• 한국생산제조학회지
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• 제23권4호
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• pp.355-360
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• 2014

Recently, the use of LED is increasing. This paper presents the new package process of thermal compression bonding using metal layered LED chip for the high power LED device. Effective thermal dissipation, which is required in the high power LED device, is achieved by eutectic/flip chip bonding method using metal bond layer on a LED chip. In this study, the process condition for the LED eutectic die bonder system is proposed by using the analysis program, and some experimental results are compared with those obtained using a DST (Die Shear Tester) to illustrate the reliability of the proposed process condition. The cause of bonding failures in the proposed process is also investigated experimentally.

• 마이크로전자및패키징학회지
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• 제12권4호통권37호
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• pp.331-338
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• 2005

The rapid advances in high power light sources and arrays as encountered in incandescent lamps have induced dramatic increases in die heat flux and power consumption at all levels of high power LED packaging. The lifetime of such devices and device arrays is determined by their temperature and thermal transients controlled by the powering and cooling, because they are usually operated under rough environmental conditions. The reliability of packaged electronics strongly depends on the die attach quality, because any void or a small delamination may cause instant temperature increase in the die, leading sooner or later to failure in the operation. Die attach materials have a key role in the thermal management of high power LED packages by providing the low thermal resistance between the heat generating LED chips and the heat dissipating heat slug. In this paper, thermal transient characteristics of die attach in high power LED package have been studied based on the thermal transient analysis using the evaluation of the structure function of the heat flow path. With high power LED packages fabricated by die attach materials such as Ag paste, solder paste and Au/Sn eutectic bonding, we have demonstrated characteristics such as cross-section analysis, shear test and visual inspection after shear test of die attach and how to detect die attach failures and to measure thermal resistance values of die attach in high power LED package. From the structure function oi the thermal transient characteristics, we could know the result that die attach quality of Au/Sn eutectic bonding presented the thermal resistance of about 3.5K/W. It was much better than those of Ag paste and solder paste presented the thermal resistance of about 11.5${\~}$14.2K/W and 4.4${\~}$4.6K/W, respectively.

• 한국기계가공학회지
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• 제14권6호
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• pp.129-135
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• 2015

This paper shows significant methods that improve the lifespan of LED modules as well as efficiently using an aluminum heat-sink for LED module in high power. It proposes a method that raises stability and lifespan to protect LED modules and the power unit when the LED module has been used for a long hours at high temperatures. During the research, we applied a method of pulse-width modulation (PWM) in order to prevent the phenomenon that the entire power of a system is turned off and the lifespan is reduced when the LED nodule reacts to the high temperatures. To protect the LED module and SMPS based on high efficiency, a temperature sensor is attached underneath the circuit board and the sensor measures the temperature of circuit board when the LED module is powered on. The electrical power connected to SMPS is controlled by PWM when the temperature of the LED module reaches a particular temperature.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1459-1461
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• 1996

The optical and electrical properties of High Power AlGaAs/AlGaAs Infrared LED with DDH( Double power Double Hetero Junction) structure are investigated. The high power LED is recently studied in order to apply to high speed communication devices. The power out of AlGaAs/AlGaAs with DDH structure is 13.0[mW], the forward voltage is 1.45[V], and the average decrease rate of power out is about 5[%] after aging test. The optical and electrical properties of DDH structure LED are superior than that of SH structured LED. The DDH structured LED is suitable to the high speed communication devices.

• 한국산학기술학회논문지
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• 제11권8호
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• pp.2999-3004
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• 2010

LED는 다른 광원에 비해 동작수명이 길고, 친환경적이며, 에너지 효율이 높은 장점을 가지고 있다. 최근 LED 기술의 발전으로 인해 고휘도, 고용량의 LED가 개발됨에 따라, 표시장치에만 적용되던 LED를 조명장치에도 적용하는 기술이 확산되고 있다. 조명장치에 적용되는 파워 LED는 발열문제로 인한 소손을 막기 위해 구동전류를 일정한 전류값 이하로 제어할 필요성이 있다. 본 논문은 파워 LED의 구동전류를 설정된 값 이하로 제어하는 전류제 한 기능을 갖는 파워 LED 태양광 보안등 개발에 관한 연구이다. 태양광 발전에 의해 생산된 전력을 DC12[V] 축전지에 저장한 후, 야간에 승압형 DC-DC 컨버터를 통해 DC24[V]로 승압시켜 파워 LED로 공급한다. 태양광 보안등 제어기, 승압형 DC-DC 컨버터, 72[W]급 파워 LED 램프를 개발하여 동작을 확인하고 관련 데이터를 도출함으로써 제안된 시스템의 타당성을 입증하였다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.1326-1329
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• 2009

In large-area LCD displays, we have developed two new control technologies for high-power LED backlight. The Novel control technology called scanning control and local gray control. In addition, a conceptual display system power management was developed. We have implemented high power-LED module driving system which can achieve power saving and cost down. Finally, we designed LED light-bar module of the side type as a backlight source. It not only achieved light & thin but also reduced the quantity of LEDs.

• 한국생산제조학회지
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• 제21권3호
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• pp.487-492
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• 2012

In this study we researched a spotlight in LED lighting. Ordinary LED spotlight was manufactured with characterized property of traveling straightness of LED light source, but multiple use of shell type LED, a yellow band has formed caused by light source interference between the LED. Also, there was a high miscellaneous light efficiency with losing light source homogeneity and efficiency due to light source control uneasiness. The study uses aspheric reflector and aspheric lens, so we can control the light source of LED spotlight with effectively and we reached surface light source by using COB/COM for LED module. Furthermore it can change its use by a reduced scale of light system. It has been designed to make its various application from low power consumption of bicycle lamp, up to high power consumption of automobile lamps and lighthouse.

• 전기전자학회논문지
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• 제18권3호
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• pp.335-340
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• 2014

친환경 및 에너지 효율에 대한 관심이 증대되고 있는 가운데 LED(Light Emitting Diode)는 제어방식이 정 전류구동과 SMPS(Switching Mode Power Supply)방식으로 구동하므로 소형화 및 경량화를 이룰 수 있고 전력 소모가 적으며 효율이 높아 광원 및 조명장치에 활용하는데 유용하다. LED 생산업체는 고출력 LED 모듈의 칩 설계 원천기술의 확보가 필요하고, LED 를 조명으로 적용시키기 위해 전력손실을 줄일 수 있는 고출력 LED 모듈 개발을 위한 구동회로 설계와 역률 개선의 방안 연구가 필요하다. 산업현장에서 교류(AC) 직결 LED 구동소자인 HV9910를 일반적으로 사용하고 있다. 본 논문에서 HV9910에 PFC와 Noise Filter를 추가한 구동회로의 역률 및 효율에 대한 개선방법을 시뮬레이션을 통해 검증하는데 있다.

• 전력전자학회논문지
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• 제18권5호
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• pp.492-500
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• 2013

A balanced forward-flyback converter for high efficiency and high power factor using a foward and flyback converter topologies is proposed in this paper. The conventional AC/DC flyback converter can achieve a good power factor but it has the high offset current through the transformer magnetizing inductor, which results in a large core loss and low power conversion efficiency. And, the conventional forward converter can achieve the good power conversion efficiency with the aid of the low core loss but the input current dead zone near zero cross AC input voltage deteriorates the power factor. On the other hand, since the proposed converter can operate as the forward and flyback converters during switch turn-on and turn-off periods, respectively, it cannot only perform the power transfer during an entire switching period but also achieve the high power factor due to the flyback operation. Moreover, since the current balanced capacitor can minimize the offset current through the transformer magnetizing inductor regardless of the AC input voltage, the core loss and volume of the transformer can be minimized. Therefore, the proposed converter features a high efficiency and high power factor. To confirm the validity of the proposed converter, theoretical analysis and experimental results from a prototype of 24W LED driver are presented.

• 한국전기전자재료학회논문지
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• 제26권8호
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• pp.629-634
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• 2013

The rectified voltage supplied to LED lamp is used in load and then the surplus voltage can be produced in LED lighting. In this case, LED lighting is proposed that can recyclable the excess voltage to supply power to the controller.