• Electrical & Electronic Materials
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• v.10 no.7
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• pp.668-673
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• 1997

A Single-crystalline Mn-Zn Ferrite (110 orientation) was masklessly etched by focused Ar laser irradiation in an H$_3$PO$_4$ solution. The depth of the etched grooves increases with increasing a laser power, decreasing a scan speed, and increasing the H$_3$PO$_4$concentration. The width of the etched grooves increases with a increasing laser power, but was relatively insensitive to the scan speed and H$_3$PO$_4$concentration. High etching rate of up to 714 ${\mu}{\textrm}{m}$/s and an aspect ratio of 6 for vertical slab structure have been obtained by the light-guiding effect of the laser bean in the H$_3$PO$_4$ solution.

• Restorative Dentistry and Endodontics
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• v.29 no.3
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• pp.273-280
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• 2004

The purpose of this study was to evaluate the etching effects and bond strength of total etching and self-etching adhesive system on unground enamel using scanning electron microscopy and microtensile bond strength test. The buccal coronal unground enamel from human extracted molars were prepared using low-speed diamond saw. Scotchbond Multi-Purpose (group SM). Clearfil SE Bond (group SE), or Adper Prompt L-Pop (group LP) were applied to the prepared teeth. and the blocks of resin composite (Filtek Z250) were built up incrementally. Resin tag formation was evaluated by scanning electron microscopy. after removal of enamel surface by acid dissolution and dehydration. For microtensile bond strength test. resin-bonded teeth were sectioned to give a bonded surface area of $1\textrm{mm}^2$. Microtensile bond strength test was perfomed. The results of this study were as follows. 1. A definite etching pattern was observed in Scotchbond Multi-Purpose group. 2. Self-etching groups were characterized as shallow and irregular etching patterns. 3. The results (mean) of microtensile bond strength were SM: 26.55 MPa, SE: 18.15 MPa, LP: 15.57 MPa. SM had significantly higher microtensile bond strength than 8E and PL (p < 0.05). but there was no significant differance between SE and PL.

• 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.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.139.2-139.2
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• 2013

6" Multi-crystal Silicon wafer has etched suing a remote - type RF Dielectric barrier discharge (RF DBD) at atmospheric pressure. DBD source is composed of Al electrode and coated Al2O3 dielectric as function of Ar/NF3 gas combination and input power used 13.56 MHz power supply. Ar gas flow rate is changed from 2 to 10 Slm, and NF3 flow rate is changed from 0.2~1 slm. At the result, NF3 flow rate Si etching rate also increase whit the increasing of NF3 flow rate But at 2 slm etching rate was decrease. In this experience, Max etching rate is 2.3 ${\mu}m/min$ when the scan time is 45 sec.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.8
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• pp.12-16
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• 2002

It is confirmed that the ITO(Indium Tin Oxide) thin films can be etched by low-temperature plasma at atmospheric pressure. The etching happened deepest at a hydrogen flow rate of 4 sccm, and the etch rate was 120 /min. The etching speed corresponded to the H$\alpha$* emission intensity The etching mechanism of the ITO thin films is as follows; thin films were reduced by H$\alpha$*, and the metal compound residues were detached from the substrate by reacting on the CH* The etching was started after etching time of initial 50 sec and above the threshold temperature of 145$^{\circ}C$. The activation energy of 0.16 eV(3.75 Kcal/mole) was obtained from the Arrehenius plots.

• Korean Journal of Materials Research
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• v.27 no.9
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• pp.501-506
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• 2017

Surface morphology and optical properties such as transmittance and haze effect of glass etched by physical and chemical etching processes were investigated. The physical etching process was carried out by pen type sandblasting process with $15{\sim}20{\mu}m$ dia. of $Al_2O_3$ media; the chemical etching process was conducted using HF-based mixed etchant. Sandblasting was performed in terms of variables such as the distance of 8 cm between the gun nozzle and the glass substrate, the fixed air pressure of 0.5bar, and the constant speed control of the specimen stage. The chemical etching process was conducted with mixed etching solution prepared by combination of BHF (Buffered Hydrofluoric Acid), HCl, and distilled water. The morphology of the glass surface after sandblasting process displayed sharp collision vestiges with nonuniform shapes that could initiate fractures. The haze values of the sandblasted glass were quantitatively acceptable. However, based on visual observation, the desirable Anti-Glare effect was not achieved. On the other hand, irregularly shaped and sharp vestiges transformed into enlarged and smooth micro-spherical craters with the subsequent chemical etching process. The curvature of the spherical crater increased distinctly by 60 minutes and decreased gradually with increasing etching time. Further, the spherical craters with reduced curvature were uniformly distributed over the etched glass surface. The haze value increased sharply up to 55 % and the transmittance decreased by 90 % at 60 minutes of etching time. The ideal haze value range of 3~7 % and transmittance value range of above 90 % were achieved in the period of 240 to 720 minutes of etching time for the selected concentration of the chemical etchant.

• Journal of Technologic Dentistry
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• v.29 no.2
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• pp.141-150
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• 2007

The purpose of this study was to ascertain the bonding durability of self-etching dentin bonding agents to dentin by means of shear bonding strength. Several acid-etching dentin bonding system (ESPE Z100) and self-etching dentin bonding systems (DEN-FIL, GRADIA DIRET) were used. The occlusion surface of human molars were ground flat to expose dentin and treated with the etch bonding system according to manufactures instruction and followed by composite resin application. After 24hours of storage at 37$^{\circ}C$, the shear bonding strength of the specimens was measured in a universal testing machine with a 1mm/min crosshead speed. An one-way analysis of variance and the scheffe test were performed to identify significant differences (p<0.05). The bonded interfacial surfaces and treated dentin surfaces were examined using a SEM. Through the analysis of shear bond strength data and micro-structures of dentin-resin interfaces, following results are obtained. In dentin group, the shear bond strength of DEN-FIL showed statistical superiority in comparison to the other groups and followed by ESPE Z100 and GRADIA DIRECT (p<0.05).

• Journal of Institute of Control, Robotics and Systems
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• v.4 no.4
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• pp.506-516
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• 1998

In this paper, an algorithm is proposed to detect the malfunction of plasma-etching characteristics using EPD signal trajectories. EPD signal trajectories offer many information on plasma-etching process state, so they must be considered as the most important data sets to predict the wafer states in plasma-etching process. A recent work has shown that EPD signal trajectories were successfully incorporated into process modeling through critical parameter extraction, but this method consumes much effort and time. So Principal component analysis(PCA) can be applied. PCA is the linear transformation algorithm which converts correlated high-dimensional data sets to uncorrelated low-dimensional data sets. Based on this reason neural network model can improve its performance and convergence speed when it uses the features which are extracted from raw EPD signals by PCA. Wafer-state variables, Critical Dimension(CD) and uniformity can be estimated by simulation using neural network model into which EPD signals are incorporated. After CD and uniformity values are predicted, proposed algorithm determines whether malfunction values are produced or not. If malfunction values arise, the etching process is stopped immediately. As a result, through simulation, we can keep the abnormal state of etching process from propagating into the next run. All the procedures of this algorithm can be performed on-line, i.e. wafer to wafer.

• The Journal of Korean Academy of Prosthodontics
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• v.39 no.2
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• pp.184-196
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• 2001

The objective of this study was to investigate the influence of resin cements and ceramic etching on shear bond strength of Empress 2 ceramic and observe the change of microstructure of ceramic according to etching time. Sixty-six square ceramic specimens($6{\times}6{\times}1.5mm$) were prepared. 6 specimens were etched with different etching times(0, 10, 20, 30, 40 and 60 seconds) and observed by means of a scanning electron microscope(SEM). Other sixty specimens were divided into 6 groups with 10 specimens in each group. 3 groups were etched with 4% hydrofluoric acid and each groups was bonded with 3 resin cements(Variolink II, Super-Bond C&B, Panavia F). Each specimen was subjected to a shear load in an Instron at a cross-head speed of 0.5mm/min and was observed with SEM after mechanical testing to establish modes of failure. The results were as follows : 1. Within etched groups, Variolink II and Super-Bond C&B exhibited significantly greater bonding strengths than Panavia F(p<0.05) 2. Bond strength of etching groups had three to five times greater than that of no-etching groups. 3. All of no-etching groups showed adhesive failure and etching groups mostly showed mixed failure. And, 20-second etching specimen showed the most distinct lithium disilicate crystal. so it is considered that 20-second etching is optimal time for bonding.

• Laser Solutions
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• v.16 no.4
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• pp.12-16
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• 2013

For mass production of electronic devices, the processing of the printing roll is one of the most important key technologies for printed electronics technology. A roll of printing process, the gravure printing that is used to print the electronic device is most often used. The indirect laser processing has been used in order to produce printing roll for gravure printing. It consists of the following processing that is coating of photo polymer or black lacquer on the surface of printing roll, pattering using a laser beam and etching process. In this study, we have carried out study on the coating and etching for $25{\mu}m$ line width on the printing roll. To do this goals, a $4{\mu}m$ coating thickness and 20% average coating thickness of the coating homogeneity of variance is performed. The factors to determine the thickness and homogeneity are a viscosity of coating solution, the liquid injection, the number of injection, feed rate, rotational speed, and the like. After the laser patterning, a line width of $25{\mu}m$ or less was confirmed to be processed through etching and the chromium plating process.