• 마이크로전자및패키징학회지
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• 제20권2호
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• pp.23-28
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• 2013

마이크로렌즈 어레이는 광학 시스템의 기본 부품으로, 사용 목적에 따라 초점거리가 다르게 제작되며, 대체로 긴 초점거리의 렌즈들이 많이 제작되고 있다. 본 논문에서는 졸겔(sol-gel) 내부에 들어있는 형광으로 염색된 물질을 관찰하기 위하여 마이크로렌즈 어레이를 제작하였다. 일반적으로 형광 현미경에서 관찰되는 형광 빛은 그 강도가 약하지만 마이크로렌즈를 이용할 경우 빛을 집중시켜 선명한 관찰이 가능하게 한다. 이를 실현시키기 위해 photoresist thermal reflow법을 사용하여 초점 거리가 짧은 마이크로렌즈를 제작하였으며, 렌즈의 형상 관련 오차를 측정하였다. 측정 오차에 기반을 둔 포토마스크 보정 및 스핀 코팅 조건을 조정하여 적합한 마이크로렌즈의 직경과 형상을 구현하였다.

• 한국진공학회지
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• 제6권3호
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• pp.206-212
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• 1997

차세대 반도체 소자의 배선재료로 사용될 것으로 예상되는 구리의 reflow 특성을 조 사하였다. 구리박막을 hole 및 trench 패턴 위에 금속유기화학증착법으로 증착하고 $350^{\circ}C$에 서 $550^{\circ}C$까지의 열처리 온도 범위 및 질소, 산소 분위기에서 열처리하였다. 질소 분위기에서 열처리 한 경우에는 구리가 패턴을 채우지 못하였고 열처리 온도 $450^{\circ}C$ 이상의 산소 분위기 에서 열처리 한 경우에는 reflow에 의하여 구리가 패턴을 채웠다. 이러한 현상은 구리의 산 화시 발생되는 열에 의하여 부분적으로 액상화된 구리가 표면에너지 및 위치에너지를 감소 시키기 위하여 패턴을 채우면서 발생하는 것으로 생각된다. 산소 분위기에서 열처리한 경우 에는 응집물 표면에 300$\AA$이하의 구리 산화물이 형성되었으며 열처리 온도 $550^{\circ}C$에서 구리 의 응집에 의하여 비저항이 급격하게 증가하였다.

• 한국표면공학회지
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• 제36권5호
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• pp.373-378
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• 2003

With increasing environmental concerns, application of lead-free solder and fluxless soldering process have been taken attention from the electronic packaging industry. Plasma treatment is one of the soldering methods for the fluxless soldering, and it can prevent environmental pollution cased by flux. On this study fluxless soldering process under $Ar-H_2$plasma using lead free solders such as Sn-3.5 wt%Ag, Sn-3.5 wt%Ag-0.7 wt%Cu and Sn-37%Pb for a reference was investigated. As the plasma reflow has higher soldering temperature than normal air reflow, the effects of UBM(Under Bump Metallization) thickness on the interfacial reaction and bonding strength can be critical. Experimental results showed in case of the thin UBM, Au(20 nm)/Cu(0.3 $\mu\textrm{m}$)/Ni(0.4 $\mu\textrm{m}$)/Al(0.4 $\mu\textrm{m}$), shear strength of the soldered joint was relatively low as 19-27㎫, and it's caused by the crack observed along the bonded interface. The crack was believed to be produced by the exhaustion of the thin UBM-layer due to the excessive reaction with solder under plasma. However, in case of thick UBM, Au(20 nm)/Cu(4 $\mu\textrm{m}$)/Ni(4 $\mu\textrm{m}$)/Al(0.4 $\mu\textrm{m}$), the bonded interface was sound without any crack and shear strength gives 32∼42㎫. Thus, by increasing UBM thickness in this study the shear strength can be improved to 50∼70%. Fluxed reflow soldering under hot air was also carried out for a reference, and the shear strength was 48∼52㎫. Consequently the fluxless soldering with plasma showed around 65∼80% as those of fluxed air reflow, and the possibility of the $Ar-H_2$ plasma reflow was evaluated.

• 한국진공학회지
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• 제4권S1호
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• pp.102-107
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• 1995

We review the copper CVD line, via fill properties, and CMP line resistance. With CVD, trenches and vias with high aspect ratio(above 3) can be filled completely. Sputtering-reflow technique, a new method to filling copper into lines, is also reviewed to compare the CVD process.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2003년도 추계학술발표대회 개요집
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• pp.80-82
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• 2003

• Journal of Welding and Joining
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• 제19권5호
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• pp.520-525
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• 2001

The Sn-Pb eutectic solder bump formation ($150\mu\textrm{m}$ diameter, $250\mu\textrm{m}$ pitch) by electroplating was studied for flip chip package fabrication. The effect of current density and plating time on Sn-Pb deposit was investigated. The morphology and composition of plated solder surface was examined by scanning electron microscopy. The plating thickness increased wish increasing time. The plating rate became constant at limiting current density. After the characteristics of Sn-Pb plating were investigated, Sn-Pb solder bumps were fabricated in optimal condition of $7A/dm^$. 4hr. Ball shear test after reflow was performed to measure adhesion strength between solder bump and UBM (Under Bump Metallurgy). The shear strength of Sn-Pb bump after reflow was higher than that of before reflow.

• 한국정밀공학회지
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• 제32권3호
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• pp.299-305
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• 2015

In this paper, we propose a simple and low-cost fabrication method of polymer microlens using solvent-vapor-assisted reflow (SVAR). Metal molds for replication of polymer were fabricated using micro milling and the cylindrical shape of polymer was imprinted using hot-embossing process. The cylindrical shape of polymer was changed to hemispherical lens shape by SVAR. The characteristics of fabricated microlens were evaluated according to the condition of SVAR such as temperature and time. The focal length of polymer microlens could be controlled more easily in low-temperature and long-time condition than in high-temperature and short-time condition. That is, the level of concentrated light to focal point could be improved through the control of temperature and time. Also, we confirmed that toluene was more appropriate solvent than acetone in fabrication of PMMA polymer microlens using SVAR.

• 소성∙가공
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• 제16권8호
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• pp.596-602
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• 2007

LGP (Light Guiding Plate) of LCD-BLU (Liquid Crystal Display - Back Light Unit) is one of the major components that affect the product quality of LCD. The optical patterns of LGP(2.2") molds are fabricated by three different methods, namely, (1) laser ablation, (2) chemical etching and (3) LiGA-reflow, respectively. The characteristics of surface patterns and roughnesses of molds and injection molded parts were compared to evaluate the optical characteristics. The optical patterns of injection molded LGP with mold fabricated by LiGA - reflow method showed the best geometric structure. The surface roughness (Ra) of LGP#s with molds fabricated by (1) laser ablation: $Ra={\sim}31nm$, (2) chemical etching: $Ra={\sim}22nm$, and (3) LiGA-reflow: $Ra={\sim}4nm$.

• Korea-Australia Rheology Journal
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• 제19권3호
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• pp.171-176
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• 2007

LCD-BLU (Liquid Crystal Display-Back Light Unit) of medium size is usually manufactured by forming numerous dots with $50{\sim}300\;{\mu}m$ in diameter by etching process and V-grove shape with $50\;{\mu}m$ in height by mechanical cutting process. However, the surface of the etched dots is very rough due to the characteristics of the etching process and V-cutting needs rather high cost. Instead of existing optical pattern made by etching and mechanical cutting, 3-dimensional continuous micro-lens of $200\;{\mu}m$ in diameter was applied in the present study. The continuous micro-lens pattern fabricated by modified LIGA with thermal reflow process was tested to this new optical design of LGP. The manufacturing process using LIGA-reflow is made up of three stages as follows: (i) the stage of lithography, (ii) the stage of thermal reflow process and (iii) the stage of electroplating. The continuous micro-lens patterned LGP was fabricated with injection molding and its test results showed the possibility of commercial use in the future.

• Journal of the Optical Society of Korea
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• 제18권1호
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• pp.71-77
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• 2014

We present design and fabrication of a multi-focusing microlens array (MLA) using a thermal reflow method. To obtain multi-focusing properties with different numerical apertures at the elemental lens of the MLA, double-cylinder photoresist (PR) structures with different diameters were made within the guiding pattern with both photolithographic and partial developing processes. Due to the base PR layer supporting the thermal reflow process and the guiding structure, the thermally reflowed PR structure had different radii of curvatures with lens shapes that could be precisely modeled by the initial volume of the double-cylinder PR structures. Using the PR template, the hexagonally packed multi-focusing MLA was made via the replica molding method, which showed four different focal lengths of 0.9 mm, 1.1 mm, 1.6 mm, and 2.5 mm, and four different numerical apertures of 0.1799, 0.2783, 0.3973, and 0.4775.