Structure and characteristics of inductors

Inductors are generally composed of a skeleton, winding, shielding cover, packaging material, magnetic core or iron core, etc.

1. Skeleton: Skeleton refers to the support for winding coils. Some larger fixed or adjustable inductors (such as oscillation coils, choke coils, etc.) are mostly wrapped with enameled wire (or gauze wrapped wire) around the skeleton, and then magnetic or copper cores, iron cores, etc. are installed into the inner cavity of the skeleton to increase its inductance. The skeleton is usually made of plastic, bakelite, or ceramic, and can be made into different shapes according to actual needs. Small inductors (such as color coded inductors) generally do not use a skeleton, but instead directly wrap the enameled wire around the magnetic core. Hollow inductors (also known as unbound coils or hollow coils, commonly used in high-frequency circuits) do not require magnetic cores, skeletons, and shielding covers. Instead, they are wound around the mold before removing the mold, and a certain distance is drawn between the coils.

2. Winding: A winding refers to a set of coils with specified functions, which is the basic component of an inductor. The winding can be divided into single-layer and multi-layer. There are two forms of single-layer winding: close winding (when winding, the wires are wound one by one) and interval winding (when winding, each wire is spaced at a certain distance); There are various methods for multi-layer winding, such as layered flat winding, random winding, and honeycomb winding.

3. Magnetic cores and bars: Magnetic cores and bars are generally made of materials such as nickel zinc ferrite (NX series) or manganese zinc ferrite (MX series), which have various shapes such as "I" shape, column shape, cap shape, "E" shape, and can shape.

4. Iron core: Iron core materials mainly include silicon steel sheets, permalloy, etc., and their appearance is mostly "E" type.

5. Shielding cover: To avoid the magnetic field generated by some inductors during operation from affecting the normal operation of other circuits and components, a metal screen cover (such as the oscillation coil of a semiconductor radio) has been added. The use of a shielded inductor will increase the loss of the coil and reduce the Q value.

6. Packaging materials: After some inductors (such as color code inductors, color ring inductors, etc.) are wound, the coil and magnetic core are sealed with packaging materials. The packaging material is made of plastic or epoxy resin.