• Title/Summary/Keyword: droplet 형성

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A Study on Pb/63Sn Solder Bumps Formation using a Solder Droplet Jetting Method (Solder Droplet Jetting 방법을 이용한 Pb/63Sn 솔더 범프의 형성에 관한 연구)

  • 손호영;백경욱
    • Proceedings of the International Microelectronics And Packaging Society Conference
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    • 2003.11a
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    • pp.122-127
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    • 2003
  • 본 논문에서는 새로운 솔더 범프 형성 방법 중의 하나인 Solder droplet jetting에 의한 솔더 범프 형성 공정에 대해 연구하였으며, 이를 위해 솔더 제팅 직후의 안정한 솔더 액적(solder droplets)의 형성을 위한 공정 변수들의 영향에 대해 먼저 알아보았다 이를 위해 제팅 노즐에 가해지는 파형과 용융 솔더의 온도, 질소 가스의 압력 등에 의한 영향을 주로 살펴보았다. 다음으로 리플로를 거쳐 솔더 범프를 형성하였으며, 다양한 크기의 솔더 범프를 간단한 방법으로 형성하였다. 또한 무전해 니켈/솔더 계면 반응과 Bump shear test를 통한 기계적 성질을 고찰하는 한편, 계면 반응 결과는 스크린 프린팅에 의해 형성된 솔더 범프의 결과와 비교함으로써, 저가의 공정으로 미세 피치를 갖는 솔더 범프를 형성할 수 있는 Solder droplet jetting 방법이 기존의 방법에 의해 형성된 솔더 범프의 특성과 유사함을 고찰하였다. 마지막으로 실제 칩에 적용 되는 솔더 범프를 형성하여 플립칩 어셈블리 및 전기적 테스트를 수행하여, Solder droplet jetting이 실제 차세대 플립칩용 솔더 범프 형성 방법으로서 적용될 수 있음을 고찰하였다.

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Lysozyme Crystallization in Droplet-based Microfluidic Device (액적기반 미세유체장치에서 라이소자임 결정화)

  • Ko, Kwan-Young;Kim, In-Ho
    • Korean Chemical Engineering Research
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    • v.51 no.6
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    • pp.760-765
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    • 2013
  • Lysozyme crystallization was performed by using flow-focusing chip in droplet-based microfluidic system. Water-in-oil droplets were formed in the system and collected on petri-dish and cross type mold. Liquid-liquid reaction of lysozyme and sodium chloride occurred in the droplet and crystals were observed through microscope. Solution pH was varied as 4.8 and 7.2. Crystals of polyhedron and plate-like shape were obtained at pH 4.8, while needle structure crystals formed at pH 7.2. Lysozyme in single droplet for two pHs were crystallized with constant or decreased droplet size. However, crystals at pH 4.8 were only obtained in the droplet of which size was increased by the interaction between droplets. Droplet volume did not change at pH 7.2 and crystals formed in both droplets.

Visualization of Drop Formation and Droplet Velocity Measurement of a Piezoelectric-type Inkjet (피에조 구동형 잉크젯에서 액적 형성의 가시화 및 토출속도 측정)

  • Kwon, D.H.;Choi, Y.S.;Lee, S.J.
    • Journal of the Korean Society of Visualization
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    • v.6 no.2
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    • pp.9-13
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    • 2008
  • The reproducibility of water droplet formation which is indispensible in the investigation of a drop-on-demand piezoelectrically driven inkjet was verified by checking the size of droplet and distance from the nozzle tip of inkjet head to droplet. Based on the reproducibility of droplet formation, we visualized the formation of micro-scale droplets by acquiring consecutive images at the jetting frequency of 500 Hz for which air bubbles were not generated. Two different electric waveforms were used to drive the piezoelectric actuator. The visualization system consists of a high-speed camera that can capture images up to 250,000fps, a long-distance microscope and a halogen lamp as a light source.

On the Characteristics of the Droplet Formation from an Inkjet Nozzle Driven by a Piezoelectric Actuator (피에조 구동형 잉크젯 노즐에서의 미세 액적 형성 특성)

  • Shin, Pyung-Ho;Sung, Jae-Yong;Lee, Suk-Jong
    • Journal of the Korean Society of Visualization
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    • v.6 no.1
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    • pp.47-52
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    • 2008
  • The present study has focused on the characteristics of droplet formation from an inkjet nozzle driven by a piezoelectric actuator. As an operating fluid, ethylene glycol was used and the physical properties of it such as viscosity, surface tension, contact angle and shear stress were measured. During the experiments, various temperatures and driving voltages are imposed on a capillary tube. These conditions result in a proper drive condition or an overdrive condition. In case of the proper drive condition, an image processing technique is applied to measure the diameter of a single free drop. As a result, the size of droplet is increased when the driving voltage is increased from 160 V to 190 V at 25$^{\circ}C$ In the overdrive condition where temperature or driving voltage becomes higher than the proper drive condition, satellites and the misdirected jets happen.

Micro-PIV Measurement on the droplet formation in a microfluidic channel (미세유체소자 내부에서의 Droplet 형성에 대한 Micro-PIV 측정)

  • Yoon, Sang-Youl;Ko, Choon-Sik;Kim, Jae-Min;Kim, Kyung-Chun
    • Proceedings of the KSME Conference
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    • 2004.11a
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    • pp.1534-1539
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    • 2004
  • This experiment has been carried out to measure the process of droplet formation between water phase fluid(PVA 3%) and organic phase fluid(oil) and vector fields measured by a Dynamic Micro-PIV method in the inside of a droplet while generated. Droplet length controlled by changing flow rate conditions in microchannel. Water-in-oil(W/O) droplets successfully generated at a Y junction and cross microchannel. But oil-in-water(O/W) droplets could not be formed at a Y junction microchannel. That is, PVA 3% flow could not be detached from the PDMS surface and ran parallel with oil flow. When PVA 3% flow rate was constant, droplet length and time period decreased as oil flow rate increased, but droplet frequency increased. When PVA 3% and oil flow rate ratio was constant, droplet length and time period decreased as flow rate increased, but droplet frequency increased. All that case, Standard deviation of droplet formation have less than 5% at averaged droplet length and regular-sized droplets were reproducibly formed.

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Droplet Formation of a Piezoelectric Inkjet Nozzle According to the Variation of Pulse Widths in Bipolar Waveform (양극파형의 펄스폭 변화에 따른 피에조 구동형 잉크젯 노즐의 액적 토출 특성)

  • Choi, Sung-Hoon;Sung, Jae-Yong;Lee, Myeong-Ho
    • Journal of the Korean Society of Visualization
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    • v.10 no.1
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    • pp.9-14
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    • 2012
  • In this study, a piezoelectric inkjet nozzle with a rectangular shaped channel has been developed, and the characteristics of droplet formation have been investigated according to the variation of pulse widths in bipolar waveform. The channel of the nozzle was fabricated transparently by a precision machining technique. A tantalum membrane which was attached to a piezoelectric material covers the channel. By applying two types of bipolar waveforms to the piezoelectric actuators, droplet formation through the nozzle was monitored by a CCD camera. For the variety of the first and second pulse widths in the bipolar waveforms, the regimes of single and double droplet formations are presented. The change of droplet velocity which depends on the pulse width and the type of waveform is also discussed.

A Study on the Droplet Formation of Liquid Metal in Water-Mercury System as a Surrogate of Molten Salt-Liquid Metal System at Room Temperature (용융염-액체금속 계의 대용물인 물-수은 계에서 액체금속 액적의 생성에 대한 연구)

  • Kim, Yong-il;Park, Byung Gi
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.16 no.2
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    • pp.165-172
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    • 2018
  • As an approach for estimation of the droplet size in the molten salt-liquid metal extraction process, a droplet formation experiment at room temperature was conducted to evaluate the applicability of the Scheele-Meister model with water-mercury system as a surrogate that is similar to the molten salt-liquid metal system. In the experiment, droplets were formed through the nozzle and the droplet size was measured using a digital camera and image analysis software. As nozzles, commercially available needles with inner diameters (ID) of 0.018 cm and 0.025 cm and self-fabricated nozzles with 3-holes (ID: 0.0135 cm), 4-holes (ID: 0.0135 cm), and 2-holes (ID: 0.0148 cm) were used. The mercury penetration lengths in the nozzles were 1.3 cm for the needles and 0.5 cm for the self-fabricated nozzles. The droplets formed from each nozzle maintained stable spherical shape up to 20 cm below the nozzle. The droplet size measurements were within a 10% error range when compared to the Scheele-Meister model estimates. The experimental results show that the Scheele-Meister model for droplet size estimation can be applied to nozzles that stably form droplets in a water-mercury system.