Electronic Capacitors

Mica is a very important material in the manufacture of electronic capacitors due to its high dielectric strength and its ability to hold and store electronic energy.The two prominent features of Mica are that it has a very low power factor over a wide range in temperature and frequency and a uniformly high dielectric constant.Certain capacitors, especially those used in high voltage and in high frequency applications, can only be made with Mica materials.

The Mica capacitor is normally used in applications where it is very important to maintain an impedance to close limits in regard to temperature, frequency and aging.Mica capacitors are best in meeting the following performance specifications:
A. Capacitance lower than 0.05 mf.
B. High Accuracy (up to 0.25%)
C. Low Capacitance Drift (Less than 0.1%)
D. Low Power Factor, over a wide frequency range (Q Factor more than 2000)

Mica capacitors with very high level specifications are generally made from superior quality block Mica, such as Stained 'A' and better. The block Mica is split into a film with an accurate close range of thickness up to 1/10th of a mil (0.0001").Before use, each piece of Film Mica is tested electrically for defects such as, conducting particles and pinholes with high frequency spark test equipment.

The quality of Mica used in the manufacture of a capacitor can vary, based on the application where the capacitor will be used. Normally, Standard capacitors will be manufactured only from the finest quality Mica film that is flawless, clear and flat.On other types of capacitors, such as transistor capacitors, receiver capacitors and trimming capacitors lower quality grades of Mica film can be used.

Mica film that has been silvered on both surfaces and the ends is also used in manufacturing of high quality Mica capacitors.