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.

Thermal Performance of Microelectronic Substrates With Submillimeter Integrated Vapor Chamber

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Sangbeom Cho ◽  
Yogendra Joshi
Keyword(s):  
Heat Transfer ◽  
Thermal Performance ◽  
Printed Circuit Board ◽  
Mechanical Design ◽  
Three Dimensional ◽  
Circuit Board ◽  
Working Fluid ◽  
Vapor Chamber ◽  
Conduction Model ◽  
Printed Circuit

We develop a vapor chamber integrated with a microelectronic packaging substrate and characterize its heat transfer performance. A prototype of vapor chamber integrated printed circuit board (PCB) is fabricated through successful completion of the following tasks: patterning copper micropillar wick structures on PCB, mechanical design and fabrication of condenser, device sealing, and device vacuuming and charging with working fluid. Two prototype vapor chambers with distinct micropillar array designs are fabricated, and their thermal performance tested under various heat inputs supplied from a 2 mm × 2 mm heat source. Thermal performance of the device improves with heat inputs, with the maximum performance of ∼20% over copper plated PCB with the same thickness. A three-dimensional computational fluid dynamics/heat transfer (CFD/HT) numerical model of the vapor chamber, coupled with the conduction model of the packaging substrate is developed, and the results are compared with test data.

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

Studying heat transfer on inclined printed circuit boards during vapour phase soldering

2017 ◽  
Vol 29 (1) ◽  
pp. 34-41 ◽  
Author(s):  
Attila Geczy ◽  
Daniel Nagy ◽  
Balazs Illes ◽  
Laszlo Fazekas ◽  
Oliver Krammer ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Printed Circuit Boards ◽  
Printed Circuit Board ◽  
Vapour Phase ◽  
Circuit Board ◽  
Efficient Production ◽  
Content Type ◽  
Printed Circuit ◽  
Heat Transfer Efficiency ◽  
Uneven Heating

Purpose The paper aims to present an investigation of heating during vapour phase soldering (VPS) on inclined printed circuit board (PCB) substrates. The PCB is a horizontal rectangular plate from the aspect of filmwise condensation with a given inclination setting. Design/methodology/approach The paper focuses on the measurement of temperature distribution on the PCBs with a novel setup immersed in the saturated vapour space. The measuring instrumentation is optimized to avoid and minimize vapour perturbing effects. Findings The inhomogeneity of the heating is presented according to the lateral dimensions of the PCB. The inclination improves temperature uniformity, improves heat transfer efficiency; however, a minor misalignment may affect the flow and result in uneven heating. Practical implications The results can be implemented for practical improvements in industrial ovens with the use of intended inclination. The improvements may consequently point to more efficient production and better joint quality. Originality/value The novel method can be used for deeper investigation of inclination during and can be complemented with numerical calculations. The results highlight the importance of precise PCB holding instrumentation in VPS ovens.

scholarly journals Modelling of temperature distribution along PCB thickness in different substrates during reflow

Circuit World ◽  
2019 ◽  
Vol 46 (2) ◽  
pp. 85-92
Author(s):  
Daniel Straubinger ◽  
István Bozsóki ◽  
David Bušek ◽  
Balázs Illés ◽  
Attila Géczy
Keyword(s):  
Heat Transfer ◽  
Printed Circuit Board ◽  
Vapour Phase ◽  
Circuit Board ◽  
Transfer Coefficients ◽  
Content Type ◽  
Printed Circuit ◽  
Heat Transfer Coefficients ◽  
Significant Temperature ◽  
The Difference

Purpose In this paper, analytical modelling of heat distribution along the thickness of different printed circuit board (PCB) substrates is presented according to the 1 D heat transient conduction problem. This paper aims to reveal differences between the substrates and the geometry configurations and elaborate on further application of explicit modelling. Design/methodology/approach Different substrates were considered: classic FR4 and polyimide, ceramics (BeO, Al2O3) and novel biodegradables (polylactic-acid [PLA] and cellulose acetate [CA]). The board thicknesses were given in 0.25 mm steps. Results are calculated for heat transfer coefficients of convection and vapour phase (condensation) soldering. Even heat transfer is assumed on both PCB sides. Findings It was found that temperature distributions along PCB thicknesses are mostly negligible from solder joint formation aspects, and most of the materials can be used in explicit reflow profile modelling. However PLA shows significant temperature differences, pointing to possible modelling imprecisions. It was also shown, that while the difference between midplane and surface temperatures mainly depend on thermal diffusivity, the time to reach solder alloy melting point on the surface depends on volumetric heat capacity. Originality/value Results validate the applicability of explicit heat transfer modelling of PCBs during reflow for different heat transfer methods. The results can be incorporated into more complex simulations and profile predicting algorithms for industrial ovens controlled in the wake of Industry 4.0 directives for better temperature control and ultimately higher soldering quality.

Evaluation of Effective Thermal Conductivity of Multilayer Printed Circuit Board

2011 ◽  
Author(s):  
Toshio Tomimura ◽  
Yoshihiro Shiotsu ◽  
Yasushi Koito ◽  
Masaru Ishizuka ◽  
Tomoyuki Hatakeyama
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Printed Circuit Board ◽  
Evaluation Method ◽  
Circuit Board ◽  
Printed Circuit ◽  
Plane Direction ◽  
Simple Evaluation

To perform a rational thermal design of a printed circuit board (PCB) with highly anisotropic heat transfer nature in its initial stage, effective thermal conductivities in thickness direction and in in-plane direction must be given depending on the electric circuit of the board. However, a simple evaluation method for the effective thermal conductivities of such PCB has not been developed yet. In this study, as the first step to propose a simple evaluation method, the heat transfer coefficient by natural convection around a horizontal disk, which is indispensable for measuring the effective thermal conductivity, has been evaluated. Furthermore, the thermal conductivity of the glass epoxy resin in in-plane direction has been evaluated by applying the evaluated heat transfer coefficient, and then, the validity of the proposed thermal conductivity measurements of the anisotropic PCB has been confirmed.

Prognostics Assessment of Aluminum Support Structure on a Printed Circuit Board

2006 ◽  
Vol 128 (4) ◽  
pp. 339-345 ◽  
Author(s):  
Sony Mathew ◽  
Diganta Das ◽  
Michael Osterman ◽  
Michael Pecht ◽  
Robin Ferebee
Keyword(s):  
Heat Transfer ◽  
Printed Circuit Board ◽  
Electronic Circuit ◽  
Circuit Board ◽  
Life Test ◽  
Support Structure ◽  
Printed Circuit ◽  
Bracket Failure

This paper presents an analysis of an unexpected failure during vibration and shock life test of an electronic circuit board that has been in use for more than 15 years. During testing, an aluminum bracket used to mount a transistor and provide a path for heat transfer was damaged. Prognostic methods were employed to determine whether the bracket failure could have been predicted prior to the life test. Details of the analytical calculations and modeling results are described in this paper. Results show that the failure could have been predicted before actual testing.

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