• 한국초전도학회:학술대회논문집
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• v.10
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• pp.207-210
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• 2000

Properties of SrTiO$_3$ thin films were characterized under the influence of an applied dc voltage utilizing a gold resonator with a flip-chip capacitor. The measurements were performed at microwave frequency ranges and low temperatures cryogenic temperatures. The dielectric constant of 830 and the low loss tangent of 6X10$^{-3}$ at 3.64 GHz were observed at 90 K and 100 V. The quality in the SrTiO$_3$ film was presented in terms of fractional frequency under the bias voltages and cryogenic temperatures.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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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.

• Journal of Welding and Joining
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• v.25 no.3
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• pp.45-50
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• 2007

The present study is devoted to investigate the transient flow and to estimate the filling time fur underfill process by using the numerical model established on the fluid momentum equation. For optimization of the design and selection of process parameters, this study extensively presents an estimation of the filling time in the view points of some important factors related to underfill materials and flip-chip geometry. From the results, we conclude that the filling time changes with respect to the under fill materials because of different viscosity, surface tension coefficient and contact angle. It reveals that, as the gap height increases, the filling time decreases substantially, and goes to the saturated values.

• Proceedings of the KWS Conference
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• 2007.11a
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• pp.245-247
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• 2007

Sn-base solder bump is mainly used in micro-joining for flip chip package. The quantity of intermetallic compounds that was formed between Cu pad and solder interface importantly affects reliability. In this research, micro-bump was fabricated by two binary electroplating and the intermetallic compounds(IMCs) was estimated quantitatively. When the micro Sn-Ag solder bump was made by electroplating, SiC powder was added in the plating solution for protecting of intermetallic growth. Then, the intermetallic compounds growth was decrease with increase of amount of SiC power. However, if the mount of SiC particle exceeds 4 g/L, the effect of the growth restraint decrease rapidly.

• Electronics and Telecommunications Trends
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• v.9 no.1
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• pp.109-122
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• 1994

소자가 고속, 고주파화 되고 ASIC 칩의 개발이 가속화되면서 패키징과 interconnection 의 중요성이 더욱 증대되고 있다. 소자의 성능에 가장 직접적인 영향을 주는 것이 1차 패키징인데 현재 가장 많이 실행되고 있는 것이 wire 등에 의한 본딩 방법이었다. 이러한 기존의 방법은 소자의 고속화와 입출력 숫자의 증가에 따라 점차 그 한계를 보이고 있는데 이에 대한 방안으로는 플립칩 본딩 방식에 의한 패키징을 들 수 있다. 약 20여년 전에 IBM 에서 개발된 이래 많은 발전을 거듭한 이 기술은 최근 기본 기술에 대한 특허권의 소멸과 함께 많은 응용 분야에서 개발이 활발히 진행되고 있다. 따라서 본 고에서는 향후의 가장 유력한 패키징 기술로 인정되고 있는 플립칩 본딩 기술의 특징과 제조 관련 사항을 정리함과 동시에 응용 분야, 특히, OEIC(Optoelectronics Integrated Circuit) 분야에서의 이용 및 개발 현황을 분석, 소개함으로써 이 새로운 패키징 기술에 대한 인식을 제고하고자 한다.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2002.11a
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• pp.27-32
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• 2002

In this paper, global full 3D finite element analysis fatigue models are constructed for flip-chip BGA on board to predict the creep fatigue life of solder joints during the thermal cycling test. The fatigue model applied is based on Darveaux's empirical equation approach with non-linear viscoplastic analysis of solder joints. It was estimated by the creep life as the variations of the four kinds of thermal cycling test conditions, pad structure, composition and size of solder ball. The shortest fatigue life of results was obtained at the thermal cycling testing condition of -65℃ ∼ 150℃. It was increased about 3.5 times in comparison with that of 0℃ ∼ 100℃. As the change of pad structure at the same other conditions, the fatigue life of SMD structure increased about 5.7% as compared with NSMD structure. Consequently, it was confirmed that the fatigue life became short as the creep strain energy density increased in solder joint.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2002.11a
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• pp.49-53
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• 2002

The Sn-Cu eutectic solder bump formation ($140{\mu}{\textrm}{m}$ 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-Cu deposit was investigated. The morphology and composition of plated solder surface was examined by scanning electron microscopy. The plating thickness increased with increasing time. The plating rate increased generally according to current density. After the characteristics of Sn-Cu plating were investigated, Sn-Cu solder bumps were fabricated on optimal condition of 5A/dm$^2$, 2hrs. Ball shear test after reflow was performed to measure adhesion strength between solder bump and UBM (Under Bump Metallization). The shear strength of Sn-Cu bump after reflow was higher than that of before reflow.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2357-2359
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• 2005

In this paper, we analyzed the effect of flip chip interconnect which is a part of FC-BGA package on the transmission characteristics of interconnect. We designed simple interconnect model and analyzed the change of the transmission characteristics as the size of each component change. And we provided design guide of interconnect which shows more enhanced results.

• Journal of Welding and Joining
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• v.23 no.5
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• pp.49-54
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• 2005

The effective charge number and the critical current density of electromigration in eutetic SnPb and Pb Free $(SnAg_{3.8}Cu_{0.7)$ flip chip solder bumps are studied. The effective charge number of electromigration in eutectic SnPb solder is obtained as 34 and the critical current density is $j=0.169{\times}({\delta}_{\sigma}/{\delta}_x})\;A/cm^2,\;where\;({\delta}_{\sigma}/{\delta}_x})$ is the electromigration-induced compressive stress gradient along the length of the line. While the effect of electromigration in Pb free solder is much smaller than that in eutectic SnPb, the product of diffusivity and effective charge number $DZ^{\ast}$ has been assumed as $6.62{\times}10^{-11}$. The critical length for electromigration are also discussed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.207-208
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• 2009