In the EMC design of electronic devices, the core constraint faced by absorbing materials is always space - the thickness left for the absorbing layer is often only a few tenths of a millimeter, or even thinner. Traditional absorbing materials rely on sufficient thickness to increase the propagation path of electromagnetic waves, but this path is not feasible in spatially limited scenarios.

Ultra high permeability absorbing materials provide another path: compensating for thickness deficiencies with higher permeability. When the real part of the magnetic permeability (μ ') of a material is increased from several tens to over 100 or even hundreds, the material's ability to concentrate magnetic flux is significantly enhanced, and the amount of electromagnetic energy that can be absorbed per unit thickness is greatly increased. This is the engineering essence of the "ultra-high magnetic permeability" technology direction - not to make the material "thick", but to make the material "strong".

2、 μ 'and μ ": a pair of parameters that require precise balance

The performance of ultra-high permeability absorbing materials is determined by two key electromagnetic parameters. The complex magnetic permeability can be expressed as μ=μ '- j μ ", where μ' is the real part of the magnetic permeability, representing the material's ability to store magnetic field energy; The imaginary part of the magnetic permeability is represented by μ ", which characterizes the material's magnetic loss ability to electromagnetic wave energy.

Real part of magnetic permeability (μ ')The ability of a material to 'gather' magnetic flux is determined. The higher the μ ', the more inclined the magnetic field lines are to propagate along the interior of the material, and the easier it is for electromagnetic waves to be introduced into the interior of the material.Advanced Institute of TechnologyThe XJY-MH series products of Yanbo brand ultra-high magnetic permeability absorbing materials cover a frequency range of ≥ 100 to ≥ 200 μ '@ 1MHz and can provide significant magnetic response in different frequency bands.

Imaginary part of magnetic permeability (μ ″)The efficiency of converting electromagnetic energy into thermal energy is determined by the material. Magnetic losses mainly come from mechanisms such as hysteresis losses, domain wall resonance, natural resonance, and eddy current losses. The higher the μ ″, the stronger the loss ability. However, it should be noted that the requirements for μ "vary greatly for different application scenarios.

Advanced Institute of Science and Technology Research Platinum brand absorbing materials can be directionally designed between "high magnetic loss" and "low magnetic loss" according to application requirements by adjusting the material formula and microstructure.

3、 Material system: performance differences between ferrite, soft magnetic alloy, and nanocrystals

The performance of ultra-high permeability absorbing materials is rooted in their absorbent system. The current mainstream material systems include ferrite, soft magnetic alloys, and nanocrystals, each of which has its own trade-offs in terms of magnetic permeability, saturation magnetization, applicable frequency bands, and mechanical properties.

Ferrite classIt is the most mature ultra-high permeability absorbing material system in application. Nickel zinc ferrite and manganese zinc ferrite have high magnetic permeability and good magnetic loss characteristics. The real part of the magnetic permeability of ferrite hard plate absorbing materials can reach around 200 μ ', indicating superior application performance. However, the preparation process of ferrite hard sheets is complex, with poor mechanical properties. The product size is limited by the sintering process (generally not exceeding 125mm × 125mm), and cracks are prone to occur during processing and storage, resulting in magnetic leakage.

Soft magnetic alloysRepresented by FeSiAl, FeNi, FeCo and other alloys, they have higher saturation magnetic induction intensity. The saturation magnetic induction intensity of soft magnetic alloys can reach 1.2-1.5T, much higher than the 0.2-0.5T of ferrites. Its resistivity is higher than that of high magnetic conductive alloys, and its eddy current loss is lower at high frequencies. The magnetic permeability performance of soft magnetic alloy flexible absorbing materials is slightly weaker than that of ferrite hard sheets, but their flexible size can meet the low loss requirements of product processing. Good processing performance can reduce scrap rates and processing costs.

NanocrystalsThis is the direction of technological breakthroughs in recent years. Advanced Institute Technology adopts advanced nanotechnology to control the grain size of ferrite within the range of tens of nanometers. Compared with micrometer sized grains, the magnetic permeability is increased by about 30%, and the stability is better at different temperatures. Nanocrystalline materials can maintain high magnetic permeability in the GHz frequency band by breaking through the Snoek limit, compensating for the rapid attenuation of magnetic permeability in the high-frequency range of traditional ferrites.

4、 Advanced Institute of Technology Research Platinum Brand Ultra high Magnetic Permeability Absorbing Material Product System

Advanced Institute (Shenzhen) Technology Co., Ltd. has formed a complete series of high permeability absorbing material products for the MHz to GHz frequency band. The Yanbo brand ultra-high permeability absorbing material series includes three main models: XJY-MH100, XJY-MH150, and XJY-MH200, covering the low-frequency to microwave frequency range. The substrate is a flexible polymer composite system, and the surface can be covered with a conductive layer, insulation layer, or aluminum foil. It supports precision die-cutting and adhesive bonding.

Data Source:Advanced Institute of Technology

The research platinum brand ultra-high permeability absorbing material can achieve a reflection loss of over 20dB in the target frequency band, indicating that at least 99% of the incident electromagnetic wave energy is absorbed by the material. The material has a wide absorption frequency band, a flat response curve, and stable absorption ability over a wide frequency range. In the multi-layer structure design, the reflection loss value of the research platinum brand multi-layer absorbing film reached -54.1dB at 14.08GHz, and the effective absorption bandwidth reached 6.3GHz (11.7-18GHz).

5、 Engineering constraints: boundary conditions that engineers must understand

Ultra high permeability absorbing materials face several engineering constraints in practical applications, and understanding these boundary conditions is a prerequisite for correct selection.

6、 Application Layout: From EMI Suppression to Electromagnetic Stealth

7、 Selection considerations: Decision logic from frequency to engineering constraints

When engineers choose ultra-high permeability absorbing materials, the following dimensions deserve special attention:

• Target frequency matching.The frequency response of different material systems varies significantly. Ferrites are suitable for MHz frequency bands; Nanocrystalline materials have more stable magnetic permeability over a wide frequency range; GHz level applications require the selection of material models optimized for high frequency bands. The interference frequency that needs to be processed should be confirmed first, and then materials with sufficient magnetic permeability and loss in that frequency band should be selected.
• Selection of magnetic loss types.EMC/EMI suppression applications require high magnetic losses; RFID/NFC anti metal interference applications require high μ 'and low μ' '(low magnetic loss). When selecting, the required loss type should be determined based on the electromagnetic environment characteristics of the application scenario.
• Thickness and spatial constraints.The thickness range of Yanbo brand ultra-high permeability absorbing materials is 0.2-2.0mm. In applications with limited space, models with higher μ 'and thinner thickness should be preferred; In applications with ample space, thicker models can be chosen to achieve higher absorption efficiency.
• Mechanical strength assessment.In scenarios where mechanical stress or bending installation is required, it is necessary to evaluate whether the compressive, tensile, and bending properties of the material meet the requirements. For applications with a bending radius less than 20mm, it should be evaluated whether structural reinforcement of the material or selection of flexible models is necessary.

8、 Conclusion

The essence of ultra-high magnetic permeability absorbing materials is to "gather" more electromagnetic energy into the material's interior with a higher real part of magnetic permeability, and then efficiently convert it into thermal energy and consume it with an appropriate imaginary part of magnetic permeability. It is not pursuing the maximization of the single indicator of μ ', but rather finding the optimal balance between μ' and μ ', and between impedance matching and loss capability.

The evolution of materials from ferrite to nanocrystals reflects the upgrade of absorption demand from "MHz level applicability" to "wideband stability". Understanding the synergistic relationship between μ 'and μ' ', the frequency response differences of different material systems, and the constraints of mechanical strength on application scenarios - these are the key to upgrading ultra-high permeability absorbing materials from "functional materials" to "engineering decisions".