Structural composition of SMD inductors

author: MagTop
Chip Bead Suppliers
Inductors are generally composed of skeletons, windings, shields, packaging materials, magnetic cores or iron cores.

1. The skeleton skeleton generally refers to the bracket for winding the coil. Some larger fixed inductors or adjustable inductors (such as oscillating coils, choke coils, etc.), most of which are enameled wire (or yarn-covered wire) around the skeleton, and then the magnetic core or copper core, iron core, etc. Installed 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 a bobbin, but instead have the enameled wire wound directly around the core. Air-core inductors (also known as unwrapped coils or air-core coils, mostly used in high-frequency circuits) do not use magnetic cores, skeletons and shields, etc., but are first wound on the mold and then take off the mold, and the coil is pulled between each coil. Drive a certain distance.
2. Winding Winding refers to a group of coils with specified functions, which are the basic components of inductors. There are single-layer and multi-layer windings. There are two types of single-layer windings: dense winding (conductors are wound one circle after another) and intermediate winding (each circle of wires is separated by a certain distance during winding); multi-layer windings have layered flat winding, random winding winding method, etc.

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, which have "I" shape, column shape, hat shape, "E" Shape, can shape and other shapes.

4. Iron core The iron core material mainly includes silicon steel sheet, permalloy, etc., and its shape is mostly "E" type.

5. In order to prevent the magnetic field generated by some inductors from affecting the normal operation of other circuits and components, a metal screen cover (such as the oscillation coil of a semiconductor radio, etc.) is added to the shield cover. The use of shielded inductors will increase the loss of the coil and reduce the Q value.

6. Packaging materials After winding some inductors (such as color code inductors, color ring inductors, etc.), seal the coils and magnetic cores with packaging materials. The encapsulation material is plastic or epoxy resin.