Polymer film capacitors, or film dielectric capacitors or plastic film capacitors or film capacitors are generally known as power film capacitors and "film caps". These are those electrical capacitors having an insulating plastic film (dielectric).

Depending on the needed dielectric strength, the dielectric films are drawn into a much thinner thickness and are then offered with electrodes. The electrodes used in these capacitors might be metalized zinc or aluminum applied legitimately to the plastic film’s surface, or a different metallic foil. 2 of the conductive layers are winded in a cylindrical shape, generally flattened to decrease the requirement of mounting space on a printed circuit board. They may be also stacked as multiple layers to form the body of a capacitor. Along with electrolytic capacitors and ceramic capacitors, film capacitors are the most popular and common capacitors type for utilizing electrical equipment. They are utilized in several DC and AC electronics and microelectronics circuits.

Though the constructions and materials utilized for larger power film capacitors are very much the same as that of ordinary film capacitors, capacitors coming with a very high rating of power for power system applications and electrical installations are often categorized separately due to some historical reasons. Today several modern electronic equipment have got the ability to manage the level of high powers that was earlier one of the biggest constraints of components related to "electrical power". The difference between "electrical" and "electronic" rating of power has become less distinct. In the earlier time, the line of boundary between these two families was approximately 200 Volt-Ampere but the modern ones are well made to manage high power levels.

Example manufacturing process

The example discussed below describes a common assembling process stream for wound metalized plastic film capacitors.

• Metallization and Film stretching – To uplift the value of capacitance of the capacitor, the plastic film is drawn utilizing an exceptional expulsion procedure of bi-pivotal extending in transverse and longitudinal direction.
• Film slitting - The mother folds are cut into little portions of plastic film in the necessary width.
• Winding – 2 films are then made to roll together into a cylindrical winding.
• Flattening – The winding is then generally flattened into the shape of an oval by utilizing mechanical pressure.
• Application of Metallic Contact layer – A liquefied contact metal like zinc or tin is used to cover up the projecting end electrodes.
• Healing – Healing is done by applying an absolutely adjusted voltage over the electrodes of the winding with the goal that any current deformities will be "consumed with extreme heat".
• Impregnation – For protection from moisture, the winding is made to impregnate using silicone oil (insulating fluid).
• Attachment of terminals – The capacitor’s terminals are welded on the end metal contact layers.
• Coating – Succeeding the attachment, the body of the capacitors is dunked into a protective coating.
• Electrical final test – Before the use of every capacitor it is important to test it for the desired parameters, like, Impedance, Capacitance or dissipation factor.

Brands that manufacture film capacitors are Kemet, Panasonic, and EPCOS. Make sure to follow them using the links as provided.

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