• 청정기술
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• 제21권2호
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• pp.85-89
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• 2015

다양한 전자부품에 활용되는 금속 잉크 기술은 전자부품산업의 주요 기술로 자리매김하였으며 이에 대한 연구 개발이 점차 증가하고 있다. 그 중에서 실버 잉크는 뛰어난 전도성과 안정성을 가지고 있어서 전자부품산업에 오랫동안 이용되어 왔으며 최근에는 입자 크기를 나노 크기로 분산시킨 실버 나노 잉크를 개발하여 디스플레이, 전자태그, 반도체와 연성회로 기판 등에 사용되는 전자소재로써 각광받고 있다. 그러나 이러한 전자산업기기의 첨단화는 제품의 생산량과 소비량을 증가시켜 제조 공정 중에 발생되는 환경오염 물질과 사용하고 버려지는 제품들에 의해 심각한 환경 문제를 가져올 것으로 예상된다. 따라서 본 연구에서는 습식환원법에 의해 제조된 실버나노 잉크의 제조 공정이 환경에 미치는 영향을 전과정평가(life cycle assessment, LCA) 기법을 이용하여 평가하였다. 전과정 평가 소프트웨어로는 GaBi 6를 사용하였고, 유관기관으로부터 받은 실버 나노 잉크의 제조 공정 데이터를 참고하여, 인벤토리를 구축하였으며 전과정목록분석(international organization for standardization, ISO) 14040, 14044 규격의 4단계에 걸쳐 LCA를 수행하였다.

• 한국분말재료학회지
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• 제30권4호
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• pp.318-323
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• 2023

The thermoelectric effect, which converts waste heat into electricity, holds promise as a renewable energy technology. Recently, bismuth telluride (Bi2Te3)-based alloys are being recognized as important materials for practical applications in the temperature range from room temperature to 500 K. However, conventional sintering processes impose limitations on shape-changeable and tailorable Bi₂Te₃ materials. To overcome these issues, three-dimensional (3D) printing (additive manufacturing) is being adopted. Although some research results have been reported, relatively few studies on 3D printed thermoelectric materials are being carried out. In this study, we utilize extrusion 3D printing to manufacture n-type Bi_1.7Sb_0.3Te₃ (N-BST). The ink is produced without using organic binders, which could negatively influence its thermoelectric properties. Furthermore, we introduce graphene oxide (GO) at the crystal interface to enhance the electrical properties. The formed N-BST composites exhibit significantly improved electrical conductivity and a higher Seebeck coefficient as the GO content increases. Therefore, we propose that the combination of the extrusion 3D printing process (Direct Ink Writing, DIW) and the incorporation of GO into N-BST offers a convenient and effective approach for achieving higher thermoelectric efficiency.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 춘계학술발표대회
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• pp.1.1-1.1
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• 2011

Printed electronics based on the direct writing of solution processable functional materials have been of paramount interest and importance. In this talk, the synthesis of printable inorganic functional materials (conductors and semiconductors) for thin-film transistors (TFTs) and photovoltaic devices, device fabrication based on a printing technique, and specific characteristics of devices are presented. For printable conductor materials, Ag ink is designed to achieve the long-term dispersion stability and good adhesion property on a glass substrate, and Cu ink is sophisticatedly formulated to endow the oxidation stability in air and even aqueous solvent system. The both inks were successfully printed onto either polymer or glass substrate, exhibiting the superior conductivity comparable to that of bulk one. In addition, the organic thin-film transistor based on the printed metal source/drain electrode exhibits the electrical performance comparable to that of a transistor based on a vacuum deposited Au electrode. For printable amorphous oxide semiconductors (AOSs), I introduce the noble ways to resolve the critical problems, a high processing temperature above $400^{\circ}C$ and low mobility of AOSs annealed at a low temperature below $400^{\circ}C$. The dependency of TFT performances on the chemical structure of AOSs is compared and contrasted to clarify which factor should be considered to realize the low temperature annealed, high performance AOSs. For photovoltaic application, CI(G)S nanoparticle ink for solution processable high performance solar cells is presented. By overcoming the critical drawbacks of conventional solution processed CI(G)S absorber layers, the device quality dense CI(G)S layer is obtained, affording 7.3% efficiency CI(G)S photovoltaic device.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2010년도 춘계학술발표대회
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• pp.18.2-18.2
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• 2010

For the past a few years, we have intensively researched the printable inorganic conductors and ZnO-based amorphous oxide semiconductors (AOSs) for thin-film transistors. For printable conductor materials, we have focused on the aqueous Ag and Cu ink which possess a variety of advantages, comparing with the conventional metal inks based on organic solvent system. The aqueous Ag ink was designed to achieve the long-term dispersion stability using a specific polymer which can act as a dispersant and capping agent, and the aqueous Cu ink was carefully formulated to endow the oxidation stability in air and even aqueous solvent system. The both inks were successfully printed onto either polymer or glass substrate, exhibiting the superior conductivity comparable to that of bulk one. For printable ZnO-based AOSs, we have researched the noble way to resolve the critical problem, a high processing-temperature above $400^{\circ}C$, and recently discovered that Ga doping in ZnO-based AOSs promotes the formation of oxide lattice structures with oxygen vacancies at low annealing-temperatures, which is essential for acceptable thin-film transistor performance. The mobility dependence on annealing temperature and AOS composition was analyzed, and the chemical role of Ga are clarified, as are requirements for solution-processed, low-temperature annealed AOSs.

• 한국인쇄학회지
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• 제25권1호
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• pp.43-52
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• 2007

Offset printing is one of the well known printing technique of lithographic process and consists of image area and 'non-image area on a flat image carrier. The surface tension of dampening water can be controlled by adding IPA after mixing of raw water and etching solution. The etching solution contains a surfactant for reducing surface energy, a clean agent for non-imaging area, wetting agent for protecting non-imaging area from oil components like ink and also an emulsifying agent for controlling emulsification. In this study, the present situation of dampening water maintenance has examined by collecting dampening water using at domestic companies. The pH related to dampening water, conductivity, contact angle, emulsification curve are measured to define the current situation of dampening water control of each companies and to analyze the relationship among measured properties. In the study most of companies among 16 printing companies tested controlling dampening water through pH value. However, the quality of printing has varied depending upon conductivity, contact angle, IPA content, and emulsification value. The control of dampening water should be carry at the state of the standard when adding proper ratio of etching solution. It would be more effective when pH or conductivity control carries out in parallel with controlling dampening water. Therefore the concept that pH5.5 is correct is based concept. Based on these initial tests it is defined that the standardization of dampening water control is required.

• 한국기계가공학회지
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• 제18권12호
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• pp.82-90
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• 2019

This analysis demonstrates the effective removal of heat generated from a solar panel's output degradation factor solar cells (the solar panel's output deterioration factor), and solves the problems of oxidation and corrosion in existing metal heat sinks. The heat-dissipating test specimen was prepared using carbon materials; then, its thermal conductivity and its effectiveness in reducing temperatures were studied using heat transfer numerical analysis. As a result, the test specimen of the 30g/㎡ basis weight containing 80% of carbon fiber impregnated with carbon ink showed the highest thermal conductivity 6.96 W/(m K). This is because the surface that directly contacted the solar panel had almost no pores, and the conduction of heat to the panels appeared to be active. In addition, a large surface area was exposed to the atmosphere, which is considered advantageous in heat dissipation. Finally, numerical analysis confirmed the temperature reduction effectiveness of 2.18℃ in a solar panel and 1.08℃ in a solar cell, depending on the application of heat dissipating materials.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.154-154
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• 2006

글씨 전도성 잉크의 인쇄공정에 있어서 반복인쇄를 정밀하게 수행할 수 있는 기술로서 align system을 개발하였다. 이 system의 resolution 은 0.5um 이며 인쇄 working plate의 이송속도는 최대 1.5m/s 이다. 현재 소성 공정을 포함한 반복인쇄 실험은 30um이상의 drop탄착점 오차를 보이고 있으며, 두께와 전기전도도 향상을 위한 정밀한 align system이 필요하게 되었다. 이를 충족시키기 위해 개발되어진 초정밀 align system은 $1{\sim}2{\mu}m$이내의 오차로 반복인쇄가 가능하며, head가 토출하는 잉크의 straightness 및 전도성 잉크를 토출하는 인쇄평가기의 기계적 정밀도도 확인할 수 있다. 모든 잉크 배선의 두께 항상 인쇄실험이 가능하며, substrate의 종류와 잉크에 제한적이지 않다. 특히 prototype의 기판배선을 위해 PCB에 배선을 형성할 시에 본 system으로 직접 align mark를 지정할 수 있어 기판 내에 미리 제작되어진 align용 인식마크가 불필요하다. 이 system을 이용하여 drop과 배선의 반복인쇄실험을 진행하였으며, 광학현미경과 3D profiler를 사용하여 분석해 보았다.

• 한국표면공학회지
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• 제48권4호
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• pp.158-162
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• 2015

To substitute indium tin oxide (ITO), many substituents have been studied such as metal nanowires, carbon based materials, 2D materials, and conducting polymers. These materials are not good enough to apply to an electrode because theses exhibit relatively high resistance. So metal grids are required as an additionalelectrode to improve the conductivities of substituents. The metal grids were printed by electrohydrodynamic printing system using Ag nanoparticle based ink. The Ag grids showed high uniformity and the line width was about $10{\mu}m$. The Ag nanoparticles are surrounded by dispersants such as unimolecular and polymer to prevent aggregation between Ag nanoparticles. The dispersants lead to low conductivity of Ag grids. Thus, the sintering process of Ag nanoparticles is strongly recommended to remove dispersants and connect each nanoparticles. For sintering process, the interface and microstructure of the Ag grid were controlled in 1.0 torr Ar atmosphere at aound $400^{\circ}C$ of temperature. From the sintering process, the uniformity of the Ag grid was improved and the defects on the Ag grids were reduced. As a result, the resistivity of Ag grid was greatly reduced up to $5.03({\pm}0.10){\times}10^{-6}{\Omega}{\cdot}cm$. The metal grids embedded substrates containing low pressure Ar sintered Ag grids showed 90.4% of transmittance in visible range with $0.43{\Omega}/{\square}$ of sheet resistance.

• 한국정밀공학회지
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• 제27권9호
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• pp.20-25
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• 2010

The effect of micro surface structure on printing for printed electronics has been studied experimentally. The photolithography MEMS fabricationwass used to make a SU-8 molder which has micro structures on the surface, and the PDMS micro structure was fabricated by the PDMS molding method. In the aspect of printed electronics, we used silver paste conductive ink. We measured the surface energy variation on pillar microstructure. The microstructure was used to real printing experiment by a screen printing. We printed 1cm micro lines which have $30{\sim}250{\mu}m$ width, and checked the conductivity to sort out opened line pattern. Printability was defined by success probability of printed patterns and we found that the present microstructures improve the printability significantly.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2012년도 춘계학술발표대회
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• pp.63.1-63.1
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• 2012

In recent years, the functional inks for printed electronics that can be combined with a variety of printing techniques have attracted increasingly significant interest for use in low cost, large area, high performance integrated electronics and microelectronics. In particular, the development of solution-processable conductor, semiconductor and insulator materials is of great importance as such materials have decisive impacts on the electrical performance of various electronic devices, and, therefore, need to meet various requirements including solution processability, high electrical performance, and environmental stability. Semiconductor inks such as IGO, CIGS are synthesized by chemical solution method and microwave reaction method for TFT and solar cell application. Fine circuit pattern with high conductivity, which is valuable for flexible electrode for PCB and TSP devices, can be printed with highly concentrated and stabilized conductor inks such as silver and copper. Solution processed insulator such as polyimide derivatives can be use to all printed TFT device. Our research results of functional inks for printed electronics provide a recent trends and issues on this area.