• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2001년도 추계 기술심포지움
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• pp.138-140
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• 2001

Fluxless flip chip bonding using plasma & ultrasonic wave was investigated in order to evaluate the effect of plasma & ultrasonic treatment on the bondability of the Sn-3.5wt%Ag solder bumped die to TSM-coated glass substrate. The $Ar+10%H_2plasma$ was effective in removing tin oxide on solder surface. The die shear strength of the plasma-treated Si-chip is higher than that of non-treated specimen but lower than that of specimen bonded with flux. The die shear strength with the bonding load at 25W ultrasonic power increased to 0.8N/bump for all bonding temperature but decreased above 1.0N/bump.

• 한국전기전자재료학회논문지
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• 제17권3호
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• pp.267-271
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• 2004

The joint strength and fracture surface of Sn-Pb solder bump in photo diode packages after isothermal aging testing were studied experimentally. Cu/Sn-Pb solders were adopted, and aged for up to 900 hours at 12$0^{\circ}C$ and 17$0^{\circ}C$ to analyze the effect of intermetallic compound(IMC). In 900-hour aging experiments, the maximum shea strength of Sn-Pb solder decreased by 20％ and 9％. The diffraction patterns of Cu$_{6}$Sn$_{5}$, scallop-shape IMC, and planar-shape Cu$_3$Sn were observed by Transmission Electron Microscopy (TEM).EM).

• 한국전기전자재료학회논문지
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• 제25권7호
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• pp.496-499
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• 2012

Modified structure of copper pillar bump which has trapezoidal cross section on the top region is suggested with simulation results and concept of fabrication process. Due to the large surface area of joint region between bump and solder in suggested structure, electro-migration effect can be reduced. Reduction of electro-migration is related with current density and joule heating in bump and investigated with finite element methods with variation of dimensional parameters. Mechanical characteristics are also investigated with comparing modified copper pillar bump and conventional copper pillar bump.

• 한국재료학회지
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• 제9권3호
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• pp.288-294
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• 1999

솔더 범프를 사용하는 플립 칩 접속기술에서 범프와 칩 사이에 위치하는 금속 충들의 조합을 UBM(Under Bump Metallurgy)라고 부르며 이 UBM을 어떤 조합으로 사용하는 가에 따라 접속의 안정성이 크게 좌우된다. 본 연구에서는 UBM중에서 솔더 접착 층으로 사용되는 구리 층의 두께를 $1\mu\textrm{m}와 5\mu\textrm{m}$로 하는 한편 barrier 층으로 사용되는 금속 층을 Ti, Ni, Pd으로 변화시키면서 이들 UBM과 공정 납-주석 사이의 계면반응을 살펴보았다. 이를 위해 $100\mu\textrm{m}$ 크기의 솔더 범프를 전해도금법을 사용하여 제작하고 리플로 횟수와 시효시간에 따른 각 UBM에서의 금속간 화합물의 성장을 관찰하였다. $Cu_6Sn_5 \eta'$-상 금속간 화합물이 모든 조건에서 형성되었고 Cu층의 두께가 $5\mu\textrm{m}$로 두꺼운 경우에는 $Cu_3Sn \varepsilon$-상도 관찰되었다. Pd을 사용한 UBM 구조에서는 시효 처리시에 $Cu_6Sn_5$ 상 아래쪽에 $PdSn_4$상이 형성되었다. 또한 이들 계면에서의 금속간 화합물의 성장은 솔더 범프의 접속강도 값과 밀접한 관계를 가진다.

• ETRI Journal
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• 제35권2호
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• pp.340-343
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• 2013

A novel bumping process using solder bump maker is developed for the maskless low-volume solder on pad (SoP) technology of fine-pitch flip chip bonding. The process includes two main steps: one is the aggregation of powdered solder on the metal pads on a substrate via an increase in temperature, and the other is the reflow of the deposited powder to form a low-volume SoP. Since the surface tension that exists when the solder is below its melting point is the major driving force of the solder deposit, only a small quantity of powdered solder adjacent to the pads can join the aggregation process to obtain a uniform, low-volume SoP array on the substrate, regardless of the pad configurations. Through this process, an SoP array on an organic substrate with a pitch of $130{\mu}m$ is successfully formed.

• 마이크로전자및패키징학회지
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• 제12권1호
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• pp.87-93
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• 2005

Au 층의 두께를 $0.1{\~}0.7{\mu}m$로 변화시킨 $0.1{\mu}m$ Ti/3 ${\mu}m$ Cu/Au UBM 상에서 48Sn-52In 솔더를 $150-250^{\circ}C$의 온도 범위에서 리플로우시 UBM/솔더 반응에 의한 금속간화합물의 형성거동을 분석하였다. 또한 Ti/Cu/Au UBM의 Au 두께 및 리플로우 온도에 따른 볼 전단강도와 전단에너지를 분석하였다. $150^{\circ}C$와 $200^{\circ}C$에서 리플로우 시에는 UBM/솔더 계면에 $Cu_6(Sn,In)_5$와 $AuIn_2$ 금속간 화합물이 형성되어 있으나, $250^{\circ}C$에서 리플로우 시에는 솔더 반응이 크게 증가하여 UBM이 대부분 소모되었다. 볼 전단강도는 UBM/솔더 반응과 일치하지 않는 결과를 나타내었으나, 전단 에너지는 UBM/솔더 반응과 잘 일치하는 변화 거동을 나타내었다.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2001년도 추계 기술심포지움
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• pp.49-54
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• 2001

This paper presents several UBM (Under Bump Metallurgy) systems which are currently used for wafer level solder bumping technology. The advantages and disadvantages of each UBM are summarized from the point of view of process compatability and interface morphological stability.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.661-662
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• 2006

This research is on a laser soldering using the micro solder-balls used in flip chip packaging process. A laser source used in laser soldering is Nd:YAG laser(250W and 60W). Solder-balls of 100, 300, $500{\mu}m$ size are used in experiments. The laser head to deliver a laser beam and the nozzle to transfer solder-balls are manufactured to bump solder-balls. After soldering solder-balls the shear test is carried out to determine the wetting at the interface between the surface and a solder-balls With the results of solder bumping tests a laminated molding is accomplished for manufacturing the three dimensional molding.

• 한국표면공학회지
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• 제35권1호
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• pp.11-16
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• 2002

As environmental concerns increasing, the electronics industry is focusing more attention on lead free solder alternatives. In this research, we have researched wettability of intermediate solder of Sn3Ag9Bi5In, which include In and Bi and has similar melting temperature to Sn37Pb eutectic solder. We investigated the wetting property of Sn3Ag9Bi5In. To estimate wettability of Sn3Ag9Bi5In solder on various substrates, the wettability of Sn3Ag9Bi5In solder on high-pure Cu-coupon was measured. Cu-coupon that plated Sn, Ni and Au/Ni and Si-wafer adsorbed Ni/Cu under bump metallurgy on one side. As a result, the wetting property of Sn3Ag9Bi5In solder is a little better than that of Sn37Pb and Sn3.5Ag.

• ETRI Journal
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• 제33권4호
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• pp.637-640
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• 2011

A novel bumping material, which is composed of a resin and Sn3Ag0.5Cu (SAC305) solder power, has been developed for the maskless solder-on-pad technology of the fine-pitch flip-chip bonding. The functions of the resin are carrying solder powder and deoxidizing the oxide layer on the solder power for the bumping on the pad on the substrate. At the same time, it was designed to have minimal chemical reactions within the resin so that the cleaning process after the bumping on the pad can be achieved. With this material, the solder bump array was successfully formed with pitch of 150 ${\mu}m$ in one direction.