An Experimental Investigation of the Thermal Interaction of Electro-Optical Components on a Printed Circuit Board in Natural and Forced Convection

2003 ◽  
Author(s):  
Amy S. Fleischer ◽  
Randy D. Weinstein
Keyword(s):  
Natural Convection ◽  
Forced Convection ◽  
Power Dissipation ◽  
Printed Circuit Board ◽  
Circuit Board ◽  
Total Power ◽  
Heat Sources ◽  
Thermal Interaction ◽  
Relative Location ◽  
Optical Components

The thermal interaction of an electrical and an optical component located on the same vertical circuit board is studied experimentally. The effects of component proximity and convective flow rate on overall power dissipation from each component are analyzed. The components are represented by isothermal heat sources mounted to a standard 1.59mm (0.0625 in) thick FR4 circuit board. In natural convection situations, when the spacing between components is great enough that the component thermal footprints do not interfere, the power dissipation reaches a maximum “plateau” value that is independent of spacing. If the components are located close enough together that their thermal footprints interfere then the total power dissipation is highly dependent on component spacing (relative location of the electrical source and the geometric positioning of both sources). In forced convection, the total power dissipated increases with both Reynolds number and component spacing. As in natural convection, the relative location of the electrical sources and the positioning of the sources are found to have a strong influence on power dissipation.

Natural Convection and Passive Heat Rejection from Two Heat Sources Maintained at Different Temperatures on a Printed Circuit Board

2004 ◽  
Vol 126 (1) ◽  
pp. 14-21 ◽  
Author(s):  
Randy D. Weinstein ◽  
Amy S. Fleischer ◽  
Kimberly A. Krug
Keyword(s):  
Natural Convection ◽  
Power Dissipation ◽  
Printed Circuit Board ◽  
Circuit Board ◽  
Heat Sources ◽  
Circuit Boards ◽  
Vertical Orientation ◽  
Heat Rejection ◽  
Different Temperatures ◽  
Independent Heat

Natural convection and passive heat rejection from two independent heat sources maintained at different temperatures (60°C and 100°C above ambient) on single circuit boards (FR4 and copper clad FR4) are experimentally studied. The effect of heat source location on maximum power dissipation is presented for both horizontal and vertical orientations. Heat losses due to radiation, natural convection and board conduction are quantified. As long as the heat sources are more than 2 cm apart, they do not influence each other on the FR4 board. Vertical orientation increases the power dissipation in the components by up to 30% for the FR4 board and 15% for the copper clad board. Two ounces of copper cladding increases the overall power dissipation by 150–190%.

scholarly journals A CLASS OF IRREDUNDANT ENCODING TECHNIQUES FOR REDUCING BUS POWER

2002 ◽  
Vol 11 (05) ◽  
pp. 445-457 ◽  
Author(s):  
YAZDAN AGHAGHIRI ◽  
FARZAN FALLAH ◽  
MASSOUD PEDRAM
Keyword(s):  
Power Consumption ◽  
Power Dissipation ◽  
Printed Circuit Board ◽  
Circuit Board ◽  
Total Power ◽  
Switching Activity ◽  
Printed Circuit ◽  
Memory Address ◽  
Total Power Consumption ◽  
Bus Encoding

This paper proposes a number of encoding techniques for decreasing power dissipation on global buses. The best target for these techniques is a wide and highly capacitive memory bus. Switching activity of the bus is reduced by means of encoding the values that are conveyed over them. More precisely, three irredundant bus-encoding techniques are presented in this paper. These techniques decrease the bus activity by as much as 86% for instruction addresses without the need to add redundant bus lines. Having no redundancy means that exercising these techniques on any existing system does not require redesign and remanufacturing of the printed circuit board of the system. The power dissipation of the encoder and decoder blocks is insignificant in comparison with the power saved on the memory address bus. This makes these techniques capable of reducing the total power consumption.

Separation of Natural Convection and Radiation by Changing Rotational Acceleration

Volume 1 ◽  
2004 ◽  
Author(s):  
Arnout Willockx ◽  
Gilbert De Mey ◽  
Michel De Paepe ◽  
Boguslaw Wiecek ◽  
Mariusz Felczak ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Printed Circuit Board ◽  
Circuit Board ◽  
Centripetal Force ◽  
Rotational Acceleration ◽  
Governing Equations ◽  
Total Heat Transfer ◽  
Closed Cavity ◽  
Printed Circuit

The objective is to separate natural convection and radiation experimentally. Therefore a heat source is placed inside a closed cavity and the acceleration inside the cavity can be changed. A centrifuge is used to change the acceleration. A flat resistor etched on a printed circuit board of 10mm × 48mm, is placed in a hermetically sealed cylinder, which hangs under the arm of the centrifuge. The resistor is powered by a battery, dissipates 0,35W and has a surface temperature of 60°C at 1g. Natural convection is maintained inside the cylinder. Conduction is reduced to a negligible amount by construction of the experiment, thus convection and radiation are the main modes of heat transfer. The rotational speed of the centrifuge determines the centrifugal force in the cylinder. When the centripetal force increases, the temperature of the resistor decreases due to the increase of natural convection. The amount of radiation and total heat transfer can be determined from the experiment, so the amount of natural convection can also be determined. The experimental results are compared with the governing equations to validate the experiment. The reproducibility of the experiment is also checked.

An Experimental Assessment of Numerical Predictive Accuracy for Electronic Component Heat Transfer in Forced Convection—Part II: Results and Discussion

2003 ◽  
Vol 125 (1) ◽  
pp. 76-83 ◽  
Author(s):  
Peter J. Rodgers ◽  
Vale´rie C. Eveloy ◽  
Mark R. Davies
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Printed Circuit Board ◽  
Predictive Accuracy ◽  
Numerical Models ◽  
Circuit Board ◽  
Junction Temperature ◽  
Electrical Performance ◽  
Test Cases ◽  
Computational Fluid Dynamics Cfd

Numerical predictive accuracy is assessed for component-printed circuit board (PCB) heat transfer in forced convection using a widely used computational fluid dynamics (CFD) software. In Part I of this paper, the benchmark test cases, experimental methods and numerical models were described. Component junction temperature prediction accuracy for the populated board case is typically within ±5°C or ±10%, which would not be sufficient for temperature predictions to be used as boundary conditions for subsequent reliability and electrical performance analyses. Neither the laminar or turbulent flow model resolve the complete flow field, suggesting the need for a turbulence model capable of modeling transition. The full complexity of component thermal interaction is shown not to be fully captured.

Natural-convection cooling of a housed, simulated printed-circuit board

1991 ◽  
Vol 38 (4) ◽  
pp. 245-252 ◽  
Author(s):  
K.F. Chan ◽  
C.W. Leung ◽  
S.D. Probert
Keyword(s):  
Natural Convection ◽  
Printed Circuit Board ◽  
Circuit Board ◽  
Printed Circuit ◽  
Convection Cooling

Thermal Analysis of Natural Convection Cooled Switch Mode Power Supplies

2003 ◽  
Author(s):  
Katsuhiro Koizumi ◽  
Akito Joboji ◽  
Kuniaki Nagahara ◽  
Masaru Ishizuka
Keyword(s):  
Natural Convection ◽  
Printed Circuit Board ◽  
Semiconductor Devices ◽  
Flow Simulation ◽  
Circuit Board ◽  
Switch Mode Power Supply ◽  
Power Semiconductor ◽  
Power Semiconductor Devices ◽  
Switch Mode ◽  
The Difference

This paper describes an application example of thermal flow simulation to the design of a switch mode power supply (SMPS) that is natural convection air-cooled. In this analysis, the modeling of printed circuit board (PCB) and power semiconductor devices was examined using the design of experiments method. The PCB was treated as a simple plate, and average thermal conductivity was not considered. The power semiconductor devices were modeled as a simple hexahedral resistive network block. As the heat generation sources, a field effect transistor (FET) and a diode were considered in the simulation, and the calculation method of power loss is described. The difference between measured and calculated values for power semiconductor devices was found to be within approximately 10 K.

THERMAL ANALYSIS OF A PRINTED CIRCUIT BOARD COOLED BY FORCED CONVECTION

1994 ◽  
Author(s):  
U. Navon ◽  
S. Kreitenberger ◽  
Chaim Gutfinger
Keyword(s):  
Thermal Analysis ◽  
Forced Convection ◽  
Printed Circuit Board ◽  
Circuit Board ◽  
Printed Circuit

Effects of Substrate Conductivity on Convective Cooling of Electronic Components

1994 ◽  
Vol 116 (3) ◽  
pp. 198-205 ◽  
Author(s):  
C. Y. Choi ◽  
S. J. Kim ◽  
A. Ortega
Keyword(s):  
Heat Transfer ◽  
Printed Circuit Board ◽  
Circuit Board ◽  
Maximum Temperature ◽  
Dimensionless Temperature ◽  
Heat Sources ◽  
Flow Conditions ◽  
Conductive Materials ◽  
Simple Boundary ◽  
Transfer Problems

The coupled conduction and forced convection transport from substrate-mounted modules in a channel is numerically investigated to identify the effects of the substrate conductivity. The results presented apply to air and two-dimensional laminar flow conditions. It was found that recirculating cells as well as streamwise conduction through the substrate play an important role in predicting convective heat transfer from the printed circuit board (PCB) and modules and in determining the temperature distributions in the PCB, modules, and fluid. The dimensionless temperature and the local Nusselt number along the interface between the fluid and the module or PCB are rather complicated, and therefore, predetermined simple boundary conditions along the solid surface may be inappropriate in many conjugate heat transfer problems. In general, the results show that the maximum temperature within heat sources can be greatly reduced by increasing the conductivity of the PCB. The effectiveness of the use of highly conductive materials for PCB, however, depends on the distance between the heat generating modules on the PCB. In addition, finite thermal resistance between the module and the PCB would serve to diminish the PCB conduction effects, thereby reducing the effectiveness of the enhancement afforded by increased conductivity.

scholarly journals Analytical study of the temperature distribution in solids subjected to nonuniform moving heat sources

2013 ◽  
Vol 17 (3) ◽  
pp. 687-694 ◽  
Author(s):  
Mohamed Hamraoui ◽  
Mounir Chbiki ◽  
Najib Laraqi ◽  
Luis Roseiro
Keyword(s):  
Steady State ◽  
Temperature Distribution ◽  
Power Dissipation ◽  
Relative Velocity ◽  
Analytical Study ◽  
Three Dimensional ◽  
Total Power ◽  
Heat Sources ◽  
Reference Case ◽  
Made In

We propose in this paper an analytical study of the temperature distribution in a solid subjected to moving heat sources. The power dissipated by the heat sources is considered nonuniform. The study was made in steady state. The model is three-dimensional. It is valid regardless of the relative velocity of the source. We have considered three cases of semi-elliptic distribution of the power with: (i) the maximum at the center of the source, (ii) the maximum at the inlet of the source, (iii) the maximum at the output of the source. These configurations simulate the conformity imperfection of contact due to wear and / or the non-uniformity of contact pressure in frictional devices. We compare the temperature change for these different scenarios and for different relative velocities, considering the same total power dissipation. The reference case is that of a uniform source dissipating the same power.

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