| Electronic aluminum foil is a high-end aluminum foil; it mainly used in the electrolytic capacitor materials which is an important component electronic industry. The performance and integration of mechanical-electrical products are increasing with the rapid development of electronic industry in recent years, which is made of electronic components higher demand-ensuring and improving the performance and simultaneously posses the volume as small as possible. Therefore, Small electrolytic capacitor (That is to achieve high capacitance) is often the key to develop high performance electrical products. At present, the demands of high-voltage aluminum foils are an amount of 1.5 million ton/year at domestic, and were about 20% of the rate of annual increase. But there is few of high-voltage electronic aluminum foil manufacturers in domestic.So it need to import large quantities. Therefore, the study of the gap between domestic and foreign high-voltage electronic aluminum foil and to identify ways to improve its quality are of great significance to develop China's aluminum industry to a higher level.In this paper, various properties of three kinds of final annealed high-voltage aluminum foils, such as the main impurity elements Fe content and its distribution, surface quality, dislocation pits, grain size, mechanical properties, cube texture and corrosion resistance were comparative studied by means of chemical analysis, SIMS, SEM, EDS, EBSD, DC electrochemical corrosion and mechanical properties testing means. The results showed:the main factors that effect capacitance of etched foil are impurity elements Fe content and its distribution, cube texture and surface quality.We identified the gap between domestic and Japan high-voltage electronic aluminum foils, and proposed improvement measures and recommendations.The comparative studies of content of three main impurity elements in high voltage aluminum foils have shown that:the average Fe content (0.0018%) of Showa is the lowest of the three, and Join world (0.0027%) is the highest. Cube texture becomes weaker with increasing of the Fe content. Therefore, the Fe contents of high voltage aluminum foils need to control in less than 0.0020%. Fe in Japan's high voltage aluminum foils are approximately linear distribution along the thickness direction, while Join world are curve distribution, and there are enrichment impurities Fe in heart ministry. Fe atoms in Join world and its uneven distribution of the matrix, resulting in high voltage aluminum foil thick grains, uniform corrosion, and thus reduce the capacitance of etched foil. The average Si content of Showa (0.0022%) is highest of the three; Join world (0.0019%) is the lowest, with the small differences. Influence of Si to the formation of cube texture is far from the negative effects of Fe. Influence of Si on aluminum foil is not isolated, but also by Fe/Si. Fe/Si of Showa (0.8182) is smallest; Join world (1.4211) is largest. It will affect their existing format when the two impurities simultaneously in high-pure aluminum, the smaller Fe/Si, the more help to improve the specific capacitance of aluminum foil. Therefore, Si content should be controlled with in 0.0030%.Domestic Join world high voltage aluminum foils possess more surface fluctuations and the defects, There are still rolling roll indentations. The average grain size of Showa is 209.1μm, it is moderate and changed little; Mitsubishi has the minimum grain size (207.6μm); the average grain size of Join world is 223.2μm, it is maximum and distribution is disorder, there are great differences between them. Showa posses the most cubic pits after the electrochemical etched. Which has a direct relationship between (001)<100>cube orientation of the matrix with aluminum foil. Therefore, there is a certain gap between the domestic and Japan product in quality control of the surface with aluminum foil, and it need to improve.Horizontal tensile strength and elongation are higher than the rolling direction in the three kinds of high voltage aluminum foils; in which the tensile strength of Mitsubishi (horizontal tensile strength is 28.85MPa, elongation tensile strength is 28.30MPa) are the highest of the three. Join world and Showa with fairly. Fracture surface of tensile specimen with aluminum foil are fairly flush, there are river-like patterns and tear ridge. There are little differences in hardness at different locations with high voltage aluminum foils. The average hardness of Mitsubishi (17.93HV) is the highest; Join world (16.77HV) is the lowest of the three. The reason is that the grain of Mitsubishi is finest. The smaller the grain, the higher the hardness value according to the fine grain strengthening theory. Therefore, the domestic high voltage aluminum foils need to be strengthened in intensity.Comparative studies of texture showed that:Domestic Join World has almost reached equal level with Japan in volume fraction of cube texture. Both can reach the international advanced level (≥95%), However, texture content in domestic Join World of 96.23% compared to Showa of 97.89% and Mitsubishi of 97.75% is slightly lower, and the domestic Join World has also other texture orientations, such as a small amount of (124)<211>R texture. Therefore, the content of non-cube texture should be controlled in domestic high voltage aluminum foil.The process parameters of DC Electrochemical corrosion with high-voltage electronic aluminum foil through experiment was optimized as follows:etching solution composition:HCl+H2SO4 mixed solution, the concentration of HCl is 2.0mol/L, the concentration of H2SO4 is 0.5mol/L; etching current density: 0.2A/cm; etching time:120S; etching temperature:60 C. Comparative studies of three high voltage aluminum foils showed that:the specific capacitance of Showa is up to 0.78μF/cm2 under 520V. Etched holes of Showa distributed even, larger and deeper, Overall It has excellent performance; the specific capacitance of Mitsubishi formed foil was 0.76μF/cm2; domestic Join World has the smallest specific capacitance 0.69μF/cm2 and fat-hole uniformity of is not good, there will appear local over corrosion making aluminum foil thinning or perforation, because of inequality triggered hole. |
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