• 한국전기전자재료학회논문지
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• 제23권4호
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• pp.298-302
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• 2010

We investigated the resistance change behavior of SABiT (Samsung Advanced Bump interconnection Technology) technology-applied PCB (Printed Circuit Board) with the various bump sizes and fabrication conditions. Many testing samples with different bump size, prepreg thickness, number of print on the formation of Ag paste bump, were made. The resistance of Ag paste bump itself was calculated from the Ag paste resistivity and bump size, measured by using 4-point probe method and FE-SEM (Field Emission Scanning Electron Microscope), respectively. The contact resistance between Ag paste bump and conducting Cu line were obtained by subtracting the Cu line and bump resistances from the measured total resistance. It was found that the contact resistance drastically changed with the variation of Ag paste bump size and the contact resistance had the largest influence on total resistance. We found that the bump size and contact resistance obeyed the power law relationship. The resistance of a circuit in PCB can be estimated from this kind of relationship as the bump size and fabrication technique vary.

• 대한금속재료학회지
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• 제46권9호
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• pp.585-592
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• 2008

Flip-chip bonding using Cu-Sn mushroom bumps composed of Cu pillar and Sn cap was accomplished, and the contact resistance and the thermal cycling reliability of the Cu-Sn mushroom bump joints were compared with those of the Sn planar bump joints. With flip-chip process at a same bonding stress, both the Cu-Sn mushroom bump joints and the Sn planar bump joints exhibited an almost identical average contact resistance. With increasing a bonding stress from 32 MPa to 44MPa, the average contact resistances of the Cu-Sn mushroom bump joints and the Sn planar bump joints became reduced from $30m{\Omega}/bump$ to $25m{\Omega}/bump$ due to heavier plastic deformation of the bumps. The Cu-Sn mushroom bump joints exhibited a superior thermal cycling reliability to that of the Sn planar bump joints at a bonding stress of 32 MPa. While the contact resistance characteristics of the Cu-Sn mushroom bump joints were not deteriorated even after 1000 thermal cycles ranging between $-40^{\circ}C$ and $80^{\circ}C$, the contact resistance of the Sn planar bump joints substantially increased with thermal cycling.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.140-143
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• 2006

Load/Unload(L/UL) technology includes the benefits, that is, increased areal density, reduced power consumption and improved shock resistance. The main issues of L/UL are no slider-disk contact and no media damage. To make sure L/UL stability, we consider many design parameters in L/UL systems. This paper is focused on disk design parameters through designing a disk bump in outer guard band(OGB). In the case of bump design on the disk, we create a bump by changing bump design parameters as like size and amplitude. From dynamic analysis, we choose optimal bump model with the highest flying height and the longest rising time. When a slider passes over a bump in dynamic system, the slider rise above bump according to bump shape. On the basis of this rising effect on the bump, we apply bump design to classical L/UL system having slider-disk contact possibility. This study is based on the simulation, we finally realize improved slider unloading performance by applying slider dynamic result on unload simulation.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.833-836
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• 2007

Load/Unload technology has more benefits than the conventional CSS technology. However, it remains unsolved technical problem on the unloading process. While the slider climbs up the ramp at the outer edge of the disk, the possibility of the slider-disk contact by lift-off force and rebound of the slider increases. This paper focuses on no slider-disk contact. To prevent the slider-disk contact, we apply the disk bump on disk outer edge proceeding unload. Firstly, in the simulation, the bump dimension is determined by changing bump design parameters. Secondly, dynamic stability of slider have to be checked on disk bump before unload analysis, and unload analysis is performed by applying stable bump shapes to unload simulation. Thirdly, we select optimal bump shape to improve unload performance by unload analysis. Finally, in the experiment, the disk bump is mechanically manufactured by pressing disk surface using diamond tip. That is variously processed by changing pressing pressure. After confirming bump shape by nano-scanner, proper bump shape is applied to real experimental unload process. Through this investigation, we propose the optimal bump design to prevent the slider-disk contact, and then we can realize improved unloading performance.

• Tribology and Lubricants
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• 제18권1호
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• pp.42-48
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• 2002

Experiments were conducted to determine the structural dynamic characteristics of bump foil bearing. The housing of the bearing on the journal was driven by two shakers which were used to simulate dynamic forces acting on the bump foil strips. Three different bump foils(Cu-coated bump, silicon bump, viscoelastic bump) are tested and the dynamic coefficients of three bump foils compared, based on the experimental measurements for a wide range of operating conditions. From the test results, the high damping coefficients of viscoelastic bump are achieved and the possibility of the super-bending-critical operation is suggested.

• 한국광학회지
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• 제7권4호
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• pp.434-439
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• 1996

본 연구에서는 가우스 진폭을 갖는 입사광의 단락된 정도와 광학 디스크 상의 bump의 형태가 재생신호에 미치는 영향과 디스크 bump에 맺히는 회절광 PSF(point spread function)와의 관계를 알아보기 위해 스칼라 회절 이론을 사용하였다. 단락된 가우스 진폭으로 .sigma.=0, 0.5, 1.5, 2.5인 경우를 고려하였으며 bump의 높이는 n.DELTA.$_{o}$ =.lambda./4로서 이는 위상 높이 .PHI.$_{o}$ =.pi.가 된다. 또한 본 연구에서 고려한 bump 형태 즉 직사각형(.DELTA.p$_{o}$ =0)과 준 원추형(.DELTA.p$_{o}$ /2) 그리고 원추형(.DELTA.p$_{o}$ =p$_{o}$ )의 세 가지 경우이다. 본 연구에서 고려한 입사광의 단락된 정도가 작을 수록 bump에 맺는 중심 회절상의 반경이 작게 나타났으며 이때 재생 신호의 극대치는 입사광의 단락된 정도가 작을수록 bump에 맺는 중심 회절상의 반경이 작계 나타났으며 이때 재생 신호의 극대치는 입사광의 단락된 정도가 큰 경우보다 크게 나타났고 bump의 크기도 작게 나타났다. 이러한 결과들로부터 입사광의 단락된 정도가 작을수록 광학 디스크로부터 큰 재생 신호를 얻을 수 있으며 cross-talk가 줄어듬을 알 수 있었다. 그러므로 실제 광학 디스크에 가능한 단락된 정도가 작은 가우스 진폭을 갖는 레이저 광을 입사광으로 사용하면 유용하리라 생각된다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 추계학술대회 논문집
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• pp.477-478
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• 2012

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2003년도 추계학술발표대회 개요집
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• pp.86-88
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• 2003

The characteristic of induction heating solder bump(solder ball: Sn-37Pb, Sn-3.5Ag, Sn-3.0Ag-0.5Cu) has analyzed in this paper. The initial condition of induction heating depends on the time and current. The shape of lead-free solder bump is better than lead solder. The shear strength of lead solder bump has decreased with aging time. The average of shear strength of solder bump is about 10N, 11N, and 11N respectively. The lead-free solder bump's shear strength is better than lead solder and varies irregularly with aging time.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2001년도 제34회 추계학술대회 개최
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• pp.282-289
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• 2001

Experiments were conducted to determine the structural dynamic characteristics of bump foil bearing. The housing of the bearing on the journal was driven by two shakers which were used to simulate dynamic forces acting on the bump foil strips. Three different bump foils(Cu-coated bump, silicon bump, viscoelastic bump) are tested and the dynamic coefficients of three bump foils compared, based on the experimental measurements for a wide range of operating conditions. From the test results, the high damping coefficients of viscoelastic bump are achieved and the possibility of the super-bending-critical operation is suggested.

• 한국광학회지
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• 제4권4호
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• pp.403-410
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• 1993

광 disc상의 bump(pit)의 형태가 재생신호에 미치는 영향을 알아보기 위해 스칼라 회절이론을 사용하였다. 이를 위하여 직사각형과 준원추형 그리고 원추형의 bump를 가정하여 신호를 계산한 결과 재생신호는 bump의 형태에 따라 현저한 차이를 보였다. 또한 세가지 bump의 형태중 직사각형 bump에서 가장 좋은 신호를 재생시킬 수 있음을 알 수 있었다. 실제로는 이러한 직사각형의 이상적인 형태의 bump는 제작상 어려움이 있으나 "둥글기" 정도에 따라 만족할 만한 재생 신호를 얻을 수 있다는 것을 보였다.