• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1993.11a
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• pp.49-54
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• 1993

This paper discusses the reliability of solder joints of electronic devices on printed circuit board. Solder application is usually done by screen printing method for the bonding between outer leads of devices and thick film(Ag/Pd) pattern on Hybrid IC as wel1 as Cu lands on PCB. As result of thermal stresses generated at the solder joints due to the differences of thermal expansion coefficients between packge body and PCB, Micro cracking often occurs due to thermal fatigue failure at solder joints. The initiation and the propagate of solder joint crack depends on the environmental conditions, such as storage temperature and thermal cycling. The principal mechanisms of the cracking pheno- mana are the formation of kirkendal void caused by the differences in diffusion rate of materials, ant the thermal fatigue effect due to the differences of thermal expansion coefficient between package body and PCB. Finally, This paper experimentally shows a way to supress solder joints cracks by using low-${\alpha}$ PCB and the packages with thin lead frame, and investigates the phenomena of diffusion near the bonding interfaces.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.91-92
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• 2006

Aluminum-doped zinc oxide (AZO) films are attractive materials as transparent conductive electrode because they are inexpensive, nontoxic and abundant element compared with indium tin oxide (ITO). AZO films have been deposited on glass (corning 1737) substrates by RF magnetron sputtering system. The electrical resistivity of AZO films was $1.81{\times}10^{-2}{\Omega}cm$ and the average transmittance in the visible range 400-800 nm was more than 76% Organic light-emitting diodes (OLEDs) with AZO/TPD/$Alq_3$/Al configuration were fabricated. The current density-voltage properties of devices were studied and compared with ITO devices fabricated under the same conditions.

• Journal of Power System Engineering
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• v.18 no.1
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• pp.14-21
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• 2014

Piezoelectric fans are thin elastic beams whose vibratory motion is actuated by means of a piezoelectric material bonded to the beam. These fans have found use as a means to enhance convective heat transfer while requiring only small amounts of power. This study presents new types of models with heat sink having air passage and investigates experimentally their heat transfer characteristics. From the comparison results for four models, the heat transfer coefficients of model 1 are approximately 44~66% higher than those of the reference model 0. The model 1 show the best overall performance about heat transfer and cooling capability. As shown in above results, it is necessary to design the heat sink with air pass for cooling of electronic devices, in order to increase the convective heat transfer coefficient of a piezoelectric fan for electronic cooling.

• Proceedings of the KIEE Conference
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• 2004.11d
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• pp.40-42
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• 2004

Electronic equipments made from electrical circuits with small-sized semiconductor are very weak against lightning surge. So, electronic equipments is protected by SPD(surge protective devices) such as Zno varistor. The SPD protect electronic circuit in electronic equipments and AC power lines from the lightning surge. Therefore to achieve effective method of surge protection, there are needs for correlation between lightning surge protective effect and installation method of surge protective device. Therefore this paper describes as a result of experiments for correlation between lightning surge protective effect and installation method of surge protective device.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.2
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• pp.83-87
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• 2020

In this letter, we propose and analyze a new asymmetric structure that can be used for next-generation power semiconductor devices. We compare and analyze the electrical characteristics of the proposed device with respect to those of symmetric devices. The proposed device has a p-emitter on the right side of the cell. The peak electric field is reduced by the shielding effect caused by the p-emitter structure. Consequently, the breakdown voltage is increased. The proposed asymmetric structure has an approximately 100% higher Baliga's figure of merit (~94.22 MW/㎠) than the symmetric structure (~46.93 MW/㎠), and the breakdown voltage of the device increases by approximately 70%.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.31-36
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• 2003

Recently, the power consumption and heat generation in an electronic equipment increase as the components are miniaturized and the computing speed becomes faster. Effective cooling method is required to ensure the guaranteed performance and reliable operation of the electronic devices. The aim of the present study is to investigate the cooling characteristics of a pin-fin heat exchanger as a candidate for cooling system of the electronic devices. Various configuration of the pin-fin array is selected in order to find out the effect of spacing and diameter of the pin-fin on the heat transfer characteristics. The results are compared with the experimental data or correlations of several researchers for the channel flow with pin-fin arrays.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1479-1481
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• 2002

AlN thin films were deposited on Si(100) and $SiO_2$/Si substrates using R.F. magnetron sputtering system. The effect of various deposition conditions on the crystal orientation of AlN films was investigated to obtain a highly (002)-oriented films. SAW filters were fabricated using AlN films with various thicknesses and their frequency response characterizations were measured. Experimental results showed that the (002)-orientation and surface roughness of AlN films played a crucial role of determining the frequency response of AlN SAW devices.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.469-470
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• 2006

Surface Acoustic Wave(SAW) devices can be used to as wireless sensor elements, called SAW transponders, for measuring shysical quantities such as temperature that do not need any power supply and may be accessed wirelessly. SAW devices were fabricated on Y-Z $LiNbO_3$ piezoelectric substrate with a good temperature coefficient property. The signal response of SAW sensor on the temperature change were compared. To measure the change of SAW velocity. Temperature changed form $20^{\circ}C$ to $400^{\circ}C$ was linearly changed, the SAW sensor is application to the temperature sensor.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.146-149
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• 1999

Langmur-Blodgett (LB) method has a unique characteristic of making molecularly mutilayered aggregation structures. LB method makes the thickness of organic insulation layer controllable at molecular scale in various electronic devices. In this study, the organic materials applicable to crosslinked LB insulation layers of electronic devices have developed and the electrical properties of their LB films have examined such as Brewster angle microscopy(BAM), Scanning Maxwell-stress microscopy(SMM), and Current-voltage(1-V) properties.

• Korean Journal of Computational Design and Engineering
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• v.14 no.5
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• pp.330-337
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• 2009

Nowadays a lot of high-tech electronic products such as TVs, monitors and camcorders are being developed. The more functions the electronic devices have, the more heat problems occur. Therefore, most of electronic products have air-ventilation holes to eliminate heat that is generated inside the products. The shapes of ventilation holes are usually complicated since aesthetic appearance of the products is important these days. In order to create those complicated shapes, designers should do time-consuming jobs because most of commercial CAD systems do not provide the functions that create patterns of lofted parts along freeform surfaces. In this research, an automated air-ventilation hole modeling system was proposed. The system generates patterns of lofted objects on freeform surfaces. Standard process to create air-ventilation holes manually was established, and vent-hole types and pattern types were classified into several categories. Designers can create many kinds of vent-holes by combining vent-hole types and pattern types. Users can also utilize user-defined pattern which can give users more flexibility. Developed system was applied to several design examples and the results are presented.