• 한국전기전자재료학회논문지
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• 제31권2호
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• pp.122-127
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• 2018

In an attempt to estimate the life projection of LED packages, IESNA published a paper regarding an LED package measurement test method in 2008, and a life projection technical document in 2011, to be used for LED life estimation. IESNA's publications regarding LED package measurement methods were functional, but they were not internationally standardized before 2017. In order to develop a standardized method, the International Standard chose to use the LM-80 as a measurement method for LED life projection in their publication in 2017. Many projection methods have been discussed by the IEC Technical Committee 34 working group, including the method using an exponential function, which reflects lumen degradation characteristics well. This study is designed to explore alternative LED package life estimation methods using an exponential function with statistical analysis, other than the one suggested by the International Standard.

• 한국전기전자재료학회논문지
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• 제29권2호
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• pp.79-83
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• 2016

This research was analyzed thermal characteristics that was appointed disadvantage when smart LED driver ICs was packaged and we applied extracted thermal characteristics for optimal layout design. We confirmed reliability of smart LED driver ICs package without additional heat sink. If the package is not heat sink, we are possible to minimize package. For extracting thermal loss due to overshoot current, we increased driver current by two and three times. As a result of experiment, we obtained 22 mW and 49.5 mW thermal loss. And we obtained optimal data of 350 mA driver current. It is important to distance between power MOSFET and driver ICs. If thhe distance was increased, the temperature of package was decreased. And so we obtained optimal data of 3.7 mm distance between power MOSFET and driver ICs. Finally, we fabricated real package and we analyzed the electrical characteristics. We obtained constant 35 V output voltage and 80% efficiency.

• 한국진공학회지
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• 제21권4호
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• pp.185-192
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• 2012

Light Emitting Diode (LED) 칩의 크기는 전도를 통한 열의 방출에 있어 면적의 확대로 인한 열 밀도의 감소와 칩의 외부양자효율 변화로 인하여 LED 칩의 p-n 정션 온도와 패키지의 열 저항에 영향을 미친다. 본 연구에서는 16칩 LED 패키지에서 칩의 크기가 0.6 mm와 1 mm인 두 가지 경우에 대하여 순전압(forward voltage)을 측정하였고, 순간열분석법(thermal transient analysis)을 이용하여 정션 온도와 열 저항을 평가하였으며, 이를 LED 칩의 전기적인 특성과 LED 패키지의 구조적인 특성과 연관하여 해석하였다.

• 한국정밀공학회지
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• 제30권3호
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• pp.349-355
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• 2013

Recent high oil price results in the development of energy saving technology such as LED lighting system. Street-lighting system using COH LED package can save energy because the heat dissipation through cupper base is better than conventional technology. Studies on manufacturing processes of lighting system are insufficient even though LED package design and its heat analysis have been studied. This study focuses on the problem and solution of manufacturing processes such as LED packaging process, optimized emission angle, and LED bar dimension for mechanical assembly. As a result, we established better manufacturing alternatives of LED packaging and street-lighting system with higher lighting efficiency of 84 lm/W, as well as good illumination intensity of 39.7 lux at 6 m from lighting source.

• 조명전기설비학회논문지
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• 제26권2호
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• pp.1-7
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• 2012

LED package with 4[mm]-height mold was manufactured and the surface temperature was measured directly using both thermocouple and thermal infrared (IR) camera. FVM simulation was conducted to estimate the surface temperature of the same LED package under the same condition, by which the accuracy of the simulation was secured. Then, the effects of the height and thermal conductivity of the mold on the junction temperature of the LED package were investigated by FVM simulation. The results showed that the junction temperature decreased by 10[$^{\circ}C$] when the mold height was 3~5[mm], but the thermal conductivity of the mold didn't affect the junction temperature significantly.

• 한국광학회지
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• 제24권6호
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• pp.342-346
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• 2013

고출력 LED 패키지의 방열 특성 향상을 위하여, 다이 접합부에 실리콘 접착제와 금속 패턴의 병렬 접합 구조를 적용하여 열 유동 해석을 수행하였다. 그 결과, LED 칩에서 발생한 열은 주로 금속 패턴 구조물을 통해 기판으로 효과적으로 전달되고 있으나, 패턴 구조물의 크기에 따라 효율의 차이가 있음을 확인하였고, 그 효과를 정량화하기 위해 정규화 길이를 도입하여 칩과 금속 패턴 구조물의 면적에 따른 열 저항을 비교하였다. 정규화 길이가 길어지면 금속 패턴 구조물에 의한 열 우회 경로가 칩에 고르게 분포하여 열 저항이 감소하였으며, 그 값은 단순 병렬 열 저항 이론 값보다 다소 큰 수치로 수렴하지만, 충분한 열 저항 개선 효과를 얻을 수 있었다.

• 조명전기설비학회논문지
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• 제29권4호
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• pp.1-10
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• 2015

The light emitting diodes(LED) package of new structure is proposed to promote the reliability and lifespan by maximize heat dissipation occurred on the chip. We designed and fabricated the LED packages mixing the advantages of chip on board(COB) based on conventional metal printed circuit board(PCB) and the merits of Si sub-mount using base as a substrate. The proposed LED package samples were selected for the superior efficiency of the material through the sealant properties, chip characteristics, and phosphor properties evaluations. Reliability test was conducted the thermal shock test and flux rate according to the usage time at room temperature, high-temperature operation, high-temperature operation, high-temperature storage, low-temperature storage, high-temperature and high-humidity storage. Reliability test result, the average flux rate was maintained at 97.04% for each items. Thus, the Si sub-mount based LED package is expected to be applicable to high power down-light type LED light sources.

• 마이크로전자및패키징학회지
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• 제23권4호
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• pp.35-41
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• 2016

고출력 LED 조명용 패키지를 제조함에 있어서 발열은 LED의 광출력과 수명에 매우 중요한 영향을 주는 인자로 알려져 있다. 본 연구에서는 가로등용 고출력 LED 패키지를 개발함에 있어서 효과적인 방열을 하기 위하여 방열효과가 상대적으로 우수한 구조인 chip-on-a-heat sink 구조를 가지는 세라믹-메탈 기반의 패키지를 제조하였다. 열확산 기능을 하는 heat sink 기판소재는 알루미늄 합금을, LED 어레이 회로를 형성하는 절연막으로는 저온동시소성용 glass-ceramics을 사용하였다. 특히 열처리 시 가장 이슈가 되는 세라믹-금속 하이브리드 패키지 기판의 휨을 억제하기 위한 수단으로서, glass-ceramic 절연막을 부분 코팅함으로써 휨현상을 용이하게 줄일 수 있게 되었다. 또한, LED 패키지의 방열특성의 향상 즉 열저항도 기존의 MCPCB 패키지나 전면 코팅형 절연막 패키지에 비해 훨씬 낮아지는 효과를 얻었을 뿐 아니라, 세라믹 코팅소재의 절감효과도 볼 수 있게 되었다.

• 마이크로전자및패키징학회지
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• 제19권4호
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• pp.79-83
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• 2012

신뢰성이 우수하며, 소형화가 가능하고, 우수한 열전도도의 은 전극을 이용할 수 있는 LTCC (Low temperature co-fired ceramic) 패키징은 환경 및 열에 약한 플라스틱 패키징을 대체할 것으로 기대받고 있다. 현재 LTCC 패키징의 원료 분말로는 주로 $Al_2O_3$을 사용하는데, 본 연구에서는 $Al_2O_3$보다 열전도도가 2배 우수한 ZnO을 일부 첨가 또는 대체한 조성 변화를 통하여 패키징의 열 특성 변화에 대해 연구하였다. 소량의 ZnO를 첨가하여 열전도도가 최대 25%까지 상승하는 결과가 나타났으며, 이 결과로 LED 수명이 증가할 것으로 예상된다. ANSYS 시뮬레이션 결과 열 유속의 값이 ZnO가 첨가된 경우 최대 56% 증가함을 확인할 수 있었다. 실제 LED 패키징을 제작하여 측정한 결과도 ZnO를 첨가한 LTCC 패키징은 $Al_2O_3$로만 이루어진 패키징보다 열저항이 최대 14.9% 감소하였다.

• 소성∙가공
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• 제19권8호
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• pp.474-479
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• 2010

Newly suggested hybrid LED package can reduce the number of LED processes and enhance light efficacy in virtue of its integrated optical patterns. Square-type pyramid pattern was chosen for the integrated optical pattern in this study, and it was proved that the pattern enhances illuminance about three times and luminance about two and half times by optical simulation. Square-type pyramid patterns of 0.02mm height and 0.04mm pitch were successively machined on a copper mold which is necessary for imprinting the integrated pattern. Hybrid LED package with integrated optical pattern will be manufactured with ultra-fine machined mold in future study.