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Cooling techniques for electronic equipment
07 Nov 1980-
TL;DR: In this article, the authors present practical guides for Natural Convection and Radiation Cooling for Electronic Components. But they do not consider the effects of thermal stresses in lead wires, Solder Joints and Plated Throughholes.
Abstract: Evaluating the Cooling Requirements. Designing the Electronic Chassis. Conduction Cooling for Chassis and Circuit Boards. Mounting and Cooling Techniques for Electronic Components. Practical Guides for Natural Convection and Radiation Cooling. Forced--Air Cooling for Electronics. Thermal Stresses in Lead Wires, Solder Joints, and Plated Throughholes. Predicting the Fatigue Life in Thermal Cycling and Vibration Environment. Transient Cooling for Electronic Systems. Special Applications for Tough Cooling Jobs. Effective Cooling for Large Racks and Cabinets. Finite Element Methods for Mathematical Modeling. Environmental Stress Screening Techniques. References. Index.
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TL;DR: A neural network is trained and tested using the results of the CFD program package Fluent to find a neural network solution for obtaining suitable thickness levels and material for a chip subjected to a constant heat power.
Abstract: A CFD simulation usually requires extensive computer storage and lengthy computational time. The application of artificial neural network models to thermal management of chips is still limited. In this study, the main objective is to find a neural network solution for obtaining suitable thickness levels and material for a chip subjected to a constant heat power. To achieve this aim a neural network is trained and tested using the results of the CFD program package Fluent. The back-propagation learning algorithm with three different variants, single layer and logistic sigmoid transfer function is employed in the network. By using the weights of the network, various formulations are designed for the output. The network has resulted in R
2 values of 0.999, and the mean% errors smaller than 0.8 and 0.7 for the training and test data, respectively. The analysis is extended for different thickness and input power values. Comparison of some randomly selected results obtained by the neural network model and the CFD program has yielded a maximum error of 1.8%, mean absolute percentage error of 0.55% and R
2 of 0.99994.
11 citations
TL;DR: In this paper, the performance of polyalphaolefin (PAO) and a silicate ester-based fluid (Coolanol 25R) used as liquid coolants in avionic systems is compared.
Abstract: A general method for the comparison of hydraulic and thermal performance of different liquid coolants in complex systems is offered. As a case study, the performance of polyalphaolefin (PAO) and a silicate ester-based fluid (Coolanol 25R) used as liquid coolants in avionic systems is presented. Thermophysical property expressions for the variation of density, specific heat, thermal conductivity, and kinematic viscosity with temperature for PAO and Coolanol 25R were developed. The range of temperature for this study was from — 54 to 135°C. Based on the results, the hydraulic performance of Coolanol 25R is much better than that of PAO at low temperatures (below 0°C) and in the laminar flow regime. In the turbulent region, PAO outperforms Coolanol 25R hydraulically over the entire temperature range. The thermal performance of PAO at temperatures below 6PC and in the laminar flow region is slightly better than that of Coolanol 25R: In the low-temperature turbulent region, Coolanol 25R outperforms PAO thernial...
11 citations
15 Dec 2011
TL;DR: In this paper, the thermal performances of throughhole thermal vias used for heat transfer between layers on printed circuit boards are investigated by simulation using Computational Fluid Dynamics (CFD) software in order to determine steady state thermal behavior.
Abstract: For power electronics and Light Emitting Diode (LED) lighting applications, thermal management represents a critical factor having important consequences on electrical performance and overall cost of the assembly. Although advanced solutions for heat removal like Isolated Metal Substrates (IMS) base materials or thermally conductive epoxies have entered the market for a few years they still have a high price tag and add significant manufacturing costs to the finished assembly. Obtaining a good thermal management by using conventional materials and manufacturing techniques is often a key design challenge that engineers have to overcome. By creating thermal paths from one layer to another, the equivalent cooling area for an electronic component can be significantly increased thus lowering the junction-to-ambient thermal resistance which is the main indicator of cooling performance. These thermal paths between layers are commonly defined as through-hole plated vias connected to copper areas. Our paper presents a study of the thermal performances of through-hole thermal vias used for heat transfer between layers on printed circuit boards. Different geometries and scenarios are investigated by simulation using Computational Fluid Dynamics (CFD) software in order to determine steady state thermal behavior.
11 citations
Cites methods from "Cooling techniques for electronic e..."
...By applying (1) for the via geometry presented in figure 2 the thermal resistance of the copper walls for single via is obtained:...
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TL;DR: In this paper, the steady flow of power-law fluids past a semicircular cylinder (flat face oriented upstream) has been investigated numerically, and the governing equations (continuity, momentum, and energy) have been solved in the steady symmetric flow regime over the range of the Reynolds number (0.01 −1 −1, Re −1, Re −25), power law index ( 0.2 −1.8), and Prandtl number(0.72 −1).
Abstract: In this study, the two-dimensional steady flow of power-law fluids past a semicircular cylinder (flat face oriented upstream) has been investigated numerically. The governing equations (continuity, momentum, and energy) have been solved in the steady symmetric flow regime over the range of the Reynolds number (0.01 ≤ Re ≤ 25), power-law index (0.2 ≤ n ≤ 1.8), and Prandtl number (0.72 ≤ Pr ≤ 100). Extensive new results reported here endeavor to elucidate the role of power-law index (0.2 ≤ n ≤ 1.8) on the critical Reynolds number denoting the onset of flow separation (Re c ) and of vortex shedding (Re c ). In shear-thinning fluids, both of these transitions are seen to be delayed than that in Newtonian and shear-thickening fluids. Furthermore, the influence of the Reynolds and Prandtl numbers, power-law index on drag phenomenon, and heat characteristics of semicircular cylinder have been studied in the steady flow regime. Finally, the present numerical values of the critical Reynolds numbers and the average...
11 citations
TL;DR: Transactions of the ASME, Journal of Electronic Packaging (ISSN 1043-7398) is published quarterly (March, June, Sept., Dec.) by The American Society of Mechanical Engineers, Three Park Avenue, New York, NY 10016.
Abstract: Transactions of the ASME, Journal of Electronic Packaging (ISSN 1043-7398) is published quarterly (March, June, Sept., Dec.) by The American Society of Mechanical Engineers, Three Park Avenue, New York, NY 10016. Periodicals postage paid at New York, NY and additional mailing offices. POSTMASTER: Send address changes to Transactions of the ASME, Journal of Electronic Packaging, c/o THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS, 22 Law Drive, Box 2300, Fairfield, NJ 07007-2300. STATEMENT from By-Laws. The Society shall not be responsible for statements or opinions advanced in paper or ... printed in its publications (B7.1, Par. 3). COPYRIGHT © 2000 by the American Society of Mechanical Engineers. Authorization to photocopy material for internal or personal use under circumstances not falling within the fair use provisions of the Copyright Act is granted by ASME to libraries and other users registered with the Copyright Clearance Center (CCC) Transactional Reporting Service provided that the base fee of $3.00 per article is paid directly to CCC, Inc., 222 Rosewood Drive, Danvers, MA 01923. Request for special permission or bulk copying should be addressed to the Reprints/Permission Department. INDEXED by Applied Mechanics Reviews and Engineering Information, Inc. Canadian Goods & Services Tax Registration #126148048 TECHNICAL PAPERS
10 citations