Thermal Management of Power LED System

JST: Smart Systems and Devices, 2021

Light Emitting Diodes (LED) shows an important role in replacing traditional lamps due to their longevity, high efficiency, and environment-friendly operation. However, a large portion of the electricity applied on LED converts to heat, raising up the p-n junction working temperature, and lowering the output-light quality and the LED lifetime as well. Therefore, thermal management for LED is one of the key issues in LEDs lighting application. In order to investigate the impact of each component of the LED module on the junction temperature of the LED, we have performed thermal simulations of a typical single LED module by using the finite element method. Effects of thermal conductivity and thickness of each module’s components on junction temperature were analyzed systematically. The results provided a detailed understanding of thermal behavior of a single LED module and established a crucial insight into thermal management design for high-power white LED lamp. Thermal-interface-mat...

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.

Thermal, Mechanical and Multiphysics Simulation and Experiments in Micro-Electronics and Micro-Systems EuroSimE, 2006

High brightness white light emitting diodes (LEDs) have shown to be very promising for many illumination applications such as outdoor illumination, task and decorative lighting as well as aircraft and automobile illumination, including automotive headlights. The objective of this paper is to investigate the cooling solutions of such LEDs in automotive applications. In this research, a thermal design from device

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.

2008

Light Emitting Diodes (LEDs) have been around for years, primarily concentrated as the lighting source for a variety of applications. Besides their electrical properties the optical parameters of LEDs also depend on junction temperature. The junction temperature of the power LEDs affects the device’s luminous flux, the color of the device, and its forward voltage. The key in that case is maintaining the specified junction temperature. For this reason thermal characterization and thermal management play important role in case of power LEDs, necessitating both physical measurements and simulation tools.

2014

This paper describes the effects of various parameters on the temperature of the LED device to optimize the heat sink structure of LED light bulb, and a design guideline is shown. Although the original efficiency and life of the LED device is excellent, the performance cannot be obtained due to the local temperature rise of LED element and the surrounding polymer molding material. Therefore, heat transfer analysis considering the heat convection and radiation was carried out systematically using finite element method by changing parameters of the heat sink shape. The result has shown that open type structure has advantage, and the proper design guideline for the structure of shape was obtained. Furthermore, an experimental model was prototyped, then the temperature distribution was measured, consequently it has been verified that the analysis results were well consistent with the empirical data.

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 incandescent light sources. This study describes two methods of determining the junction temperature of an LED or array of LED's, direct and indirect. Both are based on temperature measurements, but the indirect method also requires a thermal resistance specified by the manufacturer. The direct method utilizes the intrinsic behavior of the junction voltage drop at low current (<0.1mA). A computer model for a typical plate finned heat sink design for a high power LED automotive lamp was experimentally calibrated. Design of experiment analysis was performed using a 3 level 3 input factor full factorial test matrix. The factors were defined as an active heat sink surface area, convection coefficient correlated to an airflow, and environment temperature. A quadratic model is generated from the results of the factors and significant interactions to the response.

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...

Journal of Semiconductors, 2011

Recently, the high-brightness LEDs have begun to be designed for illumination application. The increased electrical currents used to drive LEDs lead to thermal issues. Thermal management for LED module is a key design parameter as high operation temperature directly affects their maximum light output, quality, reliability and life time. In this review, only passive thermal solutions used on LED module will be studied. Moreover, new thermal interface materials and passive thermal solutions applied on electronic equipments are discussed which have high potential to enhance the thermal performance of LED Module.

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%.