• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.1
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• pp.87-92
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• 2010

Micromachining technology using a ultra-precision micromachining system is widely applied in the fields of optics, biotechnology and analytical chemistry, etc. specially in microfabrication of fresnel lens, light guide panels of TFT-LED and PDP ribs with micro-patterns, machining errors have an effect on the performance of those products. The deflection of tool and tool holder is known to be one of the very important factors that is due to machining errors in micromachining. The deflections of diamond tool and tool holder used in micro-grooving are analysed by FEM. We analysed by FEM. With an linearity valuation of FEM, deflection of tool and tool holder is calculated by using the data of cutting force which is acquired from micro-V groove machining experiments in micromachining system.

• Korean Journal of Metals and Materials
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• v.48 no.1
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• pp.90-100
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• 2010

Micro-conductive patterns were microfabricated on an insulating substrate ($SiO_2$) surface by a selective electroless nickel plating process in order to investigate the formation of seed layers. To fabricate micro-conductive patterns, a thin layer of metal (Cu.Cr) was deposited in the desired micropattern using laser-induced forward transfer (LIFT). and above this layer, a second layer was plated by selective electroless plating. The LIFT process. which was carried out in multi-scan mode, was used to fabricate micro-conductive patterns via electroless nickel plating. This method helps to improve the deposition process for forming seed patterns on the insulating substrate surface and the electrical conductivity of the resulting patterns. This study analyzes the effect of seed pattern formation by LIFT and key parameters in electroless nickel plating during micro-conductive pattern fabrication. The effects of the process variables on the cross-sectional shape and surface quality of the deposited patterns are examined using field emission scanning electron microscopy (FE-SEM) and an optical microscope.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.709-713
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• 2004

Characteristics of laser-assisted wet etching of titanium in phosphoric acid were investigated to examine the feasibility of this method for fabrication of high aspect ratio microchannels. Laser power, number of scans, etchant concentration, position of beam waist and scanning speed were taken into consideration as the major process parameters exerting the temperature distribution and the cross sectional profile of etched channels. Experimental results indicated that laser power influences on both etch width and depth while number of scans and scanning speed mainly affect on the etch depth. At a low etchant concentration, the cross sectional profile of an etched channel becomes a U-shape but it gradually turns into a V-shape as the concentration increases. On the other hand, surface of the laser beam focus with respect to the sample surface is found to be a key factor determining the bubble dynamics and thus the process stability. It is demonstrated that metallic microchannels with different cross sectional profiles can be fabricated by properly controlling the process parameters. Microchannels of aspect ratio up to 8 with the width and depth ranges of 8∼32 m and 50∼300 m, respectively, were fabricated.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.4
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• pp.106-112
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• 2021

Thermoplastic microfluidic devices are used in BioMEMS for medical and biotechnology applications, such as gene extraction, DNA analysis, and virus detection. In this research, a simple fabrication protocol with a commercially available pneumatic hot press is proposed and demonstrated for polycarbonate microfluidic devices. Microfluidic channels with a width of 200 ㎛ and a height of 10 ㎛ were designed and machined onto a brass plate as a mold insert using a CNC milling machine. The resulting microfluidic channels on the mold insert were assessed and found to have an actual width of 198 ㎛ and a height of 10 ± 0.25 ㎛. The microfluidic channels were replicated on a polycarbonate sheet using the proposed replication technique at 146℃ for 20 minutes under a constant load of 2400 kgf. The devices were then naturally cooled to 100℃ while maintaining the same pressure. It was found that the microchannels were successfully replicated in the polycarbonate, with a width of 198 ㎛ and a height of 10.07 ㎛. The proposed replication technique thus offers the rapid mass production of high-quality microfluidic devices at a low cost with a process that, unlike conventional photolithography systems, does not require expensive equipment.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.497-502
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• 2002

This paper describes a design methodology of a tri-axial silicon-based farce sensor with square membrane by using micromachining technology (MEMS). The sensor has a maximum farce range of 5 N and a minimum force range of 0.1N in the three-axis directions. A simple beam theory was adopted to design the shape of the micro-force sensor. Also the optimal positions of piezoresistors were determined by the strain distribution obtained from the commercial finite element analysis program, ANSYS. The Wheatstone bridge circuits were designed to consider the sensitivity of the force sensor and its temperature compensation. Finally the process for microfabrication was designed using micromachining technology.

• Laser Solutions
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• v.3 no.2
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• pp.25-33
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• 2000

One of perspective direction of microfabrication is direct laser writing technology that allows to create metal, semiconductive and dielectric micropatterns on substrate surface. In this work, a two step method, the combination of seed forming process, in which metallic Al seed was selectively generated on AlN ceramic substrate by direct writing technique using a pulsed Nd : YAG laser and subsequent electroless Ni plating on the activated Al seed, was presented. The effects of laser parameters such as pulse energy, scanning speed and pulse frequency on shape of Alseed and conductor line after electroless Ni plating were investigated. The nature of the laser activated surface is analyzed from XPS data. The line width of this metallic Al and Ni is analyzed using SEM. As a results, Al seed line with 24㎛ width and 100㎛ isolated line space is obtained. Finally, laser direct writing can be applied in the field between thin and thick film technique in electronic industry.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.12
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• pp.2221-2225
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• 2007

Hollow-type microneedle array can be used for painless, continuous and stable drug delivery through a human skin. The needles must be sharp and have sufficient length in order to penetrate the epidermis. An array of hollow-type silicon microneedles was fabricated by using deep reactive ion etching and HNA wet etching with two oxide masks. Isotropic etching was used to create tapered tips of the needles, and anisotropic etching of Bosch process was used to make the extended length and holes of microneedles. The microneedles were formed by three steps of isotropic, anisotropic, and isotropic etching in order. The holes were made by one anisotropic etching step. The fabricated microneedles have $170{\mu}m$ width, $40{\mu}m$ hole diameter and $230{\mu}m$ length.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1433-1436
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• 2008

Flagellate bacteria such as Escherichia coli or Serratia marcescens possess a remarkable motility system based on a reversible rotary motor. We have employed S. marcescens as microactuators in low Reynolds number fluidic environments to move a larger engineering element around. Microstructures fabricated using conventional microfabrication techniques are blotted on the swarm plate, which leaves a bacterial monolayer on the surface of the microstructure. We have investigated microstructures powered by bacteria to determine how cell orientation on the microstructure surface relates to the swarming patterns as well as how the orientation is affected by the blotting process. This study will help to refine directional control of bacterial transporters by exploiting bacterial sensory mechanisms.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.18 no.6
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• pp.636-641
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• 2009

Recently, expansion of micro-technology parts requires micro-precision machining technology. Micro-groove machining is important to fabricate micro-grating lens and many micro-parts such as microscope lens, fluidic graphite channel etc. Conventional groove fabrication methods such as etching and lithography have some problems in efficiency and surface integrity. But, mechanical micromachining methods using single crystal diamond tools can reduce these problems in chemical process. For this reason, microfabrication methods are expected to be very efficient, and widely studied. This study deals with machinability in micro-precision V-grooves machining of nickel plated layer using non-rotational single crystal diamond tool and 3-axis micro stages. Micro V-groove shape, chip formation and tool wear were investigated for the analysis of machinability of Ni plated layer.

• Polymer(Korea)
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• v.29 no.4
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• pp.418-421
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• 2005

Three-dimensional (3D) microfabrication process using two-photon polymerization (TPP) is developed to fabricate the curved microstructures in a layer, which can be applied potentially to optical MEMS, nano/micro-devices, etc. A 3D curved structure can be expressed using the same height-contours that are defined by symbolic colors which consist of 14 colors. Then, the designed bitmap figure is transformed into a multi-exposure voxel matrix (MVM). In this work a multi-exposure voxel matrix scanning method is used to generate various heights of voxels according to each laser exposure time that is assigned to the symbolic colors. An objective lens with a numerical aperture of 1.25 is employed to enlarge the variation of a voxel height in the range of 1.2 to 6.4 um which can be controlled easily using the various exposure time. Though this work some 3D curved micro-shapes are fabricated directly to demonstrate the usefulness of the process without a laminating process that is generally required in a micro-stereolithography process.