Electrolytic Capacitor Paper

2. Electrolytic capacitor paper

(1) Concept of electrolytic capacitor paper

Electrolytic capacitor paper, also known as electrolytic paper, is one of the three key materials that make up aluminum electrolytic capacitors. It serves as an adsorption carrier for the electrolyte, forming the cathode of the electrolytic capacitor together with the electrolyte, and also functions as an isolation foil between the two poles, also known as isolation paper. The aluminum electrolytic capacitor and electrolytic capacitor paper are shown in the following figure:

Capacitors are the most widely used, largest and irreplaceable electronic components, accounting for about 40% of electronic components in production. Capacitors are mainly divided into four categories based on different dielectrics: aluminum electrolytic capacitors, tantalum electrolytic capacitors, ceramic capacitors, and thin film capacitors. Among them, aluminum electrolytic capacitors have significant advantages such as high CV value per unit volume and high cost-effectiveness, occupying more than 30% of the capacitor market share. With the development of new energy and new energy vehicles, frequency conversion technology and other new industries, their proportion is on the rise. The global capacitor classification market size is shown in the following figure:

(2) Classification of electrolytic capacitor paper

There are many types of electrolytic capacitor paper, and due to the different raw materials and production processes used by various manufacturers, the classification methods and standards adopted are also different. At present, there are dozens of series and hundreds of specifications of electrolytic capacitor paper. According to the voltage strength that electrolytic capacitor paper can withstand, it can be divided into two categories: medium high voltage electrolytic capacitor paper and low voltage electrolytic capacitor paper.

Medium and high voltage electrolytic capacitor paper refers to electrolytic capacitor paper that can withstand voltages above 160V. It is mainly used for capacitors used in switching power supplies, energy storage and discharge capacitors, AC motor starting capacitors, and flash lamp capacitors. In terms of performance, on the one hand, medium and high voltage electrolytic capacitor paper requires high voltage resistance and resistance to aluminum box burrs, which is reflected in the high tightness of the paper; On the other hand, medium and high voltage electrolytic capacitor paper requires good absorption performance to improve its electrical performance, which is reflected in the lower tightness of the paper. The two are contradictory. Electrolytic capacitor paper production enterprises generally adopt the method of producing double-layer double density paper to solve this contradiction, but the production technology of double-layer double density paper is difficult and the production cost is high, so the price is relatively high.

Low voltage electrolytic capacitor paper refers to electrolytic capacitor paper with a working voltage below 100V, mainly used for low-voltage capacitors such as filter capacitors, high-quality audio capacitors, bipolar capacitors, and low impedance capacitors. From a performance perspective, low-voltage electrolytic capacitor paper has high impedance requirements, so the tightness of the paper is relatively low. Raw materials with relatively low impedance values are used in the production process, and their prices are lower than those of medium and high-voltage electrolytic capacitor paper.