• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.304-309
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• 2004

As it is difficult to construct a micro-fluidic system composed of micro-mixers, micro-channels and/or micro-chambers in a single process, an assembly process is typically used. The assembling and bonding of micro-parts, however, introduces other problems. In this work, a virtual assembly process was developed that can be used to design various micro-fluidic systems before actual fabrication commences. In the process, the information required for the micro-stereolithography process is generated automatically. Consequently, complex micro-fluidic systems can be fabricated in a single process, thereby avoiding the need for additional assembly or bonding processes. Using the developed process, several examples were fabricated.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.5
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• pp.812-817
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• 2013

This study demonstrates the diffusion bonding process between a tungsten carbide shank (K30) and tungsten carbide (DX5) for micro WC-PCD tool fabrication. A type of nickel alloy was used as the filler met alto improve the bond ability between K30 and DX5. The bonding pressure, time, and surrounding conditions were kept constant. In particular, the normal pressure was controlled precisely under buckling analysis. Diffusion bonding was performed at various operation temperatures (1170-1770 K) by using a specially designed jig. The microstructure on the localized bonded surface was analyzed using scanning electron microscopy and optical microscopy. In the case of diffusion bonding of WCat 1370-1770K, the filler metal melted completely and diffused between the two base metals, and they were bonded more tightly on both sides than at temperatures below 1370 K. Our results demonstrated the importance of sensitive temperature dependence of diffusion bonding.

• Journal of the Microelectronics and Packaging Society
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• v.24 no.1
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• pp.17-25
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• 2017

Recently, research and application for a power module have been actively studied according to the increasing demand for the production of vehicles, smartphones and semiconductor devices. The power modules based on the transient liquid phase (TLP) technology for bonding of power semiconductor devices have been introduced in this paper. The TLP bonding has been widely used in semiconductor packaging industry due to inhibiting conventional Pb-base solder by the regulation of end of life vehicle (ELV) and restriction of hazardous substances (RoHS). In TLP bonding, the melting temperature of a joint layer becomes higher than bonding temperature and it is cost-effective technology than conventional Ag sintering process. In this paper, a variety of TLP bonding technologies and their characteristics for bonding of power module have been described.

• Journal of the Korean Society for Heat Treatment
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• v.6 no.1
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• pp.9-16
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• 1993

To investigate the properties of diffusion bonding of 7050 Al alloy, the diffusion bonding joints have been produced in self-made diffusion bonding hot-press which admits a defined application of the bonding pressure during the heating phase and also rapid cooling after the bonding process with various bonding condition. The strength of the bond increases with increasing the bonding time and temperature. Shear test at toom temperature showed that high strength up to 70% that of parent metal (320 MPa), 220 MPa for the specimen bonded 14 hr at $560^{\circ}C$, with 3 MPa. In this case, however, there is large deformation more than 20% reduction in thickness. The results were correlated with joint characteristics found by optical microstructure and by fractography by SEM. When the strengths of the bonds are more than 50% that of parent metal, a great deal of dimples stretched along the direction of shear stress are observed over the fractured surface of the bond. On the microstructure of the bond line, initial mophology of the bond line disapeared for the grain boundary migration with increasing the bonding time.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.7
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• pp.21-27
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• 2010

The effect of COG bonding parameters, especially the bonding temperature, on the bonding quality and reliability was investigated in this paper. We measured the bubble area formed in the ACF resin during the bonding process and tried to investigate the relationship between bubble area and bonding peel strength. 85/85 test which exposes a sample to a 85% humidity and $85^{\circ}C$ temperature condition was also carried out. The bubble area was dramatically increased under ~$10^{\circ}C$ lower than recommended bonding temperature. The bubble area formed at the edge of IC chip was larger than the other parts of IC chip. But the peel strength was not associated with the bubble area. High temperature and humid condition made the bubble area larger, but we could not find clear trend of change in the peel strength.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.2
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• pp.87-93
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• 2015

Recently, the heat exchangers are requiring higher performance and reliability since they are being used under the operating condition of high temperature and pressure. To satisfy these requirements, we need special materials and bonding technology. This study presents a manufacturing technology for high temperature and high pressure micro channel heat exchanger using Inconel 617. The bonding performance for diffusion bonded heat exchanger was examined and analyzed. The analysis were conducted by measuring thermal and mechanical properties such as thermal diffusivity and tensile strength, and parametric studies about bonding temperature and pressing force were also carried out. The results provided insight for bonding evaluation and the bonding condition of $1200^{\circ}C$, and 50 tons was found to be suitable for this heat exchanger. From the results, we were able to establish the base technology for the manufacturing of Inconel 617 heat exchanger through the application of the diffusion bonding.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.8
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• pp.700-704
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• 2003

This paper describes on characteristics of 2" 3C-SiC wafer bonding using PECVD (plasma enhanced chemical vapor deposition) oxide and HF (hydrofluoride acid) for SiCOI (SiC-on-Insulator) structures and MEMS (micro-electro-mechanical system) applications. In this work, insulator layers were formed on a heteroepitaxial 3C-SiC film grown on a Si (001) wafer by thermal wet oxidation and PECVD process, successively. The pre-bonding of two polished PECVD oxide layers made the surface activation in HF and bonded under applied pressure. The bonding characteristics were evaluated by the effect of HF concentration used in the surface treatment on the roughness of the oxide and pre-bonding strength. Hydrophilic character of the oxidized 3C-SiC film surface was investigated by ATR-FTIR (attenuated total reflection Fourier transformed infrared spectroscopy). The root-mean-square suface roughness of the oxidized SiC layers was measured by AFM (atomic force microscope). The strength of the bond was measured by tensile strength meter. The bonded interface was also analyzed by IR camera and SEM (scanning electron microscope), and there are no bubbles or cavities in the bonding interface. The bonding strength initially increases with increasing HF concentration and reaches the maximum value at 2.0 ％ and then decreases. These results indicate that the 3C-SiC wafer direct bonding technique will offers significant advantages in the harsh MEMS applications.ions.

• Journal of Welding and Joining
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• v.33 no.3
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• pp.12-18
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• 2015

The ultimate goal of developing body is revealed the "lightweight" at latest EuroCarBody conference 2012 and the most core technology is joining process to make lightweight car body design. Accordingly, in this study, the car body assembly line for the assembly process applies to any introduction, particularly in the assembly of aluminum alloy and composite materials applied by the process for the introductory approached. Process were largely classified by welding (laser, arc, resistance, and friction stir welding), bonding (epoxy bonding) and mechanical fastening (FDS, SPR, Bolting and clinching). Applications for each process issues in the case and the applicable award was presented, based on the absolute strength of the test specimens and joining characteristics for comparative analysis were summarized. Finally, through this paper, we would tried to establish the characteristics of the joint for lightweight structure.

• Journal of the Microelectronics and Packaging Society
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• v.30 no.4
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• pp.98-104
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• 2023

The feasibility of an efficient process proposed for Cu-Cu flip-chip bonding was evaluated by forming a porous Cu layer on Cu pillar and conducting thermo-compression sinter-bonding after the infiltration of a reducing agent. The porous Cu layers on Cu pillars were manufactured through a three-step process of Zn plating-heat treatment-Zn selective etching. The average thickness of the formed porous Cu layer was approximately 2.3 ㎛. The flip-chip bonding was accomplished after infiltrating reducing solvent into porous Cu layer and pre-heating, and the layers were finally conducted into sintered joints through thermo-compression. With reduction behavior of Cu oxides and suppression of additional oxidation by the solvent, the porous Cu layer densified to thickness of approximately 1.1 ㎛ during the thermo-compression, and the Cu-Cu flip-chip bonding was eventually completed. As a result, a shear strength of approximately 11.2 MPa could be achieved after the bonding for 5 min under a pressure of 10 MPa at 300 ℃ in air. Because that was a result of partial bonding by only about 50% of the pillars, it was anticipated that a shear strength of 20 MPa or more could easily be obtained if all the pillars were induced to bond through process optimization.

• Journal of Powder Materials
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• v.20 no.2
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• pp.114-119
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• 2013

In the DBC (direct bonding of copper) process the oxygen partial pressure surrounding the AlN/Cu bonding pairs has been controlled by Ar gas mixed with oxygen. However, the direct bonding of Cu with sound interface and good adhesion strength is complicated process due to the difficulty in the exact control of oxygen partial pressure by using Ar gas. In this study, we have utilized the in-situ equilibrium established during the reaction of $2CuO{\rightarrow}Cu_2O$ + 1/2 $O_2$ by placing powder bed of CuO or $Cu_2O$ around the Cu/AlN bonding pair at $1065{\sim}1085^{\circ}C$. The adhesion strength was relatively better in case of using CuO powder than when $Cu_2O$ powder was used. Microstructural analysis by optical microscopy and XRD revealed that the interface of bonding pair was composed of $Cu_2O$, Cu and small amount of CuO phase. Thus, it is explained that the good adhesion between Cu and AlN is attributed to the wetting of eutectic liquid formed by reaction of Cu and $Cu_2O$.