• Journal of Information Display
• /
• v.13 no.1
• /
• pp.1-6
• /
• 2012

Decreasing the thermal resistance is the critical issue for high-brightness light-emitting diodes. In this paper, the effects of some design factors, such as chip size (24 and 35 mil), substrate material (AlN and high-temperature co-fired ceramic), and die-attach material (Ag epoxy and PbSn solder), on the thermal-dissipation characteristics were investigated. Using the thermal transient method, the temperature sensitivity parameter, $R_{th}$ (thermal resistance), and junction temperature were estimated. The 35-mil chip showed better thermal dissipation, leading to lower thermal resistance and lower junction temperature, owing to its smaller heat source density compared with that of the 24-mil chip. By adopting an AlN substrate and a PbSn solder, which have higher thermal conductivity, the thermal resistance of the 24-mil chip can be decreased and can be made the same as that of the 35-mil chip.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.11a
• /
• pp.126-129
• /
• 2001

A p-n junction was obtained by the deposition of an n-type ZnO thin film on a p-type Zn-doped InP substrate. The Zn-doped InP substrate has been made by the diffusion of Zn with sealed ampoule technique. The ZnO deposition process ws performed by pulsed laser deposition (PLD). The p-n junction was formed and showed a typical I-V characteristic. We will also discuss about the realization of an ultraviolet light-emitting diode (LED). The structure of n-ZnO/p-Zn-doped InP could be a good candidate for the realization of an ultraviolet light-emitting diode or an ultraviolet laser diode.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.57 no.12
• /
• pp.2276-2280
• /
• 2008

In this paper, we present thermal dependancy of LED package element by changing temperature of MCPCB for design high efficiency LED lamp, and confirmed influence of LED chip against temperature with analysis of thermal resistance and thermal capacitance. As increasing temperature, WPOs were decreased from 25 to 22.5 [%] and optical power were also decreased. that is decreased reason of optical power that forward voltage was declined by decrease of energy bandgap. Therefore optical power by temperature of MCPCB should consider to design lamp for street light and security light. Moreover, compensation from declined optical efficiency is demanded when LED package is composed. Also, thermal resistances from chip to metal PCB were decreased from 12.18 to 10.8[$^{\circ}C/W$] by changing temperature. Among the thermal resistances, the thermal resistance form chip to die attachment was decreased from 2.87 to 2.5[$^{\circ}C/W$] and was decreased 0.72[$^{\circ}C/W$] in Heat Slug by chaning temperature. Therefore, because of thermal resistance gap in chip and heat slug, reliability and endurance of high power LED affect by increasing non-radiative recombination in chip from heat.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.27 no.8
• /
• pp.535-540
• /
• 2014

Because of the development of LED technology, products due to high output and compact, the material with high thermal conductivity has been developed. Now that heat radiating part of the LED lamp is currently used for die casting of aluminum. The development of aluminum with excellent thermal conductivity is required. In this study, we measured the thermal properties and compared them while we produced the alloy by changing the component of die casting aluminum. From this study, the thermal conductivity and thermal resistance of the developed alloy were superior to die casting aluminum.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.6
• /
• pp.1178-1182
• /
• 2011

The best methods for distribution controled of LED lighting fixtures is control to designed LED chip array, lens and reflector. However, lens design need distribution design to reflector for low-wattage LED lighting because of difficulty of production and reduction of light efficiency. In addition, it needs maximize of thermal performance to improve the efficiency and reliability of device. As a result, for the height of reflector 40[mm] and Inclination 25[$^{\circ}$], we can see the best distribution properties, and, in the thermal properties, junction temperature MCPCB 62.9 [$^{\circ}C$], FR4 PCB 89.6 [$^{\circ}C$], FR4 PCB from Via-hole is 63.1 [$^{\circ}C$]. it may improve for thermal properties for makes the Via-hole.

• Proceedings of the KIEE Conference
• /
• 2009.07a
• /
• pp.1613_1614
• /
• 2009

In this paper, thermal movement of high power LED on the MCPCB is analyzed with structural function and CFdesign V10 program. thermal resistance is decreased as 10.1 [$^{\circ}C$/W] in MCPCB from 12.2 [$^{\circ}C$/W] in LED package. Junction temperature which is calculated with thermal computational analysis program shows 85.113 [$^{\circ}C$] and almost same to measured data.

• New & Renewable Energy
• /
• v.5 no.4
• /
• pp.34-37
• /
• 2009

Using six SMD(surface mount device) type AlGaAs/GaAs single junction solar cells connected in series, a power source was fabricated for a white GaN LED. The electrical properties of the power source was measured and analyzed under one sun (100mW/$cm^2$) and various indoor light (300 - 900 lux) conditions. Under 600 lux indoor light condition, output power was 17.06 ${\mu}W$ and it was 30.75 ${\mu}W$ under 900 lux indoor light condition. Using the fabricated solar cell power supply, we have turned on the white GaN LED. It was worked well under 15 ${\mu}W$(at 480 lux) power supplied from solar cell array. This kind of solar cell power supply can be used as a power source for ubiquitous sensor network (USN).

• Proceedings of the KIEE Conference
• /
• 1996.07c
• /
• pp.1459-1461
• /
• 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.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.27 no.10
• /
• pp.673-677
• /
• 2014

In this paper, thermal analysis of HDU (Heat Dissipation Unit) for infrared CCTV is performed by using SolidWorks Simulation (Thermal analysis) package, in order to change the part materials and HDU shape is optimized. Furthermore, HDU disperses the aggregated heat around the LED inside the housing. The junction temperature of infrared LED checked by HDU check was $65.83^{\circ}C$, $42.02^{\circ}C$, respectively. In addition, the Thermoelement by changing the shape of the HDU was possibly designed and equipped with. Comparison with simulation and prototype measurement results, without HDU model was $65.83^{\circ}C$, $61.99^{\circ}C$, respectively. In addition to with HDU model was $42.02^{\circ}C$, $39.01^{\circ}C$, respectively. Only HDU mounted into infrared CCTV is usable in the ordinary house or outdoors. Also HDU with thermal element, fan mounted into infrared CCTV is usable in a blast furnace workplace or high temperature workplace.

• Proceedings of the Optical Society of Korea Conference
• /
• 2009.10a
• /
• pp.294-295
• /
• 2009