• Journal of the Microelectronics and Packaging Society
• /
• v.20 no.4
• /
• pp.17-23
• /
• 2013

As a basic research to develop stretchable electronic packaging technology, CNT-Ag composite pads were formed on top of Cu/Sn chip bumps and flip-chip bonded using anisotropic conductive adhesive. Average contact resistances of the flip-chip joints were measured with respect to bonding pressure and presence of the CNT-Ag composite pads. When Cu/Sn chip bumps with CNT-Ag composite pads were flip-chip bonded to substrate Cu pads at 25MPa or 50 MPa, contact resistance was too high to measure. The specimen processed by flip-chip bonding the Cu/Sn chip bumps with CNT-Ag composite pads to the substrate Cu pads exhibited an average contact resistance of $213m{\Omega}$. On the other hand, the flip-chip specimens processed by bonding Cu/Sn chip bumps without CNT-Ag composite pads to substrate Cu pads at 25MPa, 50MPa, and 100MPa exhibited average contact resistances of $370m{\Omega}$, $372m{\Omega}$, and $112m{\Omega}$, respectively.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.15 no.1
• /
• pp.139-144
• /
• 1991

Chip flow angle is one of the important factors to be determined for the scheme of Chip Control. Up to now, however, a dependable way to predict the chip flow angle in practical cutting has not been established satisfactorily. In this paper a rather simple theoretical prediction of chip flow angle is tried based on some already widely confirmed hypotheses. The developed equation of chip flow angle contains the parameters of depth of cut d, feed rate f, nose radius $r_{n}$ side cutting edge angle $C_{s}$, side rake angle .alpha.$_{s}$ and back rake angle .alpha.$_{b}$. Theoretical results of chip flow angle given by this study bas been shown in a good agreement with experimental ones.s.s.s.s.

• Journal of the Korean Society for Precision Engineering
• /
• v.20 no.11
• /
• pp.64-70
• /
• 2003

This paper suggests a systematic methodology to predict chip forms using the experimental design technique and the neural network. Significant factors determined with ANOVA analysis are used as input variables of the neural network back-propagation algorithm. It has been shown that cutting conditions and cutting tool shapes have distinct effects on the chip forms, so chip breaking. Cutting tools are represented using the Z-map method, which differs from existing methods using some chip breaker parameters. After training the neural network with selected input variables, chip forms are predicted and compared with original chip forms obtained from experiments under same input conditions, showing that chip forms are same at all conditions. To verify the suggested model, one tool not used in training the model is chosen and input to the model. Under various cutting conditions, predicted chip forms agree well with those obtained from cutting experiments. The suggested method could reduce the cost and time significantly in designing cutting tools as well as replacing the“trial-and-error”design method.

• Asian Journal of Turfgrass Science
• /
• v.16 no.1
• /
• pp.19-30
• /
• 2002

This study was conducted to investigated the effects of rubber chips from used tires on sports turf ground as soil conditioner to improve soil physical properties. The release of heavy metal ions was detected to check the soil contamination by incorporation of recycled rubber chips with topsoil. The effects of the chips were also evaluated as topdressing material to improve surface resilience. The rate of rubber chips showed a positive relationship with soil temperature increasement. Incorporation of rubber chips increased soil temperature on surface at 2.5 cm-depth. The rates of rubber chip showed a negative relationship with ground cover rate of turfgrass in early growth season. However, after 20 weeks, treatment of 10% rubber chips at 2.5 cm-depth showed a prominent cover rate of 70% which was not significantly different with untreated control. Incorporation of rubber chips within topsoil seemed to reduce soil compaction, but the effects was not prominent on physical properties. Rubber chips did not affect chemical properties and heavy metal contamination to soil environment. Rubber chips improved resilience of the compacted ground surface as topdressing material, this effect was prominent when aerification practise was preceded.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.07a
• /
• pp.757-760
• /
• 2001

We have used the random fluidic self-assembly (RFSA) technique based on the chip pattern of hydrophobic self-assembly layers to assemble microfabricated particles onto the chip pattern. Immobilization of DNA, fabrication of the particles and the chip pattern, arrangement of the particles on the chip pattern, and recognition of each using DNA fluorescence measurement were carried out. Establishing the walls, the arrangement stability of the particles was improved. Each DNA is able to distinguish by using the lithography process on the particles. Advantages of this method are process simplicity, wide applicability and stability. It is thought that this method can be applicable as a new fabrication technology to develop a minute integration type biosensor microarray.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.1663-1667
• /
• 2003

This thesis is on tile development of LD(Laser Diode) chip tester and the control system based on graphical programming language(LabVIEW) to control the equipment. The LD chip tester is used to test the optic power and the optic spectrum of the LD Chip. The emitter size of LD chip and the diameter of the receiver(optic fiber) are very small. Therefore, in order to test each chip precisely, this tester needs high accuracy. However each motion part of the tester could not accomplish hish accuracy due to the limit of the mechanical performance. Hence. an image processing with machine vision was carried out in order to compensate for the error. and also a load test was carried out so as to reduce tile impact of load on chip while the probing motion device is working. The obtained results were within ${\pm}$5$\mu\textrm{m}$ error.

• Journal of Welding and Joining
• /
• v.20 no.4
• /
• pp.498-504
• /
• 2002

Fluxless flip chip bonding process using plasma treatment instead of flux was investigated. The effect of plasma process parameters on tin-oxide etching characteristics were estimated with Auger depth profile analysis. The die shear test was performed to evaluate the adhesion strength of the flip chip bonded after plasma treatment. The thickness of oxide layer on tin surface was reduced after Ar+H2 plasma treatment. The addition of H2 improved the oxide etching characteristics by plasma. The die shear strength of the plasma-treated Sn-Pb solder flip chip was higher than that of non-treated one but lower than that of fluxed one. The difference of the strength between plasma-treated specimen and non-treated one increased with increase in bonding temperature. The plasma-treated flip chip fractured at solder/TSM interface at low bonding temperature while the fracture occurred at solder/UBM interface at higher bonding temperature.

• Journal of the Korean Society for Precision Engineering
• /
• v.31 no.6
• /
• pp.521-525
• /
• 2014

Circulating tumor cells (CTCs) in the bloodstream of cancer patients provide an accessible source for detection, characterization, and monitoring of nonhematological cancers. The effectiveness of the CTC-Chip for the isolation of ovarian cancer cells was demonstrated by adapting the herringbone-chip (HB-Chip). The motions of the particles on the HB chip were simulated by a unique combination of buoyant, gravitational forces, and helical flows with a computational modeling. The motions of cells are demonstrated by applying polystylene bead and ovarian cancer cells into the microfabricated HB-Chip. The experimental results from beads and cells are well accordance with the simulated ones, as previously reported by Toner group. Thus, I expect that these modeling and experimental skills will play key roles in the clinical applications on CTC isolation as well as the basic research on characterization of CTCs under flow.

• Genomics & Informatics
• /
• v.9 no.2
• /
• pp.89-91
• /
• 2011

DNA chips are becoming increasingly popular as a convenient way to perform vast amounts of experiments related to genes on a single chip. And the importance of analyzing the data that is provided by such DNA chips is becoming significant. A very important analysis on DNA chip data would be clustering genes to identify gene groups which have similar properties such as cancer. Clustering data for DNA chips usually deal with a large search space and has a very fuzzy characteristic. The Particle Swarm Optimization algorithm which was recently proposed is a very good candidate to solve such problems. In this paper, we propose a clustering mechanism that is based on the Particle Swarm Optimization algorithm. Our experiments show that the PSO-based clustering algorithm developed is efficient in terms of execution time for clustering DNA chip data, and thus be used to extract valuable information such as cancer related genes from DNA chip data with high cluster accuracy and in a timely manner.

• Proceedings of the KIEE Conference
• /
• 2006.07c
• /
• pp.1315-1316
• /
• 2006

Microarray-based DNA chips provide an architecture for multi-analyte sensing. In this paper, we report a new approach for DNA chip microarray fabrication. Multifunctional DNA chip microarray was made by immobilizing many kinds of biomaterials on transducers (particles). DNA chip microarray was prepared by randomly distributing a mixture of the particles on a chip pattern containing thousands of m-scale sites. The particles occupied a different sites from site to site. The particles were arranged on the chip pattern by the random fluidic self-assembly (RFSA) method, using a hydrophobic interaction for assembly.