• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.1128-1131
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• 2004

SFF(solid freeform fabrication) is another name of RP(rapid prototyping). The SFFS for office type wishes to develop system that can produce small object such as hand phone, cup, accessory etc. with high speed, and also intend suitable system in office environment by compact design, and buy easily by inexpensive price. As can manufacture high speed in existent SFF process technology, representative process that have competitive power in price is 3DP (three dimensional printing) technology. The 3DP technology is way to have general two dimensional printing technology and prints to three dimension, is technology that make three-dimensional solid freeform that want binder doing jetting selectively on powder through printer head. We designed and manufactured SFFS for office based on 3DP process technology design and manufactured, and composed head system so that use 3 printer heads at the same time to improve the fabrication speed of system. We used printer head of INCJET company and cartridge used HP45 series model who can buy easily in general city. And we directly fabricated three dimensional solid freeform using developed SFFS for office type.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.2160-2163
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• 2005

Solid freeform fabrication (SFF) technology plays a major role in industry and represents a reasonable percentage of industrial rapid prototyping/tooling/manufacturing (RP/RT/RM) development applications. However, SFF technology still has long way to progress to achieve satisfactory process speed, surface finish and overall quality improvement of its application. Today, three dimensional printing (3DP) technique that is one of SFF technology is receiving many interests, and is applied by various fields. It can fabricate three dimensional objects of solid freeform with high speed and low cost using ink jet printing technology. However, need long curing time after manufacture completion. And it must do post-processing process necessarily to heighten strength of objects because strength of fabricated objects is very weak. Therefore, in this study, we proposed an improved 3DP process that can solve problems of conventional 3DP process. The general 3DP process is method to spout binder simply through printer head on powder, but proposed process is method to cure jetted UV resin by UV lamp after jet UV resin using printhead on powder. The hardening of resin is achieved strongly at early time by UV lamp in proposed method. So, the proposed process can fabricate three dimensional objects with high speed without any post-processing.

• 대한기계학회논문집B
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• 제30권11호
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• pp.1107-1116
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• 2006

The droplet ejection process driven by an evaporating bubble in a thermal inkjet printhead is investigated by numerically solving the conservation equations for mass, momentum and energy. The phase interfaces are tracked by a level set method which is modified to include the effect of phase change at the interface and extended for multiphase flows with irregular solid boundaries. The compressibility effect of a bubble is also included in the analysis to appropriately describe the bubble expansion behaviour associated with the high pressure caused by bubble nucleation. The whole process of bubble growth and collapse as well as droplet ejection during thermal inkjet printing is simulated without employing a simplified semi-empirical bubble growth model. Based on the numerical results, the jet breaking and droplet formation behaviour is observed to depend strongly on the bubble growth and collapse pattern. Also, the effects of liquid viscosity, surface tension and nozzle geometry are quantified from the calculated bubble growth rate and ink droplet ejection distance.

• 한국전산유체공학회지
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• 제17권3호
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• pp.33-38
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• 2012

The droplet ejection behavior from drop-on-demand printhead are investigated numerically for Newtonian and shear-thinning fluid. The numerical simulation is performed using a volume-of-fluid model. In this study, we compare the printable range in terms of Z number and pinch-off time for Newtonian and shear-thinning fluids. The printability range are found to be 1.08 $$\leq_-$$ Z $$\leq_-$$ 12.9 for Newtonian fluid and 0.8 $$\leq_-$$ Z $$\leq_-$$ 12.9 for shear-thinning fluid. However, air entrainment is observed during merging of primary and satellite droplet within the printability range. The pinch-off time of the shear-thinning fluid is apparently shorter compared to the corresponding Newtonian fluid due to shear-thinning effects and the differences in the pinch-off time is enlarged significantly when the capillary number is larger than 0.5.

• 한국정밀공학회지
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• 제24권5호
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• pp.97-103
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• 2007

A novel selective metallization process to fabricate the fine conductive line based on inkjet printing has been investigated. Recently, Inkjet printing has been widely used in flat panel display, electronic circuits, biochips and bioMEMS because direct inkjet printing is an alternative and cost-effective technology for patterning and fabricating objects directly from design without masks. The photosensitive etching resist used in this process is an organic polymer which becomes solidified when exposed to ultraviolet lights and has high viscosity at ambient temperature. A piezoelectric-driven inkjet printhead is used to dispense 20-30 ${\mu}m$ diameter droplets onto the copper substrate to prevent subsequent etching. Repeatability of circuitry fabrication is closely related to the formation of steady droplets, adhesion between etching resist and copper substrate. Therefore, the ability to form small and stable droplets and surface topography of the copper surface and chemical attack must be taken into consideration for fine and precise patterns. In this study, factors affecting the pattern formation such as adhesion strength, etching mechanism, UV curing have been investigated. As a result, microscale copper patterns with tens of urn high have been fabricated.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1892-1897
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• 2003

A new thermal inkjet printer head on SOI wafer with virtual valve was proposed. It was composed of two rectangular heaters with same size. So we could call it T-jet(Twin jet). T-jet has a lot of merits. It has the advantage of being fabricated with one wafer and is easy to change the size of chamber, nozzle, restrictor and so on. However, above all, It is the best point that T-jet has a virtual valve. And it was manufactured on SOI wafer. The chamber was formed in its upper silicon whose thickness was 40um. The chamber's bottom layer was silicon dioxide of SOI wafer and two heaters were located underneath the chamber's ceiling. And the restirctor was made beside the chamber. Nozzle was molded by process of Ni plating. Ni was 30um thick. Nozzle ejection test was performed by printer head having 56 nozzles in 2 columns with 600NPI(nozzle per inch) and black ink. It measured a drop velocity of 12m/s, a drop volume of 30pl, and a maximum firing frequency of 12KHz for single nozzle ejection. Throwing out the ink drop in whole nozzles at the same time, it was observed that the uniformity of the drop velocity and volume was less than 4%.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.504-504
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• 2011

최근 디지털 프린팅 기술의 핵심기술로 떠오르고 있는 잉크젯 프린팅 기술은 최근 기존의 문서인쇄 뿐 아니라, 직물 인쇄, 태양전지 등의 다양한 반도체 소자 제조에 널리 활용되고 있으며, 점차 그 응용 분야를 넓혀가고 있다. 특히 thermal 방식의 잉크젯 피린팅 기술은 etching, thin film process, lithography등의 반도체 공정 기술을 이용하여 제작할 수 있기 때문에, 현재 잉크젯 프린팅 기술은 대부분 thermal 방식을 체택하고 있다. 이러한 thermal 잉크젯 프린팅 방법에서는 잉크를 토출시키기 위하여, 전기적 에너지를 열에너지로 전환하는 전자저항막층이 필수적으로 필요하게 되는데, 이러한 전자저항막층은 수백도가 넘는 고온 및 잉크와 접촉으로 인한 부식 및 산화 문제가 발생할 수 있는 열악한 환경에서 사용되므로, Ta, SiN과 같은 보호층을 필수적으로 필요로 한다. 그러나 최근 잉크젯 프린터의 고해상도 고속화, 대면적 인쇄성 등과 같은 다양한 요구 증가에 따라, 잉크젯 프린터의 저전력 구동이 이슈로 떠올라 열효율에 방해가 되는 보호층을 제거할 필요성이 제기되고 있다. 지금까지는 Poly-Si, $HfB_2$, TiN, TaAl, TaN _0.8 등의 물질들이 잉크젯 프린터용 전자저항막 물질로 연구되거나 실제로 사용되어져 왔으나, 이러한 물질들을 보호층을 제거하는 경우 쉽게 산화되거나, 부식되는 문제점을 가지고 있다. 따라서, 기존 전자저항막의 기능을 만족시키면서, 산화나 부식에 대한 강한 내성을 가져 보호층을 제거하더라도 안정적으로 구동이 가능한 하이브리드 기능성(히터 + 보호층)을 가지는 잉크젯 프린터용 전자저항막 물질의 개발이 시급한 실정이다. 본 연구에서는 자기조립특성을 가져 정밀제어가 가능한 원자층증착법(Atomic Layer Deposition)을 이용하여 원자/나노 단위의 미세 구조 컨트롤을 통해 내열 내산화 내부식성 저온도저항계수를 동시에 가지는 다기능성 전자저항막을 설계 및 개발하고자 하였다. 전자저항막 개발을 위하여 우수한 내부식 내산화성을 가지고 결정립 크기에 따른 온도저항계수 조절이 가능한 platinum group metal들과 전기 저항 및 내열성 향상을 위한 물질의 복합구조막을 원자증증착법으로 증착하였다. 또한, 전자저항막 증착시 미세구조와 공정 변수가 내부식성, 내산화성, 그리고 온도저항계수에 미치는 영향을 체계적으로 연구하여, proto-type의 inkjet printhead를 구현하였다.