Browsing by Author "Chen, Ming-Fei"

Now showing 1 - 5 of 5

Characteristics of Ni-Ir and Pt-Ir hard coatings surface treated by pulsed Nd:YAG laser
(2010-12-25)
Tseng, Shih-Feng
;
Hsiao, Wen-Tse
;
Huang, Kuo-Cheng
;
Chen, Ming-Fei
;
Lee, Chao-Te
The subjects of the presented paper are to develop a laser surface treatment technology for the protective coatings of glass-molding dies and to better understand the interaction between laser beam and materials coated on the die surface. A variety of alloy films, including Ir-25 at.% Pt. Ir-50 at.% Pt, Ir-75 at.% Pt. Ir-25 at.% Ni, Ir-50 at.% Ni, and Ir-75 at.% Ni compositions are deposited by the ion source assisted magnetron sputtering system (ISAMSS). A Cr layer that functioned as a buffer layer is deposited between the alloy film and die surface. After an alloy film and the buffer Cr layer were sequentially coated on tungsten carbide (WC) surface, Nd:YAG laser was directly applied in the writing process. The temperature profile of the film stack structure is simulated by ANSYS software. The surface roughness was analyzed by atomic force microscopy (AFM) to compare the coating surface roughness before and after the laser surface treatments. The treated coatings for oxidation prevention test were examined by energy dispersive x-ray spectrometry (EDS). Nanoindentation instrument was performed to evaluate microhardness and reduced modulus of the coatings. The cross-sectional structures between the hard coating layer and buffer layer were also inspected by a scanning electron microscope (SEM). The Pt-Ir and Ni-Ir film coatings are unable to withstand the working temperature over 1500 degrees C, which is considered for quartz molding process and hot embossing process. The films showed high roughness, low microhardness and low reduced modulus because the film oxidation occurred in a high working temperature process. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.
Hydrophobic Templates with Rough Patterns Fabricated by Laser Micromachining for Liquid Droplets Generation
(2011)
Tseng, Shih-Feng
;
Huang, Kuo-Cheng
;
Chiang, Donyau
;
Chen, Ming-Fei
;
Hsiao, Sheng-Yi
This paper presents an approach to utilize high precision pulsed Nd:YAG laser to fabricate a rough array-pattern on a soda-lime glass plate by a laser-induced backside writing (LIBW) process, and a laser-induced plasma assisted ablation (LIPAA) technique. The current study investigates the effect of process parameters such as single-shot laser exposure time and number of passes on the material removal rate. After depositing 695 nm thick Teflon thin film on the glass plate, the surface of the laser micro-machined template becomes hydrophobic. The surface roughness, annular groove profile and surface micrograph were measured by an atomic force microscope, a profilometer, and a scanning electron microscope, respectively. A uniform liquid droplet by the sessile drop method is generated on the hydrophobic template. Droplet characteristics, such as contacted angle, size, and shape, are measured with a surface tension analyzer and microscope. This work also discusses the relationship between the formed droplets and the process recipe of the micro-machined template. The proposed approach can apply to future for uniform lens array formation.
Laser scribing of indium tin oxide (ITO) thin films deposited on various substrates for touch panels
(2010-12-15)
Tseng, Shih-Feng
;
Hsiao, Wen-Tse
;
Huang, Kuo-Cheng
;
Chiang, Donyau
;
Chen, Ming-Fei
In this study, a Nd:YAG laser with wavelength of 1064nm is used to scribe the indium tin oxide (ITO) thin films coated on three types of substrate materials, i.e. soda-lime glass, polycarbonate (PC), and cyclic-olefin-copolymer (COC) materials with thickness of 20 nm, 30 nm, and 20 nm, respectively. The effect of exposure time adjusted from 10 mu s to 100 mu s on the ablated mark width, depth, and electrical properties of the scribed film was investigated. The maximum laser power of 2.2W was used to scribe these thin films. In addition, the surface morphology, surface reaction, surface roughness, optical properties, and electrical conductivity properties were measured by a scanning electron microscope, a three-dimensional confocal laser scanning microscope, an atomic force microscope, and a four-point probe. The measured results of surface morphology show that the residual ITO layer was produced on the scribed path with the laser exposure time at 10 mu s and 20 mu s. The better edge qualities of the scribed lines can be obtained when the exposure time extends from 30 mu s to 60 mu s. When the laser exposure time is longer than 60 mu s, the partially burned areas of the scribed thin films on PC and COC substrates are observed. Moreover, the isolated line width and resistivity values increase when the laser exposure time increases. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.
Surface wettability of silicon substrates enhanced by laser ablation
(2010-11-01)
Tseng, Shih-Feng
;
Hsiao, Wen-Tse
;
Chen, Ming-Fei
;
Huang, Kuo-Cheng
;
Hsiao, Sheng-Yi
Laser-ablation techniques have been widely applied for removing material from a solid surface using a laser-beam irradiating apparatus. This paper presents a surface-texturing technique to create rough patterns on a silicon substrate using a pulsed Nd:YAG laser system. The different degrees of microstructure and surface roughness were adjusted by the laser fluence and laser pulse duration. A scanning electron microscope (SEM) and a 3D confocal laser-scanning microscope are used to measure the surface micrograph and roughness of the patterns, respectively. The contact angle variations between droplets on the textured surface were measured using an FTA 188 video contact angle analyzer. The results indicate that increasing the values of laser fluence and laser pulse duration pushes more molten slag piled around these patterns to create micro-sized craters and leads to an increase in the crater height and surface roughness. A typical example of a droplet on a laser-textured surface shows that the droplet spreads very quickly and almost disappears within 0.5167 s, compared to a contact angle of 47.9A degrees on an untextured surface. This processing technique can also be applied to fabricating Si solar panels to increase the absorption efficiency of light.
Surface wettability of silicon substrates enhanced by laser ablation
(2010-11-01)
Tseng, Shih-Feng
;
Hsiao, Wen-Tse
;
Chen, Ming-Fei
;
Huang, Kuo-Cheng
;
Hsiao, Sheng-Yi
Laser-ablation techniques have been widely applied for removing material from a solid surface using a laser-beam irradiating apparatus. This paper presents a surface-texturing technique to create rough patterns on a silicon substrate using a pulsed Nd:YAG laser system. The different degrees of microstructure and surface roughness were adjusted by the laser fluence and laser pulse duration. A scanning electron microscope (SEM) and a 3D confocal laser-scanning microscope are used to measure the surface micrograph and roughness of the patterns, respectively. The contact angle variations between droplets on the textured surface were measured using an FTA 188 video contact angle analyzer. The results indicate that increasing the values of laser fluence and laser pulse duration pushes more molten slag piled around these patterns to create micro-sized craters and leads to an increase in the crater height and surface roughness. A typical example of a droplet on a laser-textured surface shows that the droplet spreads very quickly and almost disappears within 0.5167 s, compared to a contact angle of 47.9A degrees on an untextured surface. This processing technique can also be applied to fabricating Si solar panels to increase the absorption efficiency of light.