A misunderstanding of the working principle of electrolytic capacitor

Jinmaoyuan author has found that many people do not correctly understand the working principle of aluminum electrolytic capacitors. We know that a capacitor is made up of a dielectric sandwiched between two conductive plates. A friend who has dismantled the aluminum electrolytic capacitor knows that the aluminum electrolytic capacitor is made by winding a piece of aluminum foil with a layer of paper impregnated with electrolyte.

Many people mistakenly believe that the paper in the middle is the dielectric of the capacitor. Actually not, this layer of paper is actually a plate of capacitance, which is electrically conductive. The true dielectric function of the dielectric is actually a thin layer of aluminum oxide on the surface of the aluminum foil. Since the thickness of this layer of alumina is very thin, and the paper is immersed in the conductive liquid as the electrode, the distance between the two plates of the capacitor is small (the electrode made of liquid can flow to any corner); And the surface of the aluminum foil is very rough after special treatment, and the surface area can be large. We know that the capacity of the capacitor is proportional to the positive facing area of the plate and inversely proportional to the distance between the plates. Therefore, the structure of the aluminum electrolytic capacitor allows its unit capacity to be made high. In addition, since aluminum-alumina has a certain unidirectional conductivity, the aluminum electrolytic capacitor is polar, and a leakage current is formed when the reverse connection is made. When the leakage current is large, the capacitor is heated. When the temperature reaches a certain level, The electrolyte will boil and generate a large amount of gas, which will cause the aluminum electrolytic capacitor to explode, which is what we call "shooting."

In order to reduce the power of the explosion, aluminum electrolytic capacitors generally process a release channel, such as an X-shaped, Y-shaped or K-shaped weak area at the top, allowing gas to be discharged in time, and some rubber seals at the bottom. Plug the small holes in the weak area. When the aluminum electrolytic capacitor is broken, the electrolyte will flow out or evaporate until it is dry, so that the capacity gradually becomes smaller, resulting in abnormal circuit operation, such as the power supply ripple becomes larger, the coupling degree becomes weaker, and the like. Since aluminum electrolytic capacitors are difficult to precisely control the thickness and surface roughness of alumina during processing, the capacity error of aluminum electrolytic capacitors is usually large, and some even become as high as 100%.

I believe that everyone knows the working principle of aluminum electrolytic capacitors. Jinmaoyuan is a professional manufacturer and seller of electrolytic capacitors. The model is complete and the quality is more secure. Welcome to contact us for more information about electrolytic capacitors.