An Analytical Convergence Study of the Forced Air Cooling in Electronic Packaging

2016 ◽  
Vol 819 ◽  
pp. 34-41 ◽  
Author(s):  
K.A. Ong ◽  
Mohd Zulkifly Abdullah
Keyword(s):  
Thermal Resistance ◽  
Air Flow ◽  
Simulation Method ◽  
Input Power ◽  
Junction Temperature ◽  
Air Cooling ◽  
Element Analysis ◽  
Total Thermal Resistance ◽  
Minimum Number ◽  
Forced Air

A forced air thermal cooling model has been developed by using Ansys software, to study at each step of the input power, what will be the corresponding junction temperature? Few approaches were used to ensure the accuracy of the thermal simulation method, ranging from the minimum number of simulation iterations required in the finite element analysis, to the residuals target in terms of the momentum, continuity and energy equations, the objective is to ensure the simulations are converged and provide the reasonable results, which is also an indication of how the partial equations have successfully been solved with analytic method. The thermal resistance network in the model has also been established, mainly to understand the next level details in this thermal model by analyzing the correlation between the air flow and the thermal resistance at each junction, and also to understand the effect of the air flow with respect to the total thermal resistance. The thermal analytic model that built has proven to be healthy and it requires 200 iterations to achieve steady state with the reasonable temperature output, and there is no convergence issue in which the continuity, momentum and energy graphs showed the healthy trend, it achieved 10-7 for continuity, energy and momentum equations. it shows that when the air flow reduces the overall thermal resistance increases, in other word, reducing the air flow will increase the thermal resistance

Operating Temperature Analysis of LED with Cylindrical Cu Slug

2014 ◽  
Vol 487 ◽  
pp. 145-148 ◽  
Author(s):  
Rajendaran Vairavan ◽  
Zaliman Sauli ◽  
Vithyacharan Retnasamy
Keyword(s):  
Natural Convection ◽  
Operating Temperature ◽  
Simulation Method ◽  
Input Power ◽  
Junction Temperature ◽  
Temperature Analysis ◽  
Light Emitting ◽  
New Era ◽  
Lighting Systems

High power light emitting diodes is the new era of lighting due to momentous supremacy in terms of lighting efficacy over traditional lighting systems. The reliability of LED is dependent on its junction temperature. This study confers on the thermal and stress characterization of LED chip with copper cylindrical heat slug through simulation method. The simulation characterization was carried out with Ansys version 11 at ambient temperature of 25°C under natural convection condition. The LED package was powered with input powers of 0.1 W, 0.5 W and 1W .Results indicated that input power influences the junction temperature and stress of LED chip.

Packaging of High Power UV-LED Modules on Ceramic and Aluminum Substrates

2012 ◽  
Vol 2012 (1) ◽  
pp. 000225-000232 ◽  
Author(s):  
Marc Schneider ◽  
Benjamin Leyrer ◽  
Christian Herbold ◽  
Stefan Maikowske
Keyword(s):  
Thermal Resistance ◽  
Heat Sink ◽  
Input Power ◽  
Thermal Interface Material ◽  
Maximum Temperature ◽  
Thermal Interface ◽  
Uv Led ◽  
Forward Current ◽  
Water Cooler ◽  
Forced Air

An LED module consisting of 98 UV-LEDs with an emission wavelength of 395 nm placed on a ceramic substrate of 211 mm2 is presented. The module is cooled by a forced air heat sink as well as a high performance microstructured water cooler to lower the thermal resistance. For high thermal conductance a liquid metal as the thermal interface material between substrate and heat sink is used. With the forced air heat sink a maximum irradiance of 27.3 W/cm2 at a forward current of 700 mA and 220 W electrical input power was achieved. The microstructured water cooler enabled an almost doubling of the electrical input power (430 W) while maintaining the chip's maximum temperature. For a reduction of the module's thermal resistance a thick film process for aluminum sheet metal substrates was developed. A prototype LED module with 25 UV-LED chips on an area of 54 mm2 achieved a maximum optical power density of 31.6 W/cm2 at a forward current of 900 mA using a forced air heat sink. For an improved cooling of the LED chips a chip-on-heat sink-technology with embedded water cooling channels is developed to eliminate the thermal interface between substrate and heat sink.

Variation of thermal resistance with input current and ambient temperature in low-power SMD LED

2018 ◽  
Vol 35 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Muna E. Raypah ◽  
Dheepan M.K. ◽  
Mutharasu Devarajan ◽  
Shanmugan Subramani ◽  
Fauziah Sulaiman
Keyword(s):  
Low Power ◽  
Thermal Resistance ◽  
Ambient Temperature ◽  
Light Emitting Diode ◽  
Operating Conditions ◽  
Input Current ◽  
Junction Temperature ◽  
Total Thermal Resistance ◽  
Content Type ◽  
Thermal Transient

Purpose Thermal behavior of light-emitting diode (LED) device under different operating conditions must be known to enhance its reliability and efficiency in various applications. The purpose of this study is to report the influence of input current and ambient temperature on thermal resistance of InGaAlP low-power surface-mount device (SMD) LED. Design/methodology/approach Thermal parameters of the LED were measured using thermal transient measurement via Thermal Transient Tester (T3Ster). The experimental results were validated using computational fluid dynamics (CFD) software. Findings As input current increases from 50 to 90 mA at 25°C, the relative increase in LED package (ΔRthJS) and total thermal resistance (ΔRthJA) is about 10 and 4 per cent, respectively. In addition, at 50 mA and ambient temperature from 25 to 65°C, the ΔRthJS and ΔRthJA are roughly 28 and 22 per cent, respectively. A good agreement between simulation and experiment results of junction temperature. Originality/value Most of previous studies have focused on thermal management of high-power LEDs. There were no studies on thermal analysis of low-power SMD LED so far. This work will help in predicting the thermal performance of low-power LEDs in solid-state lighting applications.

A Design for Loop Thermosyphon Including Effect of Non-Condensable Gas

2011 ◽  
Author(s):  
Hiroyuki Toyoda ◽  
Tadakatsu Nakajima ◽  
Yoshihiro Kondo ◽  
Akio Idei ◽  
Shigemasa Sato
Keyword(s):  
Thermal Resistance ◽  
Ambient Temperature ◽  
Partial Pressure ◽  
Total Pressure ◽  
Air Cooling ◽  
Total Thermal Resistance ◽  
Cooling Performance ◽  
Design Information ◽  
Cooling Part

We have developed a loop thermosyphon for cooling electronics devices. Its cooling performance changes with the ambient temperature and amount of input heating. Especially it deteriorates with non-condensable gas (NCG) increase. NCG leakage of thermosyphon cannot detect below under 10−10 Pa-m3/s, though we have to design the thermosyphon considering these characteristics to provide guaranteed performance for 5–10 years. In this study, the effect of the amount of NCG in each component of a thermosyphon was measured while changing the amount of heater input, and the amount of NCG. As a result, we obtained some useful design information. The performance of air cooling part does not depend on the NCG amount in this case. The performance of evaporation part depends on the total pressure that includes the partial pressure of vapor and the partial pressure of NCG. The performance of condensation part is deteriorated strongly by NCG amount increase. Additionally, we expressed these performances as approximations. These expressions let us predict the total thermal resistance of this thermosyphon by the NCG amount and the input heating amount. Then, using the leakage of a thermosyphon and the amount of dissolved NCG in water, we predicted the amount of NCG that will be in the thermosyphon after 10 years. These results also let us predict the thermosyphon’s total thermal resistance after 10 years. Though there is a slight leakage on thermosyphon, using this technique, we are able to design a thermosyphon that is guaranteed the cooling performance for a long term.

Thermal and Structural Analysis of a Suspended Physics Package for a Chip-Scale Atomic Clock

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
A. D. Laws ◽  
R. Borwick ◽  
P. Stupar ◽  
J. DeNatale ◽  
Y. C. Lee
Keyword(s):  
Thermal Resistance ◽  
High Speed ◽  
Atomic Clock ◽  
Metal Vapor ◽  
Cavity Surface ◽  
Power Budget ◽  
Element Analysis ◽  
Total Thermal Resistance ◽  
Vapor Cell ◽  
Fea Model

The power dissipation for chip-scale atomic clocks (CSAC) is one of the major design considerations. 12 mW of the 30 mW power budget is for temperature control of the vertical-cavity-surface-emitting laser (VCSEL) and the alkali-metal vapor cell. Each of these must be maintained at 70+/−0.1°C even over large ambient temperature variations of 0–50°C. Thus the physics package of a CSAC device, which contains the vapor cell, VCSEL, and optical components, must have a very high thermal resistance, greater than 5.83°C/m W, to operate in 0°C ambient temperatures while dissipating less than 12 mW of power for heating. To create such a high level of insulation, the physics package is enclosed in a gold coated vacuum package and is suspended on a specially designed structure made from Cirlex, a type of polyimide. The thermal performance of the suspended physics package has been evaluated by measuring the total thermal resistance from a mockup package with and without an enclosure. Without an enclosure, the thermal resistance was found to be 1.07°C/m W. With the enclosure, the resistance increases to 1.71°C/m W. These two cases were modeled using finite element analysis (FEA), the results of which were found to match well with experimental measurements. A FEA model of the real design of the enclosed and suspended physics package was then modeled and was found to have a thermal resistance of 6.28°C/m W, which meets the project requirements of greater than 5.83°C/m W. The structural performance of the physics package was measured by shock-testing, a physics package mockup and recording the response with a high-speed video camera. The shock tests were modeled using dynamic FEA and were found to match well with the displacement measurements. A FEA model of the final design, not the mockup, of the physics package was created and was used to predict that the physics package will survive a 1800 g shock of any duration in any direction without exceeding the Cirlex yield stress of 49 MPa. In addition, the package will survive a 10,000 g shock of any duration in any direction without exceeding the Cirlex tensile stress of 229 MPa.

Experimental, Numerical and Analytical Investigation of Thermal Resistance in High Brightness LED Arrays

2014 ◽  
Author(s):  
Mahmood R. S. Shirazy ◽  
Andréane D’Arcy-Lepage ◽  
Michel Gilbert ◽  
Samuel Richard ◽  
Luc G. Fréchette
Keyword(s):  
Thermal Resistance ◽  
Heat Sink ◽  
Analytical Investigation ◽  
Analytical Models ◽  
Junction Temperature ◽  
Total Thermal Resistance ◽  
High Brightness ◽  
Finite Element Software ◽  
Led Array ◽  
Analytical Approaches

Thermal performance of a commercial LED array module has been studied by experimental, numerical and analytical approaches to find the dominant thermal resistance in the thermal circuit. The light quality, lifetime and reliability of the LED modules depend strongly on the junction temperature which can be obtained and modified by a suitable thermal resistance model. Analytical models for the first level packaging (Die) and second level packaging (PCB and heat sink) have been developed with special attention to the thermal spreading resistance. Numerical modeling has been performed using commercial finite element software (COMSOL) and the results are in good agreement with the analytical models. An LED array module has also been studied experimentally by measuring the temperature field in the PCB and heat sink using thermocouples and infrared thermography. The results of the experimental part are used to validate the numerical and analytical models. It is shown that more than 50% of the total thermal resistance is caused by the heat sink while the PCB and LED package each share 25% of the total thermal resistance.

Comprehensive Reduction of Thermal Resistance in Air Cooled Condensers

2015 ◽  
Author(s):  
Ahmad Saleh ◽  
Jayanta Kapat
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Heat Pipe ◽  
Transfer Process ◽  
Cooling System ◽  
Ambient Air ◽  
Heat Transfer Process ◽  
Air Cooling ◽  
Total Thermal Resistance ◽  
Fin Efficiency

Restriction on water consumption is becoming an increasing problem for the power generation industry. As an alternative both to once-through cooling and to surface condenser/wet-cooling tower combination, utility companies and equipment manufacturers are considering, and even implementing, air-cooled condenser (ACC). However, the industry is quite reluctant to switch over to ACC for three important reasons: (a) lower power output, (b) higher capital cost, and (c) larger physical foot-print, all because of the same reason — it is not as efficient to transfer heat from condensing steam to air as it is to transfer to water. In other words, overall thermal resistance from condensing steam to the ambient air is significantly higher than to cooling water. To get a clear and full understanding of the heat transfer process occur in air-cooling condenser, Detailed mathematical equations were derived to model the heat transfer process through the fined-tubes of the ACC. The total thermal resistance model was analyzed and investigated to identify the design components with highest affect in the process. The paper proposes a viable cooling system based on novel heat pipe technology which addresses these problems. This technology employs boiling as the means to store and transfer heat energy. A detailed mathematical set of equations was derived to model the heat pipe thermal resistance. A comparison of the heat transfer performances of the ACC technology and the proposed method is presented. The proposed cooling system suggests a solution for each of the three components of the thermal resistance, the super-hydrophobic coating of the steam ducts internal surfaces increased the condensing heat transfer rate by an order of magnitude, the proposed design of the heat pipes improved the external heat transfer, and the installation mechanism improves the fin efficiency by eliminating the contact resistance between steam duct and the heat pipe.

Characteristics of Thermal Performance in High Power LED Package with Heat Pipe

2007 ◽  
Vol 124-126 ◽  
pp. 85-88 ◽  
Author(s):  
Woong Joon Hwang ◽  
Hwa Jun Yeo ◽  
Moo Whan Shin
Keyword(s):  
Thermal Resistance ◽  
Heat Pipe ◽  
Thermal Performance ◽  
High Power ◽  
Pure Water ◽  
Input Power ◽  
Junction Temperature ◽  
Working Fluid ◽  
Sintered Metal ◽  
Forced Cooling

This paper discusses about thermal performance of high power light emitted diode (HPLED) implemented with sintered metal wick type heat pipe(SWHP). The HPLED(2.5 W) samples were surface mounted device(SMD) package used in our experiments. The experiments were made for SWHP with diameters of 6.0 mm. The length of the SWHP is 150 mm. The working fluid in the heat pipes is pure water. The electrical-thermal transient technique was employed for the junction temperature measurement. It was found that the SWHP leads to decreased of thermal resistance by 35 % compared with a simple copper bar in oil bath (forced cooling condition). Employment of copper cap as a LED attachment was more advantageous over the phosphor bronze. After the increase of input power, the thermal resistance of HPLED package has decreased with the increase of effective thermal conductivity of SWHP.

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