With the rapid development of technology and the rise of electronic products, people’s lives have improved significantly. As basic needs are met, people now aim for even better living standards—seeking more functionality in electronics, but in devices that are thinner, smaller, and more space-efficient.
The same goes for electronic components: the smaller they are, the less space they occupy. One such component is the film capacitor, which uses metal foil as the electrodes and plastic film as the dielectric. The electrodes are stacked or wound into a cylindrical shape after overlapping at both ends.
Film capacitors are favored for their small size, high capacitance, stability, non-polarity, and low dielectric loss, making them crucial in many electronic devices and systems. They are called film capacitors because they are made with a plastic film dielectric, which is extremely thin—thinner than a human hair.
So, why does the plastic film in a film capacitor need to be so thin?
1. To Store More Charge
The primary function of a capacitor is to store charge. The amount of charge a capacitor can store is influenced by the electrode area, distance between the electrodes (which is the thickness of the film), and the properties of the dielectric material.
When the thickness of the film is reduced, the capacitance increases for the same electrode area. This characteristic allows film capacitors to achieve higher capacitance within a compact space, making them ideal for high-frequency circuits, power supply filtering, and other applications.
2. To Enhance High-Frequency Performance
In high-frequency circuits, the performance of capacitors is not only dependent on capacitance but also on the equivalent series inductance (ESL) and equivalent series resistance (ESR).
The thinner the film, the shorter the current path between the electrodes. This results in lower ESL and ESR, meaning that signal transmission delays and losses are minimized. As a result, film capacitors perform better in high-frequency applications.
3. Better Heat Dissipation and Cost Reduction
The thinner the film, the more compact the structure of the capacitor, and the shorter the heat dissipation path. This makes heat dissipation more efficient. Especially in high-frequency or high-current applications (such as solar inverters and electric vehicles), good heat dissipation extends the lifespan of the film capacitor.
In addition, a thinner film means the capacitor’s overall size is smaller, and less material is needed for manufacturing. This reduces production costs while maintaining high performance.
Conclusion
The reason why film capacitors use such thin films is to improve their performance and meet the growing demand for miniaturized electronics. This allows them to store more charge, perform better in high-frequency circuits, and remain durable while being compact.
This article is provided by JYH HSU (JEC) Electronics. JEC is a research, development, production, and sales-oriented company specializing in manufacturing and selling various electronic components such as capacitors and resistors.
Post time: Dec-05-2025