• Journal of the Korean institute of surface engineering
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• v.42 no.5
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• pp.232-239
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• 2009

This study presented the effect of membrane thickness on hydrogen permeability. Microvoids on the surface of the membrane should not exist for the exact values of hydrogen permeability. Pd-Cu-Ni hydrogen alloy membranes were fabricated by Ni powder sintering, substrate plasma pretreatment, sputtering and Cu reflow process. And this leaded to void-free surface and dense film of Pd-Cu-Ni hydrogen alloy membrane. Hydrogen permeation test showed that hydrogen permeability increased from 2.7 to $15.2ml/cm^2{\cdot}min{\cdot}atm^{0.5}$ as membrane thickness decreased from 12 to $4{\mu}m$. This represented the similar trend as a hydrogen permeability of pure palladium membrane based on solution-diffusion mechanism.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.377-380
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• 2003

Recently, demand of digital products with optoelectronic device is increasing rapidly. A microlens array is applied to improve optical efficiency on optoelectronic device, and it is usually fabricated by photolithography and reflow process after planarization layer coating process. UV molding process is more suitable for mass production of high quality microlens array than photolithography and reflow process. In the present study, microlens array was fabricated on the simulated optoelectronic device with planarization layer by aligned UV molding process. The shape of replicated microlens was measured, and the section image of molded part was examined.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1682-1683
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• 2011

Through-silicon microlens array has been implemented using glass thermal reflow process. Design, numerical analysis, fabrication, and measurement results are discussed. Microlenses with six different volumetric dimensions were successfully fabricated and characterized. Radius of curvature of each microlenses were measured with less than 1% deviation compared to calculated value. Measured average roughness of the microlens surface was 16.5 nm.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.7
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• pp.127-133
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• 1996

In this paper, we propose a new fabrication method for poly-Si TFTs with a self-aligned offset gated structure by employing a photoresist reflow process. Compared with the conventional poly-Si TFTs, the device is consist of two gate electrodes, of which one is the entitled main gate where the gate bias is employed and the other is the entitled subgate which is separate form both sides of the main gate. The poly-Si channel layer below the offset oxide is protected form the injected ion impurities for the source/drain implantation and acts as an offset region of the proposed device. The key feature of oru new device is the offset region due to the offset oxide. our experimental reuslts show that the offset region, due to the photoresist reflow process, has been sucessfully obtained in order to fabricate the offset gated poly-Si TFTs. The maximum ON/OFF ratio occurs at the L$_{off}$ of 1.1${\mu}$m and exceeds 1X10$^{6}$.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2003.11a
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• pp.99-102
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• 2003

Reactions between 48Sn-52In solder and under bump metallurgies(UBM) such as 100nm $Ti/8{\mu}m$ Cu and 300nm Al/400nm Ni(V)/400nm Cu have been investigated, and the shear strength of 48Sn-52In solder bumps on each UBM has been evaluated. While intermetallic compounds with two different morphologies were continuously thickened on Ti/Cu with repeating the reflow process, the intermetallics on Al/Ni(V)/Cu spalled into the solder with increasing the number of reflow times. The solder bumps on Ti/Cu exhibited higher shear strength than those on Al/Ni(V)/Cu.

• Applied Science and Convergence Technology
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• v.23 no.6
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• pp.345-350
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• 2014

The surface oxidation mechanism of lead-free solder alloys has been investigated with multiple reflow using X-ray photoelectron spectroscopy. It was found that the solder surface of Sn-Ag-Cu-In solder alloy is surrounded by a thin $InO_x$ layer after reflow process; this coating protects the metallic surface from thermal oxidation. Based on this result, we have performed a wetting balance test at various temperatures. The Sn-Ag-Cu-In solder alloy shows characteristics of both thermal oxidation and wetting balance better than those of Sn-Ag-Cu solder alloy. Therefore, Sn-Ag-Cu-In solder alloy is a good candidate to solve the two problems of easy oxidation and low wettability, which are the most critical problems of Pb-free solders.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.280-283
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• 2004

Micro-lens patterned micro-mold fabrication method for Light Guiding Plate(LGP), kernel part of LCD-BLU(Back Light Unit), was presented. Instead of erosion dot pattern for LGP optical design, micro-lens pattern, fabricated by LIGA-reflow process, was applied. Optical pattern design method was also developed not only for negative pattern LGP, but also positive pattern LGP. During injection molding process, experimental study was conducted to improve replication quality and brightness of ${\sim}50um$ micro-lens pattern mold. The effect of mold temperature for the replication quality of micro-lens array was studied.

• Journal of Welding and Joining
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• v.19 no.2
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• pp.176-181
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• 2001

Reflow soldering characteristics of Sn-3.5Ag and Sn-37Pb balls for BGA(Ball grid Array) were investigated. Diameter of 0.76mm ball was set on a Cu/Ni/Au-coated pad and reflowed in air with changing peak soldering temperature and conveyor speed. Peak temperatures were changed from 240 to 28$0^{\circ}C$ for Sn-3.5Ag, and from 220 to 26$0^{\circ}C$ for Sn-37Pb balls. As results, heights of solder balls increased and widths decreased with peak soldering temperature. Through aging treatment at 10$0^{\circ}C$ for 1.000 hrs, average hardness of Sn-3.5Ag balls bonded at 25$0^{\circ}C$ cecreased from 14.90Hv to 12.83Hv And with same aging conditions, average shear strength of Sn-3.5Ag balls bonded at 26$0^{\circ}C$ decreased from 1727gf to 1650gf.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.11a
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• pp.284-284
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• 2015

반도체 Ball Grid Array(BGA)에 사용되던 종래의 Solder Ball은 Sn96.3 Ag3.0 Cu0.7의 용융솔더를 이용하여 제작하고 있다. 이는 SMT Reflow공정에서 BGA Ball의 퍼짐현상으로 인해 원래의 Ball Height에 영향을 미쳐 접합불량의 원인이 되고 있다. 이러한 문제를 해결하기 위해 Copper Core Ball위에 SnAgCu 삼원합금도금공정을 이용해 문제점을 해결하고자 했으며, 본 실험을 통해 구현한 CCSB를 이용해 SMT Reflow를 진행한 결과 종래의 BGA Ball보다 우수한 효과를 확인할 수 있었다.

• Design & Manufacturing
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• v.2 no.4
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• pp.1-4
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• 2008

Micro pattern is applied to the light guiding plate(LGP) to enhance the uniformity of the brightness of the LCD. The micro cones are molded in intaglio on the surface of the LGP. The surface roughness of each cone was 40nm and 38nm in negative and positive die for laser ablation. In chemical etching, the surface roughness was 25nm, 24nm in negative and positive. And the surface roughness of negative and positive dies were 4nm and 5nm for LIGA-reflow process.