• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.89-90
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• 2010

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.737-738
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• 2010

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.1
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• pp.7-14
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• 2010

AE(acoustic emission) sensor has been used for a state monitoring and observation during a ultra-precision machining because AE signal, which has high frequency range, is sensitive enough. In case of ceramic fabrication, a monitoring of machining state is important because of its hard and brittle nature. A machining characteristic of ceramic is susceptibly different in accordance with variable machining conditions. In this study, Yttria($Y_2O_3$) ceramic was fabricated using the ultra-precision lapping process with in-process electrolytic dressing(IED) method. And the surface machining characteristic and AE sensor signal were compared and analyzed.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.5
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• pp.616-621
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• 2010

New type of the base material of the light-emitting diode requires copper wafer in view of heat and electrical conductance. Therefore, polishing process of the substrate level is needed to get a nanometer level of surface roughness as compared with pattern structure of nano-size in the semiconductor industry. In this paper, a series of lapping and polishing technique is shown for the rough and deflected copper substrate of thickness 3mm. Lapping by sand papers tried air cooling method. And two steps of polishing used the diamond abrasives and the $Al_2O_3$ slurry of size 100mm considering the residual scratch. White-light interferometer proved successfully a mirror-like surface roughness of Ra 6nm on the area of $0.56mm{\times}0.42mm$.

• Korean Journal of Materials Research
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• v.15 no.3
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• pp.183-188
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• 2005

It was studied in this article how the flexural strength of bare silicon chips is influenced by adopting dual wafer back-lapping process. The experimental results showed that an additional finishing process after the conventional grinding process improves the flexural strength of bare chips by more than 2-fold. In particular, this work showed that the proper removal of the grinding marks$(Ra=0.1\;{\mu}m)$existing on the wafer back-surface resulting from the grinding process significantly contiributes to the enhancement of chip strength.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.914-917
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• 2000

Application of ceramics, carbide, ferrite has grown considerably due to significant improvement in their mechanical properties such as light weight, chemical stability , super wear resistance and electronical. Despite these character, the me of advanced material has not increased because of poor machinability. The method of using of metal bond wheel was proposed. But it is difficult that metal bond wheel can be dressed. Recently, the technology of in-process electrolytic dressing is developed to solve this problem. This method need wheel for electrolytic dressing, power supply and electrolyte. But development of wheel for electrolytic dressing is the most need. The aim of this study is development of wheel for electrolytic and appraisement of CIB-diamond lapping wheel

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.4 s.235
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• pp.632-638
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• 2005

The surface lapping process on sapphire wafer was carried out for the epitaxial process of thin film growth of GaN semiconducting material. The planarization of the wafers was investigated by the introduction of the dummy wafers. The diamond lapping process causes the surface deformation of dislocation and micro-cracks. The material deformation due to the mechanical stress was analyzed by the X-ray diffraction and the Vickers indentation. The fracture toughness was increased with the increased annealing temperature indicating the recrystallization at the surface of the sapphire wafer The sudden increase at the temperature of $1200^{\circ}C$ was correlated with the surface phase transition of sapphire from a $-A1_{2}O_{3}\;to\;{\beta}-A1_{2}O_{3}$.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.858-861
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• 2000

Application of ceramics, carbide, ferrite has grown considerably due to significant improvement in their mechanical properties such as light weight chemical stability super wear resistance and electronical. Despite these character, the use of hi-tech material has not increased because of poor machinability. The method of using of metal bond wheel was proposed. But it is difficult that metal bond wheel can be dressed. Recently, the technology of in-process electrolytic dressing is developed to solve this problem. This method need wheel for electrolytic dressing, power supply and electrolyte. But development of wheel for electrolytic dressing is the most need. The aim of this study is development of wheel for electrolytic and appraisement of CIB-diamond lapping wheel

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.223-226
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• 2002

Appropriate design/manufacturing conditions, to give outstanding material properties to the $Si_3$$N_4$-BN and AIN-BN based composite materials, will be investigated using the experimental design methods. Ultra-precision machinability of the developed ceramics will be systematically studied in the viewpoint of microstructure and material properties. Also, finite element methods will be applied to define basic principles to significantly improve machinability and various properties. Basic experiments will be performed to develop optimum ultra-precision machining technologies for the developed ceramics. For ultra-precision lapping machining, need to develop a ultra-precision lapping system, suitable metal bonded diamond wheel, and appropriate condition of ultra-precision lapping machining.

• Proceedings of the KWS Conference
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• 2005.06a
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• pp.226-228
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• 2005

Of typical welding techniques, to employ the heat for joining process is the most commonly used welding process. But there arise difficulties when this process is applied to light weight alloys such as Aluminium alloy. In this respect, Friction Stir Welding(FSW), a solid-state joining process, is the most effective welding technique with significant potential for various industrial applications. In this study, the characteristics of lapping FSW Al 5052 alloy are shown under a variety of welding parameters such as the rotation speed of FSW tool and welding velocity. Conclusively, the welding properties of lapping FSW Al 5052 were found to be dominated by the deformation of non-joining area near the welding nugget rather than other factors such as the thermal input.