Thermal performance evaluation of various heat sinks for air cooling

Forced convection air cooling using heat sinks is one of the most prevalent methods in thermal management of microelectronic devices. Improving the performance of such a solution may involve minimizing the external thermal resistance (Rext) of the package. For a given heat sink design, this can be achieved by reducing the thermal interface material (TIM) thickness through promotion of a uniform interfacial pressure distribution between the device and heat sink. In this study, a dual-CPU rackmount server is considered and modifications to the heat sink assembly such as backplate thickness and bolting configuration are investigated to achieve the aforementioned improvements. A full-scale, simplified model of the motherboard is deployed in ANSYS Mechanical, with emphasis on non-linear contact analysis and torque analysis of spring screws, to determine the optimal design of the heat sink assembly. It is observed that improved interfacial contact and pressure distribution is achieved by increasing the number of screws (loading points) and positioning them as close to the contact area as possible. The numerical model is validated by comparison with experimental measurements within reasonable accuracy. Based on the results of numerical analysis, the heat sink assembly is modified and improvement over the base configuration is experimentally quantified through interfacial pressure measurement. The effect of improved interfacial contact on thermal performance of the solution is discussed.

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Effect of Flow Bypass on the Performance of Longitudinal Fin Heat Sinks

Journal of Electronic Packaging ◽

10.1115/1.2905687 ◽

1994 ◽

Vol 116 (3) ◽

pp. 206-211 ◽

Cited By ~ 63

Author(s):

R. A. Wirtz ◽

Weiming Chen ◽

Ronghua Zhou

Keyword(s):

Heat Transfer ◽

Forced Convection ◽

Thermal Performance ◽

Heat Sink ◽

Design Guidelines ◽

Heat Sinks ◽

Air Cooling ◽

Regular Array ◽

Electronic Package ◽

And Performance

Heat transfer experiments are reported on the thermal performance of longitudinal fin heat sinks attached to an electronic package which is part of a regular array of packages undergoing forced convection air cooling. The effect of coolant bypass on the performance of the heat sink is assessed and performance correlations for reduced heat transfer due to this effect are developed. These correlations are used to develop design guidelines for optimal performance.

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“Heat Shield”—An Enhancement Device for an Unshrouded, Forced Convection Heat Sink

Journal of Electronic Packaging ◽

10.1115/1.2188955 ◽

2006 ◽

Vol 128 (2) ◽

pp. 172-176 ◽

Cited By ~ 18

Author(s):

Suzana Prstic ◽

Avram Bar-Cohen

Keyword(s):

Pressure Drop ◽

Thermal Performance ◽

Heat Sink ◽

Thin Sheet ◽

Heat Sinks ◽

Heat Shield ◽

Air Cooling ◽

Thermal Enhancement ◽

Thin Sheet Metal ◽

Forced Air

The inherent advantages of forced air cooling have led to the widespread use of fully and partially shrouded heat sinks for the thermal management of high power microprocessors. The superior thermal performance that is achievable in the fully shrouded configuration is accompanied by a significant pressure drop penalty. The concept introduced in the current study, employs a thin sheet-metal “heat shield,” placed around a partially shrouded heat sink, to channel the flow directly into the heat sink. A combined numerical and experimental study has shown that the use of this “heat shield” can substantially enhance heat sink thermal performance, in a channel geometry and air flow range typical of commercial chip packages; making it comparable to that of a fully shrouded heat sink, with a substantially lower pressure drop (∼50%). In addition, this thermal enhancement device can be easily retrofitted into existing systems; improving performance without major channel and/or fan modifications.

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Optimal Design for Thermal Performance of a Heat Sink Integrated With Thermoelectric Cooler

Heat Transfer: Volume 4 ◽

10.1115/ht2005-72234 ◽

2005 ◽

Cited By ~ 1

Author(s):

M. C. Wu ◽

C. H. Peng ◽

C. Y. Lee ◽

C. J. Fang ◽

Y. H. Hung

Keyword(s):

Sensitivity Analysis ◽

Optimal Design ◽

Thermal Performance ◽

Heat Sink ◽

Optimization Technique ◽

Empirical Method ◽

Heat Sinks ◽

Air Cooling ◽

Thermoelectric Coolers ◽

Semi Empirical

The demand for high execution speed and memory capacity for modern computers results in an increasing circuit density per unit chip and high power dissipation per unit volume. Consequently, traditional air cooling technology such as air-cooled heat sink is reaching the limits for electronic applications. Thermoelectric coolers are regarded as potential solutions for enhancing the performance of air-cooled heat sinks. In the present study, a semi-empirical method for exploring the thermal performance of a heat sink integrated with or without TEC has been successfully established. A concept of design of experiments (DOE) is applied, and a statistical method for sensitivity analysis of the influencing parameters is performed to determine the key factors that are critical to the design. By the statistical sensitivity analysis of ANOVA F-test for the temperature reduction (ΔTC−B) and COP of the TEC, the factor contributions of QP, Rext and I are 31.66%, 33.73%, 34.61% as well as 14.9%, 0%, 85.1%, respectively. By employing the gradient-based numerical optimization technique, a series of constrained optimal designs have been performed. Under the given constraints of COP≧2, the optimal value of ΔTC−B (3.3°C) is obtained with the corresponding Qp (31.99W) and Qte (16W). Comparisons between the results by the present optimal design and those obtained by the semi-empirical results have been made with a satisfactory agreement. The present optimal design shows that a heat sink integrated with TEC can extend the upper limits of thermal management for traditional air-cooled heat sinks.

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