• Journal of the Korean Institute of Intelligent Systems
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• v.23 no.4
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• pp.286-291
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• 2013

In this paper, in-line type flip chip bump 3D inspection equipment, using white light interferometer with large F.O.V., which is aimed to be used in flip chip bump test process is developed. Results of flip chip bump height measurement in many substrates and repeatability test results for the bumps in fixed location of each substrate are shown. Test results from test bench and those from developed flip chip bump 3D inspection equipment are compared and as a result repeatability is improved by reducing the impact of system vibration. A valuation basis for the testing quality of flip chip bump 3D inspection equipment is proposed.

• Tribology and Lubricants
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• v.24 no.6
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• pp.378-385
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• 2008

In foil bearings, the friction between bumps and their mating surfaces is the major factor which exerts great influence on the bearing performance. From this point of view, many efforts have been made to improve the understanding of the influence of the friction on the foil bearing performance by developing a number of analytical models. However, most of them did not consider the hysteretic behavior of the foil structure resulting from the friction. The present work developed the static structural model in which hysteretic behavior of the friction was considered. The foil structure was modeled using finite element method and the algorithm which determines the conditions of the contact nodes and the directions of the friction forces was used to take into account the friction. The developed model was integrated into the foil bearing prediction code to investigate the effects of the friction on the static performance of the bearing. The results of analysis show that multiple static equilibrium positions are presented for the one static load under the influence of the friction, inferring its great effects on the dynamic performance. However, the effect of friction on the minimum film thickness which determines load capacity of the bearing is negligible.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.4
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• pp.420-427
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• 2016

Diverse research on gearing systems have been made to resolve gear NVH problems for many decades, and transmission error (T.E.) has been identified as one of the main sources generating gear noises. While gear profiles and amounts of tooth modifications have influences on gear noise in the design aspect, it is found that bad manufacturing conditions such as burrs, bumps and damage, which result in improper gear operating conditions, produce gear noise with respect to manufacturing process. In this paper, T.E. measurement system was introduced to examine the gears damaged or improperly manufactured, while they are assembled, by comparing T.E. values and various gear conditions with theoretical ones. This T.E. measurement system, following grinding machining process, has been installed in a manufacturing line in 2014, and it results that the transmission rework to resolve manufacturing problems is not needed at the end of line.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.1
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• pp.84-91
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• 2013

Ultrasonic flip-chip bonding needs a precise bonding tool which delivers ultrasonic energy into chip bumps effectively to use the selected resonance mode and frequency of the horn structure. The bonding tool is excited at the resonance frequency and the input and output ports should locate at the anti-nodal points of the resonance mode. In this study, we propose new design method with topology optimization for ultrasonic bonding tools. The SIMP(solid isotropic material with penalization) method is used to formulate topology optimization and OC(optimal criteria) algorithm is adopted for the update scheme. MAC(modal assurance criterion) tracking is used for the target frequency and mode. We fabricate two prototypes of ultrasonic tools which are based on 3D optimization models after reviewing 2D and 3D topology optimization results. The prototypes are satisfied with the ultrasonic frequency and vibration amplitude as the ultrasonic bonding tools.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.6
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• pp.636-641
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• 2014

This paper discusses the fabrication process for a Nipkow disk using micro-lens and pinhole disks. The confocal measuring system that uses the Nipkow disk has the advantage in measuring speed, because the Nipkow disk can simultaneously provide confocal images of all pixels in a CCD camera without requiring a lateral scanning unit. A micro-lens configuration, which focuses illumination on a pinhole, overcomes the low optical efficiency of the Nipkow disk system and allows its use in practical applications. This paper describes how to design the Nipkow disk in terms of numerical aperture, particularly for measuring the height of solder bumps in packaging application and for hybrid processes combining mechanical and semiconductor processes.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.1135-1141
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• 2006

Air foil bearing supports the rotating journal using hydrodynamic force generated at thin air film. The bearing performance, stiffness, damping coefficient and load capacity, depends on the rotating speed and the performance of the elastic foundation, bump foil. The main focus of this study is to decide the dynamic performance of corrugated bump foil, structural stiffness and Coulomb damping caused by friction between bump foil and top foil/bump foil and housing. Structural stiffness is determined by the bump shape (bump height, pitch and bump thickness), dry-friction, and interacting force filed up to fixed end. So, the change of the characteristics was considered as the parameters change. The air foil bearing specification for analysis follows the general size; diameter 38.1 mm and length 38.1mm (L/D=1.0). The results show that the stiffness at the fixed end is more than the stiffness at the free end, Coulomb damping is more at the fixed end due to the small displacement, and two dynamic characteristics are dependent on each other.

• 정보저장시스템학회:학술대회논문집
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• 2005.10a
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• pp.88-95
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• 2005

The head to disk spacing must be decreased to increase recording densities in hard disk drives. Recently, to decrease the head to disk spacing, smooth disk having no bumps onto the lading zone has used. In this research, we compared the number of particles generated in HDD with smooth and textured disks. We used a sampling method using a particle sampler and a CPC (condensation particle counter) to detect particles in HDD. First, we sampled and counted panicles generated with disk rotational speed and various rest times when the smooth disk and textured disks were used, then analyzed the sampled particles by SEM (scanning electron microscopy) and AES (auger electron spectroscopy). In results of measuring particles, more particles in case of LZT disk drive generated than that of the smooth disk drive in all test modes. The number of particles generated in the smooth disk was very low. The particle generation increased as the rest time increased (smooth/LZT disks) and more particles in case of LZT disk drive generated than that of the smooth disk drive. In results of analyzing particle components, Al, Ti, Si components were detected and we could not found differences between components in case of smooth/LZT disk drive.

• Journal of Auto-vehicle Safety Association
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• v.9 no.2
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• pp.6-12
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• 2017

An autonomous driving system based on a precise digital map is developed. The system is implemented to the Hyundai's Tucsan fuel cell car, which has a camera, smart cruise control (SCC) and Blind spot detection (BSD) radars, 4-Layer LiDARs, and a standard GPS module. The precise digital map has various information such as lanes, speed bumps, crosswalks and land marks, etc. They can be distinguished as lane-level. The system fuses sensed data around the vehicle for localization and estimates the vehicle's location in the precise map. Objects around the vehicle are detected by the sensor fusion system. Collision threat assessment is performed by detecting dangerous vehicles on the precise map. When an obstacle is on the driving path, the system estimates time to collision and slow down the speed. The vehicle has driven autonomously in the Hyundai-Kia Namyang Research Center.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.9
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• pp.916-921
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• 2009

The technology to inspect and measure an inner structure of micro parts has become an important tool in the semi-conductor industrial field with the development of automation and precision manufacturing. Especially, the inspection skill on the inside of highly integrated electronic device becomes a key role in detecting defects of a completely assembled product. X-ray inspection technology has been focused as a main method to inspect the inside structure. However, there has been insufficient research done on the customized inspection technology for the flip-chip assembly due to the interior connecting part of flip chip which connects the die and PCB electrically through balls positioned on the die. In this study, therefore, it is implemented to detect shape error of flip chip bonding without damaging chips using an x-ray inspection system. At this time, it is able to monitor the solder bump shape by introducing an edge-extracting algorithm (exponential approximation function) according to the attenuating characteristic and detect shape error compared with CAD data. Additionally, the bonding error of solder bumps is automatically detectable by acquiring numerical size information at the extracted solder bump edges.

• Journal of the Semiconductor & Display Technology
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• v.19 no.2
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• pp.45-50
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• 2020

We investigated the Si_1-xGe_x surface properties when dry cleaning the films using NF₃ / H₂O remote plasma. After the dry cleaning process, it was found that about 80-250 nm wide bumps were formed on the SiGe surface regardless of Ge concentration in the rage of x = 0.1 ~ 0.3. In addition, effects of the dry cleaning processing parameters such as pressure, substrate temperature, and H₂O flow rates were examined. It was found that the surface bump is significantly dependent on the flow rate of H₂O. Based on these observations, we would like to provide additional guidelines for implementing the dry cleaning process to SiGe materials.