Papers by Keyword: Junction Temperature

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Authors: K.G.P. Eriksson, Martin Domeij, Hyung Seok Lee, Carl Mikael Zetterling, Mikael Östling
Abstract: To determine the maximum allowed power dissipation in a power transistor, it is important to determine the relationship between junction temperature and power dissipation. This work presents a new method for measuring the junction temperature in a SiC bipolar junction transistor (BJT) that is self-heated during DC forward conduction. The method also enables extraction of the thermal resistance between junction and ambient by measurements of the junction temperature as function of DC power dissipation. The basic principle of the method is to determine the temperature dependent I-V characteristics of the transistor under pulsed conditions with negligible self-heating, and compare these results with DC measurements with self-heating. Consistent results were obtained from two independent temperature measurements using the temperature dependence of the current gain, and the temperature dependence of the base-emitter I-V characteristics, respectively.
Authors: Rishita Saini, Neha Bansal, Meenakshi Bansal, Lakshay Kalra, Preet Mohan Singh, Bishwajeet Pandey, D.M. Akbar Hussain
Abstract: —Thermal aware design is currently gaining importance in VLSI research domain. In this work, we are going to design thermal aware energy efficient ROM on Virtex-5 FPGA. Ambient Temperature, airflow, and heat sink profile play a significant role in thermal aware hardware design life cycle. Ambient temperature is a temperature of surroundings. Airflow is measured in Linear Feet per Minute (LFM). Medium profile and high profile are two different heat sink profile available in XPower analyzer.When frequency goes from 4.0GHz to 1.0GHz, there is 21.8% reduction in clock power, 75% reduction in I/O Power, 35.6% reduction in leakage power and 53.8% reduction in total power at the same frequency.
Authors: De Huai Zeng, Yuan Liu, Li Li, De Gui Yu, Gang Xu
Abstract: With the development of high power LED technology, junction temperature as a key factor constrains the performance and the service life of LED, and the main parameter of junction temperature is thermal resistance. Therefore, how to measure the thermal resistance of high power LED quickly and accurately plays an important part in improving the performance and the service life of LED. In this paper the accurate and fast measurement equipment was applied to study the thermal characteristics of high power LED. The forward-voltage based method was conducted to measure the junction temperature of high power. Then, support vector regression (SVR) combined with genetic algorithm (GA) for its parameter optimization, was proposed to establish a model to predict the thermal resistance of high power LED. The prediction performance of GA-SVR was compared with those of BPNN model. The result demonstrated that the estimated errors GA-SVR models, such as Mean Absolute Relative Error (MARE) and Root Mean Squared Errors (RMSE), all are smaller than those achieved by the BPNN applying identical samples.
Authors: Mazlan Mohamed, A.M. Mustafa Al Bakri, Razak Wahab, A.K. Zulhisyam, M.R. Mohd Sukhairi, M.H.M. Amini, A. Mohammad Amizi
Abstract: This paper presents the comparison between thermal interface materials made of nano carbon tube (NCT) with Gad Pad 2500 in term of junction temperature by using CFD Software, FluentTM. 3D model of electronic packaging is built using GAMBIT and simulated using FLUENT software. The study was made for a microprocessors arranged in line under different types of inlet velocities and package (chip) powers. The results are presented in terms of average junction temperature when chip powers have been increased from 0.5 W to 2 W. The junction temperature is been observed and it was found that the junction temperature of the electronic packaging using nano carbon has lower junction temperature compare to the Gad Pad 2500. It also found that the NCT was able to reduce the junction temperature up to 20-30% compare to others thermal interface material.
Authors: N. Teeba, D. Mutharasu
Abstract: Proper heat management is necessary for better performance of the LEDs. In the present study, the thermo-optical properties of the LED with different type of PCBs were analyzed. The measurement was done with two different testing conditions to identify the effect of increasing drive current at constant ambient temperature and increasing ambient temperature at constant drive current on the the LEDs with different PCBs. In both the conditions, the thermal behaviors of the LED are affected much due to different type of boards. As the drive current increases, the junction temperature and RthJA of the LED with MCPCB reduces around 3.7K/W and 15.3K/W compare with the LED with FR4. The change in magnitude of chromaticity coordinates of LED with FR4PCB and MCPCB calculated as 0.154 and 0.132 respectively. At a lower ambient temperature, the LEDs with FR4 and MCPCB record the RthJA as 71.2K/W and 50.6K/W respectively. However, these values were lowered around 15% at higher ambient temperatures for both the LEDs. As ambient temperature increases, the shift in chromaticity coordinates for the LEDs with MCPCB and FR4 was obtained as 0.0163 and 0.0165. The influence of the different type of PCB’s performance on LEDs was observed in the increasing drive current condition rather than the increasing ambient temperatures.
Authors: Vithyacharan Retnasamy, Zaliman Sauli, Rajendaran Vairavan, Hussin Kamarudin, Mukhzeer Mohamad Shahimin, Steven Taniselass, P. Susthitha Menon
Abstract: High power light emitting diodes (LEDs) characteristics in terms of efficiency, long operating life and reliability which has lead to its application as lighting systems. However, the high power LEDs are subjected to thermal challenges due to it high input power. This work reports simulation analysis on a single chip high power LED to where thermal performances of the LED package were evaluated under varied convection condition. The simulation was carried out using Ansys version 11. The heat dissipation evaluated and compared in terms of junction temperature, von Mises stress and thermal resistance at each respective convection condition with constant input power of 1 W.
Authors: Vithyacharan Retnasamy, Zaliman Sauli, Rajendaran Vairavan, Hussin Kamarudin, Mukhzeer Mohamad Shahimin, Steven Taniselass, P. Susthitha Menon
Abstract: Excess heat generated by the high power LED package significantly impacts the performance and reliability of the light source. Significance of heat dissipation are influenced by each packaging component of high power LED. This paper demonstrates simulation analysis on single chip high power LED where the significance of the copper based heat slug structure on the heat dissipation was analyzed. The simulation analysis was carried out by using Ansys version 11 and heat dissipation of two types of heat slug structure, rectangular and cylindrical were compared. The outcome exhibited that the structure of the heat slug significantly influences the heat dissipation of LED chip due to its surface area.
Authors: Rajendaran Vairavan, Vithyacharan Retnasamy, Zaliman Sauli
Abstract: The current advancement of LED has prompt thermal challenges from the packaging point of view. The reliability of the LED is significantly influenced by each of its packaging component. This paper presents the investigation of heat slug size effect on the junction temperature and stress of single chip LED through simulation method. Ansys version 11 was utilized and the analysis was done with copper diamond rectangular heat slug under natural convection condition at ambient temperature of 25 °C.The simulation results indicated that junction temperature and the stress of the single chip LED is influenced by the size of heat slug.
Authors: Siddarth Sundaresan, Brian Grummel, Ranbir Singh
Abstract: The current gain stability of a second generation of 1200 V rated SiC Junction Transistors (SJTs) under long-term DC and pulsed current operation is investigated. A 1000-hour long, 200 A/cm2 DC current stress results in a ≈ 10% reduction of the current gain (β) during the early stages of the stress test, while the β is perfectly stable for the remainder (>90%) of the stress duration. The same amount of stress charge applied as a pulsed current in lieu of DC current results in similar extent of β degradation for the Gen-II SJTs. The pulsed current stressing is conducted at frequencies ranging from 50 kHz to 200 kHz, at a fixed duty cycle of 0.5.
Authors: Zaliman Sauli, Rajendaran Vairavan, Vithyacharan Retnasamy
Abstract: High power light emitting diodes are currently challenged by thermal issue of high heat generation which limits the reliability and efficiency. Each component in the LED package has a significant role in heat dissipation. In this paper, a simulation study was done to scrutinize the influence of heat slug shape on the heat dissipation of single chip LED package using Ansys version 11. Two types of heat slug shapes, rectangular and cylindrical were used. The analysis was carried out under natural convection condition at ambient temperature of 25°C. Simulated results indicate that rectangular shape heat slug exhibits better heat dissipation.
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