A review of passive thermal management of LED module

2012 35th International Spring Seminar on Electronics Technology, 2012

The aims of this work are connected with development of new method of LEDs' mounting onto the heat sink in lighting equipment. The technique involves usage of copper pins instead of standard MCPCBs. LEDs are soldered on copper pins. Mounting of LEDs demands boring holes in the heat sink and fixing copper pins into the holes by thermal conductive epoxy resin only. LED lamp is made using new technology and LEDs' thermal performance investigations are made at various ambient conditions (air temperatures from 20ºC to 45ºC) and different current values through LEDsup to 600 mA. Temperature regimes of operation of power LEDs soldered on MCPCBs and on copper pins (and mounted on heat sink) are experimentally tested and compared. Experimental results show that utilization of copper pins underneath LED thermal pads ensures good dissipation of heat, good manufacturability, enables varied designs of light equipment and is cost effective.

Third International Conference on Solid State Lighting, 2004

Light emitting diodes, LEDs, historically have been used for indicators and produced low amounts of heat. The introduction of high brightness LEDs with white light and monochromatic colors have led to a movement towards general illumination. The increased electrical currents used to drive the LEDs have focused more attention on the thermal paths in the developments of LED power packaging. The luminous efficiency of LEDs is soon expected to reach over 80 lumens/W, this is approximately 6 times the efficiency of a conventional incandescent tungsten bulb. Thermal management for the solid-state lighting applications is a key design parameter for both package and system level. Package and system level thermal management is discussed in separate sections. Effect of chip packages on junction to board thermal resistance was compared for both SiC and Sapphire chips. The higher thermal conductivity of the SiC chip provided about 2 times better thermal performance than the latter, while the under-filled Sapphire chip package can only catch the SiC chip performance. Later, system level thermal management was studied based on established numerical models for a conceptual solid-state lighting system. A conceptual LED illumination system was chosen and CFD models were created to determine the availability and limitations of passive air-cooling.

IOSR Journal of Mechanical and Civil Engineering, 2016

Junction temperature is an important parameter in thermal management of LEDs (Light emitting diodes) system. The junction temperature of three different types of LED is calculated numerically. Three dimension numerical simulation using ANSYS-Icepak 15 software package is presented for all cases. Appropriate heat sink is designed for each type of LED and investigates the effect of the fins height on the junction temperature. The increasing in electrical current utilized to driving the LEDs has concentrate high notice on the thermal management in the evolution of LED system. A felicitous design should have minimum thermal resistance between the heat sink base and the junction that depends on conduction heat transfer. The results showed the increase in a heat sink height 10% dissipate more heat transfer from the LEDs system at approximately 15%.

2014 11th China International Forum on Solid State Lighting (SSLCHINA), 2014

For the design of reliable light sources based on light emitting diodes (LED) efficient accurate testing is required. An innovative sensitive test method is developed to detect and distinguish failures in LED modules. The method, i.e. measurement of the relative thermal resistance, is based on transient thermal analysis and measures the structural integrity of the package by changes of the relative thermal resistance of the LED. Failure modes can be separated in the time domain. For detailed analysis and identification of the failure mode the transient signals are simulated by timeresolved finite element (FE) simulations.

Electrical and Electronics Engineering: An International Journal, 2015

The article analyses the influence of the design parameters of the structure of the heat sink with round pins on the junction temperature of the LED system. The study uses design of experiment (DOE) and thermal simulations to determine the factors that have the greatest impact to improve the cooling capacity and finding the optimal heat sink design. The results of thermal design and simulation of the LED system have been validated experimentally using a thermocouple and they show that the error between the experimentally measured and simulated temperature value of optimized heat sink structure is below 6%.

2016

Thermoelectric model of a light diode was built with a spacial separation of the heat and cold source. The differential equations system was solved, which comprises the stationary equation of the heatconductivity and the equation of Joule thermogeneration. The temperature distribution in the structural elements of LED was calculated and also the temperature of active zone overheating in dependence on the power of LED and the intensity of the heat exchange with the medium. For the numeral estimation a powerful white light diode was chosen-Gree XR7090WHT. It was found out that the light stream can be increased via current increasing, at simultaneous thermal stabilizing of its active zone.

LEDs are used in many areas today. Street lighting is one of them and high-power LEDs are utilized in this area. Electrical energy is converted into light with an efficiency in 10-25% range. The rest is converted into heat. The generated heat is largely caused from LED chip. Furthermore, Driver circuit would also causes heat rise. Removing of this heat from the system is important in order to LED system efficiency because increasing of temperature causes a reduction of luminous flux. Excellent thermal management plays a significant role in terms of efficiency, reliability and durability. In this study, losses are caused from the LED chip and the heat sink which are part of the LED lighting systems are examined. These elements are thermally analyzed. The impacts of these losses on efficiency will be presented.

Energies

Light Emitting Diode (LED) applications are increasingly used in various microelectronic devices due to their efficient light generation. The miniaturisation of the LED and its integration into compact devices within the weight limit have resulted in excessive heat generation, and inefficient management of this heat could lead to the failure of the entire system. Passive and/or active heat sinks are used for dissipating heat from the system to the environment to improve performance. An ANSYS design modeller and transient thermal conditions were utilised in this study to design and simulate the LED system. The modeller performs its function by utilising the Finite Element Method (FEM) technique. The LED system considered in this work consists of a chip, thermal interface material, and a cylindrical heat sink. The thickness of the Cylindrical Heat Sink (CHS) fins used in the investigation is between 2 mm and 6 mm, whilst ensuring the mass of heat sinks is not more than 100 g. The inpu...

2010 International Symposium on Advanced Packaging Materials: Microtech (APM), 2010

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 using IR thermography with IR camera for the middle IR spectral region (8 -13 µm). Application of infrared thermography allows obtaining temperature distribution at real operating conditions. Thermal images analyzing allow obtaining real temperature distribution on the LEDs, solder points and different areas on the heat sink at different operating conditions. Results of this investigation allow adjusting proper LEDs' regime of operation in lighting system with maximum light output in dependence of ambient temperature conditions and to ensure long life (over 50000 hours) of the LEDs.

2015

This work is related to the study of the effect of a deficient thermal interface material (TIM) on the thermal properties of LEDs package under natural convection. The used package is composed of 36 LEDs on rectangular fin heat sink. Numerical modeling using COMSOL Multiphysics® simulation software has been developed. We demonstrated that a thicker air layer, between the thermal grease and the heat sink, participates severely in the junction temperature rise.