• 한국전기전자재료학회논문지
• /
• 제28권9호
• /
• pp.593-597
• /
• 2015

Ni ink for electrohydrodynamic (EHD) continuous jet printing has been developed by using Ni nanoparticles mixed with conhesiveness provider. EHD continuous jet printing was used in order to realize $20{\mu}m$ pattern width. Ink stability was investigated by using Turbi-scan which monitors agglomeration and precipitation of nanoparticles in the ink for three days. The Turbi-scan results showed that the formulated Ni ink had been stable for 3 days without any indication of precipitation across the entire ink. Antireflection coating (ARC) layer in crystalline solar cell wafers was removed by laser ablation technique leading to the formation of 84 grooves where the Ni ink was printed by EHD continuous jet printing. The printability and microstructure of EHD-jet-printed Ni lines were investigated by using optical and electron microscopes. 84 Ni lines with the width less than $20{\mu}m$ were successfully printed by one-time printing without any misalignment and fill the laser-ablated ARC grooves.

• 한국정밀공학회지
• /
• 제29권4호
• /
• pp.449-454
• /
• 2012

The method for spraying of liquid through an electrical filed has become a printing method since it can make very small droplet. To increase the reliability using the electro-hydrodynamic (EHD) jet printing, the jetting status needs to be monitored. Vision measurement techniques using high speed camera has been used to visualize the jet images. However, it requires image processing of a lot of images after image acquisitions. So, it is difficult to understand jet behavior such as jetting frequency, jet repeatability etc. In this work, a low cost electrical current measurement method was developed to measure electrical current from EHD jet printing. To verify the jetting monitoring capability of developed circuit, images from high speed camera were processed for comparison purpose.

• 한국세라믹학회지
• /
• 제52권5호
• /
• pp.356-360
• /
• 2015

The specific role of current collectors was investigated at the electrolyte/electrode interface of solid oxide fuel cells (SOFCs). Ag grids were fabricated as current collectors using electrohydrodynamic (EHD) jet printing for precise control of the grid geometry. The Ag grids reduced both the ohmic and polarization resistances as the pitch of the Ag grids decreased from $400{\mu}m$ to $100{\mu}m$. The effective electron distribution along the Ag grids improved the charge transport and transfer at the interface, extending the active reaction sites. Our results demonstrate the applicability of EHD jet printing to the fabrication of efficient current collectors for performance enhancement of SOFCs.

• 대한기계학회논문집B
• /
• 제37권9호
• /
• pp.873-877
• /
• 2013

잉크젯 기술은 가정용 프린터에서부터 제조 도구로 확대 되었다. 최근 인쇄전자 분야에서 고해상도 인쇄가 요구되고 있다. 기존의 잉크젯 인쇄 패터닝 방식을 향상 시키기 위해 전기수력학잉크젯 기술이 최근 주목을 받고 있는데 노즐 직경보다 작은 방울을 토출할 수 있고 넓은 점도 범위와 재료를 사용할 수 있기 때문이다. 본 논문에서는 미세 패터닝을 위한 EHD 프린팅 시스템이다. 요구 적출형 프린팅에 의해 다양한 패턴을 인쇄하고 벡터와 레스터 프린팅 알고리즘을 개발하였다. 내경이 $8{\mu}m$ 인 노즐을 이용하여 $7{\mu}m$ 이하의 미세 전도성 선폭을 EHD 방식을 통해 만들 수 있다.

• 한국정밀공학회지
• /
• 제29권3호
• /
• pp.295-301
• /
• 2012

The method for spraying of liquids through an electrical field has become a printing method since it can make very small droplet. For electro-hydrodynamic jet printing to become a reliable jetting tool, the jetting performance should be characterized with respect to various jetting conditions. To optimize jetting conditions, the jetting behavior should be measured. In this study, we present a visualization techniques to measure jetting behavior from electro-hydrodynamic (EHD) inkjet head. Unlike most previous method, we use the CCD camera to measure the jetting behavior. For this purpose, LED light is synchronized with jetting signal and sequential image was obtained by adjusting the delay time of the LED light. Finally, merits and demerits of using CCD camera were discussed to measure jetting image from EHD inkjet head.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2009년도 춘계학술대회 논문집
• /
• pp.351-352
• /
• 2009

On-demand ejection of ultra-fine droplets that uses both electrohydrodynamic (EHD) force and mechanical actuation is presented. The liquid meniscus was controlled by a piezoelectric actuator and droplets were ejected by EHD force. Through these effects, it was possible to obtain a high operational jetting frequency of 5kHz with a short delay-time (about 50 us) when compared with existing on-demand EHD jetting methods, such as the pulsating jet mode (3-10 msec) and the pulsed-voltage cone-jet mode(3.6 msec). Also, we obtained ultra-fine droplets at a volume that was at the femto-liter level simultaneously. The jetting characteristics were examined for both hydrophobicity and hydrophilicity of the surface of a capillary.

• 항공우주시스템공학회지
• /
• 제12권6호
• /
• pp.1-8
• /
• 2018

투명 전극에 사용되는 필름인 이방성전도필름은 전도성 입자를 재료로 하여 열 압착법으로 제조되고 있다. 하지만 열 압착법은 낭비되는 재료가 많고 공정이 복잡하다는 단점을 가지고 있으며, 이와 같은 단점을 극복하기 위해 전도성 입자 잉크를 이용한 잉크젯 프린팅 기술을 제안하였다. 잉크의 특성 및 프린팅 조건은 패터닝 선 두께에 영향을 주게 되며, 미세 패터닝을 위한 최적 조건 도출이 중요하다. 본 논문에서는 전도성 입자 잉크를 제작하였으며, 노즐의 두께와 유량을 변화하여 패터닝 결과물을 제작하였고, 전도성 입자 잉크의 토출에 따른 전기전도도를 도출하였다.

• 대한기계학회논문집B
• /
• 제39권4호
• /
• pp.379-384
• /
• 2015

최근 전기방사를 이용한 프린팅이 미세 패터닝 분야에 응용이 되고 있다. 전기방사를 이용한 패터닝은 연속 프린팅 방식으로 기존의 요구적출형 방식에 비해 패터닝 속도가 빠르다는 장점이 있다. 안정적인 연속 프린팅을 위해서는 고분자의 폴리머를 프린팅하려고 하는 잉크에 혼합하는 것이 필요하다. 본 연구에서는 PEO 를 이러한 첨가 폴리머로 사용하였다. 이러한 폴리머의 첨가에 대한 잉크의 점도 및 Taylor cone 형성에 대해 미치는 영향을 조사하였다. 마지막으로 전기방사 프린팅의 예로서 실버 페이스트 잉크를 유리 기판 위에 패터닝하였다.

• 한국정밀공학회지
• /
• 제31권1호
• /
• pp.83-90
• /
• 2014

EHD (electro-hydro-dynamics) patterning was performed under atmospheric pressure at room temperature in a single step. The drop diameter smaller than nozzle diameter and applied high viscosity conductive ink in EHD patterning method provide a clear advantage over the piezo and thermal inkjet printing techniques. The micro electrode pattern was printed by continuous EHD patterning method using 3-type control parameters (input voltage, patterning speed, nozzle pressure). High viscosity (1000cps) conductive ink with 75wt% of silver nanoparticles was used. EHD cone type nozzle having an internal diameter of $50{\mu}m$ was used for experimentation. EHD jetting mode by input voltage and applied 1st order linear regression in stable jet mode was analyzed. The stable jet was achieved at the amplitude of 1.4~1.8 kV. $10{\mu}m$ micro electrode pattern was created at optimized parameters (input voltage 1.6kV, patterning speed 25mm/sec and nozzle pressure -2.3kPa).

• 한국가시화정보학회지
• /
• 제9권2호
• /
• pp.48-53
• /
• 2011

The shape of nozzle cross-section plays an important role in stabilizing electrospray jet. The angle of contact line is governed based on the famous Young-Laplace equation. Compared to a round nozzle that has a constant curvature along the orifice, the square nozzle has four square corner edges and four straight edges that hold the meniscus in a different manner and is of interest in this study. By utilizing both square and round capillary nozzle, we examine the effect of nozzle shape in electrohydrodynamic jetting. The ejections were recorded with a high speed camera and analyzed to examine the jetting repeatability based on dynamic movement of meniscus. The result suggests that if the corner edges are not sharp, then its effect on repeatability is also limited.