• Journal of the Semiconductor & Display Technology
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• v.5 no.3 s.16
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• pp.29-32
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• 2006

Because of new requirements related to the employment of SMT(Surface Mounting Technology) manufacturing and the diversity of components on high density PCB(Printed Circuit Boards), Thermal control of the reflow process is required in order to achieve acceptable yields and reliability of SMT assemblies. Accurate control of the temperature distribution during the reflow process is one of the major requirements, especially in lead-free assembly. This study has been performed for reflow process using the commercial CFD(Computational Fluid Dynamics) tool for predicting flow and temperature distributions. Porous plate was installed to prevent leakage flow which was one of the major problem of temperature uniformity in the reflow process. There is a separation region where the flow is turned. Outside wall made of porous plate is to prevent and minimize separation region for acquiring uniform temperature during operation. This paper provided design concept from CFD results of the steady state temperature distribution and flow field inside a reflow oven.

• The Journal of Internal Korean Medicine
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• v.20 no.1
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• pp.111-121
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• 1999

Cervus elaphus (CE), being known to reinforce Kidney, have tested to study the effects concerning damages of renal tissue induced by oxygen free radicals. I had observed the effects of CE extract on damages of rat's kidney following ischemia and reflow. Before ischemia was caused, CE extract was applied $0.2m{\ell}$ per 250g through femoral vein in ischemia and reflow group and normal sailine was applied in normal group, Ischemia was caused by renal artery's clamp for 60 min and reflowed by clamp remove after 30 min. It was increased on the content of lipid peroxidation, activies and type conversion ratio of xanthine oxidase following ischemia and reflow. by clamp remove after 30 min. It was increased on the content of lipid peroxidation, activies and type conversion ratio of xanthine oxidase following ischemia and reflow. However, they were decreased when CE extract was pre-applied. Glutathione level was decreased in ischemia and reflow group, and increased in CE extract's pre-applied group. However, it could not seen special changes on aldehyde oxidase activities, either. In conclusion, CE extract recovers the damage of kidney due to ischemia and reflow by decreasing the lipid peroxidation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.179-182
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• 2011

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.561-564
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• 2006

Because of new requirements related to the employment of SMT(Surface Mounting Technology) manufacturing and the diversity of components on high density PCB(printed circuit boards), Thermal control of the reflow process is required in oder to achieve acceptable yields and reliability of SMT assemblies. Accurate control of the temperature distribution during the reflow process is one of the major requirements, especially in lead-free assembly. This study has been performed for reflow process using the commercial CFD tool(Fluent) for predicting flow and temperature distributions. There was flow recirculation region that had a weak point in the temperature uniformity. Porous plate was installed to prevent and minimize flow recirculation region for acquiring uniform temperature in oven. This paper provided design concept from CFD results of the steady state temperature distribution and flow field inside a reflow oven.

• Journal of Welding and Joining
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• v.21 no.6
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• pp.46-54
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• 2003

The thermal response of electronic assemblies during forced convection-infrared reflow soldering is studied. Soldering for attaching electronic components to printed circuit boards is performed in a process oven that is equipped with porous panel heaters, through which air is injected in order to dampen temperature fluctuations in the oven which can be established by thermal buoyancy forces. Forced convection-infrared reflow soldering process with air injection is simulated using a 2-dimensional numerical model. The multimode heat transfer within the reflow oven as well as within the electronic assembly is simulated. Parametric study is also performed to study the effects of various conditions such as conveyor speed, blowing velocity, and electronic assembly emissivity on the thermal response of electronic assemblies. The results of this study can be used in the process oven design and selecting the oven operating conditions to ensure proper solder melting and solidification.

• Journal of Welding and Joining
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• v.15 no.6
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• pp.105-115
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• 1997

A numerical study is performed to predict the thermal response of a detailed card assembly during infrared reflow soldering. The card assembly is exposed to discontinuous infrared panel heater temperature distributions and high radiative/convective heating and cooling rates at the inlet and exit of the oven. The convective, radiative and conduction heat transfer within the reflow oven as well as within the card assembly are simulated and the predictions illustrate the detailed thermal responses. The predictions show that mixed convection plays an important role with relatively high frequency effects attributed to buoyancy forces, however the thermal response of the card assembly is dominated by radiation. The predictions of the detailed card assembly thermal response can be used to select the oven operating conditions to ensure proper solder melting and minimization of thermally induced card assembly tresses and warpage.

• Journal of the Korean institute of surface engineering
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• v.38 no.1
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• pp.28-36
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• 2005

In this study, the reflow characteristics of copper thin films which is expected to be used as interconnection materials in the next generation semiconductor devices were investigated. Cu thin films were deposited on the TaN diffusion barrier by metal organic chemical vapor deposition (MOCVD) and annealed at the temperature between 250℃ and 550℃ in various ambient gases. When the Cu thin films were annealed in the hydrogen ambience compared with oxygen ambience, sheet resistance of Cu thin films decreased and the breakdown of TaN diffusion barrier was not occurred and a stable Cu/TaN/Si structure was formed at the annealing temperature of 450℃. In addition, reflow properties of Cu thin films could be enhanced in H₂ ambient. With Cu reflow process, we could fill the trench patterns of 0.16～0.24 11m with aspect ratio of 4.17～6.25 at the annealing temperature of 450℃ in hydrogen ambience. It is expected that Cu reflow process will be applied to fill the deep pattern with ultra fine structure in metallization.

• The Journal of Internal Korean Medicine
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• v.20 no.1
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• pp.167-180
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• 1999

Cervus elaphus, being known to reinforce Kidney, have tested to study the effects concerning damages of brain tissue induced by lipid peroxidation. In vitro, the level of lipid peroxide in brain tissue was decreased proportinally according to dose by Cervus elaphus extract solution for aqua-acupuncture (CESAA). It was much more decreased, when lipid peroxidation was induced with Fe(II). And, it was seen proportinally decrease according to the dose of CESAA on xanthine oxidase activities and type conversion ratio. However, I can not find special changes about aldehyde oxidase activities. And, I had observed the effects of CESAA on damages of rat's brain following ischemia and reflow. Before ischemia was caused, CESAA was applied 0.2 ml per 250 g through femoral vein in ischemia and reflow group and normal sailine was applied in normal group. Ischemia was caused by cervical artery's clamp for 30 min and reflowed by clamp remove after 15 min. It was increased on the content of lipid peroxidation, activies and type conversion ratio of xanthine oxidase following ischemia and reflow. However, they were decreased when CESAA was pre-appllied. However, it could not seen special changes on aldehyde oxidase activities, either. In conclusion. CESAA recovers the damage of brain due to ischemia and reflow by decreasing the lipid peroxidation through decreasing of xanthine oxidase activies and type conversion ratio.

• Korean Journal of Metals and Materials
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• v.47 no.4
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• pp.261-266
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• 2009

The mechanical and electrical properties of ball grid array (BGA) solder joints were measured, consisting of Sn-3.5Ag, with organic solderability preservative (OSP)-finished Cu pads and Electroless Nickel/Immersion Gold (ENIG) surface finishes. The mechanical properties were measured by die shear test. When ENIG PCB was upper joint and OSP PCB was lower joint, the highest shear force showed at the third reflow. When OSP PCB was upper joint and ENIG PCB was lower joint, the highest shear force showed at the forth reflow. For both joints, after the die shear results reached the highest shear force, shear force decreased as a function of increasing reflow number. Electrical property of the solder joint decreased with the function of increasing reflow number. The scanning electron microscope results show that the IMC thickness at the bonding interface gets thicker while the number of reflow increases.

• Proceedings of the KWS Conference
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• 1997.10a
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• pp.68-73
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• 1997