• Journal of the Microelectronics and Packaging Society
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• v.7 no.4
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• pp.31-35
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• 2000

The stress state developed in a thin adhesive layer bonded between the semiconductor chip and the leadframe and subjected to a shear loading is investigated. The boundary element method (BEM) is employed to investigate the behavior of interface stresses. Within the context of a linear elastic theory, a stress singularity of type $\gamma^{\lambda=1}$(0<1<1) exists at the point where the interface between one of the rigid adherends and the adhesive layer intersects the free surface. Such singularity might lead to edge crack or delamination.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.7
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• pp.171-176
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• 2003

In this study, stress analysis using Boundary Element Method (BEM) was carried to investigate stress distribution in the brazing joint between a Hardmetal and a HSS. The two models were proposed to analyze the stress singularity in the interfaces of the brazing joint. The material type, thickness of the filler metal and the length of the vertical brazing adhesive are considered in the BEM analysis. As results, the peak point of the stress is founded to be in the lower interface of the brazed joint. It should be noted that the maximum stress of the peak point is being affected by the thickness and length of the brazing joint.

• Proceedings of the KIEE Conference
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• 1988.11a
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• pp.179-182
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• 1988

This study is to investigate the adhesive strength of composite material's interface on the experimental methode of tree growth in the material. The results are as fellows 1) The irradiations of ultrasonic energy cause the mechanical vibration in the polymer composite materials of fluid state, so then bring about physical dispersion and heat form inorganic materials, being supposed to produce chemical crosslinking reaction, decreasing of voids between filler and matrix. 2) The characterics of the breakdown are increased by using coupling agent in the composite material. 3) As the intensity of ultrasonic energy and its irradiated time are larger, the tree inception and break-down voltages increase and the tree growing is slower. so we obtain that the interface adhesive force tan be strengthened by the irradiation of ultrasonic energy.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.813-816
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• 1988

This study is to investigate the adhesive strength of composite material's interface on the experimental methode of tree growth in the material. The results are as follows 1) The irradiations of ultrasonic energy cause the mechanical vibration in the polymer composite materials of fluid state, so then bring about physical dispersion and heat for inorganic materials, being supposed to produce chemical interlinking reaction, decreasing of voids between filler and matrix. 2) As the intensity of ultrasonic energy and its irradiated time are larger, the tree inception and breakdown voltages increase and the tree growing is slower. so we obtain that the interface adhesive force can be strengthened by the irradiation of ultrasonic energy.

• Restorative Dentistry and Endodontics
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• v.24 no.2
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• pp.381-391
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• 1999

A new 5th generation adhesive system(ONE-STEP) has been supplied which operators can apply to conditioned tooth surfaces by one simplified step. The purpose of this study was to determine whether different methods of adhesive application and various air drying duration after applying adhesive affect the shear bond strength of composite resin to dentin, and to evaluate the adhesive pattern of composite resin and dentin under SEM. Seventy-seven extracted human molar teeth were cleaned and mounted in palstic test tubes. The occlusal dentin surfaces were exposed with Diamond Wheel Saw and smoothed with Lapping and Polishing Machine (South Bay Technology Co., U.S.A.). Teeth were randomly divided into 7 groups (n=11), In experimental A group, adhesive was applied to dentin with agitation for 20 sec. In experimental N-A group, adhesive were continuously applied to dentin for 20 sec. Also control and experimental 1, 2, 3, 4 groups were dried for 10, 0, 5, 20, 30 seconds after applying adhesive, respectively, Adhesives were light cured for 10 sec. A gelatin capsule 5mm in diameter was filled with Aelitefil$^{TM}$ composite resin, placed on the treated dentin surface and light cured for 40 see, from three sides, All specimens were stored in distilled water at room temperature for 24 hours. The shear bond strengths were measured using a universal testing machine(AGS-1000 4D, Japan) at a crosshead speed of 5mm/min. An one-way ANOVA and LSD test were used for statistical analysis of the data. For SEM evaluation, seven specimens were made and sectioned. Representive postfracture and seven specimens were mounted on brass stubs, sputter-coated with gold and observed under SEM. The results were as follows : 1. The shear bond strength of experimental A group which adhesive were applied to dentin with agitation was higher than that of experimental N-A group (continuous application), and there was significant difference between two groups (p<0.01). 2. The interface between composite and dentin according to different application methods showed close adaptation in experimental A group and showed tinny gap in experimental N-A group. 3. The shear bond strength accoding to various air drying duration was the lowest value(7.57${\pm}$2.60 MPa) in experimental 1 group, so there was significant difference between experimental 1 group and other four groups (p<0.05). But there was no significant difference of shear bond strength between four groups (p>0.05). 4. The interface between composite and dentin according to various air drying duration showed close adaptation in control group and tinny gap in experimental 3 and 4 groups. But experimental 1 and 2 groups showed $30{\mu}$ and 6 - $10{\mu}m$ thick gaps, respectively.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.230-237
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• 2012

The ultrasonic resonance method was applied to detect the disbond interface and empty layer between steel and FRP of the exit cone. The ultrasonic resonance method can easily detect the disbond interface and empty layer by amplifying the ultrasonic signal, but pulse echo method is difficult to distinguish adhesive interface from disbond interface or empty layer. The resonance frequency was predicted using the pressure reflection coefficient of 3-layered medium, and measured from ultrasonic signal of the test block using Fast Fourier Transform. The ultrasonic resonance proved that the predicted resonance frequency was in good agreement with the measured resonance frequency.

• Journal of Adhesion and Interface
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• v.11 no.1
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• pp.26-34
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• 2010

We synthesized polyurethane adhesive having thermal characteristic could be debonded by heat treatment and made a dismantlable polyurethane adhesive including thermally expansive bead. We used dynamic mechanical thermal analyzer (DMA) to confirm thermal characteristic and investigated bond strength, dismantlement property of dismantlable polyurethane adhesive by content of thermally expansive bead, heating trigger and treatment conditions. The dismantlable polyurethane adhesive could be expanded by hot-air or microwave treatment and the dismantlement of the specimens became easier as the weight fraction of the thermally expansive bead increased. At the dismantlable polyurethane adhesive, the content of thermally expansive bead 40% was suitable for both bond strength and dismantlement, in case of using hot-air treatment as trigger for dismantlement, bonded joints were separated easily at $160^{\circ}C$ for 30 min and in case of using microwave as trigger, bonded joints were separated easily by irradiating microwave for 4 min.

• Journal of Adhesion and Interface
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• v.17 no.3
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• pp.89-95
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• 2016

An environmentally friendly water-based pressure sensitive adhesive (PSA) was designed in an attempt to replace the solvent-based adhesive for dry lamination used in flexible food packaging films. Instead of using a low molecular weight surfactant, which may have variable material properties, a high molecular weight dispersant was used for emulsification. A polymeric nano-dispersant (PND) was synthesized using solution polymerization, and it was used as a micelle seed in the surfactant, resulting in the synthesis of a core/shell grafted acrylic adhesive. The shell and core exhibited different $T_g$ values, so that the initial adhesion strength and holding power were complemented by the film's flexibility, which is required to provide good adhesion of thin films. Results showed that the PSA designed in this study using the PND instead of traditional low molecular weight surfactant had adhesive properties applicable to the flexible packaging with appropriate tack.

• Composites Research
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• v.35 no.2
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• pp.86-92
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• 2022

This study was conducted to determine the effect of molecular formation of adhesive on interface characterization of thermoplastic composites. Carbonfiber/polyetherketoneketone (CF/PEKK) thermoplastic composites were fusion bonded and PEEK, PEI adhesive bonded using a high-temperature oven welding process. In addition, lap shear strength test and fracture surface analysis using a digital optical microscope and a scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR) were performed. As a result, the adhesive bonding method improved adhesion strength with interphase having increased molecular formation of ether groups, ketone groups, and imide groups which mainly constitutes the CF/PEKK and adhesives. Furthermore, it was found that the use of PEEK containing more ether groups and ketone groups forms a more strongly bonded interphase and enhances the adhesive force of the CF/PEKK composites.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.14 no.2
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• pp.104-109
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• 2005

This article has been investigated the use of FFT for adhesive joints analysis between metal sheets. The method is based on the measurement of the reflection wave at the metal/adhesive interface. After describing briefly the physical aspects of the phenomenon, an index is defined to detect defective zone of the joint(both for the lack of adhesive and for insufficient adhesion): the influence of the experimental variables(variable stress...) on the measurement is discussed. By means of a control experiment it is shown that stress variation in adhesive joints are separate to be distinguished. In this paper, Nondestructive evaluation in adhesive joints are evaluated together with ultrasonic testing and finite element analysis.