• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.565-566
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• 2006

Slurry used in metal chemical mechanical polishing normally consists of an oxidizer, a complexing agent, a corrosion inhibitor and an abrasive. This paper investigates effects of citric acid as a complexing agent for Cu CMP with $H_2O_2$ as an oxidizer. In order to study chemical effects of a citric acid, x-ray photoelectron spectroscopy were performed on Cu sample after Cu etching test. XPS results reveal that CuO, $Cu(OH)_2$ layer decrease but Cu/$Cu_2O$ layer increase on Cu sample surface. To investigate nanomechanical properties of Cu sample surface, nanoindentation was performed on Cu sample. Results of nanoindentation indicate wear resistance of Cu Surface decrease. According to decrease of wear resistance on Cu surface, removal rate increases from $285\;{\AA}/min$ to $8645\;{\AA}/min$ in Cu CMP.

• Proceedings of the KSME Conference
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• 2001.06c
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• pp.71-76
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• 2001

In general, it is known that the wear rate of the abrasive and the removal rate of the metal bond of the grinding wheel should be balanced to maintain the depth of the insulating surface layer to an appropriate level. In order to accomplish, the high quality ELID grinding, therefore, it is necessary to measure the depth of the insulating layer in real-time and then to control the electrolytic conditions to keep the depth to a certain level. In this study, an in-process measurement system of the insulated layer using two gap sensors - a capacitor type and an eddy current type - developed and the change of the status of the insulated layer during ELID grinding is detected. And from the experimental data, we have chosen the best mathematical model to predict the depth of the insulating layer.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.48-52
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• 2004

Ultrasonic machining is effective for machining of extreme hard and brittle materials, including glass, ceramic, carbide, graphite. The major machining principle involves the direct hammering as well as the impact of abrasive panicles on the workpiece. Also, it involve cavitation erosion. The general workpiece is flat side. This study attempted micro hole machining of a curved surface of glass tube. Ultrasonic machining is fault of the slow machining speed. An experiment does and got 16 seconds validity machining time as increasing the processing speed. Moreover, entrance crack and surface roughness was similar both machining speed is slow and fast. Several micro hole of glass tube machined using one micro tool, but tool wear is infinitesimal.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.956-959
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• 2002

In this work, a new non-lithographic micro-fabrication technique is presented. The motivation of this work is to overcome the demerits of the most commonly used photo-lithographic techniques. The micro-fabrication technique presented in this work is a two-step process which consists of mechanical scribing followed by chemical etching. This method has many advantages over other micro-fabrication techniques since it is simple, cost-effective, rapid, and flexible. Also, the technique can be used to obtain a metal structure which has sub-micrometer width patterns. In this paper, the concept of this method and its application to microsystem technology are described.

• International Journal of Precision Engineering and Manufacturing
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• v.4 no.5
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• pp.22-26
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• 2003

In this work, a new non-photolithographic micro-fabrication technique is presented. The motivation of this work is to overcome the demerits of the most commonly used photolithographic techniques. The micro-fabrication technique presented in this work is a two-step process which consists of mechanical scribing followed by chemical etching. This method has many advantages over other micro-fabrication techniques since it is simple, cost-effective, rapid, and flexible. Also, the technique can be used to obtain a metal structure which has sub-micrometer width patterns. In this paper, the concept of this method and its application to microsystem technology are described.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.11
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• pp.228-233
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• 2002

In this work, a new non-photolithographic micro-fabrication technique is presented. The motivation of this work is to overcome the demerits of the most commonly used photolithographic techniques. The micro-fabrication technique presented in this work is a two-step process which consists of mechanical scribing followed by chemical etching. This method has many advantages over other micro-fabrication techniques since it is simple, cost-effective, rapid, and flexible. Also, the technique can be used to obtain a metal structure which has sub-micrometer width patterns. In this paper, the concept of this method and its application to microsystem technology are described.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.3
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• pp.21-27
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• 1997

This paper aims to clarify the effects of grinding conditions in form grinding of Sr-ferrite with the electro-plated diamond wheel. The main conclusions obtained were as follows. (1) The flexural strength and surface roughness of ferrite became the best at the peripheral wheel speed of 1700 m/min. (2) In the case of the depth of cut larger than 0.4mm, crack layers is induced in the ground surface, and the fracture type of chips exhibits slight ductile mode in the depth of cut smaller than 0.2mm. (3) Whe the depth of cut exceeds 0.6mm, the wheel life becomes extremely severe due to the large chipping and brack- age in the diamond grains. However, at the depth of cut .leq. 0.05mm, the diamond grain shows abrasive wear. (4) The decrease of flexural strength and the increase of surface roughness is in proportion to the increase of the feed rate. (5) Most effective nozzle setting angles with various delivery conditions of the grinding fluid, such as nozzle position .PHI. , flow rate Q, etc., were made clear.

• Tribology and Lubricants
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• v.18 no.3
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• pp.204-210
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• 2002

Automotive brake pads with four different sizes of zircon particles (average sizes of 1㎛, 6㎛, 75㎛, and 140㎛, respectively) were investigated to evaluate the size effect of abrasive particles on friction performance. Results showed that the brake pads with the larger size of zircon particles tend to show better frictional stability and low pad wear. However, the rotor surface was severely abraded in the case of using larger zircon particles. On the other hand, the small zircon particles in the pads showed the fast increase of the coefficient of friction with friction force oscillation and the tendency was pronounced at low sliding speeds. The brake pads with small particle sizes also exhibited strong fade phenomena at elevated temperatures.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.7
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• pp.1280-1287
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• 2002

The old technique of sandblasting which has been used for decoration of glass surface has recently been developed into a powder blasting technique for brittle materials such as glass, silicon and ceramics, capable of producing micro structures larger than $100{\mu}$ m. This paper describes the performance of powder blasting technique in micro-line grooving of glass and the effect of the number of nozzle scanning on the depth and width of line groove. Experimental results showed that increasing the no. of nozzle scanning resulted in the increase of depth and width in grooves. Increase of width which may cause several problems in the precision machining results from wear of mask film. Therefore, well-controlled masking process is the most important factor for micro machining of glass with accuracy.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.1060-1063
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• 2001

The mechanical etching technique has recently been developed to a powder blasting technique for various materials, capable of producing micro structures larger than 100$\mu$m. This paper describes the performance of powder blasting technique in micro-pocketing of stainless steel and the effect of the number of nozzle scanning and the nozzle height on the depth and width of pockets. Experimental results showed that increasing the no. of nozzle scanning and decreasing the nozzle height resulted in the increase of depth and width in pockets. Increase of width results from wear of mask film.