• Corrosion Science and Technology
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• v.6 no.6
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• pp.282-285
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• 2007

Smaller size and higher integration of electronic systems make narrower interconnect pitch not only in chip-level but also in package-level. Moreover electronic systems are required to operate in harsher conditions, that is, higher current / voltage, elevated temperature / humidity, and complex chemical contaminants. Under these severe circumstances, electronic components respond to applied voltages by electrochemically ionization of metals and conducting filament forms between anode and cathode across a nonmetallic medium. This phenomenon is called as the electrochemical migration. Many kinds of metal (Cu, Ag, SnPb, Sn etc) using in electronic packages are failed by ECM. Eutectic SnPb which is used in various electronic packaging structures, that is, printed circuit boards, plastic-encapsulated packages, organic display panels, and tape chip carriers, chip-on-films etc. And the material for soldering (eutectic SnPb) using in electronic package easily makes insulation failure by ECM. In real PCB system, not only metals but also many chemical species are included. And these chemical species act as resources of contamination. Model test systems were developed to characterize the migration phenomena without contamination effect. The serpentine-shape pattern was developed for analyzing relationship of applied voltage bias and failure lifetime by the temperature / humidity biased(THB) test.

• Korean Journal of Metals and Materials
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• v.48 no.11
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• pp.1035-1040
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• 2010

The research efforts on GaN-based light-emitting diodes (LEDs) keep increasing due to their significant impact on the illumination industry. Surface mount technology (SMT) is widely used to mount the LED packages for practical application. In surface mount soldering both the device body and leads are intentionally heated by a reflow process. We studied on the effects of multiple reflows on microstructural variation and joint strength of the solder joints between the LED package and the substrate. In this study, Pb-free Sn-3.0Ag-0.5Cu solder and a finished pad with organic solderability preservatives (OSP) were employed. A $Cu_6Sn_5$ intermetallic compound (IMC) layer was formed during the multiple reflows, and the thickness of the IMC layerincreased with an increasing number of reflows. The shear force decreased after three reflows. From the observation of the fracture surface after a shear test, partially brittle fractures were observed after five reflows.

• Journal of the Microelectronics and Packaging Society
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• v.29 no.4
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• pp.83-87
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• 2022

Recently, as the thickness of the semiconductor package becomes thinner, warpage has become a major issue. Since the warpage is caused by differences in material properties between package components, it is essential to precisely evaluate the material properties of the EMC(Epoxy molding compound), one of the main components, to predict the warpage accurately. Especially, the cure shrinkage of the EMC is generated during the curing process, and among them, the effective cure shrinkage that occurs after the gelation point is a key factor in warpage. In this study, the gelation point of the EMC was defined from the dissipation factor measured using the dielectric sensor during the curing process similar with actual semiconductor package. In addition, DSC (Differential scanning calorimetry) test and rheometer test were conducted to analyze the dielectrometry measurement. As a result, the dielectrometry was verified to be an effective method for monitoring the curing status of the EMC. Simultaneously, the strain transition of the EMC during the curing process was measured using the FBG (Fiber Bragg grating) sensor. From these results, the effective cure shrinkage of the EMC during the curing process was measured.

• Journal of Korean Institute of Industrial Engineers
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• v.10 no.2
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• pp.51-65
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• 1984

A process quality control system is designed which incorporates run tests, normality test, process capability studies, etc., into control chart scheme, and a software package for microcomputers is developed. The system is interactive and has data base management capabilities. All programs are written in BASIC language.

• 전기의세계
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• v.38 no.7
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• pp.46-52
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• 1989

지금까지 Vector supercomputer를 비롯한 여러종류의 supercomputer의 기술발전 추세를 간단히 살펴보았다. 앞으로의 Supercomputer는 VLSI기술의 발달, GaAs같은 새로운 소재의 chip, optical connection을 이용한 더 나은 Package방식, 보다 큰 memory 그리고 parallel processing을 최대한 이용하여 현재의 supercomputer성능보다 엄청나게 강력한 Test FLOPS급의 성능을 발휘할 것으로 기대된다. 또한 전문분야별 Supercomputer들도 발전을 거듭하면서 성능은 크게 증가하고 값은 떨어져서 과학기술 분야를 포함한 각분야에 일상적으로 쓰이게 될 것이다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.11
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• pp.1012-1019
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• 2000

A proficiency test is one of programs which Korea Research Institute of Standards and Science(KRISS), as national metrology institute, is putting in operation for the mutual recognition arrangement. The Fluid Flow Group of KRISS evaluated the measurement capability for liquid flowmeter calibrator of the national calibration and test organizations. The uncertainty of national standard system was estimated in accordance with Guide to The Expression of Uncertainty in Measurement (ISO), and the turbine flowmeter, which was used for the round-robin test as a reference flowmeter, was characterized. The round-robin tests with the turbine flowmeter package were carried out in 1995 and 1999. The test results of the organizations and those of KRISS agreed within $\pm0.2$%. It is found thus that the organizations have the traceability of the national standard for liquid flow measurement.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.11a
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• pp.245-246
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• 2008

• Proceedings of the Korean Society of Food and Cookery Science Conference
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• 2003.10a
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• pp.98-98
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• 2003

본 연구는 대학생의 음주와 식생활 관련 지식 및 행동에 관한 실태를 조사 하고자 경산지역 남자 대학생 177명과 여자대학생 189명을 대상으로 설문지를 이용하여 실시하였다. 설문지 내용은 일반적인 사항과 건강, 음주량과 음주와 관련된 사항 그리고 식습관과 영양지식과 관련된 문항으로 나누어서 자가기입 방식으로 응하도록 하였다. 자료는 각 문항들에 대해서 빈도와 백분율로 표기 하였고 통계적 분석은 SAS Package Program을 이용하여 t-test와 x$^2$-test로 하였다. (중략)

• Communications for Statistical Applications and Methods
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• v.7 no.3
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• pp.927-935
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• 2000

In this paper we propose a poll system n the internet. This system expects to increase the confidence of the internet poll results by sampling theory(proportional allocation). This system provides a cross-tale and result of hypothesis test which plays an important role for decision making. These results do offer a few statistical packages(such as SAS, SPSS) in the world wide web.

• Journal of KSNVE
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• v.2 no.1
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• pp.41-47
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• 1992

In order to reduce the shock which may occur during shipping of a drumtype container, rubber mounts were designed using a commercial FEM package and manufactured, and then the performance was checked by static and dynamic test. According to the design specifications, the container system was tested by dropping. The experimental results are compared with the theoretical ones.