Papers by Author: Sung Ho Jeong

Abstract: The micromachining technique for the fabrication of Fe-36%Ni (Invar®) microgrooves using a novel laser-induced wet etching system with an optical fiber as the light waveguide and machining tool is investigated. Microgrooves fabricated at the optimal process conditions with the proposed etching system have good surface morphology and dimensional accuracy. It is shown that the variation of etch profiles such as etch width and depth depends significantly upon the process parameters. Fiber damage, which is attributed to macrobubbles, can be dramatically reduced by adjusting the distance between the workpiece surface and the fiber terminal. The effects of process parameters such as laser power, scan speed, and threshold distance on etch width, depth, and crosssectional profiles are reported and the optimal process conditions to fabricate Invar® microgrooves with excellent shape and size are provided. Also, the applicability of the Invar® microgrooves for the manufacturing of shadow mask for an organic light emitting diode (OLED) is demonstrated.

Abstract: The curing characteristics of a photocurable resin are critical factors that often decide the ultimate resolution and structural sharpness of a final product fabricated by microstereolithography (μ-STL). In this study, we investigated the curing characteristics of the FA1260T photopolymer under a visible laser light of 442nm wavelength. Modification of the curing property of the FA1260T is attempted to reduce the cure depth (Dc) by adding a radical quencher to the resin. Also, an organic solvent was used to reduce the resin viscosity for an improvement of the flatness of the liquid surface during layer-by-layer curing. As a result, the minimum Dc has been reduced over a factor of 3 with no abrupt increase. Samples of three dimensional microstructures fabricated using the modified FA1260T are presented.