Polystyrene film is extruded flat and free from pin-holes. Film is made from polystyrene granules by extruding heated tube of polymer which is then spread out and stretched state. Heat treatment is given above relaxation temperature after winding film with aluminium foil electrodes. This ensures that the film contracts firmly into contact with electrodes and voids are eliminated. During manufacturing, it is necessary to use dust proof room.

Specifications

Range of values                                                                            up to 1μf

Power factor                                                                     0.0002

Operating voltage                                                                     100V

Temperature coefficient                                                                     -100 to -200ppm/⁰C

Applications:

(1) Radio frequency tuned circuit.

(2) As storage capacitors in digital equipment.

 (3) In measuring equipment of ionization current of radioactive materials.

(4) In dosage measurement in X-ray therapy.

(5) In long time constant circuits.