetic wave frequency bands, but in nature, electromagnetic wave frequency bands are abundant and interfere with each other. To maintain stable communication, it is necessary to shield against interference from other electromagnetic waves.
On June 3rd, the WHKJ team developed a new type of absorbing material (a material that absorbs electromagnetic waves), which is made into an iron cobalt ruthenium ternary alloy thin film. It can absorb more than 90% of interference electromagnetic waves for integrated circuits, effectively solving the problem of electromagnetic wave interference.
Urgent need to develop new anti electromagnetic interference materials
In daily life, electromagnetic waves are ubiquitous. The electronic products we use are often affected by electromagnetic interference, such as snowflakes on TV screens and noise from mobile phone earphones, which may be caused by electromagnetic interference.
At present, domestic and foreign scientists have been committed to developing new types of absorbing materials – absorbing all interfering signals within the widest possible frequency range to reduce electromagnetic interference.
Especially after the large-scale application of 5G communication, the working frequency of integrated circuits continues to increase, and the bandwidth continues to increase. Some existing electromagnetic wave interference resistant materials have a poor ability to absorb electromagnetic waves within a wide frequency range. "Li Xiangcheng said, and the development of new electromagnetic wave interference resistant materials has become a new hot research topic for scientists at home and abroad.
The R&D team attempts to mix ruthenium and iron, cobalt, two common magnetic elements in a certain proportion evenly and melt them to improve the performance of absorbing materials.
Team member and third year graduate student Wu Yuanyuan said that they mixed ruthenium, iron, and cobalt to make a magnetic powder film and measured its absorption performance.
The team has found through multiple calculations, simulations, and experimental verification that a unique alloy crystal structure can be formed when the doping ratio of ruthenium is around 1%. At this time, the magnetic powder film has the highest efficiency in absorbing electromagnetic waves, reaching 97%.
Due to the electromagnetic wave being emitted at a certain angle, the team calculated that when the magnetic particles are arranged in a layered and parallel manner, the electromagnetic wave passes through the thin film, and its absorption effect is the best.
Continuously optimizing raw materials and production processes
There are two difficulties in combining ruthenium with iron and cobalt to produce thin films and achieve industrialization. One is to obtain the optimal doping ratio of ruthenium through theoretical calculation; The second is to achieve homogeneous production of high-density and highly oriented thin films through device improvement and process optimization.
After thousands of designs and verifications, repeated experiments to adjust and improve, the WHKJ R&D team finally developed a new type of absorbing material before the 2023 Spring Festival.
The team's latest developed magnetic absorbing material – iron cobalt ruthenium ternary alloy thin film – is placed on an adult palm sized integrated circuit board, with a magnetic particle thin film thickness of only 200 microns.
Under an electron microscope, it has 13 layers of thin film, and the magnetic powder is not in the form of granules, but in the form of flakes.
”The magnetic powder film is composed of ternary alloy magnetic powder and resin material bonded together. Without technical intervention, the magnetic powder is disorderly arranged and skewed in the resin, which will reduce the absorption efficiency of electromagnetic waves.
In order to achieve layer by layer stacking and orderly arrangement of magnetic particles, the team derived the magnetic field orientation of iron cobalt ruthenium flake magnetic particles and pioneered the "torque model under magnetic field". By intervening with a rotating magnetic field, the magnetic particles were arranged in parallel and distributed in the resin to achieve the optimal absorption effect.
The team has also developed relevant devices to monitor the magnetic field distribution in real-time during the production of magnetic powder thin films, ensuring homogeneous production – cutting a piece at will can achieve the same level of absorption performance. While improving the ability to resist electromagnetic interference, the team continuously optimizes raw materials and production processes, controlling costs within a reasonable range, laying the foundation for achievement transformation and large-scale production.
Internationally, absorbing materials can absorb 80% of interfering electromagnetic waves throughout the entire 5G communication frequency band.
The new absorbing material developed by WHKJ has an average absorption efficiency of 90% in this frequency band At certain frequency points with higher usage frequencies, the new absorbing material developed by WHKJ can achieve an absorption efficiency of over 95%, better solving the problem of electromagnetic interference, and reducing costs by about 30% compared to international companies.