• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.87-87
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• 2010

We report a new patterning technique of inorganic materials by using thin-film transfer printing (TFTP) with atomic layer deposition. This method consists of the atomic layer deposition (ALD) of inorganic thin film and a nanotransfer printing (nTP) that is based on a water-mediated transfer process. In the TFTP method, the Al2O3 ALD growth occurs on FTS-coated PDMS stamp without specific chemical species, such as hydroxyl group. The CF3-terminated alkylsiloxane monolayer, which is coated on PDMS stamp, provides a weak adhesion between the deposited Al2O3 and stamp, and promotes the easy and complete release of Al2O3 film from the stamp. And also, the water layer serves as an adhesion layer to provide good conformal contact and form strong covalent bonding between the Al2O3 layer and Si substrate. Thus, the TFTP technique is potentially useful for making nanochannels of various inorganic materials.

• International Journal of Highway Engineering
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• v.15 no.4
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• pp.85-94
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• 2013

PURPOSES: The performance of tack coat, commonly used for layer interface bonding, is affected by application rate and curing time. In this study, bonding strength tests were performed according to the application rate and curing time of asphalt emulsion. Based on finding from this study, optimum application rates and curing times are proposed. METHODS: In order to investigate bonding characteristic of asphalt emulsion, tests were performed on both asphalt concrete pavement and portland concrete pavement. Also, asphalt emulsions were tested at the application rate of 0, 0.2, 0.4, 0.6, and $0.8{\ell}/m^2$ and at the curing time of 0, 0.5, 1, 2, and 24 hours. Pull-off test and shear bonding strength test, which commonly used for bonding strength measurement of asphalt emulsion, were adopted for this study. To assess field performance under different testing condition, asphalt emulsions were applied to in-service pavement. Throughout coefficient of determination analysis between material index properties from asphalt emulsion and mechanical response from bonding strength tests, performance correlativity was analyzed. RESULTS: Test results show that optimum application rate for asphalt overlay on asphalt concrete pavement (AOA) and asphalt overlay on concrete pavement (AOC) was $0.4{\sim}0.5{\ell}/m^2$ and $0.3{\sim}0.5{\ell}/m^2$, respectively. According to the curing time increment, tensile strength and shear strength of AOC were increased to 22~44% and 20~39%, respectively. AOA case also show strength increment in tensile strength (42%) and shear strength (9%). We tested the applicability of tack coat materials at the field sites, and our findings demonstrated that the bonding (for D and E) and rapid curing (for B, C, and D, E) performances were superior than others. Among material index properties, there was a high correlation between penetration ratio and bonding strength test result. CONCLUSIONS : Result show that interlayer bonding strength was affected by asphalt emulsion type, application rate and curing time. AOC required slightly higher application ($0.1{\ell}/m^2$) than AOA. Both AOA and AOC cases show higher strength at longer curing time. Up to 2hours of curing, rapid strength increments were observed, but strength increment ratio was decreased after 2hours of curing. From the observed correlation between penetration ratio and bonding strength, it is expected that penetration ratio can be used as one of important factors affecting bonding strength analysis.

• Korean Journal of Materials Research
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• v.6 no.2
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• pp.210-220
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• 1996

The purpose of this study is to develop the processing techniques of Fiber Reinforced Metal by Liquid Phase Diffusion Bonding method with SiC fiber as a reinforcing material and CP Ti(Commercial Pure) as a matrix. The microstructure and the distribution of elements in reaction and CP Ti(Commercial Pure) as a matrix. The microstructure and the distribution of elements is reaction zone among CP Ti/Ti-15wt%Cu-20wt%Ni(TCN20)/SiC long fiber were investigated by Optical Microscope, SEM/EDX, EPMA, X-ray and AES. The results obtained in this study are as follows. 1) When Ti matrix composite materials are fabricated under the bonding condition of 1273Kx1200sec, the SiC long fiber was the most suitable reinforcing material for Ti matrix composite materials. 2) With SiC long fiber under same condition, a TiC layer(1.0-1.6$\mu\textrm{m}$) was observed on the surface of SiC long fiber. 3) Liquid Phase Diffusion Bonding has shown the feasibility of production of Ti matrix composite materials.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.2
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• pp.25-30
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• 2015

This study involved the fabrication of precision machine tools using a polycrystalline diamond tip [sintered PCD and cemented carbide (WC-Co) tip] and WC-Co shanks via diffusion bonding with a paste-type nickel alloy filler metal. Diffusion bonding is a process whereby two materials are pressed together at high temperature and high pressure for a sufficient period of time to allow significant atomic diffusion to occur. For smooth progress, a filler metal of nickel alloy was used at the interface. Optical microscopy images were used to observe the copula of the bonded layer. It was confirmed that cracks occurred near the junction in all cases. The tensile strength of the bond was measured using a universal testing machine (UTM) with WC-Co proportional test specimens.

• Journal of Sensor Science and Technology
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• v.16 no.1
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• pp.62-67
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• 2007

This paper presents a novel MEMS condenser microphone with rigid backplate to enhance acoustic characteristics. The MEMS condenser microphone consists of membrane and backplate chips which are bonded together by gold-tin (Au/Sn) eutectic solder bonding. The membrane chip has 2.5 mm${\times}$2.5 mm, $0.5{\mu}m$ thick low stress silicon nitride membrane, 2 mm${\times}$2 mm Au/Ni/Cr membrane electrode, and $3{\mu}m$ thick Au/Sn layer. The backplate chip has 2 mm${\times}$2 mm, $150{\mu}m$ thick single crystal silicon rigid backplate, 1.8 mm${\times}$1.8 mm backplate electrode, and air gap, which is fabricated by bulk micromachining and silicon deep reactive ion etching. Slots and $50-60{\mu}m$ radius circular acoustic holes to reduce air damping are also formed in the backplate chip. The fabricated microphone sensitivity is $39.8{\mu}V/Pa$ (-88 dB re. 1 V/Pa) at 1 kHz and 28 V polarization voltage. The microphone shows flat frequency response within 1 dB between 20 Hz and 5 kHz.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.12 s.117
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• pp.1272-1278
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• 2006

This paper presents a novel MEMS condenser microphone with rigid backplate to enhance acoustic characteristics. The MEMS condenser microphone consists of membrane and backplate chips which are bonded together by gold-tin(Au/Sn) eutectic solder bonding. The membrane chip has $2.5mm{\times}2.5mm$, 0.5${\mu}m$ thick low stress silicon nitride membrane, $2mm{\times}2mm$ Au/Ni/Cr membrane electrode, and 3${\mu}m$ thick Au/Sn layer. The backplate chip has $2mm{\times}2mm$, 150${\mu}m$ thick single crystal silicon rigid backplate, $1.8mm{\times}1.8mm$ backplate electrode, and air gap, which is fabricated by bulk micromachining and silicon deep reactive ion etching. Slots and $50{\sim}60{\mu}m$ radius circular acoustic holes to reduce air damping are also formed in the backplate chip. The fabricated microphone sensitivity is 39.8 ${\mu}V/Pa$(-88 dB re. 1 V/Pa) at 1 kHz and 28 V polarization voltage. The microphone shows flat frequency response within 1 dB between 20 Hz and 5 kHz.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.309-311
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• 2007

Supramolecules containing double hydrogen bonding sites at their both chain ends were self-polymerized to become solid state polymer and were utilized to improve the efficiency of solid state DSSCs. Hydrogen bonding sites were attached at the chain ends of PEG of Mw=2000, such as pyrimethamine and glutaric acid. The solar cell with the solid state supramolecular polymer electrolyte resulted in the overall energy conversion efficiency of 4.63 % with a short circuit current density $(J_{sc})$ of 10.41 $mAcm^{-2}$, an open circuit voltage $V_{oc}$, of 0.71 V and a fill factor (FF) of 0.62 at one sun condition ([oligomer]:[1-methyl-3-propyl imidazolium iodide (MPII)]:$[I_2]$ = 20 : 1 : 0.19, active area = 0.16 $cm^2$, $TiO_2$ layer thickness = 10 ${\mu}m$). The ionic conductivity of the sol id state electrolyte was $5.11{\times}10^{-4}$ (S/cm). The cell performance was characterized by electrochemical impedance spectroscopy and ionic conductivity.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.160-163
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• 2003

This paper describes on anodic bonding characteristics of MLCA(Multi Layer Ceramic Actuator) to Si-wafer using evaporated Pyrex #7740 glass thin-films for MEMS applications. Pyrex #7740 glass thin-films with same properties were deposited on MLCA under optimum RF magneto conditions(Ar 100 %, input power $1\;/cm^2$). After annealing in $450^{\circ}C$ for 1 hr, the anodic bonding of MLCA to Si-wafer was successfully performed at 600 V, $400^{\circ}C$ in - 760 mmHg. Then, the MLCA/Si bonded interface and fabricated Si diaphragm deflection characteristics were analyzed through the actuation test. It is possible to control with accurate deflection of Si diaphragm according to its geometries and its maximum non-linearity is 0.05-008 %FS. Moreover, any damages or separation of MICA/Si bonded interfaces do not occur during actuation test. Therefore, it is expected that anodic bonding technology of MICA/Si wafers could be usefully applied for the fabrication process of high-performance piezoelectric MEMS devices.

• Journal of Sensor Science and Technology
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• v.14 no.3
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• pp.206-210
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• 2005

The SOI structure with buried alumina was fabricated by ALD followed by bonding and etchback process. The interface of alumina and silicon was analyzed by CV measurements and cross section was investigated by SEM analysis. The density of interface state of alumina and silicon was 2.5E11/$cm^{2}$-eV after high temperature annealing for wafer bonding. It was confirmed that the surface silicon layer was completely isolated from substrate by cross section SEM and AES depth profile. The device on this alumina SOI structure would have better thermal properties than that on conventional SOI due to higher thermal conductivity of alumina than that of silicon dioxide.

• Structural Engineering and Mechanics
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• v.78 no.3
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• pp.319-332
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• 2021

The wood-concrete composite is an interesting solution in the field of Civil Engineering to create high performance bending elements for bridges, as well as in the building construction for the design of wood concrete floor systems. The authors of this paper has been working for the past few years on the development of the bonding process as applied to wood-concrete composite structures. Contrary to conventional joining connectors, this assembling technique does ensure an almost perfect connection between wood and concrete. This paper presents a careful theoretical investigation into interfacial stresses at the level of the two interfaces in composite wooden beam- reinforced concrete slab strengthened by external bonding of prestressed composite plate under a uniformly distributed load. The model is based on equilibrium and deformations compatibility requirements in all parts of the strengthened composite beam, i.e., the wooden beam, RC slab, the CFRP plate and the adhesive layer. The theoretical predictions are compared with other existing solutions. This research is helpful for the understanding on mechanical behaviour of the interface and design of the CFRP- wooden-concrete hybrid structures.