• Laser Solutions
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• v.11 no.1
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• pp.1-6
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• 2008

We proposed new light guide panel (LGP) fabrication method exploiting laser-processed inner scatterers and surface pattern. The proposed method has achieved LGP performance improvement in both brightness and uniformity. The inner scatterers and surface pattern of grid type were fabricated with a 2nd harmonic Nd:YAG pulse laser engraving system and a $CO_2$ laser scanning system, respectively. In the implementation of LGP, inner scatterers was arranged in accordance with linear or curved pattern with changing density and surface pattern was engraved on the surface of an inner-scatterers embedded LGP. The increase of scatterers' density and the use of surface patterns in both linear and curved pattern provided high luminance and uniformity enhancement. While thecurved pattern incorporated with increased scatterers' density and surface patterns yielded brightness improvement with preserving good uniformity, the linear pattern showed highly localized brightness near the light entrance of the LGP. We can also observe that the uniformity was mainly determined by pattern of inner scatterers, and the brightness was improved by the higher density and the utilization of surface patterns. From the results, the use of laser-processed inner and surface patterns can be a potential alternative for efficient and simple LGP fabrication method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.9
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• pp.5748-5755
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• 2015

Scribing is cutting process to determine production amount and characteristic of LED chip. So it is an important process for fabrication of LED chip. Mechanical process and conventional scribing process with laser source has several problems such as thermal deformation, decreasing of material strength and limitation of cutting region. To solve these problems, internal laser scribing process that generates void in wafer and derives self-crack has been researched. However, studies of sapphire wafer cutting by internal laser scribing process for fabrication of LED chip are still insufficient. In this paper, cutting parameters were determined to apply internal laser scribing process for sapphire wafer for fabrication of LED chip. Then, foundation of cutting condition was established to set up internal laser scribing system through investigation of cutting characteristics by several experiments.

• Transactions of Materials Processing
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• v.13 no.3
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• pp.216-224
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• 2004

In this study, we have developed a new UV$({\lambda}=355nm)$ laser micromachining technology by direct ablation method without masks. This technology allows that 3D micro parts can be fabricated rapidly and efficiently with a low price. And it has a benefit of reducing fabricating process simply. Due to micro parts' fabrication, such technologies need the control of XYZ stages with high precision, the design of optical devices to maintain micron spot sizes of laser beam and the control technology of laser focus. The developed laser manufacturing process for laser micromachining is that, after extracting coordinates of shape data from CAD model data, a beam path considering manufacturing features of laser beam is created by using genetic algorithm. This generated manufacturing process is sent to stage controller. In order to improve the surface quality of micro parts, we have carried out experiments on iteration manufacturing and beam step-over by using a minimum focus size. Moreover, we have fabricated a micro-channel through the developed laser micromachining technology and verified it through the results.

• Proceedings of the Optical Society of Korea Conference
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• 1999.08a
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• pp.88-89
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• 1999

• Proceedings of the Korean Society of Laser Processing Conference
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• 1998.11a
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• pp.47-50
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• 1998

• Journal of the Korean Society for Precision Engineering
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• v.21 no.1
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• pp.46-50
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• 2004

The curing characteristics of a liquid photopolymer during microstereolithography and the shape accuracy of thereby fabricated microstructures were investigated experimentally. A He-Cd laser with a wavelength of 442nm and a photopolymer consisted of a commercial resin from SK chemical and a photoinitiat or were used for the experiment. By varying the laser beam power and scanning speed of the focused laser beam, minimum curing thickness of 50 ${\mu}ㅡ$ was obtained. The distortion of solidified structure due to adhesion force was measured and the optimum fabrication conditions were determined. Also, the feasibility of direct fabrication of three-dimensional microstructures by Super IH process was examined.

• Laser Solutions
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• v.9 no.1
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• pp.1-7
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• 2006

In order to increase the productivity of conventional microstereolithography (MSL), digital micromirror device($DMD^{TM}$) based MSL is proposed and the feasibility of 3D rnicrocomponents fabrication is demonstrated in two ways; free surface and constrained surface techniques. The clearness of optical images at the exposure plane was confirmed for the fabrication of an accurate 3D structure by controlling the dynamic viscosity of FA1260T and the shape accuracy of a structure fabricated with epoxy-based resin ($Somos^{\circledR}$ 10120) was analyzed to determine the optimum curing conditions. After finding the appropriate process variables, the feasibility of multiple microstructures is then demonstrated. Due to the high productivity, MSL using $DMD^{TM}$ showed the potential to replace the existing focused laser beam MSL.

• Proceedings of the KIEE Conference
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• 1993.11a
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• pp.231-233
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• 1993

This paper proposes a new $SiO_2$ film condenser fabrication technique by photo-chemically deposited $SiO_2$ films by Laser CVD. Laser CVD is noticeable that film deposition can be done at low temperature below $300^{\circ}C$ with less damage. After film deposition, the characteristics of Laser CVD $SiO_2$ films and $SiO_2$ film condenser is evaluated.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.659-660
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• 2006

High-aspect-ratio(max. 12.5) microchannels with excellent surface quality and good shape uniformity have been realized utilizing laser-induced etching technique. Etch width and depth variations depend largely upon process variables such as laser power and etchant concentration. Etchant concentration in association with viscosity also influence on the cross-sectional profile of the channels. The optimum process conditions for the fabrication of high-aspect-ratio microchannels applicable to micro thermal devices are demonstrated.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1439-1441
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• 1994

This paper propose a new $Ta_2O_5$ film fabrication technique by Laser CVD. Laser CVD is noticable that film formation can be done at low temperature with less damage. After film deposition, the characteristics of Laser CVD $Ta_2O_5$ film is evaluated.