• Journal of Advanced Marine Engineering and Technology
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• 제24권1호
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• pp.59-66
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• 2000

To investigate the optimum brazing condition, variation of bonded structure and mechanical properties of novel brazed pure Al with bonding condition (brazing temperature, time and Si/flux ratio) was studied. A basic study of the bonding mechanism was also examined. The optimum brazing condition was obtained at $590^{\circ}$ for 2 minutes and the bonded structure showed that it is composed of almost entirely eutectic Al-Si with near eutectic composition. At higher brazing temperature $630^{\circ}$, hypoeutectic Al-Si structure was observed in the bonded area and resulted in erosion of base metal. The thickness of eutectic layer formed in optimum brazing temperature increased linearly with the square root of time, showing a general diffusion controlled process. The ultimate tensile strength of bonded joint brazed at an optimum brazing condition was about 60% of base metal and its fracture surface showed a brittle mode.

• 한국세라믹학회지
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• 제30권5호
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• pp.357-364
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• 1993

Chemical reaction occurred in the interface of Mn-Zn ferrite and glass after bonding. Effects of the formation of reaction layer on the magnetic properties were investigated. The composition of glass was 23PbO-61SiO2-6ZnO-8Na2O-2K2O and the ferrite was chosen to have a high permeability. Toroid samples of ferrites bonded with glasses, were heat-treated at $700^{\circ}C$, 80$0^{\circ}C$ and 90$0^{\circ}C$ for 1h. The reaction was observed to increase with bonding temperature, resulting in the development of reaction layer. Subsequently the initial permeability was found to be decreased. The permeabilities decreased by 25% with increasing bonding temperature from $700^{\circ}C$ to 80$0^{\circ}C$. At the bonding temperature of 90$0^{\circ}C$, the permeability was decreased by 45%, compared to that of 80$0^{\circ}C$.

• Transactions on Electrical and Electronic Materials
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• 제15권4호
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• pp.221-225
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• 2014

Although gold wire bonding techniques have already matured in semiconductor manufacturing, weakly bonded wires in semiconductor chip assembly can jeopardize the reliability of the final product. In this paper, weakly bonded or failed aluminum bonding pads are analyzed using X-ray photoelectron spectroscopy (XPS), Auger electron Spectroscopy (AES), and energy dispersive X-ray analysis (EDX) to investigate potential contaminants on the bond pad. We found the source of contaminants is related to the dry etching process in the previous manufacturing step, and fluorocarbon plasma etching of a passivation layer showed meaningful evidence of the formation of fluorinated by-products of $AlF_x$ on the bond pads. Surface analysis of the contaminated aluminum layer revealed the presence of fluorinated compounds $AlOF_x$, $Al(OF)_x$, $Al(OH)_x$, and $CF_x$.

• Journal of Welding and Joining
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• 제20권4호
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• pp.498-504
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• 2002

Fluxless flip chip bonding process using plasma treatment instead of flux was investigated. The effect of plasma process parameters on tin-oxide etching characteristics were estimated with Auger depth profile analysis. The die shear test was performed to evaluate the adhesion strength of the flip chip bonded after plasma treatment. The thickness of oxide layer on tin surface was reduced after Ar+H2 plasma treatment. The addition of H2 improved the oxide etching characteristics by plasma. The die shear strength of the plasma-treated Sn-Pb solder flip chip was higher than that of non-treated one but lower than that of fluxed one. The difference of the strength between plasma-treated specimen and non-treated one increased with increase in bonding temperature. The plasma-treated flip chip fractured at solder/TSM interface at low bonding temperature while the fracture occurred at solder/UBM interface at higher bonding temperature.

• 한국세라믹학회지
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• 제30권11호
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• pp.949-954
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• 1993

Microstructural development at the ZrO2/NiTi bonding interface and reaction products were examined and identified with SEM and AEM. Ti-oxide, Ti2Ni and Ni2Ti layer were observed whose thickness depends on bonding temperature typically. The development of Ti-oxide layer is related with oxygen ion in ZrO2 and liquid phase Ti2Ni. It is considered that compositional deviation from homogeneity and residual stress caused by thermal expansion mismatch are closely related with the formation of the Ti2Ni phase.

• Nano
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• 제13권12호
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• pp.1850138.1-1850138.6
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• 2018

Two-dimensional (2D) or layered materials have a great potential for applications in energy storage, catalysis, optoelectronics and gas separation. Fabricating novel 2D or quasi-2D layered materials composed of relatively abundant and inexpensive atomic species is an important issue for practical usage in industry. Here, we suggest the layer-structured AlOOH (Boehmite) as a promising candidate for such applications. Boehmite is a well-known layer-structured material and a single-layer can be exfoliated from the bulk boehmite by breaking the interlayer hydrogen bonding. We study atomic and electronic band structures of both bulk and single-layer boehmite, and also obtain the single-layer exfoliation energy using first-principles calculations.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 춘계학술대회
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• pp.35-38
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• 1997

The interfacial bonding energy between laser surface treated HA layer and Ti alloy substrate was investigated using a mechanical push-out tester. The initial slope of shear-stress and reduced displacement curves, maximum interfacial bond strength and bonding energy were calculated from results of the push-out test. The calculated initial slpoes are 38 MPa for the Ti alloy(A), 65 MPa for the sandblast finished specimen(B), 95 MPa for the HA plasma spray coated specimen and 49 MPa for the laser surface treated specimen(D). The maximum interfacial bonding strength are 3 MPa for the A, 19 MPa for the B, 20 MPa for the C, 10 MPa for the D. The interfacial bonding energies are $3.3\times10^{-9}J/mm^2$ for the A, $15.5\times10^{-9}J/mm^2$ for the B, $15.6\times10^{-9}J/mm^2$ for the C and $18.3\times10^{-9}J/mm^2$ for the D. Microscopic observation shows that the breaking of the laser treated specimen had been occured through the boundary between HA layer and polymer resin, but the untreated specimen had been occured through the inside of HA coating layer.

• 대한소아치과학회지
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• 제23권4호
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• pp.867-886
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• 1996

The purpose of this study was to evaluate the shearbond strength and resin-dentin interface of three different dentinal bonding systems in primary and permanent teeth. Thirty extracted human primary molars and premolars, which were non-carious and free of obvious defect, were selected for this study. All specimens were divided into six groups with two groups allocated for each of the three dentinal bonding system(All-bond 2, Scotchbond Multi-Purpose, Gluma bonding system). After completion of bonding composite to dentin using each tested dentin bonding system, bond strength measurement and histological observation were performed. The results are as follows: 1. All-bond 2 and Scotchbond Multi-Purpose, A good quality hybrid layer was identified, the morphology of which could be equated with the zone of H-E and Brown-Brenn staining. In Gluma bonding system, hybrid layer was very thin, and separated from the solid polymer. 2. All-bond 2 had the highest mean shearbond strength, followed by Scotchbond Multi-Purpose and Gluma bonding system in both primary and permanent teeth. There was no statistically significant difference between All-bond 2 and Scotchbond Multi-Purpose. Statistically significant difference could be found between Gluma bonding system and the other two groups(p<0.05). 3. The fracture patterns observed were mainly the mixture of adhesive failure and dentin dettachment pattern in All-bond 2 and Scotchbond Multi-Purpose while adhesive failure prevailed in Gluma bonding system.

• 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.

• Restorative Dentistry and Endodontics
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• 제24권3호
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• pp.465-472
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• 1999

The aim of this study was to determine the shear bond properties of four dentin bonding systems to internal cervical dentin, and to investigate the effect of the pretreatment for removing smear layer and position of dentin on shear bond strength of dentin bonding agents. The materials tested in this study were consisted of four commercially available dentin bonding systems[Allbond 2(AB), Clearfil Linerbond 2(CL), Optibond FL(OP), Scotchbond Multi-purpose(SB)], a restorative light-cured composite resin[Z100]J and a chelating agent[RC-prep(RC)]. Fifty-six freshly extracted human molars were used in this study. Dentin specimens were prepared by first cutting the root of the tooth 1mm below the cementoenamel junction with a diamond bur in a high speed handpiece under air-water coolant, and then removing occlusal part at pulp horn level by means of a second parallel section, The root canal areas were exposed by means of cutting the dent in specimens perpendicular to the root axis. Dentin specimens were randomly assigned to two groups(pretreated group, not-pretreated group) based on the pretreatment method of dentin surface. In pretreated group, RC was applied to dentin surface for 1minute and then rinsed with NaOCl. In not-pretreated group, dentin surface was rinsed with saline Each groups were subdevided into four groups according to dentin bonding systems. Four dentin bonding systems and a restorative resin were applied according to the directions of manufacturer. The dentin-resin specimens were embedded in a cold cure acrylic resin, and were cut with a low speed diamond saw to the dimension of $1{\times}1mm$. The cut specimens were divided into three groups according to the position of internal cervical dentin. The shear bond properties of dentin-resin specimens were measured with Universal testing machine (Zwick, 020, Germany) with the cross head speed of 0.5mm/min. From this experiment. the following results were obtained : 1. In case of shear bond strength, there was no significant difference among dentin bonding systems in not-pretreated groups, whereas in pretreated groups, the shear bond strengths of AB and of SB were statistically significantly higher than those of CL and of OP. 2. The shear bond strengths of AB and of SB in pretreated groups were significantly higher than those in not-pretreated groups. 3. The shear bond strengths of radicular layer of OP were higher than those of occlusal layer of OP in not-pretreated groups, and of AB in pretreated groups. The shear bond strengths of radicular layer of AB and of CL in not-pretreated groups were higher than those in pretreated group.