Photoresist Dip-coating and Stepped Lithographic Technique for Directly Fabricating Rigid Microstructures onto Metal Rollers
Date Issued
2009
Date
2009
Author(s)
Lai, Hsin-Chun
Abstract
The Roll-to-Roll process has been attracting more attention in recent years as a result of its rapid, continuous production for mass production. However, the fabrication of microstructures on roller surface is the key technique. Most of the microstructured-roller fabrication methods are very complicated and costly, needing high-end facilities. Furthermore, mold slippery and warping problems are frequently encountered due to the weak adhesion between molds and rollers. Soft rollers with microstructures have problems of poor strength durability and temperature endurance. Methods for directly fabricating microstructures onto rollers should be developed. This study proposes an approach for fabrication of rigid microstructure on metal rollers.his process integrates the photoresist dip-coating process, the stepped lithographic process, and electroless nickel plating process to fabricate the continuous microstructures onto the metal rollers. The mechanism of dip-coating, which is composed of a motor, a lifting platform, a container and a roller fixture, is carried out in this study. This study employed on in-house built apparatus for rapid and precise measurement of photoresist-coated thickness, which is composed of a X-Y stage, a rotating stage and a spectrometer. The measured film thickness has been compared those measured with surface profiler. he dip-coating of photoresist onto roller is carried out by pulling the roller out of the glass beaker containing photoresist. The experimental results show that the photoresist (EPG-510) can be uniformly coated onto the nickel-plated roller surface (the diameter is 80 mm, and length is 120 mm) using dip-coating process. It is found that the film uniformity improves if the diameter of the beaker gets large. The thickness can be controlled with the pulling speed; thickness increases with the speed of lifting the roller out from the photoresist bath. The average minimum film thickness of the photoresist is 1,400 nm with 7.5 mm/min of beaker lifting speed in the beaker of 153 mm diameter. sing the stepped rotating lithography technique, the photoresist patterns with 5 μm, 20 μm, 40 μm line widths and 20×20 μm rectangle array have been successfully fabricated onto the nickel-plated roller. In addition, the microstructures with various pitches can be fabricated by adjusting the stepped rotating degree in this work. Subsequently, the roller is treated with electroless nickel plating process. Finally, the residual PR is removed by acetone. After that, a roller with continuous rigid nickel microstructures can be obtained.
Subjects
Roller fabrication
microstructure fabrication
Dip coating
Stepped rotating lithography
Type
thesis
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