A capacitor is a device used in electronic circuits to block DC signals, while still allowing AC signals to pass though. To accomplish this, a multilayer ceramic capacitor uses a series of alternating metal disks, called plates, and ceramic disks, called dielectrics. This type of capacitor is inexpensive, versatile, and widely used in electronics of all types. While its single-layer counterparts have been around since the 1930s, the multilayer ceramic capacitor is a more recent development and is often used as a replacement for older designs of various capacitors.
A multilayer ceramic capacitor operates through the creation of an electromagnetic field across several metal plates insulated from one another by layers of dielectric ceramic. Plates in capacitors are usually made of metals, such as tantalum; however, there are many different materials used as dielectrics. Even though many different plate materials are also used, most of a capacitor’s operational characteristics are determined by its dielectric’s composition.
Dielectrics are materials capable of electrically insulating a capacitor’s plates from one another but at the same time allowing electromagnetic fields to pass though them to some degree, depending on the design. In a capacitor‘s operational state, an electrical current enters the capacitor but cannot conduct directly to the other plates because of the insulating dielectric. This prevents electrical currents from passing directly through the capacitor, which, in effect, blocks any DC electrical signal.
An AC signal, however, creates a polarized electromagnetic field within the capacitor. This electromagnetic field can pass through the dielectrics and will induce an AC signal on the other plates in the capacitor, which will build a field around them. Once the field builds across all the plates in the capacitor, at a rate determined by the dielectrics, the subsequent AC signal will leave the device and travel to the rest of the circuit.
As the name suggests, a multilayer ceramic capacitor uses small ceramic disks as its dielectrics. These disks have some advantages over dielectrics of other materials, such as plastics or oils. Ceramics are inexpensive, are easily produced, can withstand high temperatures, and are stable electrostatically. Thus, multilayer ceramic capacitors find use in electronic devices that generate significant levels of heat or operate at high frequencies.
Ceramic disk capacitors were the first capacitors created for use in practical electronic applications and equipment. They worked alongside vacuum tubes and later helped the transistor make its debut. These devices have continued to play an important role in electronics; new and improved multilayer ceramic capacitors stand alongside some of the most advanced electronic components.
