A capacitor is a common part type that is charged with storing electrical energy in an electric field, serving as a passive electronic component that establishes capacitance in a circuit. There are many types of capacitors available, each varying in its design and capabilities. Film capacitors are a common option for many applications, and they are discernible by their thin plastic film that serves as the dielectric. In this blog, we will discuss the film capacitor
in more detail, allowing you to have a better understanding of its function and applications.
During the design phase for the film capacitor, the dielectric material is drawn to establish a desired dielectric strength beneficial for the application in question. Typically, the dielectric will be made extremely thin, and once it is established, electrodes are supplied. Capacitor electrodes
will often come in the form of metallized aluminum or zinc which is directly implemented on the plastic film surface or on a separate metallic foil. For the next step, two conductive layers are wound around the winding to establish a cylinder shape before being flattened to better fit in the constrictive space of a printed circuit board.
Film capacitors come in a variety of subtypes that differ by the material chosen as the dielectric. Across the market, metalized film, polyester film, polypropylene film, polystyrene film, and PTFE film capacitors are all common choices. It is important to choose the correct type for the application at hand. For example, PTFE film capacitors with heat-resistance are highly beneficial for aerospace and military technology applications, while a system requiring long-term stability may benefit from a low-cost, metalized polyester film capacitor. If you have a project that has a tighter budget where performance is not of the highest concern, then a cheaper plastic may be best as the dielectric.
As film capacitors are non-polarized, they are able to be used in alternating current power and signal applications. Additionally, they are able to hold their capacitance value for a long time over operation, making them fairly reliable, dependable, and precise. This is coupled with their long shelf life and low failure life, as well as low dissipation, self-inductance, and ESR. Many older film capacitors were made with soldered connectors, though modern power film capacitors will take advantage of screw-type terminals that make the replacement process much easier and convenient.
When in operation, film capacitors can handle voltage levels in the kilovolt range, and they are more than capable of supplying strong surge current bursts. However, the specific type of film capacitor
that one uses will determine exact values. For safety, it is important to note that film capacitors are at risk of catching on fire when overloaded, though this is a common issue for capacitors of all types. Whether you need film capacitors or the metal strip and plastic components they comprise, look no further than Purchasing Efficiency for all your various sourcing needs.
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