• Journal of the Korean Society for Precision Engineering
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• v.24 no.5
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• pp.89-96
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• 2007

Inkjet printing has become one of the most attractive manufacturing techniques in industry. Especially inkjet printing technology will soon be part of the PCB (Printed Circuit Board) fabrication processes. Traditional printing on PCB includes screen printing and photolithography. These technologies involve high costs, time-consuming procedures and several process steps. However, by inkjet technology manufacturing time and production costs can be reduced, and procedures can be more efficient. PCB manufacturers therefore willingly accept this inkjet technology to the PCB industry, and are quickly shifting from conventional to inkjet printing. To produce the printed circuit board by the inkjet technology, it must be harmonized with conductive nano ink, printing process, system, and inkjet printhead. In this study, micro patterning of conductive line has been investigated using the piezoelectric printhead driven by a bipolar voltage signal is used to dispense 20-40 ${\mu}m$ diameter droplets and silver nano ink which consists of 1 to 50 nm silver particles that are homogeneously suspended in an organic carrier. To fabricate a conductive line used in PCB with high precision, a printed line width was calculated and compared with printing results.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.446-450
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• 2007

It is strongly expected that inkjet printing method will be play and important role on printable electronics such as 3D integration of embedded ceramic devices(capacitor, resistor, inductor and electrode or circuit), Si-TFT and organic TFT including display C/F, RFID, FPCB, and etc. A inkjet printing method had been center of attention to strengthen the competitiveness of flat panel display on market and to open the new world of manufacturing process of printable electronics. We will survey the industrial tendency of printable electronics and flat panel display including some examples of inkjet printing and present the considerable points of inkjet printing method and some role of materials for successful inkjet printing.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1476-1478
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• 2009

The characteristics of polymer inkjet printing were investigated systematically in this paper. PEDOT/PSS as a hole injection layer and MEH-PPV as a light emitting layer were used for inkjet printing experiment. Inkjet head controlling technology and surface modification technology were also applied for polymer inkjet printing. With the developed polymer inkjet printing technology, OLED(Organic Light Emitting Display) was successfully fabricated and demonstrated.

• Journal of Electrical Engineering and Technology
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• v.7 no.1
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• pp.91-96
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• 2012

We introduce an understanding of silver (Ag) inkjet overlap-printing characteristics from the viewpoints of cohesion between ink droplets and adhesion between an ink droplet and a surface. The printing characteristics were closely monitored by changing the surface energy to elucidate the effect of adhesion and cohesion on printing instability, such as droplet merging and line bulging. The surface energy of the substrate was changed through the hydrophilization of a hydrophobic fluorocarbon-coated surface. The surface energy and ink wettability of the prepared surfaces were characterized using sessile drop contact angle analysis, and printing instability was observed using an optical microscope after drop-on-demand inkjet printing with a 50% overlap in diameter of deposited singlet patterns. We found that the surface energy is not an appropriate indicator based on the experimental results of Ag ink printing on a hydrofluoric-treated silicon surface. The analytical approach using adhesion and cohesion was helpful in understanding the instability of the inkjet overlap-printing, as adhesion and cohesion represent the direct interfacial relationship between the Ag inks used and the substrate.

• Journal of the Korean Ceramic Society
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• v.48 no.6
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• pp.543-548
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• 2011

The inkjet printing technology has undergone remarkable development since the concept of printed electronics was first introduced. The large interest which it has sparkled is due to its many enticing features such as processing simplicity, low cost and scalability as well as its compatibility with flexible electronics. Thanks to constant improvements, inkjet printing has nowadays become a mature technology which is an effective replacement for a number of intricate and expensive conventional laboratory tools and is also on the verge of gaining industrial significance. Technological challenges which still remain open include low temperature processing, high density integration and reproducibility. This paper reviews some recent advances in the inkjet printing technology, addressing those issues. And we also discuss a number of novel approaches to performing inkjet printing.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.9
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• pp.833-840
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• 2015

Inkjet technology is one of the commonly used technologies in the printed-electronics field. The primary issue regarding the usage of inkjet technology as a printed-electronics tool is the printing resolution; therefore, to print complicated patterns of precise dimensions, we developed software that can convert a CAD file into a bitmap image. Moreover, as a bitmap image is not comprised of physical dimensions, its resolution needs to be defined in terms of pixel distance to print a rasterized bitmap image. In this study, we investigated the effects of pixel distance and dot size on printing resolution; based on the experiment results, we concluded that the printed dot size should be used to determine the optimal pixel distance. Lastly, we also propose inkjet printing procedures for bitmap images.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.523-525
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• 2008

Inkjet printing is being considered as an alternative to the conventional lithography in the electronic industry. Surface energy control of substrate is a critical issue in controlling the dimension of microstructures by the inkjet printing. This study introduces the surface energy control of ITO substrate for in/q'et printing of PEDOT/PSS.

• Electronics and Telecommunications Trends
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• v.38 no.1
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• pp.26-35
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• 2023

Inkjet printing is a typical printing technology with many advantages, such as material cost reduction, noncontact pattern formation without a mask, and process simplification. With the recent and rapid development of ink materials, parts and equipment, and process technologies related to inkjet printing, it is becoming a major process in various areas of the display industry. In particular, for the QD-OLED (quantum dot-organic light-emitting diode) display announced by Samsung Display in 2022, quantum dot pixel production by applying inkjet printing is a key technology. We analyze inkjet printing technology for mass production applied to the display industry and discuss the technology development trends in academia and industry toward the realization of next-generation displays.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.3.2-3.2
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• 2011

In recent years, inkjet printing technology has received significant attention as a micro/nanofabrication technique for flexible printing of electronic circuits and solar cells, as well for biomaterial patterning. It eliminates the need for physical masks, causes fewer environment problems, lowers fabrication costs, and offers good layer-to-layer registration. To fulfill the requirements for use in the above applications, however, the inkjet system must meet certain criteria such as high frequency jetting, uniform droplet size, high density nozzle array, etc. Existing inkjet devices are either based on thermal bubbles or piezoelectric pumping; they have several drawbacks for flexible printing. For instance, thermal bubble jetting has limitations in terms of size and density of the nozzle array as well as the ejection frequency. Piezoelectric based devices suffer from poor pumping energy in addition to inadequate ejection frequency. Recently, an electrohydrodynamic (EHD) printing technique has been suggested and proposed as an alternative to thermal bubble or piezoelectric devices. In EHD jetting, a liquid (ink) is pumped through a nozzle and a strong electric field is applied between the nozzle and an extractor plate, which induce charges at the surfaces of the liquid meniscus. This electric field creates an electric stress that stretches the meniscus in the direction of the electric field. Once the electric field force is larger than the surface tension force, a liquid droplet is formed. An EHD inkjet head can produce droplets smaller than the size of the nozzle that produce them. Furthermore, the EHD nano-inkjet can eject high viscosity liquid through the nozzle forming tiny structures. These unique features distinguish EHD printing from conventional methods for sub-micron resolution printing. In this presentation, I will introduce the recent research results regarding the EHD nano-inkjet and the printing system, which has been applied to solar cell or thin film transistor applications.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.11.1-11.1
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• 2009

Bulk-heterojunction type organic photovoltaic cells have been remarkably improved due to the development of efficient donors and post treatment process. However, most of researchers have studied on the OPVs using spin-coating method during the past decade. To commercialize the OPVs, much cheaper printing process should be developed such as inkjet, screen, gravure, and so on. In this study, we have focused on the development of printing technology using Inkjet and Aerosol-Jet printing, which can offer reliable device performance. Finally, 4.5% power conversion efficiency can be achieved under AM 1.5 1sun light illumination, which is the highest value in printed OPVs. We reveal that substantial improvement can be realized by highly efficient bulk heterojunction after printing. Also, we can confirm these two printing methods are promising fabrication methods for large area OPVs. Also, flexible and large area (18 cm2) printed OPVs have been fabricated and device performance will be discussed in detail.