Ferrite is a non-metallic magnetic material, also known as ferrite core. Its manufacturing process mainly involves compounding and sintering ferric oxide with various other metal oxides. Its relative permeability can be as high as several thousand, and its resistivity is 10¹¹ times that of metals. It has low eddy current loss and is suitable for making high-frequency electromagnetic devices. It is now a widely used non-metallic magnetic material in the high-frequency weak current field.
There are also multiple types of ferrites. Among them, permanent magnet ferrite is also a commonly used material, mainly because it can retain strong magnetic properties for a long time and can be used for a long period to generate a magnetic field, which is why it is called permanent magnet ferrite.
Ferrite sheets are used as magnetic films for NFC antenna to resist metal shielding interference and enhance the receiving sensitivity of the induction signal. The 13.56 MHz antenna ferrite sheet/film is a high-temperature sintered ferrite material. In handheld devices such as NFC payment mobile phones and on electronic tags, its main functions are to reduce the absorption of the signal magnetic field by metal materials. Meanwhile, the ferrite film itself is a high-temperature sintered ferrite material. By increasing the magnetic field strength, it effectively increases the induction distance.
The RFID|NFC anti-metal ferrite sheet is a functional composite material mainly for absorbing electromagnetic waves. It eliminates the back-and-forth reflection of electromagnetic waves in the shielding cavity, reduces the interference of clutter on its own equipment, and also effectively prevents the interference and harm of electromagnetic radiation to surrounding equipment and personnel. It is a means to eliminate electromagnetic wave pollution.
The commonly used thicknesses of ferrite sheets include 0.08 mm, 0.1 mm, 0.2 mm, and 0.3 mm. For NFC ferrite sheets, which refer to flexible magnetic sheets rather than sintered ferrite hard magnetic sheets, they have an adhesive on one side, a soft texture, a smooth surface, and an ultra-thin thickness ranging from 0.15 mm to 0.5 mm. The magnetic permeability of NFC ferrite magnetic sheets can be as high as 35 under the electromagnetic wave frequency of 13.56 MHz. The functions of NFC soft magnetic sheets in NFC equipment are mainly twofold: one is to isolate metals to prevent communication radio waves from having skin effect with metals and losing electromagnetic energy; the other is to increase the "positive energy" of magnetism (that is, magnetic field strength), so that the reaction sensitivity between the reader and the transponder is high and the reading distance is long.
