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What are Film Capacitors and Their Types?

Capacitors are a common type of electrical component that may be found in countless circuits, capable of retaining electrical energy within an electric field. As passive components that come in a wide variety of types, it is imperative that one is familiar with the particular capacitor variations that they need for a particular application. Film capacitors are one of the most common types, featuring non-polarized operations, high versatility, and low cost. In this blog, we will discuss film capacitors, their functionality, and applications, allowing you to determine whether or not they will be a good fit for your particular needs.

Prior to the release of the film capacitor, paper capacitors were the most popular option for use in decoupling circuits. Generally, such components were produced with the use of impregnated paper that was rolled into cylindrical shapes alongside metal strips. Due to their materials, paper capacitors were often at risk of environmental defects and were large in size. Plastic films were soon discovered as an alternate dielectric that would improve upon the drawbacks of the paper capacitor, establishing the rise of the film capacitor.

As the plastic industry boomed, numerous types of plastic film capacitors came about, each featuring distinct qualities that could benefit varying circuit applications. As of the present, film capacitors are divided into two methods of construction, those of which are film/foil and metalized film capacitors. Film and foil capacitors are those that take advantage of plastic film as the dielectric and two layers of aluminum foil as the electrodes. Typically, film/foil capacitors may either be inductive or non-inductive, the former being wound in aluminum foil that has a leading wire that holds the wiring together. Non-inductive types, meanwhile, feature foil arranged in a way that they extend from the film to a certain degree. Plastic film capacitors are known for their high insulation resistance, good capacitance stability, and high efficiencies at high frequencies. As such, they are often used for coupling, decoupling, bypassing, circuits that require high switching frequencies, and more.

Unlike plastic film capacitors that feature layering, metal film capacitors are fused into one side of the plastic dielectric. While increasing cost and making the manufacturing process more complex, such variations supersede plastic types in terms of stability and compact construction. In order to achieve various capacitance values, metalized film capacitors may be constructed with a thickness of only 0.6 µm. Generally, metalized or metal film capacitors are known for their self-healing properties when short-circuiting occurs, increasing their overall reliability. Additionally, they are quite compact, allowing them to be more versatile in placement. With their various characteristics, metalized film capacitors are often used in power electronic circuits related to DC link circuits, switching circuits, pulse circuits, etc. Additionally, low power versions often find implementation in both decoupling and filtering applications.

While film capacitors are able to accumulate electric charges like other capacitor types, their bipolar and frequency characteristics allow them to perform quite well in high-frequency circuits with a capacitance value ranging between 1 nF to 30 muF. If a low voltage rating is required, such capacitors may even be constructed with ratings as low as 50 V. As a result, they are quite versatile. Due to the variations in operating characteristics between plastic and metal film capacitors, it is crucial that one takes the time to research choices before making a decision. If the incorrect capacitor is chosen, operations may not be carried out as efficiently, and there is always a potential for increased wear and tear or failure. When you are in the market for metal film capacitors, plastic film capacitors, and other various types of capacitors, there is no better alternative to NSN World.

NSN World is a leading supplier of film capacitors, providing customers access to top quality components that have been sourced from leading manufacturers that we trust. On our website, customers can find over 2 billion new, used, obsolete, and hard-to-find items that cater to a diverse set of industries and applications. If you find particular products that you would like to purchase, fill out and submit an Instant RFQ form as provided on our website. Once received, a dedicated account manager will reach out to you in 15 minutes or less with a personalized quote for your comparisons. Get started today and see how NSN World can serve as your strategic sourcing partner.


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