[China Aluminum Industry Network] In the electrolytic capacitor family, aluminum electrolytic capacitors have been widely used in the world for the past 20 years due to their high performance, low price, and wide range of uses. In Japan alone, for example, in 1995, the output of aluminum foil for electrolytic capacitors was about 3,000 tons. By 2001, the output had reached 70,000 to 80,000 tons, almost at an astonishing rate.
The development of aluminum electrolytic capacitors in China is also very fast. According to statistics, the output in 1997 was about 15 billion, and it is estimated that it may have exceeded 20 billion in the near future. From the perspective of the development of China's electronics industry, the output of aluminum electrolytic capacitors will be greatly improved in recent years. At present, China's aluminum foil used in electrolytic capacitors is partially made of domestic foil, and a considerable part of it is still imported. In order to change this situation, domestic manufacturers have done a lot of work in localization. Not long ago, the high-voltage aluminum foil research project for the use of aluminum electrolytic capacitors in the southwest was successfully developed. The quality of the products has reached the international advanced level and can completely replace imports. It should be said that after more than 10 years of development, especially in the past five or six years, the quality of electronic aluminum foil in China has greatly improved.
The aluminum foil used in electrolytic capacitors belongs to the category of electronic aluminum foil, which is a corrosive material that operates under polar conditions. Different polarity electronic aluminum foils require different types of corrosion. The high-voltage anode foil is corroded in the column hole, the low-voltage anode foil is spongy, and the anode foil in the middle-pressure section is corrugated.
Prior to the 1980s, most of electrolytic capacitors used manual chemical etching. After the 1980s, they used electrochemical electrochemical corrosion. The purity of aluminum foil used for manual etching is low (99. 3% to 99.7%), and the requirements for the quality of aluminum foil processing are not high. Linkage electrochemical corrosion requires higher and higher purity of aluminum foil, and more and more precision is required for the processing quality of aluminum foil. From the aspect of the purity of aluminum, the purity of aluminum in the 1980s was 99.99%, and the purity of aluminum has reached 99.993% so far. This is the demand for electrode foils and the progress in the aluminum processing industry.
The increase in the purity of the aluminum foil naturally brings about a good influence on the quality of the electrode foil, but on the other hand, the cost is increasing. At the same time, corrosive media are constantly changing, some media concentrations are increasing, and some media types are changing. All these are detrimental to environmental protection work, which leads to heavy environmental protection tasks for production companies, which may require the purity of aluminum to be reduced. From the analysis of newer components of Japanese aluminum foil, it has been found that there is a trend in this respect.
The improvement of the quality of corroded foils is inseparable from the progress made in the quality of aluminum foils. From the perspective of Japanese patents, the peak period of patents for negative foils was 1980s, and there are two peaks for anode foils: one peak. About 1977 to 1978, another peak around 1983. The peak period of these patents indicates that the technology is rapidly advancing.