Question No.  18975 :
In circuit design, is there a difference between using an electrolytic capacitor and ceramic capacitor?

Used in electronic circuits, capacitors or condensers are devices for storing electric charge. A capacitor (or condenser) consists of two or more metal plates (or conductors) separated by a dielectric (or insulator). Various materials (such as ceramics, mica, glass, and paper) are used as dielectric. Different types of capacitors are designed for different circuit applications. To get the highest possible capacitance we need to get the plates as close together as possible. In electrolytic capacitors, the dielectric is a layer of metal oxide deposited on the anode by electrolysis. The cathode may be the electrolyte itself. Electrolytic capacitors provide a high capacitance in a limited volume, but they suffer from high leakage currents. Aluminium electrolytic capacitor incorporates a metal oxide film dielectric produced from electrolysis and its anode is made of aluminium. That is the reason this type of capacitor is called aluminium electrolytic capacitor. It is possible to produce high-capacity aluminium electrolytic capacitors. Their frequency and temperature characteristics are, however, bad. This type of capacitor is used in power supply circuits, audio circuits, timer circuits, and backup circuits. Tantalum electrolytic capacitor is similar to aluminium electrolytic capacitors, but its anode is made of tantalum instead of aluminium. Tantalum electrolytic capacitors are a little inferior in electrostatic capacity to aluminium electrolytic capacitors. The frequency and temperature characteristics of tantalum electrolytic capacitors, however, excel those of aluminium electrolytic capacitors. This type of capacitor is used in noise limiters, coupling circuits, and filter circuits. Single-layered ceramic capacitor that incorporates a ceramic dielectric is either a product ideal for temperature compensation, a product that has a high dielectric constant, or a product that is of a semiconductor type, which depends on the kind of ceramic dielectric. The single-layered ceramic capacitor for temperature compensation does not have a high electrostatic capacity but it covers a wide temperature characteristic range including temperatures below 0°C. The capacitor of high dielectric constant construction is compact yet it has a high electrostatic capacity. This type of capacitor is used in circuits that require excellent frequency characteristics, such as high-frequency circuits and digital circuits. Multi-layered ceramic capacitors incorporate multiple printed layers of electrode plates made of 10 to 20µm thick ceramic sheets. These capacitors are more compact and have better temperature characteristics than single-layered ceramic capacitors. Multi-layered ceramic capacitors are, however, rather expensive because their electrode plates use precious metals. Like a single-layered ceramic capacitor, a multi-layered ceramic capacitor is either a product of high dielectric constant construction or a product that has excellent temperature characteristics ideal for temperature compensation. This type of capacitor is used in circuits of general electronic equipment. Other types of capacitors include film capacitor and metal-glazed film capacitor. The high-frequency and temperature characteristics of film capacitors excel those of ceramic capacitors. Furthermore, high-capacity film capacitors are available, which are, however, more expensive and larger than ceramic capacitors that are the same in capacity. Polyester (Myler), polypropylene, or polystyrene can be used for the film of this type of capacitors. Film capacitors are used in high-frequency circuits and analog circuits. Metal-glazed film capacitor incorporates electrode plates made of film vacuum-evaporated with metal such as aluminium. Metal-glazed film capacitors can be more compact yet higher in electrostatic capacity than film capacitors. Polyester, polypropylene, or polycarbonate can be used for the film of this type of capacitors. Metal-glazed film capacitors are used in high-frequency circuits, switching circuits, and analog circuits. Mica, glass, and paper are used for dielectric elements as well as the materials described above. Mica is the best dielectric but it is expensive. Glass ensures a stable temperature coefficient in a wide range. Paper is used for high-voltage capacitors. They are used in precision equipment and high-voltage equipment. Question Asked By:

Name: Neo

Age Group: 21 to 30

Occupation Type: Engineer

Education Level: Diploma