• Title/Summary/Keyword: Bump Height

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Resonance Phenomenon and Its Effects of Laser Texture Disk

  • Choa, Sung-Hoon;Wang, Geng
    • Journal of Mechanical Science and Technology
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    • v.14 no.7
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    • pp.744-751
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    • 2000
  • To achieve lower flying height for high areal recording density, the laser zone texturing of the disk needs to be designed to reduce glide height. One problem of the laser bump design is that the regular laser bump pattern often produces glide resonance phenomenon, which leads to failure of the glide height test. However, it was found in this study that glide resonance is an intrinsic problem of the glide head used and resonance phenomenon depends on the type of the head slider, that is, the natural frequency of the slider body. Therefore, higher glide height or glide failure caused by glide resonance does not lead to head/media interface problem in the real drive operating conditions in which the data head is used. Pseudo-random bump pattern greatly reduces the glide resonance. Smaller bump pitch will also help to reduce the glide resonance. However, as bump spacing becomes smaller, glide height will be increased due to increased air pressure developed around the bumps. Lowering bump height is the most effect way to reduce glide avalanche.

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Fabrication of Wafer Level Fine Pitch Solder Bump for Flip Chip Application (플립칩용 웨이퍼레벨 Fine Pitch 솔더범프 형성)

  • 주철원;김성진;백규하;이희태;한병성;박성수;강영일
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.14 no.11
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    • pp.874-878
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    • 2001
  • Solder bump was electroplated on wafer for flip chip application. The process is as follows. Ti/Cu were sputtered and thick PR was formed by several coating PR layer. Fine pitch vias were opened using via mask and then Cu stud and solder bump were electroplated. Finally solder bump was formed by reflow process. In this paper, we opened 40㎛ vias on 57㎛ thick PR layer and electroplated solder bump with 70㎛ height and 40㎛ diameter. After reflow process, we could form solder bump with 53㎛ height and 43㎛ diameter. In plating process, we improved the plating uniformity within 3% by using ring contact instead of conventional multi-point contact.

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Study of micro flip-chip process using ABL bumps (ABL 범프를 이용한 마이크로 플립 칩 공정 연구)

  • Ma, Junsung;Kim, Sungdong;Kim, Sarah Eunkyung
    • Journal of the Microelectronics and Packaging Society
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    • v.21 no.2
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    • pp.37-41
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    • 2014
  • One of the important developments in next generation electronic devices is the technology for power delivery and heat dissipation. In this study, the Cu-to-Cu flip chip bonding process was evaluated using the square ABL power bumps and circular I/O bumps. The difference in bump height after Cu electroplating followed by CMP process was about $0.3{\sim}0.5{\mu}m$ and the bump height after Cu electroplating only was about $1.1{\sim}1.4{\mu}m$. Also, the height of ABL bumps was higher than I/O bumps. The degree of Cu bump planarization and Cu bump height uniformity within a die affected significantly on the misalignment and bonding quality of Cu-to-Cu flip chip bonding process. To utilize Cu-to-Cu flip chip bonding with ABL bumps, both bump planarization and within-die bump height control are required.

Influence of truncated gaussian beam on read-out signal in optical disc (단락된 가우스 광이 광학 디스크 재생 신호에 미치는 영향)

  • 박성종;정창섭
    • Korean Journal of Optics and Photonics
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    • v.7 no.4
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    • pp.434-439
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    • 1996
  • To investigate influence of the incident beams which have the truncated Gaussian amplitude and of the shapes of bump on read-out signal is an optical disc, and the point spread function on bump, the scalar diffraction theory is used in this paper. We consider the truncated Gaussian amplitudes which are $\sigma$=0, 0.5, 1.5, and 2.5, the height of bump which is given by $n{\Delta}_0={\lambda}/4$, and the phase height of bump which is then given by ${\Phi}_0={\pi}$. We also consider the shapes of the bump which are a rectangular shape, a frustoconical shape, and a conical shape. It is shown that as the truncation of incident beam reduces the radius of central spot on bump decreases, the maximum value of read-out signal increases, and that the size of bump decreases. From these results, we get better read-out signal and the reduced cross-talk in optical disc when the truncation of incident beam reduces. Therefore a laser beam having less truncated Gaussian amplitude may useful for an actual optical disc.

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A Study on Head-Disk Interactions at Ultra-low Flying Height in Contact Start-Stop (Contact Start-Stop 방식에서의 극저부상 높이에서 Head-Disk Interface Interactions 연구)

  • 조언정
    • Tribology and Lubricants
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    • v.19 no.2
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    • pp.102-108
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    • 2003
  • The height of laser bumps has been considered as the limit of the minimum flying height in the contact start-stop (CSS) of hard disk drives. In this paper, tribological interactions at flying height under laser bumps are investigated in a spin stand for development of ultra-low flying head-disk interface. With the reduction of the spinning speed in a spin stand, the flying height is decreased under the height of laser bumps and, then, head-disk interactions are investigated using AE and stiction/friction signals. During seek tests and 20000 cycle-sweep tests, AE and stiction/friction signals are not significantly changed and there are no catastrophic failures of head-disk interface. Bearing analysis and AFM analysis show that there are signs of wear and plastic deformation on the disks. It is suggested that flying height could be as low as and, sometimes, lower than laser bump height.

Microbump formation during laser texturing of glass substrates (유리기층의 레이저 텍스쳐링에 의한 미소융기의 형성)

  • 김동식;오부국
    • Laser Solutions
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    • v.4 no.3
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    • pp.40-44
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    • 2001
  • Microbump formation during CO$_2$ laser texturing of glass substrates is examined in this paper. Experimental results show that different bump shapes (dome-shaped, with a central dimple, and with a peripheral rim) are generated depending on the laser fluence. A theoretical model for the process is suggested based on thermoelastic behavior but limited only to the dome-shaped bump. The dimensions (maximum height and base area) of the bump shows a logarithmic dependence on laser fluence as expected from the theory. Numerical computation reveals that the effect of thermal diffusion is not negligible for relatively long laser pulses.

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Design and analysis of disk bump to Improve unloading performance (언로드 성능향상을 위한 디스크 범프의 디자인 및 해석)

  • Lee, Hyung-Jun;Lee, Yong-Hyun;Kim, Ki-Hoon;Park, No-Cheol;Park, Young-Pil
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.11a
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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.

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Flip Chip Process for RF Packages Using Joint Structures of Cu and Sn Bumps (Cu 범프와 Sn 범프의 접속구조를 이용한 RF 패키지용 플립칩 공정)

  • Choi, J.Y.;Kim, M.Y.;Lim, S.K.;Oh, T.S.
    • Journal of the Microelectronics and Packaging Society
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    • v.16 no.3
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    • pp.67-73
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    • 2009
  • Compared to the chip-bonding process utilizing solder bumps, flip chip process using Cu pillar bumps can accomplish fine-pitch interconnection without compromising stand-off height. Cu pillar bump technology is one of the most promising chip-mounting process for RF packages where large gap between a chip and a substrate is required in order to suppress the parasitic capacitance. In this study, Cu pillar bumps and Sn bumps were electroplated on a chip and a substrate, respectively, and were flip-chip bonded together. Contact resistance and chip shear force of the Cu pillar bump joints were measured with variation of the electroplated Sn-bump height. With increasing the Sn-bump height from 5 ${\mu}m$ to 30 ${\mu}m$, the contact resistance was improved from 31.7 $m{\Omega}$ to 13.8 $m{\Omega}$ and the chip shear force increased from 3.8 N to 6.8 N. On the contrary, the aspect ratio of the Cu pillar bump joint decreased from 1.3 to 0.9. Based on the variation behaviors of the contact resistance, the chip shear force, and the aspect ratio, the optimum height of the electroplated Sn bump could be thought as 20 ${\mu}m$.

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Investigation of Head-Disk Interactions at Ultra-low Flying HDI

  • Cho, Unchung
    • KSTLE International Journal
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    • v.3 no.2
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    • pp.114-118
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    • 2002
  • In this work, head-disk interactions are studied when flying height becomes lower than laser bump height on the landing zone of a disk. With the reduction of the spinning speed in a spin stand, the flying height is decreased under the height of laser bumps. Conventional and padded pico sliders sweep between landing Bone and data zone and, then, the dynamic behavior of the pico sliders and head-disk impacts are investigated using AE and stiction/friction signals. After 200n cycle-sweep tests, bearing analysis and AFM analysis indicate that there are some signs of wear and plastic deformation in the landing zone of a disk, although AE and stiction/friction signals are not significantly changed during the sweep tests. The experimental results of this paper suggest that in CSS tests at component level, more rigorous examination methods of wear and plastic deformation might be necessary as flying height becomes getting lower.

Static FE Analysis of Air Springs for Passenger Cars Considering the Mounting Steps (체결단계를 고려한 승용차용 에어스프링 정특성 설계해석기법 개발)

  • Lee, H. W.;Hahn, H. T.;Park, J. Y.
    • Transactions of Materials Processing
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    • v.24 no.6
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    • pp.387-394
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    • 2015
  • Air springs are designed to support loads using the volume elasticity in a cylindrical shaped air bag made of a composite material with a rubber matrix and two plies of reinforced fibers. Recently, applications of these springs have been expanded from railway vehicles to passenger cars. The current study presents a finite element analysis of a manufactured air spring for a passenger car. The analysis was conducted including the mounting steps of the air bag using a static loading condition. A method for controlling the internal pressure and displacements during the mounting step was developed. The characteristic load curve and the shape of the air bag were in good agreement with the experimental data with respect to the design height, the bump height and the rebound height. Results indicate that ply angles of fibers vary from 38 degrees to 56 degrees during static loading.