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Introduction to film capacitor:types, work principle and comparison

Capacitor is a component that stores charge and is mainly divided into chip ceramic capacitor (49%), aluminum electrolytic capacitor (29%), film capacitor (8%) and tantalum electrolytic capacitor (7%) according to the dielectric materials used in capacitors.

Film capacitors are essential in the electronics industry because they offer energy storage and electrical stability in a variety of applications. These capacitors effectively store and release electrical energy by using a thin plastic sheet as the dielectric material.

In this essay, we will examine the features, benefits, and drawbacks of film capacitor, comprehend their mechanism of operation, set them apart from ceramic capacitors, and go over their lifespan, accuracy, and failure modes. We may obtain a thorough grasp of film capacitors and their importance in electronic systems by looking into these characteristics.

Table of Contents

What is a film capacitor

The dielectric material of a particular kind of capacitor known as a “film capacitor” is a thin plastic film. The film is placed between two metallic, typically conductive plates. Film capacitor is a kind of electronic component-capacitor, with metal foil as the electrode plate and plastic film as the dielectric.The film capacitor could be able to store and release electrical energy. They are used in many electrical appliances, such as power supplies, motor drives, audio equipment, and filtering circuits because of their high capacitance values, small size, and superior electrical performance.

What is a film capacitor and its types
What is a film capacitor and its types

What are the types of film capacitors

Film capacitors are widely used in a wide range of electronic applications because of their dependability, stability, and high capacitance values. There are many different types of film capacitors, each with its own characteristics and construction. Selecting the optimal capacitor for a particular application may be made easier by being aware of the many types.

One common type of film capacitor is the polyester film capacitor, also known as the Mylar capacitor. Since polyester film provides the best insulation and durability, it is employed in its construction as the dielectric material. Polyester film capacitors are tiny, cheap, and have low dielectric losses. They are frequently used in general-purpose applications such timing circuits, consumer electronics, and audio equipment.

Another kind is the polypropylene film capacitor. Polypropylene is a perfect dielectric material due to its high temperature stability and minimal dielectric losses. Polypropylene film capacitors have strong insulating resistance and low dissipation factor, which make them become the superb choice for applications requiring high precision and stability such as in communications equipment, high-speed digital circuits, and filtering applications.

They are often used in applications involving motors, power supplies, and audio amplifiers. Polycarbonate film capacitors are an additional form of capacitor that employ polycarbonate as the dielectric material. They have excellent temperature stability and are very dielectrically robust.

What are the advantages and disadvantages of film capacitors

The great dielectric strength of film capacitors, which enables them to resist high voltages, is one of their main benefits. Because of their low dielectric losses, they are appropriate for applications needing less power dissipation. Film capacitors are renowned for their remarkable stability across a broad temperature range and for having a long operating life. When compared to other capacitor kinds, they could be more costly and bigger in size.

How does a film capacitor work

How does a film capacitor work
How does a film capacitor work

By storing electrical energy in the electric field created between the conducting plates and the dielectric film, film capacitors function. Electrons build up on one plate of the capacitor when a voltage is placed across it, generating a negative charge, while the other plate develops a positive charge. Although the dielectric substance blocks direct current from moving between the plates, alternating current can still flow through. Film capacitors are beneficial for smoothing out voltage fluctuations and filtering undesirable signals because of their capacity to store and release electrical energy.

The operating principle of film capacitor is based on electric field effects in dielectrics, usually alumina or polyimide, etc. When a film capacitor is placed between two off-number electrodes, the electric field causes the positive electrode to attract negative ions and the negative electrode to attract positive ions, which will cause charge to be stored in the capacitor. The energy of these charges can also be stored in the capacitor for later use.

What is the difference between a film capacitor and a ceramic capacitor

Film capacitor offers a wider capacitance range and are often more stable over time than ceramic capacitors. Film capacitor has reduced dielectric losses and are better suited for applications like audio equipment that need exact capacitance values and little distortion.

On the other hand, ceramic capacitors often have a smaller physical size and can provide greater voltage ratings.

Their media materials are different. The dielectric material of ceramic capacitors is ceramic, and film capacitor uses metal foil as electrodes.

They have different applications. Ceramic capacitors have small capacity, good high-frequency characteristics, and the use temperature can reach hundreds or thousands of degrees, generally used in bypassing, filtering applications; Film capacitors have good stability, chip ceramic capacitors, voltage and current withstand capabilities are outstanding, but the capacity generally does not exceed 1mF, generally used for coupling.

How do you identify a film capacitor

You may look at a film capacitor’s outside appearance to identify it. Typically cylindrical or rectangular in form, film capacitors have leads protruding from either end for connecting. The capacitor’s body is often composed of plastic, and it may be marked with information about the manufacturer, the voltage rating, and the capacitance value. A colour code or an alphanumeric code that is frequently written on film capacitor can also serve as additional identifying information.

How do film capacitors fail

Several factors might cause film capacitor to fail. The dielectric substance may breakdown under overvoltage stress, especially if the voltage rating is exceeded, which might result in a catastrophic failure. The dielectric material can deteriorate at temperatures over the rated limits of the capacitors, which might result in capacitance loss or shorts. Film capacitor may also malfunction as a result of mechanical stress, such as excessive vibration or bodily harm. In some circumstances, ageing or prolonged exposure to severe environmental factors can cause the dielectric material to gradually deteriorate, which can result in lower capacitance or higher leakage current.

What is the lifespan of film capacitors

What is the lifespan of film capacitors
What is the lifespan of film capacitors?

The precise type of film used, the operating environment, and the level of manufacture all have an impact on how long a film capacitor lasts. Comparing film capacitors to other types of capacitors, they often have a longer lifespan. Film capacitors may often endure for many thousand hours of continuous usage with good operation and within their authorised limitations. However, the capacitance value may drift over time and their performance may deteriorate as they get older or are exposed to unfavourable circumstances like high temperatures. The dependability and endurance of electronic systems can be increased by performing routine maintenance, monitoring, and replacement of worn-out capacitors.


Film capacitors are still a fundamental component of contemporary electronics because they provide a dependable method of energy storage and electrical stability. They are essential in many applications due to their high dielectric strength, stability across a broad temperature range, and extended operating lifespan. Film capacitors may cost more than other types of capacitors and take up somewhat more space, but in many situations, their benefits exceed these drawbacks.

Film capacitors may provide precise and dependable performance with appropriate identification, usage within permitted limits, and routine maintenance, adding to the effectiveness and lifespan of electronic systems. Film capacitors are positioned to play an ever bigger role as technology develops in fulfilling the changing needs of the electronics industry.


1. The polyester film capacitor( the Mylar capacitor)

2. Polypropylene film capacitor.

Film capacitor is a kind of electronic component-capacitor, with metal foil as the electrode plate and plastic film as the dielectric.The film capacitor could be able to store and release electrical energy.

Several factors might cause film capacitors to fail. The dielectric substance may breakdown under overvoltage stress, especially if the voltage rating is exceeded, which might result in a catastrophic failure...

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