The medium of mica capacitors is mica sheet, and the electrodes are metal foil type and metal film type. Earlier mica capacitors consisted of metal foil or silver sprayed on the surface of the mica sheet to form electrodes, and then laminated them according to the required capacity and then diffused and pressed them into a bakelite shell. At present, most of the mica dielectrics are covered with a layer of silver electrode, and the core structure is assembled, and then packaged in the shell to form a capacitor. There are Taojia shells, metal shells and plastic shells. Plastic shells are commonly used.
Mica capacitors have the following characteristics:
①The capacity range is not wide, generally between 10-51000pF.
② High stability, high reliability, and can be made into high-precision capacitors.
③Small inherent inductance, not easy to aging, stable frequency characteristics, is one of the high-frequency capacitors with excellent performance
④The insulation resistance is high, generally up to 1000-7500MΩ.
⑤The temperature characteristic is good, and the ambient temperature of use is generally in the range of -55℃ ~ +85℃.
⑥The dielectric loss is small, and the loss tangent is generally (5-30) x 10 -4.
⑦The price is relatively expensive, and has been gradually replaced by ceramic capacitors and organic film capacitors in recent years.
Mica capacitors are suitable for occasions that require high stability and reliability and high-frequency and high-voltage electronic equipment.