• Journal of the Microelectronics and Packaging Society
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• v.15 no.2
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• pp.63-67
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• 2008

3D integration technology has been a major focus of the next generation of IC industries. In this study Si wafer ultra-thinning has been investigated especially for the effect of ultra-thinning on the silicon surface. Wafers were grinded down to $30{\mu}m\;or\;50{\mu}m$ thickness and then grinded only samples were compared with surface treated samples in terms of surface roughness, surface damages, and hardness. Dry polishing or wet etching treatment has been applied as a surface treatment. Surface treated samples definitely showed much less surface damages and better roughness. However, ultra-thinned Si samples have the almost same hardness as a bulk Si wafer.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.3
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• pp.196-200
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• 2009

Lithium niobate ($LN:LiNbO_3$) is a compound of niobium, lithium and oxygen. The characteristics of LN are piezoelectricity, ferroelectricity and photoelectricity, and which is widely used in surface acoustic wave (SAW). To manufacture LN devices, the LN surface should be a smooth surface and defect-free because of optical property, but the LN material is processed difficult b traditional processes such as grinding and mechanical polishing (MP) because of its brittleness. To decrease defects, chemical mechanical polishing (CMP) was applied to the LN wafer. In this study, the suitable parameters such as down force and relative velocity, were investigated for the LN CMP process To improve roughness, the LN CMP was performed using the parameters that were the highest removal rate among process parameters. And, evaluation of optical property was performed by the optical reflectance.

• Journal of the Korean Ceramic Society
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• v.36 no.7
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• pp.711-717
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• 1999

Biaxial fracture behavior of alumina specimens with the diameter of 20mm and four kinds of thickness of 1.9, 2.3, 2.6 and 2.8mm was studied by the ball-on-3-ball test and the fracture results were analyzed by he analysis of variance (ANOCA), The strength measured with the down speed prescribed in ASTM showed that the measured strength was not dependent on the thickness of the specimens. Equivalent radius and crack-braching number were observed to increase lineraly with the thickness of the specimens. The jog direction was observed to study the effect of grinding direction on surface flaws. It is though that the surface finishing with #600 grit diamond wheel did not affect the surface flaws of the specimens.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.3
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• pp.324-330
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• 2013

This paper describes a novel method to surface large optics mirror with an extremely high hardness, which could replace the high cost of the repetitive off-line measurement steps and the large ultra-precision grinding machine with ultra-positioning control of 10 nm resolution. A lot of diamond pellet to be attached on the convex aluminum base consists of a grinding tool for the concave large mirror, and the tool was pressured down on the large mirror blank. The tool motion at an interval on the spiral path was controlled with each feed rate as the dwell time in the conventional computer-controlled polishing. The shape to be surfaced was measured directly by a touch probe on the machine without any separation of the mirror blank. Total 40 iterative steps of the surfacing and measurement could demonstrate the form error of RMS $7.8{\mu}m$, surface roughness of Ra $0.2{\mu}m$ for the mirror blank with diameter of 1 m and spherical radius of curvature of 5400 mm.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.6
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• pp.753-760
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• 2007

For protection of the cylinder wall of the ball mill for grinding raw ore. the inner side of the cylinder is covered with rubber liner. The rubber is easily worn down because the rubber relatively soft compared with raw ore. So the rubber liner in the ball mill cylinder must be replaced almost every year and the cost for replacing rubber liner formidable. In this paper, for reducing or excluding the cost of replacing rubber liner the basalt liner is designed. The basalt materials are generally harder than raw ore and the basalt liner in the ball mill does not wear down and so it can be used almost permanently. The concave surfaces are made on the liner of the ball mill and the liner in the cylinder wall plays also the role of raising the steel balls mixed in the raw ore. The section profiles of the concave surface have an important effect on the performance of the ball mill. The deep concave grooves raise the steel balls to high levels and give the large potential energy to the steel balls impacting to the raw ore. But if the concave grooves are too deep. the steel balls raised too high by the concave grooves fly along the parabolic path and reach to the other side of cylinder wall and so the steel balls do not play the roles of grinding the raw ore. The forces acting to a steel ball in a concave groove of the cylinder liner are also analyzed in this paper. The formulas calculating the height and the impact point of the steel ball are introduced and presented. Based to these formulas, the optimum section profiles of the basalt liner are presented.