Polyester Capacitor (Polyester Capacitor) refers to the use of two pieces of metal foil as electrodes, sandwiched in a very thin insulating medium, rolled into a cylindrical or flat cylindrical core, the medium is polyester, polyester film capacitors, high dielectric constant, volume Small, large capacity, good stability, suitable for bypass capacitors. The simplest structure of a polyester capacitor can be composed of two metal plates sandwiched between a layer of insulating medium. A voltage is applied between the two metal plates (electrode plates), and the electrode plates can store electric charge. The size of the stored charge is proportional to the voltage between the plates and the area (capacity) of the plates, and inversely proportional to the distance between the plates. Q=CV, that is, C=Q/V=εS/4πd (see the Theoretical Calculation and Correction of Film Capacitors for details) Q-charge stored on the plate; C-capacitor (PF); V-voltage between the plates (V ); ε-dielectric constant (polyester film is 3.0, polypropylene film 2.1); S-metal plate area (mm); d-the distance between the plates (mm).

The outstanding advantages of polyester capacitors: the accuracy, loss angle, insulation resistance, temperature characteristics, reliability and adaptability of film capacitors are better than electrolytic capacitors and ceramic capacitors.

The polyester capacitor is an essential element in electronic products, which acts as filtering, oscillation, power decoupling, bypass and coupling of pulsating signals in the circuit.