Detailed introduction of EMI anti electromagnetic interference absorbing materials

     EMI anti electromagnetic interference absorbing materialIt is a material used for isolating and eliminating electromagnetic wave interference, with important application value and development prospects. This article will provide a detailed introduction to EMI electromagnetic interference absorbing materials.

1、 Basic principles of EMI electromagnetic interference absorbing materials

EMI stands for "Electromagnetic Interference", which refers to electromagnetic interference. Electromagnetic interference refers to the impact of electromagnetic waves on electronic devices, including radiated interference and conducted interference. In order to prevent electromagnetic interference from affecting equipment, it is necessary to use EMI anti electromagnetic wave interference absorbing materials to isolate and eliminate electromagnetic waves through mechanisms such as absorption, reflection, and scattering.

The absorption principles of EMI electromagnetic interference absorbing materials mainly include the following:

1. Resistance loss: Under high-frequency conditions, EMI electromagnetic interference absorbing materials have a certain resistance loss when electromagnetic waves enter AbsorberAt this time, it will be absorbed by the conductive properties in the material, generating thermal energy inside the material, thereby achieving absorption of electromagnetic waves.

2. Dielectric loss: When EMI electromagnetic interference absorbing materials contain certain dielectric properties, dielectric loss will occur under the action of electromagnetic waves. Polarized molecules inside the material will undergo periodic reversal under the action of an electric field, generating thermal energy and achieving dissipation and absorption of electromagnetic waves.

3. Band structure absorption: EMI anti electromagnetic interference absorbing materials can adopt special structural designs in material structure design, including band structures, plasma absorption, etc., to guide electromagnetic waves into the material through different structural features, thereby achieving absorption and elimination of electromagnetic waves.

2、 Application fields of EMI electromagnetic interference absorbing materials

Due to the increasing impact of electromagnetic interference on people's daily lives and national defense security, EMI anti electromagnetic interference absorbing materials have a wide range of application fields, mainly including the following aspects:

1. Military field: Various military electronic devices require resistance to electromagnetic wave interference and have application requirements in radar, space communication, missiles, aviation flight control, and other fields.

2. Communication field: With the continuous development of mobile communication and wireless communication, EMI anti electromagnetic interference absorbing materials have been widely used in mobile phones, base stations, satellite communication, and other fields.

3. Remote measurement field: In industrial automation and environmental monitoring, it is necessary to remotely transmit signals and detect and analyze them. At this time, it is necessary to prevent electromagnetic interference from affecting the signals.

4. Aerospace field: Aircraft and satellites need to be protected against electromagnetic interference to ensure their safety and reliability.

5. In the field of consumer electronics: In household appliances such as televisions, air conditioners, and washing machines, electromagnetic interference protection is also needed to ensure product stability and reliability.

3、 Classification of EMI anti electromagnetic interference absorbing materials

According to the different absorption mechanisms, EMI Anti electromagnetic interference absorbing materialIt can be divided into the following categories:

1. Metal powder composite material: This material uses metal powder with good conductivity as the absorbing material, and is combined with an appropriate amount of matrix adhesive to form a composite material. The absorption characteristics of metal powder composite materials mainly come from their surface reflection and scattering effects, and are mostly used for absorption in the low and medium frequency range.

2. Polymer composite material: This material uses polymer as the substrate and is mixed with absorbing materials such as metal powder. Compared to metal powder composite materials, polymer composite materials have a certain degree of elasticity and toughness, and can be used to make flexible absorbing materials with good plasticity and processability.

3. Magnetic absorbing material: This material uses magnetic materials such as ferrite as absorbing materials, and is combined with matrix adhesives to form a magnetic composite material. Magnetic absorbing materialsThe absorption effect is achieved through the hysteresis loss before and after its strong magnetic effect, which is suitable for absorption in the medium and high frequency range.

4. Porous composite materials: This material achieves absorption and scattering of electromagnetic waves by preparing a porous three-dimensional spatial structure. Porous composite materials are easy to prepare and can achieve full band absorption of different frequency bands.

4、 Preparation Technology of EMI Anti electromagnetic Interference Absorbing Materials

The preparation technology of EMI electromagnetic interference absorbing materials is an important factor affecting the material's absorption performance and application value.

The common preparation techniques for EMI anti electromagnetic interference absorbing materials mainly include the following:

1. Chemical reduction method: Metal ions are reduced to metal powders such as Ni, Fe, Co, Cu, etc., and then mixed with matrix materials to prepare absorbing materials.

2. Sol gel method: Dissolve metal salt and nitric acid plasma in water, add organic substances such as isopropanol and isooctyl acetate to form colloidal solution. Under appropriate conditions, the materials with desired microwave absorbing properties are prepared by the sol gel method.

3. Coating method: Coating metal powder, carbon black, ferrite and other absorbing materials on the substrate, with appropriate adhesive, and curing at high temperature to form a composite material with strong absorbing properties.