What is the role of the I-shaped shield? What are the unique uses?

Changzhou Nanfang Electrical Components Factory has been stationed in the field of I-shaped inductors for 30 years and has accumulated rich experience! Make the following series of answers to this question!

In order to prevent the magnetic field generated by some inductors from affecting the normal operation of other circuits and components, shields have been added with metal screen covers (such as the oscillating coils of semiconductor radios). Inductors using a shield will increase the coil loss and reduce the Q value. After packaging some inductors (such as color-coded inductors, color-ring inductors, etc.), the coils and magnetic cores are sealed with packaging materials. Packaging materials using plastic or epoxy and other commonly used tunable inductors include semiconductor radio oscillation coils, intermediate frequency notch coils, acoustic frequency compensation coils, television line oscillation coils, line linear coils, and choke coils.

Oscillation coils for semiconductor radios. This oscillation coil and a variable capacitor in the semiconductor radio form a local oscillator circuit, which is used to generate a local oscillator signal higher than the 465kHz signal received by the input tuning circuit. The outer part is a metal shield, and the inner part is made of nylon lining, I-shaped inductor core, magnetic cap and pin holder. The I-shaped core is wound with high-strength enameled wire. The magnetic cap is mounted on a nylon frame inside the shielded inductor cover, which can be rotated up and down, and the inductance of the coil can be changed by changing the distance between it and the coil. The internal structure of the TV intermediate frequency notch coil is similar to the oscillating coil, except that the magnetic cap can adjust the magnetic core.

One of the classification methods for the classification of chip inductors is related to EMI, that is, shielded inductor coils and open inductors. What can meet EMI requirements is shielded inductors, that is, they cannot affect others, nor can they affect others.

Shielded I-shaped inductor coil with magnetic shield, small magnetic leakage and better performance. However, because the coil is wrapped by the shielding cover, its heat dissipation is poor, it is not affected by external magnetic fields, and it will not interfere with the magnetic fields of peripheral components.

Because the shielded inductor coil and the non-shielded inductor have different magnetic shielding structures, the volume of the shielded inductor is larger than that of the non-shielded inductor under the same inductance and operating current. It is mainly used in circuits that have high requirements for EMC, involving signal transmission, intelligent computing, etc., such as mobile phones, computers, high-quality audio, and so on.

What is described above is the role of the I-shaped inductor and the shield! thank you all!