• Journal of the Korean Ceramic Society
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• v.41 no.4
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• pp.313-322
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• 2004

Thick film photolithography is a new technology in that the lithography process such as exposure and development is applied to the conventional thick film process including screen-printing. In this research, low-temperature cofireable silver paste, which enabled the formation of thick film fine-line using photolithographic technology, was developed. The optimum composition for fine-line forming was studied by adjusting the amounts of silver powder, polymer and monomer, and the additional amount of photoinitiator, and then the effect of processing parameter such as exposing dose on the formation of fine-line was also tested. As the result, it was found that the ratio of polymer to monomer, silver powder loading, and the amount of photoinitiator were the main factors affecting the resolution of fine-line. The developed photosensitive silver paste was printed on low-temperature cofireable green sheet, then dried, exposed, developed in aqueous process, laminated, and fired. Results showed that the thick film fine-line under 20$\mu\textrm{m}$ width could be obtained after cofiring.

• Journal of Crop Science and Biotechnology
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• v.10 no.3
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• pp.163-166
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• 2007

Diurnal changes in levels of endogenous gibberellins(GAs) were investigated in three rice cultivars i.e. Sangjubyeo, Shingeumobyeo(photo-neutral) and Chucheongbyeo(photosensitive). The rice cultivars were grown under a 12-hr photoperiod and endogenous GA levels were assayed by gas chromatography-mass spectrometry(GC-MS-SIM) every 3 h for 24 h. The endogenous bioactive $GA_1$ and its immediate precursor $GA_{20}$ contents were significantly different in both photosensitive and photo-neutral rice cultivars, though less pronounced differences were observed for endogenous $GA_{12},\;GA_{53},\;GA_{19}$, and $GA_8$ levels with in the three rice cultivars. The levels of bioactive $GA_1$ and its immediate precursor $GA_{20}$ were significantly higher in Chucheongbyeo than in the other two cultivars. In Chucheongbyeo, the $GA_1$ contents increased significantly from 11.00 to 17.00 o'clock, thus indicating a correlation with light. In Shingeumobyeo, $GA_1$ contents slightly increased during morning hours, while a similar hike in $GA_1$ contents was observed for Sangjubyeo during evening hours. $GA_{19}$ was found to be the most abundant GA form in the three rice cultivars. Our results suggested that GA production in rice depends upon the response potential of rice cultivars and that light positively correlated to GA production in photosensitive rice cultivar.

• Journal of the Korean Ceramic Society
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• v.41 no.1
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• pp.13-18
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• 2004

$La_{0.5}Sr_{0.5}CoO_3$ (LSCO) electrodes were prepared on ferroelectric $Sr_{0.9}Bi_{2.1}Ta_2O_9$(SBT) thin films by spin coating method using photosensitive sol-gel solution. Self-patterning technique of photosensitive sol-gel solution has advantages such as simple manufacturing process compared to photoresist/dry etching process. Lanthanum(III) 2-methoxyethoxide, Stronitium diethoxide. Cobalu(II)2-methoxyethoxide were used as starting materials for LSCO electrode. UV irradiation on LSCO thin films lead to decrease solubility by M-O-M bond formation and the solubility difference allows us to obtain self-patternine. There was little composition change of the LSCO thin films between before leaching and after leaching in 2-methoxyethanol. The lowest resistivity of LSCO thin films deposited on $SiO_2$/Si substrate was $1.1{\times}10^{-2}{\Omega}cm$ when the thin film was ennealed at $740^{\circ}C$. The values of Pr/Ps and 2Pr of LSCO/SBT/Pt capacitor on the applied voltage of 5V were 0.51, 8.89 ${\mu}C/cm^2$, respectively.

• Polymer(Korea)
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• v.28 no.6
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• pp.494-501
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• 2004

A new alkali developable photosensitive poly(amic acid) (PAA-0) with transmittance at 400 nm was synthesized from cyclobutane-1,2,3,4-tetracarboxylic dianhydride, 2-(methacryloyloxy)ethyl-3,5-diamino-benzoate and 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyl disiloxane in N-methyl-2-pyrrolidinone. Photosensitivity of the PAA-0 was investigated at 365-400 nm in the presence of a photoinitiator using a high pressure mercury lamp. The photo-cured poly(amic acid) was insoluble toward aqueous 2.38 wt% tetramethylammonium hydroxide solution. Negative pattern of the PAA-0 with 25 ${\mu}{\textrm}{m}$ resolution was obtained by developing with 2.38 wt% tetramethylammonium hydroxide solution after exposure of 600 mJ/$\textrm{cm}^2$ in the presence of 2,2-dimethoxy-2-phenyl-acetophenone as a photoinitiator. The patterned poly(amic acid) was converted to polyimide by thermal curing at 25$0^{\circ}C$ for 50 min, which showed chemical resistance against photoresist stripper as well as good transmittance at 400 nm.

• Polymer(Korea)
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• v.26 no.6
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• pp.701-709
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• 2002

To synthesize a new positive photosensitive polyimide precursor, parts of carboxylic acid groups in poly (amic acid) were esterified with 4,5-dimethoxy-2-nitrobenzyl bromide in the presence of K$_2$CO$_3$/HMPA followed by the chemical imidization of residual carboxylic acid units. The chemical structure of resulting polymer was characterized by $^1$H-NMR, UV/vis and FT-IR spectroscopic methods, and its thermal properties were examined by DSC and TGA. Upon UV irradiation, 4,5-dimethoxy-2-nitrobenzyl moiety underwent the photodegradation. As a result, the polymer became soluble in alkaline developer due to the formation of carboxylic acid moiety, which was used to make a micron-sized positive pattern. Sensitivity curves were obtained from the gel fraction experiments with respect to the various 4,5-dimethoxy-2-nitrobenzyl ester contents. From those curves, the sensitivity was ranged iron 4000 to 6000 mJ/㎠, and the contrast was measured to be from 3.1 to 4.9.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.6
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• pp.506-511
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• 2009

For the application of the photosensitive barrier ribs with optimal properties such as glass transition temperature, refractive index and coefficient thermal expansion, the boro-silicate glasses was studied. The glass transition temperature, coefficient thermal expansion, and refractive index of the glasses based on the $B_2O_3-Al_2O_3-Al_2O_3-SiO_2$ glass system have been investigated with the different ratio of BaO/$Na_2O$ and $B_2O_3/Na_2O$. Increasing the ratio of $B_2O_3/Na_2O$ was led to the increase of coefficient thermal expansion and the decrease of glass transition temperature. The increase of refractive index of boro-silicate glasses increased with the density of glasses. We suggest the empirical equation for the prediction of refractive index with the glass density, $n=0.123{\rho}+1.182$ with 0.042 as the standard deviation in the boro-silicate glass system. The aim of the present paper is to give a basic result of the thermal and optical properties for designing the composition of photosensitive barrier ribs in PDP.

• Polymer(Korea)
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• v.26 no.5
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• pp.634-643
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• 2002

Ultrathin film of polyamic acid having benzene and sulfonyloxyimide moieties was prepared using the Langmuir-Blodgett (LB) technique, and then photosensitive polyimide LB film was obtained by the thermal treatment of precursor polyamic acid multilayers at 200$\^{C}$ for 1 hr. The polyamic acid was synthesized by condensation polymerization under THF and pyridine cosolvent. All monomers and polymers were identified through elemental analysis, FT-IR and $^1$H-NMR spectroscopic measurements. The microarray patterning of photosensitive polyimide LB film on a gold substrate was generated with a deep UV lithography technique. The well-characterized monolayer of cytochrome c was immobilized on the microarray patterns using two different self-assembly processes. Physical and electrochemical properties of the self-assembled cytochrome c monolayer were investigated based on cyclic voltammetry and atomic force microscopy (AFM). Also, its application in bioelectronic device was examined.

• Applied Chemistry
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• v.15 no.1
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• pp.17-20
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• 2011

A disposable light exposure detector kit has been developed by UV curing of a hydrogel material. The devised light exposure detector kit consisted of light sensitive structures, bottom plate, character sheet and sticky back plate. A light exposure detector kit has a serial light sensitive structures that contain various light sensitive dyes such as rhodamine and fluorescein. The light sensitive structure composed of UV curable hydrogel polymer material as a supporing material and photosensitive dye in a certain concentration. The fabrication procedure of the ligh exposure detector kit is very simple and fast due to UV curing procedure of a photopolymerizable hydrogel material such as poly(ethylene glycol) methyl ether acrylate (PEGMEA) and poly(ethylene glycol) diacrylate (PEGDA) with a photosensitive dye. By the proposed fabrication method, various size and shape of a light exposure detector kit could be fabricated using a flexible elastomer mold. Due to a fast and inexpensive fabrication method, the light exposure detector kit could be use a single use for various industrial applications. According to light irradation, the light sensitive structure on a light exposure detector kit could be lose its color by decomposition of a photosensitive dye chemical in the structure. Thus the amount of the exposed light on a substrate could easily be recognised by changing color or transparency of the structure.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.10a
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• pp.617-618
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• 2006

• Proceedings of the Optical Society of Korea Conference
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• 2007.02a
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• pp.225-226
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• 2007