• 마이크로전자및패키징학회지
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• 제21권2호
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• pp.37-41
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• 2014

차세대 전자 소자 기술에서 전력전달은 소자의 전력을 낮추고 발열로 인한 문제 해결을 위해서 매우 중요한 기술로 대두되고 있다. 본 연구에서는 직사각형 ABL 전력 범프를 이용한, Cu-to-Cu 플립 칩 본딩 공정의 신뢰성 문제에 대해 살펴보았다. 다이 내 범프 높이 차이는 전기도금 후 CMP 공정을 진행했을 경우 약 $0.3{\sim}0.5{\mu}m$ 이었고, CMP 공정을 진행하지 않았을 경우는 약 $1.1{\sim}1.4{\mu}m$으로 나타났다. 또한 면적이 큰 ABL 전력 범프가 입출력 범프 보다 높이가 높게 나타났다. 다이 내 범프 높이 차이로 인해 플립 칩 본딩 공정 시 misalignment 문제가 발생하였고, 이는 본딩 quality 에도 영향을 미쳤다. Cu-to-Cu 플립 칩 공정을 위해선 다이 내 범프 높이 균일도와 Cu 범프의 평탄도 조절이 매우 중요한 요소라 하겠다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2000년도 특별강연 및 춘계학술발표대회 개요집
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• pp.283-286
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• 2000

• 한국정밀공학회지
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• 제31권10호
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• pp.865-871
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• 2014

Paradigm shift to 3-D chip stacking in electronic packaging has induced a lot of integration challenges due to the reduction in wafer thickness and pitch size. This study presents a hybrid bonding technology by self-alignment effect in order to improve the flip chip bonding accuracy with ultra-thin wafer. Optimization of Cu pillar bump formation and evaluation of various factors on self-alignment effect was performed. As a result, highly-improved bonding accuracy of thin wafer with a $50{\mu}m$ of thickness was achieved without solder bridging or bump misalignment by applying reflow process after thermo-compression bonding process. Reflow process caused the inherently-misaligned micro-bump to be aligned due to the interface tension between Si die and solder bump. Control of solder bump volume with respect to the chip dimension was the critical factor for self-alignment effect. This study indicated that bump design for 3D packaging could be tuned for the improvement of micro-bonding quality.

• 보건의료산업학회지
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• 제14권2호
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• pp.1-14
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• 2020

Objectives : The purpose of this study was to test fitness of the structured model of SNS activities for health information. Methods : A structured questionnaire were administered to 500 subjects. A structural equation model was applied to collected data. Results : The response rate was 73.9%. The respondents mostly used Facebook and KakaoStory. They spent 70 minutes per day and 21~30% of this usage was taken by health information. In the variances, those who has religion more actively exchanged information about diseases and medical institutions. The goodness-of-fit of the model was .81(GFI) and .90(CFI). The main path was bridging capital -> bonding capital -> credibility -> SNS activities for health information. The path from quality of sharing information to SNS activities was not significant. It could be explained by the restriction of digital literacy. Conclusions : SNS activities for health information were determined by credibility, currency and bonding social capital. Bridging social capital, indirectly, influenced SNS activities through bonding social capital. Thus building bonding social capital would be a critical success factor for SNS.

• Computers and Concrete
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• 제26권3호
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• pp.257-273
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• 2020

Concrete bond strength with steel re-bars depends on multiple factors including concrete-steel interface and mechanical properties of concrete. However, the hydration development of cementitious paste, and in turn the mechanical properties of concrete, are negatively affected by cold weather. This study aimed at exploring the concrete-steel bonding behavior in concrete cast and cured under freezing temperatures. Three concrete mixtures were cast and cured at -10 and -20℃. The mixtures were protected using conventional insulation blankets and a hybrid system consisting of insulation blankets and phase change materials. The mixtures comprised General Use cement, fly ash (20%), nano-silica (6%) and calcium nitrate-nitrite as a cold weather admixture system. The mixtures were tested in terms of internal temperature, compressive, tensile strengths, and modulus of elasticity. In addition, the bond strength between concrete and steel re-bars were evaluated by a pull-out test, while the quality of the interface between concrete and steel was assessed by thermal and microscopy studies. In addition, the internal heat evolution and force-slip relationship were modeled based on energy conservation and stress-strain relationships, respectively using three-dimensional (3D) finite-element software. The results showed the reliability of the proposed models to accurately predict concrete heat evolution as well as bond strength relative to experimental data. The hybrid protection system and nano-modified concrete mixtures produced good quality concrete-steel interface with adequate bond strength, without need for heating operations before casting and during curing under freezing temperatures down to -20℃.

• 한국공작기계학회논문집
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• 제18권1호
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• pp.116-121
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• 2009

Thermosonic flip chip bonding is an important technology for the electronic packaging due to its simplicity, cost effectiveness and clean and dry process. Mechanical properties of the horn and the shank, such as the natural frequency and the amplitude, have a great effect on the bonding capability of the transverse flip chip bonding system. In this research, two kinds of study are performed. The first is the new design of the clamp and the second is the effect of tolerance parameters to the performance of the system. The clamp with a bent shape is newly designed to hold the nodal point of the flip chip. The second is the effect of the design parameters on the vibration amplitude and planarity at the end of the shank. The variation of the tolerance parameters changes the amplitude and the frequency of the vibration of the shank. They, in turn, have an effect on the quantity of the plastic deformation of the gold ball bump, which determined the quality of the flip chip bonding. The tolerance parameters that give the great effect on the amplitude of the shank are determined using Taguchi's method. Error of set-up angle, the length and diameter of horn and error of the length of the shank are determined to be the parameters that have peat effect on the amplitude of the system.

• 마이크로전자및패키징학회지
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• 제22권3호
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• pp.31-38
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• 2015

본 연구에서는 실리콘 웨이퍼의 고속 직접접합 공정을 위하여 상압 플라즈마와 함께 에어로젤 형태의 초순수 분사를 이용하여 표면처리 활성화 및 결함이 없는 실리콘 직접접합 공정을 개발하였다. 플라즈마 공정의 다양한 인자, 즉 $N_2$ 가스의 유량, CDA(clean dry air)의 유량, 플라즈마 헤드와 기판 간의 간격, 플라즈마의 인가전압이 플라즈마 활성화, 즉 친수화 처리에 미치는 영향을 접촉각 측정을 통하여 관찰하였다. 또한 열처리 온도 및 열처리 시간이 접합 강도에 미치는 영향을 연구하였으며, 접합 강도의 측정은 crack opening 방법을 이용하였다. 접합 강도가 제일 높은 최적의 열처리 조건은 $400^{\circ}C$의 열처리 온도 및 2 시간의 열처리 시간이었다. 플라즈마 스캔 속도 및 스캔 횟수를 실험계획법을 이용하여 최적화한 결과, 스캔 속도는 30 mm/sec, 스캔 횟수는 4 회에서 최적의 접합 강도를 나타내고 있었다. 열처리 조건과 플라즈마 활성화 조건을 최적화 한 후 직접접합을 하여 적외선투과현미경 등을 이용하여 관찰한 결과, 접합된 웨이퍼에서 접합 공정으로 인한 공극이나 결함은 관찰되지 않았다. 접합된 웨이퍼의 접합 강도는 평균 $2.3J/m^2$의 접합 강도를 나타내고 있었다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제2권4호
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• pp.295-301
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• 2002

In this paper, solenoid-type 3-D passives (inductors and transformers) have been designed, fabricated, and characterized by using electroplating techniques, wire bonding techniques, multi-layer thick photoresist, and low temperature processes which are compatible with semiconductor circuitry fabrication. Two different fabrication approaches are performed to develop the solenoid-type 3-D passives and relationship of performance characteristics and geometry is also deeply investigated such as windings, cross-sectional area of core, spacing between windings, and turn ratio. Fully integrated inductor has a quality factor of 31 at 6 GHz, an inductance of 2.7 nH, and a self resonant frequency of 15.8 GHz. Bonded wire inductor has a quality factor of 120, an inductance of 20 nH, and a self resonant frequency of 8 GHz. Integrated transformers with turn ratios of 1:1 and n:l have the minimum insertion loss of about 0.6 dB and the wide bandwidth of a few GHz.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1349-1354
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• 2008

In this study, we try to find the root cause of water condensing failures in a headlamp using chemical and mechanical analysis. Through the surface inspection by OM, SEM and CT, it was found that water infiltrate into the headlamp through hotmelt adhesive debonding part caused by adhesion force degradation and poor quality. IR spectra shows that adhesion force degradation are characterized by increase of some functional group(1742, 1710, 1649, 1016). Through the ESPI measurement, it is turned out that bonding structural change by thermal expansion and degradation of adhesive can be the cause of void generation. So it is recommended that cooling passage and the bonding part should be redesigned to give a guarantee of less thermal stress and high adhesion quality.

• International Journal of Precision Engineering and Manufacturing
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• 제8권1호
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• pp.52-58
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• 2007

We propose a new contact detection algorithm for fine pitch wire bonding. Fast and stable contact detection of the z-axis in wire bonding is extremely important to maintain the quality of fine pitch gold wire bonding processes, which use a small pad less than $70{\mu}m$ in diameter. A small perturbation in the contact detection time causes a large difference in the size of the formed squashed ball. The new detection method is based on a statistical approach and designed for a discrete Kalman filter. It is faster and has smaller detection time variations than conventional detection methods. Experimental results are presented to demonstrate the advantages of the proposed algorithm.