When dealing with electromagnetic interference problems, the first reaction of most engineers is "shielding" - using highly conductive materials such as copper foil and metal covers to reflect electromagnetic waves back. But for near-field magnetic coupling systems (wireless charging, NFC, RFID, etc.), the problem is completely different. These systems rely on alternating magnetic fields rather than far-field electromagnetic waves. Using conductive materials to "shield" magnetic fields will only generate eddy currents in the metal, which in turn will produce a reverse magnetic field and weaken the effective signal of the antenna.

High permeability and low loss magnetic separators have taken a different path. Its core function is not to 'block', but to 'guide'. Magnetic separators redirect magnetic fields by providing a high magnetic permeability and low magnetic resistance path for magnetic lines, allowing them to propagate along the interior of the material rather than penetrating the material and diffusing into the surrounding environment or being consumed by metal eddy currents. This process relies on two characteristics that the material possesses simultaneously: high magnetic permeability (which can efficiently conduct magnetic flux) and low loss (which does not generate excessive thermal energy loss during the conduction process).

2、 High magnetic permeability and low magnetic loss: a pair of parameters that require precise balance

The performance of the magnetic separator is determined by two key electromagnetic parameters:

• Real part of magnetic permeability (μ ')The ability of the material to "guide" magnetic field lines is determined. The higher the μ ', the more magnetic field lines tend to propagate along the interior of the magnetic separator, rather than passing through metal or being scattered by air. In the 13.56MHz frequency band, the μ 'of TDK IFQ06 series is 56; BandSorb ® The HP series' μ 'can reach up to 150; The permeability of some high-performance nanocrystalline magnetic separators can exceed 20000 Gs/Oe at 20kHz.
• The imaginary part of magnetic loss (μ ″) and the tangent of loss angle (tan δ=μ ″/μ ′)It determines the proportion of energy consumed by the material itself when guiding magnetic flux. The lower the microgrid, the smaller the loss of the material in converting magnetic energy into thermal energy, and the higher the energy transfer efficiency of the system. In the 13.56MHz frequency band, the μ "of the IFQ06 series is about 2, and the quality factor μ '/μ" reaches 28; The microsecond of some ferrite magnetic separators at 100kHz is 2.5.

3、 Material System: Ferrite vs Nanocrystals

The mainstream material systems for high permeability and low loss magnetic separators include ferrite and nanocrystals

• Ferrite based magnetic separatorIt's a traditional solution. MnZn ferrite magnetic separators achieve high magnetic permeability and ultra-low losses by optimizing the magnetic powder formula and sintering process. The ferrite magnetic separator technology is mature and cost-effective, suitable for 13.56MHz NFC and low-frequency wireless charging scenarios. BandSorb ® The real part of the magnetic permeability of HP series ferrite sheets reaches 150 at 13.56MHz.
• Nanocrystalline magnetic separatorThis is the direction of technological breakthroughs in recent years. Nanocrystalline materials are formed into small grain structures of 10-20 nanometers through special processes, with characteristics such as high saturation magnetic induction intensity, high magnetic permeability, and low loss. The nanocrystalline magnetic separator is composed of copper foil and multiple layers of organic tape stacked together, containing tiny ferromagnetic nanocrystalline materials inside. Its advantages lie in its ultra-thin design (with a minimum thickness of 16-30 μ m), flexibility (to avoid fragmentation and magnetic leakage), and multifunctional integration (which can simultaneously meet the three functions of WPC wireless charging, MST magnetic secure transmission, and NFC near-field communication without interfering with each other). The saturation magnetization Bs (T) can reach 1.25T, and the Curie temperature can reach 570 ℃.

4、 Thickness design: thicker is not better

The thickness of the magnetic separator is an engineering variable that requires precise balancing.

• Benefits brought by increased thickness:Thicker magnetic separators can provide a larger cross-section for magnetic flux lines to pass through, reducing magnetic resistance and allowing more magnetic flux to pass through the material itself rather than leaking to the outside. Thicker layers can accommodate more guided magnetic flux, enhancing the magnetic isolation effect. Meanwhile, thicker magnetic separators help alleviate edge effects (local field strength increase caused by magnetic field concentration at the material edges).
• The cost of increasing thickness:Thick magnetic separators can lead to increased costs, increased weight, and decreased flexibility. For devices with extremely limited space such as smartphones, thickness is a hard constraint - every increase of 0.1mm may affect the overall design of the device.

Engineering trade-offs:In practical applications, it is necessary to find a balance point based on specific needs. Advanced Institute Technology can provide customized products of different thicknesses and sizes according to customer requirements.

5、 Key Performance: What Engineers Should Pay Attention to

6、 Three major application scenarios: from wireless charging to NFC anti metal

• Wireless charging:The area with the highest usage. The magnetic separator is placed between the receiving coil and the metal back plate to guide the magnetic field lines to the effective area and reduce leakage. The nanocrystalline magnetic separator can meet the requirements of WPC, MST and NFC the third mock examination without interference.
• NFC/RFID anti metal:Placed between the antenna coil and the metal surface, the magnetic flux is confined within the magnetic screen to prevent metal induced currents. The TDK IFQ06 series is designed specifically for 13.56MHz NFC, BandSorb ® The HP series has a μ 'of up to 150.
• Magnetic shielding of electronic devices:Prevent mutual interference of magnetic fields inside smartphones, tablets, and wearable devices; Avoiding interference between circuit boards in automotive electronics.

7、 Yanbo brand high permeability and low loss magnetic isolation sheet

The research platinum brand high permeability and low loss magnetic isolation sheet launched by Advanced Institute (Shenzhen) Technology Co., Ltd. adopts advanced material formulas and technological processes to ensure extremely high magnetic permeability and achieve maximum magnetic flux transmission at the minimum thickness. By optimizing the material composition, eddy current losses and other forms of energy losses have been significantly reduced, ensuring long-term stable operation. The product has sufficient flexibility and strength, is easy to process into various shapes, and is suitable for the design requirements of complex structures. The company can provide customized services of different thicknesses and sizes according to the specific requirements of customers, ensuring the best magnetic isolation effect while considering cost-effectiveness.

In the field of nanocrystalline magnetic separators, Advanced Institute Technology's products are composed of copper foil and several layers of organic tape stacked together, containing tiny ferromagnetic nanocrystalline materials inside. Its ultra-thin design (with a minimum thickness of up to 30 μ m) and flexible characteristics effectively avoid the risk of magnetic leakage caused by the breakage of the magnetic separator. The product can simultaneously meet the functions of WPC, MST, and NFC without interfering with each other.

8、 Conclusion

The essence of high permeability and low loss magnetic separators is to use "guidance" instead of "blocking" to deal with magnetic field problems. It does not use conductive materials to reflect the magnetic field back, but uses high magnetic permeability materials to build a low magnetic resistance "highway" for magnetic field lines - allowing the magnetic field to propagate along the interior of the magnetic separator, bypass metal obstacles, and concentrate in the effective area of the antenna, while minimizing energy loss with low magnetic loss.

From wireless charging of smartphones to NFC mobile payments, from electric vehicle charging stations to wearable devices - high permeability and low loss magnetic separators are pushing "magnetic field management" from "passive shielding" to "active guidance". Understanding the synergistic relationship between μ 'and μ' ', the material differences between ferrite and nanocrystals, and the engineering trade-off between thickness and magnetic isolation effect - these are the key to upgrading magnetic isolation sheets from "a single magnetic material" to "engineering decisions".