Analysis of the causes of capacity attenuation of thin film capacitors and electrolytic capacitors

1. Reasons for electrolytic capacitor attenuation

The capacity of electrolytic capacitor is the most easily decayed, and the price of electrolytic capacitor of the same type varies greatly from manufacturer to manufacturer. Many electrolytic capacitors of poor quality have short service life, and their capacity is easily decayed, resulting in failure to work normally.

The capacity of the electrolytic capacitor is controlled by the electrolyte. Because the electrolyte is organic, it will deteriorate and dry up, especially for some electrolytic capacitors with relatively poor quality, the metal electrode of the capacitor will undergo chemical decomposition, the electrolyte will become smaller, and the capacity will naturally become smaller.

The capacity attenuation of electrolytic capacitors is a common phenomenon. Generally, the capacity attenuation of better quality will be slower, while that of poor quality will be particularly fast.

2. Reasons for the attenuation of film capacitance

The market situation of film capacitors and electrolytic capacitors is similar. Brand capacitors that attach importance to quality generally have very little capacity attenuation. However, there are a large number of inferior film capacitors in the market that fight price wars. The materials used are poor, and the production process can be saved. In this way, the capacity of film capacitors produced will decline quickly.

One of the reasons for film capacitance attenuation: humid air

When the film is wound, there is a large amount of moist air in it. Under normal circumstances, the film capacitor winding workshop must be dust-free and totally enclosed, and air conditioning is required to maintain the air humidity and temperature in the workshop, but most small factories cannot meet this production environment.

At the same time, in the hot pressing process, if vacuum hot pressing is used, the moist air in the film capacitor core can be used to exhaust, but most small manufacturers will not use vacuum hot pressing, because not only the equipment is more expensive, but also the production speed is slow, and the production cost is high.

If there is a lot of moist air in the film capacitor core, the air ionization reaction will be generated during operation, and a large amount of ozone will be generated. Ozone is a strong oxidant, which damages part of the film, reduces the electrode area of the capacitor, and attenuates the capacity of the capacitor.

The second reason for the attenuation of film capacitance: poor film

Thin film raw materials can also be divided into large and small factories. Although the thin film materials produced by small factories are extremely cheap, their quality is poor. For example, the film is not evenly evaporated, some parts of the film are not evaporated, or there are dust and burrs on the film. These defects may be broken down during use. Although the thin film capacitance can heal itself, it will lead to the attenuation of the film capacitance capacity.

Suggestion: If you want to buy film capacitors with small capacity attenuation, try not to choose non-branded neutral printed products. There are too many low-quality products of such capacitors. Try to choose branded film capacitors. The quality is generally better, and the capacity attenuation will be slow.