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Analysis of Thermal and Optical Characteristics of Light Emitting Diode on Various Heatsinks
摘要： Light emitting diodes (LED) are widely used in today’s world due to its less power consumption and its high luminance capacity. Around 20-30% of energy is converted to light energy and 70-80% of energy is dissipated as heat. The excessive rise in temperature causes failure to the LED. An effective thermal management is required for the proper heat dissipation in LED. In this work, the heat dissipation and the optical characteristics of the 16 W LED are studied using different types of aluminium heat sinks. The variation of case and junction temperature as well as the optical characteristic of LED is measured for different heatsink at different It was observed that heat sink with higher surface area shows the best result in terms of lower case and junction temperature. The higher luminous intensity was observed for the parallel fin type 1 heatsink due to higher surface area.
关键词： Heatsink,Case temperature,Light Emitting Diode (LED),Junction temperature
更新于2025-09-23 15:23:52
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[IEEE 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - Shanghai (2018.8.8-2018.8.11)] 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - Thermal Analysis on the Degradation of GaN HEMTs
摘要： High temperature operation(HTO) experiments were performed on industrial GaN HEMTs devices. Several degradation failure modes of DC parameters such as transconductance reduction, threshold voltage shift, and gate leakage current increase were identified. The vertical failure localization and analysis of the devices were carried out by electrical method. The results show that the increase of the degradation of the die attach layer is the main reason for the increase of the junction temperature and thermal resistance of the devices. Furthermore, the results are analyzed by three-dimensional X-ray imaging confirming the degradation of the die attach layer. The voids in the die attach layer expanded during the high temperature operation stress experiments, led to a worse heat dissipation performance, which resulting in increased junction temperature, and further accelerate the performance degradation of the devices.
关键词： junction temperature,thermal resistance,reliability,GaN
更新于2025-09-23 15:22:29
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Online Junction Temperature Extraction of SiC Power MOSFETs with Temperature Sensitive Optic Parameter (TSOP) Approach
摘要： Accurate information of the junction temperature of SiC power MOSFETs ensures safe operation and helps reliability assessment of the devices. In this paper, an online junction temperature extraction method is proposed based on the electroluminescence phenomenon of the body diode of SiC power MOSFETs. It is found that during the forward conduction interval of the body diode, visible blue light is emitted around the chip, which ascribes to the radiative recombination in the low doped region of SiC MOSFETs. Experimental results suggest the light intensity changes linearly with the variation of the temperature and behaves as a temperature sensitive optic parameter (TSOP). Further, an electro-thermal-optic model is proposed to reveal the relationship between electroluminescence intensity, forward current and junction temperature. Based on the TSOP, an online junction temperature extraction method is proposed for SiC MOSFETs and verified in a SiC MOSFET based inverter. Compared with state-of-the-art methods, the proposed junction temperature measurement method is contactless and immune from the aging of the package.
关键词： junction temperature extraction,Body diode,thermal management,electroluminescence,SiC MOSFETs
更新于2025-09-23 15:22:29
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Counter-intuitive junction temperature behavior in AlGaN-based deep-ultraviolet light-emitting diodes
摘要： The junction temperature, one of the major parameters that strongly affect the performance of light-emitting diodes (LEDs), increases during operation because of the power dissipated as heat within an LED device. Therefore, LED devices with poor characteristics are expected to have higher junction temperatures for the same driving conditions. In this study, an observation contrary to this expectation is presented: a deep-ultraviolet LED device with superior electrical characteristics shows a higher junction temperature at the same input electrical power than a device with poor characteristics. A simple equivalent circuit comprising a diode, a series resistor, and shunt components is employed to elucidate this counter-intuitive observation by considering the possible heat sources inside the LED device. It is found that the junction temperature is mainly dominated by the power dissipated at the diode instead of the other possible heat sources including the Joule heating effect of the resistive components.
关键词： junction temperature,Joule heating,AlGaN-based deep-ultraviolet light-emitting diodes,power dissipation,equivalent circuit
更新于2025-09-23 15:21:01
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Thermal Assessment of Laminar Flow Liquid Cooling Blocks for LED Circuit Boards Used in Automotive Headlight Assemblies
摘要： This research work presents a comparative thermal performance assessment of the laminar flow cooling blocks produced for automotive headlight assembly using a high power Light Emitting Diode (LED) chip. A three-dimensional numerical model with conjugate heat transfer in solid and fluid domains was used. Laminar flow was considered in the present analysis. The validation of the numerical model was realized by using the measured data from the test rig. It was observed that substantial temperature variations were occurred around the LED chip owing to volumetric heat generation. The cooling board with lower height performs better thermal performance but higher pressure drop for the same mass flow rates. The cooling board with the finned cover plate performs better thermal performance but results in an increased pressure drop for the same mass flow rates. Increasing the power of the LED results in higher temperature values for the same mass flow rates. The junction temperature is highly dependent on the mass flow rates and LED power. It can be controlled by means of the mass flow rate of the coolant fluid. New Nusselt number correlations are proposed for laminar flow mini-channel liquid cooling block applications.
关键词： laminar flow,CFD,LED chip,finned plate,junction temperature,automotive headlight,liquid cooling
更新于2025-09-23 15:21:01
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[IEEE 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - Shanghai (2018.8.8-2018.8.11)] 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - Research on Thermal Analysis of Iris Recognition Module Package Structure
摘要： The existing iris recognition module is realized by assembly, which has large volume, high power consumption. The iris recognition module does not conform to the light and thin development trend of integrated circuits. Therefore, the industry is considering building a new iris recognition module from the bare chip and micro interconnect technology. The new module integrates a number of bare chips and passive devices in a limited space, and its thermal performance becomes more complex. It performance systematically. In this paper, thermal performance of the iris recognition module is systematically studied by the finite element method, and the influence of the thermal power of the chip, the thermal conductivity of the material and the area of PCB on the temperature and thermal resistance of the package are discussed. The results show that the thermal conductivity of chip material, the thermal power consumption of chip and the area of PCB have significant influence on packaging junction and thermal resistance of package. Package junction temperature and thermal resistance first decrease rapidly with the heat transfer coefficient of the package material, and then gradually tends to be horizontal, The effect of PCB area on the thermal performance of packaging is similar to that of the loading material, and the thermal dissipation power of the package is linearly increasing with the junction temperature of the package, and it has a horizontal linear relationship with the thermal resistance of the package.
关键词： microinterconnection technology,iris identification module,package junction temperature,package thermal resistance
更新于2025-09-23 15:21:01
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Exper?±mental and Numer?±cal Analysis of the Effect of Components on a Double-Sided PCB on LED Junction Temperature and Light Output Using CFD
摘要： In today’s lighting industry, with developing technology and a widened usage area, LEDs have become very popular due to their higher energy efficiency and longer life. In the present study, the effect of electronic components on printed circuits and the radiation level on light output was studied. The performed analysis was validated with an experimental method. For the finite volume method, FloEFD 2019, commercial software, was used. The ambient temperature was assumed to be 23 °C. The value of solar irradiance was taken as 1009 W/cm2. LEDs on a PCB were driven at 70 mA at first and then at 50 mA, and, by exerting power on all electronic components, analyses were performed. Both sides of the PCB were examined, and, in order to achieve efficient heat conduction, the power and distribution of the electronic components on the back side of the LEDs were optimized. With a new electronic circuit design, analyses were performed at 50, 55, 60, 65, and 70 mA. It was determined that the highest light output was achieved at 65 mA and that the distribution of electronic components on a PCB indirectly affects light output through junction temperature (T j).
关键词： Laminar natural convection,Junction temperature,Monte Carlo radiation,LED automotive lamp,Computational fluid dynamics (CFD)
更新于2025-09-23 15:19:57
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Determining combined effects of solar radiation and panel junction temperature on all model-parameters to forecast peak power and photovoltaic yield of solar panel under non-standard conditions
摘要： In the current study, we introduce two methods to extract model-physical parameters of a solar panel using photovoltaic metrics at key points. We use a single-diode circuit to describe a solar panel working under STC. According to the first method, we derive a new transcendental equation connecting series resistance Rs to quality factor η and photovoltaic metrics at key points. Following the second method, we establish a new analytic expression giving series resistance as a function of quality factor and key points coordinates. For both methods, we express parallel conductance Gp, photo-generation current Iph and leakage current Is in terms of quality factor and all photovoltaic metrics. We use quality factor as variational parameter to minimize RMSE between experimental and optimized characteristics. We borrow temperature coefficients from manufacturer data sheet and determine panel radiation coefficients to derive analytical expressions giving variations of photovoltaic metrics at key points as functions of panel junction temperature T and solar radiation S. To investigate dependencies of all model-physical parameters versus T and S, we consider numerical values of model-physical parameters at STC as initial conditions, and resolve the system of non-linear equations linking panel current to panel voltage at key points. We test numerical models established and mathematical expressions derived by specifying to PV solar panels such as KC130GT and SM55 operating at different environmental conditions of ambient temperature and solar radiation. As a result, for arbitrary environmental conditions, predicted characteristics agree with measured characteristics validating thereby our numerical approach.
关键词： Model-physical parameters extraction,Solar radiation effect,Panel junction temperature coefficients,Solar radiation coefficient,Panel junction temperature effect,Current-voltage characteristics
更新于2025-09-19 17:13:59
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Temperature Sensing Characteristics and Long Term Stability of Power LEDs Used for Voltage vs. Junction Temperature Measurements and Related Procedure
摘要： A detailed study about the direct measurement of junction temperature TJ of off-the-shelf power light emitting diodes (LED) is presented. The linear dependence on temperature of the voltage drop across the device terminals at a constant current is in particular exploited and fully characterized, in the temperature range from T = 35 ?C to 135 ?C, with tests repeated at one thousand different probe currents. The accurate experimental data, obtained on several LED samples bearing two different part numbers, are reported, showing that they exhibit a high degree of linearity in wide current ranges, a circumstance that allows for a fast and reliable calibration as sensors. The measurement error is also fully characterized in terms of repeatability and stability over time, with measurements repeated after 600, 900, 1200 and 1800 hours of applied electro-thermal stress, demonstrating that the relevant sensor parameters stabilize after a few hundred hours of operation. A full set of parameters is provided for the two device models, allowing the direct use of each LED for the self-monitoring of the junction temperature and ensure compliance with their safe operating area over time. Moreover, a procedure and a simple circuit for the real time measurement of TJ , while the LED is on, are presented. The procedure does not require a stable current source, and relies instead on the application of a sub-threshold current ramp for such a short time that the change in the output light is not perceived by human eyes.
关键词： junction temperature,diode sensors,light emitting diodes,temperature sensors,LED
更新于2025-09-19 17:13:59
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[IEEE 2019 16th China International Forum on Solid State Lighting & 2019 International Forum on Wide Bandgap Semiconductors China (SSLChina: IFWS) - Shenzhen, China (2019.11.25-2019.11.27)] 2019 16th China International Forum on Solid State Lighting & 2019 International Forum on Wide Bandgap Semiconductors China (SSLChina: IFWS) - Junction Temperature Prediction of the Multi-LED Module with the Modified Thermal Resistance Matrix
摘要： The junction temperature of LEDs is important for its life, reliability and efficacy. The existing transient measurement method of the junction temperature of using transient thermal tester (T3ster) based on the time-resolved measuring with a constant bias current according to the JESD51-14 is able to obtain the LED junction temperature rise based on the known temperature of thermostat module as the heatsink. In practice, without T3ster and the thermostat module, for multi-LED module with multiple heat sources in the luminaries, the thermal resistance matrix needs to be built to realize the thermal transfer between one another such that their junctions temperature raises can be calculated from their thermal power consumption. It is demonstrated that without measurement of the temperature heatsink temperature, the individual junction temperature of LEDs (groups) in multi-LED module with a thermistor (NTC or PTC) on its PCB measuring the local reference temperature can be obtained from the modified N x (N+1) thermal resistance matrix having N LED heat sources and N+1 junction temperature rise. A multi-LED module sample with 3 groups of LEDs has been studied at 5 different ambient temperatures and 2 additional different power combinations using 3 thermal resistance matrices built at 3 different ambient temperatures for comparison. The result showed that the modified method is effective and convenient for measurement of the junction temperature of the multi- LED modules with a similar accuracy comparing to the conventional one in the local reference temperature range of 20~100?C.
关键词： junction temperature,multi-LED module,T3ster,thermal resistance,thermal resistance matrix
更新于2025-09-19 17:13:59