Do all my friends know the magnetic separator? I will explain it for you in detail.
Types of magnetic separators:
1. Hard magnetic sheet: ferrite sheet sintered at high temperature, with high magnetic permeability, hard material and easy to crack. It is commonly used in the transmitter of wireless charging.
2. Soft magnetic sheet: Alloy magnetic powder is added to plastic or rubber, and then processed into a soft magnetic sheet. The material of the soft magnetic sheet is relatively soft and the thickness is very thin. It can be punched according to the shape and size of the magnetic isolation sheet required by the wireless charging scheme. The degree of customization is high, and it is often used in the wireless charging receiving end.
What role does ferrite magnetic spacer play in wireless charging products? In general, the role of the magnetic isolation sheet has no other three points: magnetic permeability, magnetic shielding, and heat conduction.
1. Magnetic permeability
As we all know, the principle of the QI wireless charging standard is electromagnetic induction. When the primary coil (wireless charging transmitter) is working, it will generate an interactive magnetic field (the direction of strength is constantly changing). In order to make the magnetic field energy emitted by the primary coil act on the secondary coil (wireless charging receiver) as much as possible, it is necessary to The magnetism of the coil is guided.
After adding a magnetic barrier at the receiving end, the magnetic lines of force are obviously gathered and concentrated, but without a magnetic barrier to guide, the magnetic lines of force are relatively scattered. Here, the magnetic sheet at the receiving end plays a role of magnetism, providing a magnetic field line loop for the transmitting end magnetic field, so as to gather the magnetic field and make it act on the coil at the receiving end as much as possible to achieve the maximum power generation efficiency.
2. Magnetic block
The magnetic isolation sheet should not only be able to effectively conduct magnetism, but also play a role in blocking magnetism. Why block the magnetism? We know that when a changing magnetic field encounters a conductor such as a metal, if the metal is a closed wire, it will generate current, if the metal is a closed wire, especially a whole piece of metal, an eddy current effect will occur.
Eddy current will generate a lot of heat, just like an induction cooker, it uses the eddy current effect to convert electrical energy into heat.
However, in wireless charging products, we must try our best to avoid heating of the device, because heating not only consumes too much power, but also causes damage to electronic devices. In order to avoid heating, it is necessary to constrain the magnetic field generated at the transmitting end, so that the magnetic field can only act on the receiving end coil, but not on other devices other than the coil.
3. Heat dissipation
The magnetic field acts on the coil to generate a high-frequency current. During this process, the coil itself will also generate heat. If this heat is not effectively dissipated, it will accumulate. Sometimes we feel very hot during wireless charging. Generally, it is caused by the heating of the coil or the heating of the circuit board.
In order to effectively conduct the heating of the coil and the circuit board, the packaging method is generally used:
The coil, magnetic isolation sheet, and circuit board are completely packaged with a thermally conductive resin material through a low-temperature and low-voltage IC packaging process, which can effectively disperse the heat and achieve a good heat dissipation effect.