フォトリソグラフィ−陽極酸化−化学エッチングによるアルミニウム圧延板の装飾的表面加工

Abstract

Surface patterning is an important technology for improving product design. This paper describes the fabrication of three-dimensional microstructures on aluminum plates using photolithography, anodization, and chemical etching. Photoresist patterns were prepared on an aluminum plate using a standard photolithography technique. The aluminum plate was anodized in sulfuric acid at a controlled concentration and bath voltage. During anodization, an anodic oxide film was formed on the photoresist/aluminum plate interface and in an open region. The oxide film formation was sensitive to both sulfuric acid concentration and bath voltage. The aluminum plate was expanded by anodization. The volume expansion factor (calculated as the ratio of the oxide film thickness to the thickness of the consumed aluminum) was 1.44-1.69.The oxide film was removed by chemical etching in phosphoric acid. Thereby, the aluminum surface was exposed, and convex shapes were formed. The surface roughness of the plate after chemical etching was comparable to its value before fabrication. The mean roughness Ra was <20 nm. Quadrangular pyramids, cones, and hexagonal pyramids were fabricated successfully on the aluminum plate by changing the photoresist mask pattern. Anodization and chemical etching conditions were controlled for accurate shape control of the three-dimensional metallic microstructures.