High permeability and low loss magnetic isolation sheet | When magnetic lines meet the "highway" - the invisible steward behind wireless charging and NFC

1、 Why does wireless charging on your phone get hot? The problem isn't with the charger, it's with 'magnetic leakage'

Wireless charging relies on electromagnetic induction - the transmitting coil generates an alternating magnetic field, and the receiving coil induces current. The principle sounds simple, but in reality, magnetic fields do not obey. It will spread outwards in a divergent manner, rather than obediently running from one coil to another.

When this part of the "leakage flux" encounters the metal back panel, battery case, or circuit board of the mobile phone, induced eddy currents will be generated inside the metal. There are two consequences of eddy currents: energy waste - electricity that should have been sent to the battery is lost as heat energy halfway through; Thermal hazard - eddy currents cause metal parts to heat up, which is the fundamental reason why many users complain about "phones overheating during wireless charging".

Nanocrystalline magnetic separators can effectively reduce energy loss, heat generation, and electromagnetic interference to the surrounding environment during wireless charging. By forming a low magnetic resistance path, the magnetic field lines are concentrated and confined within the transmission channel, significantly reducing magnetic leakage and effectively coupling more energy to the receiving end.

2、 High permeability and low loss: a "dual engine" with a single magnetic separator

The performance advantage of high permeability and low loss magnetic separators is rooted in the synergy of two core parameters.

Magnetic permeability determines the material's ability to guide magnetic field lines. The higher the magnetic permeability, the easier it is for the material to allow magnetic flux lines to pass through - meaning that it can guide more magnetic flux at the same thickness or achieve the same magnetic conductivity effect at a thinner thickness. Materials with a magnetic permeability of 150 or higher are commonly used in NFC applications for smartphones. The high magnetic permeability enables the magnetic separator to achieve efficient magnetic flux guidance at ultra-thin thicknesses (up to a minimum of 30 μ m).

Magnetic loss is an indicator that measures the conversion of electromagnetic energy into thermal energy during the working process of materials. The lower the loss, the less energy waste, and the higher the charging efficiency. The magnetic separator also has a low loss factor to ensure that as many magnetic lines as possible can circulate, avoiding the reduction of near-field communication distance and efficiency due to magnetic flux loss.

The Yanbo brand high permeability and low loss magnetic isolation sheet is made of soft magnetic materials such as amorphous, nanocrystalline alloys, or ferrites. By 2025, the global production of amorphous magnetic separators has reached approximately 29 million pieces, and the global market sales of nanocrystalline noise suppression films have reached 180 million US dollars. After adopting nanocrystalline shielding sheets, a leading car company's 15kW wireless charging system efficiency has jumped from 88% to 93%, while controlling electromagnetic radiation values within 30% of international standards.

3、 The Evolution of Material Systems: From Ferrites to Nanocrystals

The material selection of the magnetic separator directly determines its performance boundary. The current industry mainly adopts three material systems.

Ferrite magnetic separators are the most traditional solution. By 2025, the global production of ferrite shielding sheets will be approximately 1.082 billion pieces, with a market size of 920 million US dollars. Ferrite has the advantages of good insulation and low cost, but its disadvantages are hard, brittle, brittle, non bendable, and low saturation magnetic flux density (about 0.4-0.5T).

Amorphous/nanocrystalline alloy magnetic separators are currently the fastest growing technological route. Nanocrystalline magnetic separators have advantages such as extremely high magnetic permeability, extremely low iron loss (only 1/5-1/10 of silicon steel), ultra-thin (30 μ m-0.1mm), and good flexibility. The global market size of nanocrystalline magnetic sheets is expected to reach approximately 217 million US dollars by 2025. Nanocrystals combine high saturation magnetic flux density (about 1.2T, much higher than the 0.45T of ferrite) with high magnetic permeability, making them significantly advantageous in high-power wireless charging scenarios. At present, mass production of nanocrystalline soft magnetic alloy strips with a minimum thickness of only 12 microns has been achieved in China.

Soft magnetic composite materials balance complex shape forming and high-frequency performance, but have relatively low magnetic permeability.

4、 From mobile phones to cars: the three major battlefields of high permeability and low loss magnetic isolation sheets

Smartphones and consumer electronics are the fields with the highest usage of magnetic separators. At the wireless charging receiving end of the mobile phone, a magnetic separator is attached between the coil and the metal back cover, which not only prevents eddy current heating, but also gathers magnetic flux to enhance induction strength. By 2025, the number of ferrite magnets used for wireless charging of consumer electronics worldwide will reach 1.33 billion. In NFC/RFID applications, magnetic separators limit the magnetic flux generated by readers within the magnetic screen. By 2025, the global market sales of NFC/RFID magnetic shielding sheets have reached $320 million.

New energy vehicles and wireless charging in vehicles are the fastest-growing application directions. Vehicle mounted wireless charging requires higher power, wider temperature range, and higher reliability for magnetic separators. Nanocrystalline magnetic separators exhibit unique advantages in high-power wireless charging for vehicles due to their high saturation magnetic flux density and low loss characteristics. The global wireless charging system market has exceeded 42 billion US dollars by 2025.

Electromagnetic compatibility and industrial equipment represent the application of magnetic separators in a wider range of fields. In equipment such as transformers and chokes, magnetic separators are used to guide and concentrate magnetic flux, improving equipment efficiency. The global market sales of high permeability magnetic shielding films have reached 250 million US dollars by 2025.

5、 Selection points: How to choose the right magnetic separator for your device?

When selecting engineers, it is recommended to start from the following dimensions:

Frequency matching is the first principle. Ferrite is suitable for 100kHz-1MHz, while nanocrystals exhibit excellent performance in 50kHz-200kHz. 13.56MHz NFC applications require materials with high magnetic permeability (μ '>100). When selecting, it is necessary to ensure that it matches the operating frequency of the system.

The thickness and installation space determine feasibility. The thickness of the magnetic separator is usually between 0.1-0.4mm, and ultra-thin products can be as low as 30 μ m. The interior of mobile phones usually chooses ultra-thin models; Automotive electronics can choose slightly thicker specifications to meet higher power requirements.

The selection of material system is equally crucial. Ferrite has low cost but is hard, brittle, and prone to cracking; Nanocrystals have extremely high magnetic permeability, low loss, and good flexibility, and are gradually replacing traditional ferrite magnets; Amorphous materials have both high magnetic permeability and good processing adaptability.

Advanced Institute Technology provides full process technical support from material selection, sample trial production to batch delivery.

The global revenue from amorphous magnetic separators is expected to reach approximately 1.468 billion yuan in 2025, and is projected to approach 2.448 billion yuan by 2032. The global ferrite shielding film market is expected to reach $1.469 billion by 2032, with a compound annual growth rate of 7.0%. Driven by the popularization of wireless charging for smartphones, the increasing penetration rate of wireless charging for new energy vehicles, and the accelerated penetration of NFC payment and access control, high permeability and low loss magnetic separators are moving from "professional material selection" to standard configurations for electronic device magnetic shielding and electromagnetic compatibility design.

Advanced Institute (Shenzhen) Technology Co., Ltd. will continue to deepen its cultivation in the field of high permeability and low loss magnetic separators, providing customers with higher performance and more reliable solutions for magnetic flux guidance and eddy current suppression through material innovation and precision technology.