Mica capacitor is a kind of capacitor, and its shape is mostly square. Mica capacitor uses natural mica as the medium between capacitor electrodes, so its withstand voltage and high performance are quite good. The electrode plate is made of metal foil or sprayed with a silver layer on the mica sheet. The electrode plate and the mica are laminated one by one, and then die-cast in bakelite powder or sealed in epoxy resin. It is characterized by low dielectric loss, large insulation resistance, and low temperature coefficient, making it suitable for high-frequency circuits.

Mica capacitors mainly use natural muscovite as the medium, so the capacitance is very stable, the high frequency loss is small, and the error can reach ±1%, but the general error is ±5%, ±10%, ±20%. The withstand voltage can range from hundreds of volts to several thousand volts, or even tens of thousands of volts, and the capacity ranges from a few picofarads to tens of thousands of picofarads. Moisture resistance is generally 80% to 98% relative humidity, working at a temperature of minus 60°C to a temperature of plus 70°C. The capacity will not change due to the influence of humidity, high and low temperatures, so the capacity is relatively stable. For example, mica capacitors used in radios have two structures. One is to use aluminum foil (or tin foil) and mica sheets stacked one after another. The other is silver on mica flakes, layer by layer, with lead clips on both ends, and pressed into bakelite powder. The capacity of the silver foil is more stable than the aluminum foil, and the temperature coefficient is smaller, but the appearance is the same.