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One of the great advantages of LED based lighting fittings is their efficiency. Efficient cooling solutions are needed even for this type of fittings because of the high power density. This paper presents a comparison between passive cooling, with a heat sink, and active cooling using a fan. This paper discusses how fans can be used to cool high power COBs(chip on board) without significantly increasing...
The influence of viscoelastic behavior of polybutylene terephthalate (PBT) on reliability of the thermal contact of a spotlight module is evaluated. The contact between a module and the heat sink is evaluated using non-linear finite element model. The viscoelastic behavior of PBT was obtained under multiple frequencies from single cantilever DMA experiments. The relevant viscoelastic parameters (i...
For the high power LED light resource, it is reasonable to integrate several low power LEDs to improve the total output luminous. The layout of the low power chips and heat sink used has importance influence on the optical performance and the temperature distribution of the multi-chip LED packaging. But previous literatures mailing focused on the optical performance and temperature distribution respectively,...
The influence of viscoelastic behavior of polybutylene terephthalate (PBT) on reliability of the thermal contact of a spotlight module is evaluated. The contact between a module and the heat sink is evaluated using non-linear finite element model. The viscoelastic behavior of PBT was obtained under multiple frequencies from single cantilever DMA experiments. The relevant viscoelastic parameters (i...
For the high power LED light resource, it is reasonable to integrate several low power LEDs to improve the total output luminous. The layout of the low power chips and heat sink used has importance influence on the optical performance and the temperature distribution of the multi-chip LED packaging. But previous literatures mailing focused on the optical performance and temperature distribution respectively,...
The LED lighting market is growing annually, however high prices remain a barrier, especially in the incandescent replacement market [1]. Many LED bulbs, such as the A19 (the “classic” light bulb shape), MR16 (Multifaceted Reflector, 16 eights of an inch in diameter), and PAR30 (Parabolic Aluminized Reflector lamp, 30 eights of an inch in diameter) could benefit from the use of plastic materials to...
Thermal energy of many electronic components is currently managed using a heat sink cast of a conductive metal alloy. This method requires significant secondary assembly of many sub-components such as fasteners, thermal interface materials and potting compounds.
In this paper, an innovative heat management solution for the Light Emitting Diodes (LEDs) based on direct impingement cooling by Piezo fan has been proposed and evaluated. Round Piezo fans with 26 to 30 mm blade diameter, 1 to 5 mm fan thickness and narrow flow orifice (∼ 3 to 7.5 mm) were developed which could provide very high velocity air jet (> 10 m/s) for impinging heat source footprint directly...
This study proposes a novel silicon-based LED packaging module with a photo-sensing element. The photosensitive component and the base structure of LED die were directly fabricated on the silicon wafer by microfabrication processes with ion doping and inductively coupled plasma etching processes, respectively, to achieve miniaturization, integration, and low-cost smart LED packaging modules. The subsequent...
This paper reports the thermal performance of smart heat sinks (SHSs) consisting of hybrid pin fins (HPFs) containing internal channels and integrated with plate fins. The SHSs are mainly aimed at cooling high power LED modules under natural convection condition or forced convection condition with a moderate air velocity. The computational fluid dynamics (CFD) models of SHSs are generated utilizing...
The advances that have taken place in solid state lighting technology made white LED light sources suitable for general lighting application. They are very capable of being used to make excellent general lighting with sources that can replace many of the traditional lighting technologies in use today because of the fact that LED system offers high system efficacy, desired color temperature and long...
The increased electrical currents used to drive light emitting diode (LED) cause significant heat generation in the solid state lighting (SSL) system. As the temperature will directly affect the maximum light output, quality, reliability and the life time of the SSL system, thermal management is a key design aspect in terms of cost and performance. Particularly for consumer SSL system, natural convection...
Large LED (light emitting diode) array lights are currently being designed and sold as replacements for lights on roadways, tunnels, parking lots and other large areas. These lights are typically 75 W to 200 W in thermal dissipation, and the lighting structure is designed to handle a predominately conductive heat path until contact with the outer air is made. At this point convection to the ambient...
Previous studies show that the lighting quality of LED largely depends on operating temperature. LED without thermal management may fail early due to thermal runaway, epoxy degradation, and thermal stress under high-operating temperatures. In this study, the performance of a honeycomb heat sink was investigated by experimentation and three-dimensional numerical models. Two kinds of honeycomb models...
Investigation deals with LED's thermal management optimization in dependence of operating condition aided by application of infrared thermography. Thermal management calculations allow estimating temperature distribution on the LEDs, metal - core printed circuit boards (MCPCB) and heat sink but often real results may be different and experimental investigations are necessary. Good results are obtained...
Light Emitting Diodes (LEDs) are increasingly being designed into lighting products for general illumination and are now gaining traction in the market. Several LED products are already available, but have generally been accepted only for low light level applications because of the low lumen output and poor quality of light for many of the products. Much of the reason for the low lumen output is the...
A single switch multi-inductor buck-boost converter topology is presented for paralleling LED-networks. The proposed technique is based on discontinuous inductor currents to achieve a homogenous light-distribution of parallel connected high-brightness LEDs. In contrast to the common approach of driving LED-strings with constant-current, the proposed topology supplies the LEDs with constant-power....
A detailed numerical simulation of the performance of thermal module having ??thermal via?? is made in this study. The results indicate the temperature distributions from the numerical simulation are significantly affected by spreading resistance. The filled thermal via can considerably improve the performance of thermal module. For further explanation of the significant drop of junction and thermal...
The paper examines the high power Light Emitted diode (LED) and the hear distribution of the heat sink. Beside we also study the relationship between temperature and the current on the LEDs luminous efficiency. The temperature rise to over the limit level that the luminous efficiency will decrease rapidly. The current increase will cause the nonequilibrium electron diffuse out of the potential wall...
LED's in automotive lamp applications have been utilized effectively for functions with low light output requirements and for styling purposes. In recent years, high to ultra high power LED's are becoming a light source option for virtually every automotive lighting system. For exterior automotive lighting, these light sources have distinct advantages, but also unique thermal issues compared to conventional...
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