• Title/Summary/Keyword: Inkjet technology

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Relationship between Ink Jetting Speed and Inkjet input Waveform Parameters (잉크젯 입력 파형의 파라미터와 토출 속도의 관계)

  • Kwon, Kye-Si;Myung, Jae-Hwan;Um, Tai-Joon;Joo, Young-Cheol;Lee, Sang-Wook
    • Journal of the Korean Society for Precision Engineering
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    • v.26 no.9
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    • pp.143-147
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    • 2009
  • Inkjet printing makes use of ink droplets to form required patterns on a substrate. In order for the inkjet technology to produce reliable patterning tools, the jetting performance needs be controlled precisely. For controlling ink jetting performance, input waveform should be properly designed. In the past, the research was focused on designing dwell time of the input waveform for controlling jetting speed. However, the jetting performance is also closely related to rising and falling time. In this study, the effect of the rising and falling time on droplet speed will be investigated by measuring the droplet speed. In this study, the power OP amp (PA98A) was used in order to drive piezo inkjet head by amplifying the waveform generated from arbitrary function generator. The experimental results show that change of rising and falling time in the waveform not only affect the droplet speed but also optimal dwell time.

Sol-gel Derived Nano-glass for Silicon Solar Cell Metallization (솔-젤법에 의해 제조된 실리콘 태양전지 전극형성용 나노 글래스)

  • Kang, Seong Gu;Lee, Chang Wan;Chung, Yoon Jang;Kim, Chang-Gyoun;Kim, Seongtak;Kim, Donghwan;Lee, Young Kuk
    • Current Photovoltaic Research
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    • v.2 no.4
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    • pp.173-176
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    • 2014
  • We have investigated the seed layer formation of front side contact using the inkjet printing process. Conductive silver ink was printed on textured Si wafers with 80 nm thick $SiN_x$ anti reflection coating (ARC) layers and thickened by light induced plating (LIP). The inkjet printable sliver inks were specifically formulated for inkjet printing on these substrates. Also, a novel method to prepare nano-sized glass frits by the sol-gel process with particle sizes around 5 nm is presented. Furthermore, dispersion stability of the formulated ink was measured using a Turbiscan. By implementing these glass frits, it was found that a continuous and uniform seed layer with a line width of $40{\mu}m$ could be formed by a inkjet printing process. We also investigated the contact resistance between the front contact and emitter using the transfer length model (TLM). On an emitter with the sheet resistance of $60{\Omega}/sq$, a specific contact resistance (${\rho}_c$) below $10m{\Omega}{\cdot}cm^2$ could be achieved at a peak firing temperature around $700^{\circ}C$. In addition, the correlation between the contact resistance and interface microstructures were studied using scanning electron microscopy (SEM). We found that the added glass particles act as a very effective fire through agent, and Ag crystallites are formed along the interface glass layer.

Micro to Nano-scale Electrohydrodynamic Nano-Inkjet Printing for Printed Electronics: Fundamentals and Solar Cell Applications

  • Byeon, Do-Yeong
    • 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.

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Polymer Inkjet Printing: Construction of Three-Dimensional Structures at Micro-Scale by Repeated Lamination

  • Yun, Yeon-Hee;Kim, Jae-Dong;Lee, Byung-Kook;Cho, Yong-Woo;Lee, Hee-Young
    • Macromolecular Research
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    • v.17 no.3
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    • pp.197-202
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    • 2009
  • Solution-based, direct-write patterning by an automated, computer-controlled, inkjet technique is of particular interest in a wide variety of industrial fields. We report the construction of three-dimensional (3D), micro-patterned structures by polymer inkjet printing. A piezoelectric, drop-on-demand (DOD) inkjet printing system and a common polymer, PVA (poly(vinyl alcohol)), were explored for 3D construction. After a systematic preliminary study with different solvent systems, a mixture of water and DMSO was chosen as an appropriate solvent for PVA inks. The use of water as a single solvent resulted in frequent PVA clogging when the nozzles were undisturbed. Among the tested polymer ink compositions, the PVA inks in a water/DMSO mixture (4/1 v/v) with concentrations of 3 to 5 g/dL proved to be appropriate for piezoelectric DOD inkjet printing because they were well within the proper viscosity and surface tension range. When a dot was printed, the so-called 'coffee-ring effect' was significant, but its appearance was not prominent in line printing. The optimal polymer inkjet printing process was repeated slice after slice up to 200 times, which produced a well-defined, 3 D micro-patterned surface. The overall results implied that piezoelectric DOD polymer inkjet printing could be a powerful, solid-freeform, fabrication technology to create a controlled 3D architecture.

Inkjet Printing of Small Droplets Using M-shaped Waveforms (M-shaped 파형을 이용한 작은 액적의 잉크젯 프린팅)

  • Hong, Songeun;Choi, Jiho;Kim, Gieun;Park, Jongwoon
    • Journal of the Semiconductor & Display Technology
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    • v.20 no.3
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    • pp.51-56
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    • 2021
  • Using an inkjet printing process, we have investigated a droplet formation of poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) near the orifice of a piezoelectric inkjet head. With an attempt to form the smallest droplet without any satellites, we have applied various waveforms such as the unipolar, bipolar, and M-shaped waveforms. It is found that the droplet velocity and volume vary depending sensitively on the waveform width and voltage. Of those, the M-shaped waveform is shown to provide the smallest droplet volume, followed by the bipolar and then unipolar waveforms. The droplet printed on a PET film roll by the M-shaped waveform has the diameter as small as 46.1 ㎛. It is likely that the second short unipolar in the M-shape waveform increases the droplet velocity gradient, rendering the droplet smaller.

Fatigue Test of MEMS Device: a Monolithic Inkjet Print

  • Park, Jun-Hyub;Oh, Yong-Soo
    • Journal of Mechanical Science and Technology
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    • v.18 no.5
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    • pp.798-807
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    • 2004
  • A testing system was developed to improve the reliability of printhead and several printheads were tested. We developed a thermally driven monolithic inkjet printhead comprising dome-shaped ink chambers, thin film nozzle guides, and omega-shaped heaters integrated on the top surface of each chamber. To perform a fatigue test of an inkjet printhead, the testing system automatically detects a heating failure using a Wheatstone bridge circuit. Various models were designed and tested to develop a more reliable printhead. Two design parameters of the width of reinforcing layer and heater were investigated in the test. Specially., the reinforcing layer was introduced to improve the fatigue life of printhead. The life-span of heater with a reinforcing layer was longer than that without a reinforcing layer. The wider the heater was, the longer the life of printhead was.

Multifunctional Thin Film Resistors Prepared by ALD for High-Efficiency Inkjet Printheads

  • Kwack, Won-Sub;Kwon, Se-Hun
    • Proceedings of the Korean Vacuum Society Conference
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    • 2012.08a
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    • pp.126-126
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    • 2012
  • In past decades, the themal inkjet (TIJ) printer has been widely used as one of the most well-known digital printing technology due to its low cost, and high printing quality. Since the printing speed of TIJ printers are much slower than that of laser printers, however, there has been intensive efforts to raise the printing speed of TIJ printers. One of the most plausible methods to raise the printing speed of TIJ printers is to adopt a page-wide array TIJ printhead. To accomplish this goal, the high efficiency inkjet heating resistor films should be developed to settle the high power consumption problem of a page-wide array TIJ printhead. In this study, we investigated noble metal based multicomponent thin film resistor films prepared by atomic layer deposition (ALD) for a high efficiency inkjet printhead. Design concept, preparation, material properties of noble metal based multicomponent thin films will be discussed in terms of mutlfunctionality.

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Screen-printed Source and Drain Electrodes for Inkjet-processed Zinc-tin-oxide Thin-film Transistor

  • Kwack, Young-Jin;Choi, Woon-Seop
    • Transactions on Electrical and Electronic Materials
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    • v.12 no.6
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    • pp.271-274
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    • 2011
  • Screen-printed source and drain electrodes were used for a spin-coated and inkjet-processed zinc-tin oxide (ZTO) TFTs for the first time. Source and drain were silver nanoparticles. Channel length was patterned using screen printing technology. Different silver nanoinks and process parameters were tested to find optimal source and drain contacts Relatively good electrical properties of a screen-printed inkjet-processed oxide TFT were obtained as follows; a mobility of 1.20 $cm^2$/Vs, an on-off current ratio of $10^6$, a Vth of 5.4 V and a subthreshold swing of 1.5 V/dec.

Laser Sintering of Inkjet-Printed Silver Lines on Glass and PET Substrates (유리와 PET 기판에 잉크젯 인쇄된 실버 도선의 레이저 소결)

  • Kim, Myong-Ki;Kang, Heui-Seok;Kang, Kyung-Tae;Lee, Sang-Ho;Hwang, Jun-Young;Moon, Seung-Jae
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.34 no.11
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    • pp.975-982
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    • 2010
  • In this study, the laser sintering of inkjet-printed silver lines was evaluated. Silver-nanoparticle ink and a drop-ondemand (DOD) inkjet printer were used for printing on glass and polyethylene terephthalate (PET) substrates with various thicknesses. To sinter the printed silver nanoparticles, the silver layer printed on the transparent substrates was irradiated by focused CW laser beams that were incident normal to the substrates; the irradiation was carried out for various beam intensities and for various irradiation times. The electrical conductivity of the laser-sintered silver patterns was measured and compared with the conductivity of silver patterns sintered by using an oven. The increase in the temperature caused by laser irradiation was also calculated on the basis of the laser beam intensity, irradiation time, surface reflectivity, and thermophysical property of the substrate in order to estimate the increase in the electrical conductivity caused by laser sintering.

Inkjet Technology and Products for Flexible Display Manufacturing

  • Schoeppler, Martin
    • 한국정보디스플레이학회:학술대회논문집
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    • 2008.10a
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    • pp.179-181
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    • 2008
  • Major display equipment suppliers introduced equipment using inkjets for manufacturing steps such as printing polyimide alignment layers and color filters. This paper discusses how inkjets can be used in the development of flexible displays and materials printing systems designed to meet the challenges of fluids and process development.

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