A surface mount inductor can be attached to the surface of a printed circuit board (PCB) by manufacturers using special adhesives, solder pastes, and automated assembly processes. The inductor has flat terminals that are soldered onto the copper elements of the circuit. It is typically wound on bobbins that are also secured to the surface of the board. Inductors with toroidal coils that have a header with surface mount terminals are also available. The classification of a surface mount inductor can be by its power rating, the application it is used in, and how it is built.
Inductors and other PCB parts used to have pins that served to attach them to the board and the copper circuitry. Holes had to be drilled into the circuit, and the pins were then soldered. Surface mounting an inductor is a simpler process and makes circuit board manufacturing much less expensive. The bobbins and headers of a surface mount inductor are made of plastic, glass, or Teflon®, which can be molded or fabricated on site. Wire is wound by looping it under a flat edge to form a flat terminal.
A ferrite core inductor is common, but other materials, such as either laminated or taped wound silicon steel alloys, are sometimes used. Nickel-iron alloys, cobalt alloys, as well as powdered irons and nickels can also make up the core of a surface mount inductor. A ferrite bead inductor is most efficient at suppressing electromagnetic interference (EMI), and is often preferred in applications where circuitry is exposed to strong electromagnetic fields.
Depending on the application, a specific shape or a custom shape can be used. Inductors are commonly found in round and square shapes, along with various others. They also come in various sizes, and variant shapes can be adapted to larger sized inductors, although weight can be a concern because vibration can affect the soldered connections.
Inductors are available in various forms, such as the multilayer chip inductor that alternates ferrite and conductor layers and has no windings. There are also types that have magnetic shields, high shock and pressure resistance, high frequency toleration, or are made of thin film to fit inside devices such as cellular phones. No matter the type, the surface mount inductor can handle high currents in notebook PCs, digital cameras, navigational systems in cars, and other small electronic devices. It is one of the key components that have enabled such small devices to be manufactured.
