A material that can perfectly absorb electromagnetic waves with a single thin film has been developed, and expectations are high that it will be applied to rollable phones and wearable devices in the future.

The Korea Institute of Materials Science (KIMS, President Choi Cheol-jin) announced on the 8th that the research team of Dr. Park Byeong-jin and Dr. Lee Sang-bok of the Convergence and Composite Materials Research Division has developed the world's first ultra-thin film-type composite material technology that can simultaneously absorb over 99% of various frequency bands of communication electromagnetic waves (5G/6G, WiFi, autonomous driving radar, etc.) with a single material.

The advantages of this electromagnetic wave absorbing shielding material are that it has a low electromagnetic wave reflection rate of less than 1% and a high electromagnetic wave absorption rate of more than 99% in three different frequency bands with a thickness of less than 0.5 mm.

Electromagnetic waves from electronic components can interfere with other electronic components, causing performance degradation. To prevent this, electromagnetic shielding materials are used, and in order to minimize electromagnetic interference, it is more certain to absorb electromagnetic waves than to reflect them.

On the other hand, existing electromagnetic shielding materials often reflect more than 90% of electromagnetic waves, with the actual absorption rate often being only 10%. Additionally, even if a material has a high absorption rate, it has the limitation of absorbing only electromagnetic waves of a specific single frequency.

To overcome this, the research team developed a composite material technology that can absorb multiple frequencies of electromagnetic waves simultaneously with a single material. This technology can solve the secondary interference problem of electromagnetic waves by absorbing and eliminating them.

Additionally, it is made of thin and flexible material, so it has excellent performance that maintains its shape even after being folded and unfolded thousands of times, making it suitable for use in rollable phones or wearable devices.

The research team synthesized a source magnetic material that can selectively absorb a desired frequency by changing the crystal structure of a ferrite magnetic material. This was made into a thin polymer composite film, and a conductive pattern was inserted into the back of the film to control the propagation of electromagnetic waves. By changing the shape of the conductive pattern, electromagnetic wave reflection can be drastically reduced at a desired frequency.

Additionally, a high-shielding carbon nanotube film was attached to the rear surface to maximize electromagnetic shielding performance.

“As the application of 5G/6G communications expands, the importance of electromagnetic wave absorbing and shielding materials is becoming more prominent,” said Park Byeong-jin, a senior researcher at the Materials Research Institute and the head of the research team. “With these materials, we will be able to significantly increase the reliability of wireless communication devices such as smartphones and self-driving car radars.”

This research was conducted with the support of the Basic Project of the Korea Institute of Materials Science and the Electromagnetic Solution Convergence Research Group (SEIF) of the National Research Council of Science and Technology. The research results were published as the cover paper in the October 1 issue of the world-renowned academic journal 'Advanced Functional Materials (first author: Dr. Byung-Jin Park)'. The research team has completed domestic patent registration and has also applied for patents overseas, including in the US and China. In addition, the technology has been transferred to several domestic material companies and the process of applying it to actual communication devices and automobiles is in progress.