Hello everyone, I am the editor. Today, I will introduce ferrite sheets to everyone. The following content is organized by the editor, and the relevant content is for reference.
First of all, let's understand the introduction of NFC ferrite sheet: 13.56MHZ antenna ferrite sheet/film is a high-temperature sintered ferrite material. In NFC (Near Field Communication) payment mobile phones and other handheld devices, the main function of the electronic tag is to reduce the absorption of the signal magnetic field by the metal material. At the same time, the ferrite film itself is a high-temperature sintered ferrite material. The magnetic field strength effectively increases the sensing distance.
5 common NFC ferrite sheets on the market:
1. Soft ferrite
There are the most varieties of soft ferrite and the most widely used. According to different applications, there are various types of ferrites with the same composition and performance. For example, in the ultra-high frequency range, the magnetoplumbite type hexagonal ferrite can be selected. In the audio frequency, intermediate frequency, high frequency range, commonly used spinel type Mn -Zn ferrite, Ni-Zn ferrite, Li-Zn ferrite, etc.
The molding of soft ferrite is generally used in color; dry pressing, extrusion, grouting or hot die casting, and isostatic pressing, hot pressing and explosive methods. In order to reduce the sintering shrinkage of the product, make the reaction sufficient, and at the same time improve the intrinsic properties of the ferrite, it is generally necessary to perform pre-sintering first, some low-temperature pre-sintering, some high-temperature pre-sintering, and some even require two pre-sintering.
2. Hard ferrite
Hard ferrite can be called permanent magnet material, mainly including: magnetoplumbite-type Ba-ferrite, Sr-ferrite, Pb-ferrite, spinel-type CO-ferrite, etc. . The sintered density of ferrite is related to the size of the residual magnetic induction. The denser the ferrite, the greater the residual magnetic induction. Although increasing the firing temperature can increase the magnet density, it will cause the magnetic phase crystal grains to grow, which is unfavorable to the magnetic induction intensity.
3. Rotating ferrite
Rotary ferrite is mainly used to make various microwave components, so it is also called microwave ferrite. At present, there are mainly "spinel and pomegranate ferrites that are widely used. Magnetoplumbite gyromagnetic ferrites can be used in very high frequency bands. Al is used instead of Ba, Sr and pb ferrites. Part of Fe is made.
4. Moment Ferrite
Generally speaking, spinel-type ferrites with high density, uniform crystal grains and large crystal anisotropy can be made into rectangular ferrite, so that the ferrite has a good rectangular hysteresis loop, but when it is excessive, the magnetization Large current is required at the time, which is detrimental to the work of the magnetic core.
5. Piezo Ferrite
Piezoferrite is mainly composed of Ni-containing ferrite, and the density of piezoelectric ferrite is directly related to the piezomagnetic performance of ferrite. In the production process, methods such as increasing the molding pressure, increasing the firing temperature, introducing additives and high-temperature pre-sintering can be used to increase the density of the ferrite.