印刷用アルミニウム板のエッチング

抄録

Aluminum strip was electrolytically etched by applying alternating current (1∅, 3∅) in two different acidic electrolytes; hydrochloric and nitric acids. Morphology and distribution of pits, formed on aluminum was studied by using scanning electron microscopy and the stylus traverse method. The pit pattern was essentially a function of the electrolytes used and was independent of current density. On the other hand, surface roughness was primarily a function of current density and was less affected by the electrolytes. It was found that more uniform hemispherical arrays of pits were formed in nitric acid electrolytes than in the hydrochloric acid. From these facts the mechanism of etching procesesses is discussed. Etched surfaces were covered with thick layers containing anodic dissolution products and materials deposited from the electrolyte. During the cathodic process in which hydrogen gas evolves the layer is incompletely destroyed and at the same time some materials might be deposited from the electrolyte. Alternatively, when aluminum is made andodic over pitting potential in the electrolytes that attack aluminum, bared or thinned pit sites are dissolved anodically and is also covered by anodic dissolution products. The simultaneous film formation and incomplete destruction of the layer tend to roughen the surface and thus etched pits are produced. In order to obtain uniform pit pattern at will, it's necessary to controll the layer formed during etching processes.