• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2002년도 International Symposium
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• pp.203-215
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• 2002

Using eutectic In-Ag and Bi-Sn solder materials, we developed the COG technique having a minimum pitch of 50 ${\mu}{\textrm}{m}$. The maximum temperature in this process is $160^{\circ}C$. We fabricated spherical and uniform solder bumps by controlling the microstructure of Bi-Sn solder bumps. The contact resistances of Bi-Sn solder joints were 19 m$\Omega$ at $80{\mu}{\textrm}{m}$ pitch and 60 m$\Omega$ at $80{\mu}{\textrm}{m}$ pitch, respectively. These values are much lower than the contact resistance of the conventional ACF bonding. The contact resistances of the solder joint are almost the same before and after the underfill process. The contact resistance of the underfilled Bi-Sn solder joint did not change even after reliability test.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2003년도 추계학술발표대회 개요집
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• pp.83-85
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• 2003

This paper is investigated the shear strength by using the micro shear-punch test method for Sn-37Pb alloy, binary and ternary alloys of environment-friendly Pb-free solder alloys which would be surely applicable to the electronic packages. As a result, in case of Max. shear strength, Sn-4Ag-0.5Cu has the highest value and Sn-37Pb has the lowest value on every condition of experiment temperature. Also, In case of Pb-free solder joint specimens, it was found that Pb-free solder alloys have higher value of shear strength than eutectic Sn-Pb solder alloy and Sn-4Ag-0.5Cu has the highest value.

• 한국주조공학회지
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• 제20권6호
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• pp.407-418
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• 2000

The effect of various factors on the results of degassing of AC4C aluminum alloy melt by using rotary degasser were investigated. The difference between the effects of nitrogen gases of commercial pure and high purity grades on the degassing results was not significant. The optimum degassing condition was obtained. The effect of holding and degassing temperature was not significant, either. The result of degassing was deteriorated by the modification treatment of eutectic silicon, meanwhile improved by the grain refining. The effect of the latter was stronger than that of the former when the melt was treated simultaneously. The volume fractions of hydrogen porosity of the castings obtained from the molds with water moisture such as natural and green sand molds were much higher than those from the molds without that such as pep-set and $CO_2$ molds.

• Journal of Welding and Joining
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• 제19권4호
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• pp.423-428
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• 2001

The bonding phenomena of Ni base single crystal superalloy. CMSX-4 during transient liquid phase(TLP) bonding was investigated using MBF-80 insert metal. Bonding of CMSX-4 was carried out at 1,373∼1,548K for 0∼19.6ks in vacuum. The (001) orientation of each test specimen was aligned perpendicular to the bonding interface. The dissolution width of base metal was increased when the bonding temperature and holding time were increased. The eutectic width diminished linearly with the square root of holding time during isothermal solidification process. Borides were formed in the bonded layer during TLP bonding operation. The solid phase grew epitaxially into the liquid phase from substrates and single crystallization could be readily achieved during the isothermal solidification.

• 한국레이저가공학회지
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• 제17권1호
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• pp.7-12
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• 2014

The dissimilar welding between magnesium alloy and steel sheet was required in automobile industry to increase the strength of the dissimilar joints. Laser brazing is one of the good joining processes for Mg- steel dissimilar joint. In this study, AZ31 magnesium alloy and Zn coated steel dissimilar joint was brazed using diode direct laser with Mg600 filler wire and Superior #21 flux. The wetting of Mg filler wire on Zn coating was very good because of the formation of eutectic phase with low melting temperature. The strength of the brazed joint between AZ31 magnesium alloy and Zn coated steel was 131.3N/mm. The fracture occurred at brazement.

• 한국주조공학회지
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• 제15권3호
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• pp.291-297
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• 1995

The mechanical properties and fracture toughness of permanent mold cast austempered gray cast iron(AGI) were compared to those of sand cast AGI. The iron was melted to eutectic composition in order to get better castability especially in permanent mold casting. Specimens prepared for tensile, impact and fracture toughness test were austenitized at $900^{\circ}C$ and austempered at $270^{\circ}C$ and $370^{\circ}C$ for 1 hour. The strength, impact and fracture toughness of permanent mold cast AGI were found to be superior to those of sand cast AGI. The maximum value of 836 MPA in tensile strength, was obtained at the austempering temperature of $270^{\circ}C$. But ductility of AGI was not improved by permanent mold casting.

• 한국표면공학회지
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• 제35권1호
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• pp.11-16
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• 2002

As environmental concerns increasing, the electronics industry is focusing more attention on lead free solder alternatives. In this research, we have researched wettability of intermediate solder of Sn3Ag9Bi5In, which include In and Bi and has similar melting temperature to Sn37Pb eutectic solder. We investigated the wetting property of Sn3Ag9Bi5In. To estimate wettability of Sn3Ag9Bi5In solder on various substrates, the wettability of Sn3Ag9Bi5In solder on high-pure Cu-coupon was measured. Cu-coupon that plated Sn, Ni and Au/Ni and Si-wafer adsorbed Ni/Cu under bump metallurgy on one side. As a result, the wetting property of Sn3Ag9Bi5In solder is a little better than that of Sn37Pb and Sn3.5Ag.

• 한국지구과학회지
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• 제25권1호
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• pp.48-51
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• 2004

The light element candidates such as S, O, Si, and K are discussed for the reasonable compositions in the earth's core since the available data show density difference from pure iron core. These candidates are favored by the some evidences such as depletion in the crust and mantle, and lower eutectic temperature of Fe-FeS melt for sulfur. FeO phase for oxygen, lighter mass than sulfur and solubility in metallic phases for silicon, and partitioning in Fe-FeS melt for potassium. However, other problems such as short experimental data, initial compositions of these elements, and oxidation state during the formation of the earth should be solved simultaneously to confirm these light elements.

• 한국주조공학회지
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• 제17권5호
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• pp.502-509
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• 1997

The mechanical behavior and microstructural evolution in the ignition-proof Mg-Zn-Ca-Zr alloy produced by the semisolid squeeze casting are clarified and the mechanical properties are also compared with those of squeeze cast Mg-Zn-Ca-Zr alloy. The tensile strength and elongation increase slightly as the solid fraction depending on temperature decreases, while the 0.2% proof stress decreases. The size of primary crystal increases with increasing holding time. The tensile strength and 0.2% proof stress of the semi-solid squeeze cast Mg-Zn-Ca-Zr alloy decrease as the size of primary crystal increases, indicating the dependence of strength on the size of primary crystal. The elongation of the semi-solid squeeze cast Mg-Zn-Ca-Zr alloy is two times as large as the squeeze cast Mg-Zn-Ca-Zr alloy and the tensile strength is unchanged despite the growth of primary crystal, resulting from the refining of the melted ${\alpha}Mg$ phase and the brittle eutectic compound as well as the reduction of solidification shrinkage and porosities.

• 마이크로전자및패키징학회지
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• 제24권4호
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• pp.9-17
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• 2017

In these days, MEMS (micro-electro-mechanical system) devices become the crucial sensor components in mobile devices, automobiles and several electronic consumer products. For MEMS devices, the packaging determines the performance, reliability, long-term stability and the total cost of the MEMS devices. Therefore, the packaging technology becomes a key issue for successful commercialization of MEMS devices. As the IoT and wearable devices are emerged as a future technology, the importance of the MEMS sensor keeps increasing. However, MEMS devices should meet several requirements such as ultra-miniaturization, low-power, low-cost as well as high performances and reliability. To meet those requirements, several innovative technologies are under development such as integration of MEMS and IC chip, TSV(through-silicon-via) technology and CMOS compatible MEMS fabrication. It is clear that MEMS packaging will be key technology in future MEMS. In this paper, we reviewed the recent development trends of the MEMS packaging. In particular, we discussed and reviewed the recent technology trends of the MEMS bonding technology, such as low temperature bonding, eutectic bonding and thermo-compression bonding.