• Proceedings of the Korean Society of Laser Processing Conference
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• 2006.06a
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• pp.35-40
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• 2006

Laser welding is high power density welding method which is higher speed and productivity, lower thermal deformation, without material restrictions for car body welding. But, in case of zinc coated sheet metal welding, the gap is needed $0.1{\sim}0.2mm$ to avoid weld bead blowup. This paper describe that it used dimple and pressure roller tool to improve laser welding quality for 3-layer zinc coated sheet metal.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.7
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• pp.28-28
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• 2000

• Journal of the Microelectronics and Packaging Society
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• v.23 no.4
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• pp.101-105
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• 2016

Recently, the hydrophobic surface has been attracted because of the excellent opto-physical properties. Various processing methods such as chemical, mechanical, photolithographic and laser processing are competitively introduced for fabrication of hydrophobic surface of polymer, metal and ceramics. In this paper, we fabricated the hydrophobic surface of copper metal by simple method which irradiated 355 nm UV-pulsed laser in order to shape microgrooves and increased surface roughness through oxidation process at room temperature. Finally the contact angle is dramatically increased by maximum $45^{\circ}$, as a result of oxidation which simply created nanostructures on the microstructures without expensive chemical process.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.2
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• pp.322-329
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• 2009

Machinability of LAM(Laser Assisted Machining) has been studied for ceramics such as $Al_2O_3$, $Si_3_N4$ and $ZrO_2$ by $CO_2$ laser. It was possible to remove ceramics by PCBN tool because material became softening and deterioration by local laser beam irradiation. The advantage of LAM is the ability to produce larger material removal rates and tool life. But, for cutting of $Al_2O_3$ and $ZrO_2$, stage of laser power control was needed owing to thermal shock with high temperature of workpiece by laser power. And when $Si_3N_4$ was machined by LAM, $N_2$ gas spouted from surface of one cause of high temperature. Characteristics of LAM were analyzed using pyrometer, dynamometer, SEM and EDS to measure temperature of workpiece surface, cutting force, variation of machining surface and structure of lattice respectively. As the result of this study, it was found that machinability of LAM for ceramics in $CO_2$ laser and mechanism of LAM was different according to the kind of ceramics because of properties of materials.

• 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.

• 전기의세계
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• v.52 no.6
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• pp.55-59
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• 2003

• Laser Solutions
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• v.8 no.3
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• pp.27-30
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• 2005

Nowadays, most automotives companies are making use of laser welding in car body assembly shop. But even though laser welding is better than resistance spot welding in many points, its application has been limited to special technology for manufacturing. The paper introduces in the field of remote welding system (RWS) to improve the process efficiency of laser welding. Positioning time of RWS between welding stitches is dramatically reduced to zero. It is a kind of solutions to generalize laser welding in mass production. This RWS consists of fiber laser, industrial robot and 3-axis scanner.

• Laser Solutions
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• v.8 no.3
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• pp.21-26
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• 2005

A bonding process between tape-carrier package and a glass panel with anisotropic conductive film (ACF) has been investigated by making use of high power diode laser as a heat source for cure. The results from modeling of process and from optical properties of layers showed that heat absorbed from polyimide film surface and ACF layer is dominant source of curing during laser illumination. Laser ACF bonding has better bonding quality than conventional bonding in view of peel strength, flatness, pressure unbalance and processing time. New ACF bonding processes by making use of high power diode laser are proposed.

• Laser Solutions
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• v.1 no.1
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• pp.30-38
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• 1998

This study includes the efface of shielding gas types on $CO_2$ laser weldability of low carbon automotive galvanized steel. The types of shielding gas evaluated are He, $CO_2$, Ar, $N_2$, 50%Ar＋50%$N_2$. The weld penetration, strength, formability(Erichsen test) of Laser weld are found to be strongly dependent upon the types of shielding gas used. Further, the maximum travel speed and flow rate to form a keyhole weld is also dependent upon types of shielding gas. The ability of shielding gas in removing plasma plume and thus increasing weld penetration is believed to be closely related with ionization/dissociation potential, which determine the period of plasma formation and disappearance. Further, thermal conductivity and reactivity of gas with molten pool also give strong effect on penetration and porosity formation which in turn affect on the formability and strength.

• Laser Solutions
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• v.13 no.3
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• pp.13-18
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• 2010

In this paper, polyimide (PI) surface was modified by UV Laser with a low laser fluence and investigated changes of surface geometry and chemical characteristics by SEM (scanning electron microscope), X-ray diffraction (XRD), XPS (x-ray photoelectron spectroscopy) and the measurements of contact angle of water. PI surface was peeled off and modified with microstructure fabrications by photochemical ablation over the laser fluence of 50 mJ/cm2. As laser fluence increased, delamination of PI surface was occurred largely and strongly. In chemical characteristics, the O/C and N/C atomic ratios increased and contact angle decreased from $80^{\circ}$ to $40^{\circ}$.