Inductor Structure

Inductors are generally composed of skeletons, windings, shielding covers, packaging materials, magnetic cores or iron cores, etc.
1. Skeleton Skeleton refers to the bracket for winding coils. Most of the larger fixed inductors or adjustable inductors (such as oscillation coils, chokes, etc.) are made by winding enameled wire (or yarn-covered wire) around the skeleton, and then inserting the magnetic core or copper core, iron core, etc. into the inner cavity of the skeleton to increase its inductance.
The skeleton is usually made of plastic, bakelite, and ceramics, and can be made into different shapes according to actual needs.
Small inductors (such as color-coded inductors) generally do not use skeletons, but directly wind the enameled wire around the magnetic core.
Air-core inductors (also called cast-off coils or air-core coils, mostly used in high-frequency circuits) do not use magnetic cores, skeletons, shielding covers, etc., but are first wound on the mold and then removed from the mold, and the coils are pulled apart by a certain distance.
2. Winding Winding refers to a group of coils with specified functions, which is the basic component of an inductor.
Windings can be divided into single-layer and multi-layer. Single-layer winding has two forms: close winding (the wire is wound one circle after another) and intermittent winding (a certain distance is separated between each circle of wire during winding); multi-layer winding has many forms such as layered flat winding, random winding, and honeycomb winding, as shown in Figure 6-5.
3. Magnetic core and magnetic rod The magnetic core and magnetic rod are generally made of nickel-zinc ferrite (NX series) or manganese-zinc ferrite (MX series) and other materials. It has many shapes such as "I" shape, column shape, cap shape, "E" shape, and can shape, as shown in Figure 6-6.
4. Iron core The main materials of the iron core are silicon steel sheet, Permalloy, etc., and its appearance is mostly "E" type.
5. Shielding cover In order to prevent the magnetic field generated by some inductors during operation from affecting the normal operation of other circuits and components, a metal screen cover is added to it (such as the oscillation coil of a semiconductor radio, etc.). Inductors with shielding covers will increase the loss of the coil and reduce the Q value.
6. After some inductors (such as color-coded inductors, color-ring inductors, etc.) are wound, the coils and magnetic cores are sealed with packaging materials. The packaging materials are plastic or epoxy resin.