• ETRI Journal
• /
• 제29권5호
• /
• pp.667-669
• /
• 2007

This letter presents a smart integrated microfluidic device which can be applied to actively immobilize proteins on demand. The active component in the device is a temperature-controllable microelectrode array with a smart polymer film, poly(N-isopropylacrylamide) (PNIPAAm) which can be thermally switched between hydrophilic and hydrophobic states. It is integrated into a micro hot diaphragm having an integrated micro heater and temperature sensors on a 2-micrometer-thick silicon oxide/silicon nitride/silicon oxide (O/N/O) template. Only 36 mW is required to heat the large template area of 2 mm${\times}$16 mm to $40^{\circ}C$ within 1 second. To relay the stimulus-response activity to the microelectrode surface, the interface is modified with a smart polymer. For a model biomolecular affinity test, an anti-6-(2, 4-dinitrophenyl) aminohexanoic acid (DNP) antibody protein immobilization on the microelectrodes is demonstrated by fluorescence patterns.

• 마이크로전자및패키징학회지
• /
• 제8권4호
• /
• pp.1-10
• /
• 2001

유리 기판상에 증착된 패드(pad)의 접합부 가열에 의한 면배열(area array) 형태 선자 패키지의 chip-on-glass(COG) 마운팅 공정이 시도되었다. 패드는 접합층(즉, Cr 또는 Ti)과 상부 코팅층(즉, Ni 또는 Cu)으로 구성되었으며, 이 중 접합층이 유리 기판을 투과하는 UV레이저에 의해 가열되었다. 접합층에 흡수된 레이저 에너지는 열전노 과정을 통하여 패드와 물리적으로 접촉되어 있는 솔더볼의 온도를 상승시켰으며, 리플로우 과정을 통하여 솔더 범프를 형성하였다. 레이저 가열 동안 솔더볼의 온도 이력(profile)을 측정함으로써 레이저 리플로우 솔더링시 접합층 및 상부 코팅층의 영향이 조사되었다. 그 결과들은 접합층의 반사율 측정 견과에 기초하여 논의되었다. 아울러 솔더 범프의 미세구조와 기계적 특성이 조사되었다.

• Journal of Mechanical Science and Technology
• /
• 제14권9호
• /
• pp.997-1004
• /
• 2000

The experiments were conducted by using water and paraffin slurry to investigate the effect of a chip spacing in the multichip module on the cooling characteristics from an in-line $4{\times}3$ array of discrete heat sources which were flush mounted on the top wall of a channel. The experimental parameters were chip spacing in a multichip module, heat flux of simulated VLSI chip, mass fraction of paraffin slurry, and channel Reynolds number. The removable heat flux at the same chip surface temperature decreased as the chip spacing decreased at the first and fourth rows. The local heat transfer coefficients for the paraffin slurry were larger than those for water, and the chip spacing on the local heat transfer coefficients for paraffin slurry influenced less than that for water. The enhancement factor for paraffin slurry showed the largest value at a mass fraction of 5% regardless of the chip spacing, and the enhancement factors increased as the chip spacing decreased. This means that the paraffin slurry is more effective than water for cooling of the highly integrated multichip module.

• 소성∙가공
• /
• 제15권1호
• /
• pp.34-41
• /
• 2006

Microlens arrays were fabricated by a modified LIGA process composed of the exposure of a PMMA (Polymethylmethacrylate) sheet to deep x-rays and subsequent thermal treatment. A successful modeling and analyses for microlens formation were presented according to the experimental procedure. A nickel mold insert was fabricated by the nickel electroforming process on the PMMA microlens arrays fabricated by the modified LIGA process. For the replication of microlens arrays having various diameters with different foci on the same substrate, both hot embossing and microinjection molding processes have been successfully utilized with the fabricated mold insert. Replicated microlenses showed very good surface roughness with the order of 1 nm. The focal lengths of the injection molded microlenses were successfully estimated theoretically and also measured experimentally.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2005년도 금형가공,미세가공,플라스틱가공 공동 심포지엄
• /
• pp.23-28
• /
• 2005

Microlens arrays were fabricated using a modified LIGA process based on the exposure of a PMMA (Polymethylmethacrylate) sheet to deep x-rays and subsequent thermal treatment. A successful modeling and analyses for microlens formation were presented according to the experimental procedure. A nickel mold insert was fabricated by the nickel electroforming process on the PMMA microlens arrays fabricated by the modified LIGA process. For the replication of microlens arrays having various diameters with different foci on the same substrate, the hot embossing and the microinjection molding processes have been successfully utilized with the fabricated mold insert. Fabricated microlenses showed good surface roughness than the mold insert. The focal lengths of the injection molded microlenses were successfully measured experimentally and also estimated theoretically.

• Journal of Welding and Joining
• /
• 제17권3호
• /
• pp.90-95
• /
• 1999

The increase in high speed, multi-function and high I/O pin semiconductor devices highly demands high pin count, very thin, and high density packages. BGA is one of the solutions, but the package has demerits in package reliability, surface mounting problems due to the PCB warpage and solder joint crack related with TCE mismatch between the materials. On this study to verify the thermal fatigue lifetime of the solder joint FEM and experiments were performed after surface mounting BGA with different solder composition and reliability conditions. FEM showed optimum composition of Ag3.2-Sn96.5 and under the composition minimum creep deformation of the solder joint was calculated, and the thermal fatigue lifetime was improved. In view of temperature cycle condition, the conditions of $-65^{\circ}C$to $150^{\circ}C$ showed minimum lifetime and t was 1/3 of $0^{\circ}C$ to $125^{\circ}C$ condition. Test board was prepared and solder joint crack was verified. Until 1000cycle on soder joint crack was observed.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2005년도 추계학술대회 논문집
• /
• pp.100-104
• /
• 2005

The injection molding is very effective process for various plastic products due to its high productivity. It is also good fur precise products like optical parts. Various thermoplastic materials are also available with this injection molding process. In recent, however, as the overall size of the product increases and micro or nano scale of patterns are applied to the products, we now have some problems such as low fidelity of the replication of the pattern, high molding pressure, or warpage from the in-mold stress. Injection/compression molding is studied to overcome those problems in molding large thin plate with micro pattern array on its surface. An injection compression mold is designed to 3 pieces mold for side gate. We install 4 pressure transducers and 9 thermocouples to measure the melt pressure and surface temperature in the cavity during the process. As a result, the maximum molding pressure for injection compression molding is reduced to 1/3 compared to injection molding and the uniformity of the pressure in the cavity is enhanced by about 15%.

• 대한기계학회논문집B
• /
• 제28권3호
• /
• pp.304-314
• /
• 2004

An experimental study has been conducted to measure the temperature fields and the local film cooling effectiveness for two and three staggered rows of the rectangular shaped-holes with various blowing rates. The hydraulic diameter of rectangular-shaped hole is 10mm. To compare with the film cooling performance of rectangular-shaped hole, two kinds of circular holes are tested. One has the same hydraulic diameter as the rectangular hole and the other has the same cross sectional area. Also, rectangular holes with expanded exit with same inlet area as rectangular ones are tested. Temperature fields are measured using a thermocouple rake attached on three-axis traversing system. Adiabatic film cooling effectiveness on the surface are obtained based on experimental results of thermochromic liquid crystals. The film cooling effectiveness is measured for various blowing rates and compared with the results for the cylindrical holes. In case of 2 rows, the rectangular holes has better performance than circular holes due to its slot-like geometry. In case of 3 rows, the effecta of hole shape is not clear.

• 한국정밀공학회지
• /
• 제20권5호
• /
• pp.218-224
• /
• 2003

This paper describes a novel MEMS integration technique on a CMOS chip. MEMS integration on CMOS circuit has many advantages in view of manufacturing cost and reliability. The surface topography of a CMOS chip from a commercial foundry has 0.9 ${\mu}{\textrm}{m}$ bumps due to the conformal coating on aluminum interconnect patterns, which are used for addressing each MEMS element individually. Therefore, it is necessary to achieve a flat mirror-like CMOS chip fer the microelectromechanical system (MEMS) such as micro mirror array. Such CMOS chip needs an additional thickness of the dielectric passivation layer to ease the subsequent planarization process. To overcome a temperature limit from the aluminum thermal degradation, this study uses RF sputtering of silicon nitride at low temperature and then polishes the CMOS chip together with the surrounding dummy pieces to define a polishing plane. Planarization reduces 0.9 ${\mu}{\textrm}{m}$ of the bumps to less than 25 nm.

• 천문학회지
• /
• 제52권2호
• /
• pp.31-40
• /
• 2019

A long standing problem in the study of Active Galactic Nuclei (AGNs) is that the observed VLBI core is in fact a blending of the actual AGN core (classically defined by the ${\tau}=1$ surface) and the upstream regions of the jet or optically thin flows. This blending may cause some biases in the observables of the core, such as its flux density, size or brightness temperature, which may lead to misleading interpretation of the derived quantities and physics. We study the effects of such blending under the view of the Korean VLBI Network (KVN) for a sample of AGNs at 43 GHz by comparing their observed properties with observations obtained using the Very Large Baseline Array (VLBA). Our results suggest that the observed core sizes are a factor ~ 11 larger than these of VLBA, which is similar to the factor expected by considering the different resolutions of the two facilities. We suggest the use of this factor to consider blending effects in KVN measurements. Other parameters, such as flux density or brightness temperature, seem to possess a more complicated dependence.