Surface micro-texturing of metallic cylindrical surface with proximity rolling-exposure lithography and electrochemical micromachining

In this paper, a new method is developed for fabricating large-scale three-dimensional (3D) microstructures for cylindrical objects with proximity rolling-exposure lithography (PREL) and electrochemical micromachining (EMM). This method is capable of patterning a wide variety of shapes, including shapes that are impossible to fashion with conventional methods over a large area. A cylindrical rod covered with photoresist is subarea-exposed with a collimated ultraviolet source through a mask by rotating the rod through a definite angle to expose each area. To ensure the shape accuracy of the microstructures, a 2D exposure model is built to predict and optimise such parameters as the rod radius, exposure angle and effective light intensity. The experimental results show that the ideal exposure time for a cylindrical layer is three to four times longer than that for a planar layer with the same thickness. The relative errors of the microstructures decrease as the exposure angle decreases or as the microstructures increase in size. Furthermore, EMM is extended to non-planar surfaces and ordered microstructures with feature sizes down to 40 μm are obtained over large areas on the cylinder.