Thermal and EMI Performance of Composite Plastic Molded Heat Sinks and Hybrid TIM Materials

2014 ◽  
Vol 2014 (1) ◽  
pp. 000222-000228 ◽  
Author(s):  
Alpesh Bhobe ◽  
Herman Chu ◽  
Lynn Comiskey ◽  
Xiangyang Jiao ◽  
Xiao Li
Keyword(s):  
Thermal Management ◽  
Thermal Performance ◽  
Heat Sink ◽  
Heat Sinks ◽  
Thermal Impedance ◽  
Frequency Range ◽  
Reverberation Chamber ◽  
Plastic Materials ◽  
Thermally Conductive ◽  
Electro Magnetic

Heat sinks are widely used in thermal management of electronics. However, it is also well established that a heat sink can couple and radiate electro-magnetic (EM) energy from the same component that it is cooling. As the frequency of these devices continues to increase, it is more crucial to try to suppress the EM radiation at the source. The component suppliers for thermal management and EMI products have been developing materials that are thermally conductive and also have EM absorbing properties. The thermal and EMI material properties of the additives can change the properties of the final material and they may not always be complementary between thermal and EM absorbing behaviors. In this paper, two such hybrid solutions are investigated to understand the thermal and EM absorbing characteristics and interactions. These are: (1) heat sinks made of composite plastic materials; and (2) hybrid RF/thermal interface materials (HRTIMs). For the heat sink study, three heat sinks of the same physical design (40mm square x 8.25mm tall) but with different materials are tested and analyzed. Two of the heat sinks are molded from two different composite plastics (Materials A and B), while the third one is constructed from aluminum and used as the baseline heat sink for comparison. The results presented in Figure 7 show EMI improvement for composite material heat sinks over the traditional aluminum heat sink. Material A provides a broadband reduction of 2–3 dB power whereas Material B heat sink provides significant reduction at lower frequency range of 1–8 GHz. The thermal performance results are plotted in Figure 11 – Figure 14, and the results show that the composite plastic materials are more suitable for applications that have lower power and power density. For the HRTIMs, two different base materials at different thicknesses are investigated and the material details are given in Table 2 . Similar to the heat sink EMI study, Total Radiated Power (TRP) measurements are performed for the HRTIMs in an Electromagnetic Reverberation Chamber in the frequency range of 5–40 GHz show improvement for material TIM 1. The EMI results are plotted in Figure 9 and Figure 10. For thermal performance characterizations, an ASTM D-5470 compliance test stand (Figure 6) is used. The thermal impedance results of these materials are plotted in Figure 15.

scholarly journals Study of Mini Channel Heat Sink with Different Internal Configuration

2020 ◽  
Vol 319 ◽  
pp. 02004
Author(s):  
Muhammad Akif Rahman ◽  
Md Badrath Tamam ◽  
Md Sadman Faruque ◽  
A.K.M. Monjur Morshed
Keyword(s):  
Nusselt Number ◽  
Thermal Performance ◽  
Heat Sink ◽  
Rectangular Channel ◽  
Three Dimensional ◽  
Heat Sinks ◽  
Maximum Temperature ◽  
Rectangular Channels ◽  
Flow Through ◽  
Internal Configuration

In this paper a numerical analysis of three-dimensional laminar flow through rectangular channel heat sinks of different geometric configuration is presented and a comparison of thermal performance among the heat sinks is discussed. Liquid water was used as coolant in the aluminum made heat sink with a glass cover above it. The aspect ratio (section height to width) of rectangular channels of the mini-channel heat sink was 0.33. A heat flux of 20 W/cm2 was continuously applied at the bottom of the channel with different inlet velocity for Reynold’s number ranging from 150 to 1044. Interconnectors and obstacles at different positions and numbers inside the channel were introduced in order to enhance the thermal performance. These modifications cause secondary flow between the parallel channels and the obstacles disrupt the boundary layer formation of the flow inside the channel which leads to the increase in heat transfer rate. Finally, Nusselt number, overall thermal resistance and maximum temperature of the heat sink were calculated to compare the performances of the modified heat sinks with the conventional mini channel heat sink and it was observed that the heat sink with both interconnectors and obstacles enhanced the thermal performance more significantly than other configurations. A maximum of 36% increase in Nusselt number was observed (for Re =1044).

Characterization of Light Weight Heat Sink Materials for Thermal Management of Electronics

2007 ◽  
Author(s):  
Tunc Icoz ◽  
Mehmet Arik ◽  
John T. Dardis
Keyword(s):  
Thermal Management ◽  
Heat Sink ◽  
High Efficiency ◽  
Computational Study ◽  
Heat Sinks ◽  
Advanced Materials ◽  
Air Cooling ◽  
Thermal Management Of Electronics ◽  
Thermal Solution

Thermal management of electronics is a critical part of maintaining high efficiency and reliability. Adequate cooling must be balanced with weight and volumetric requirements, especially for passive air-cooling solutions in electronics applications where space and weight are at a premium. It should be noted that there are systems where thermal solution takes more than 95% of the total weight of the system. Therefore, it is necessary to investigate and utilize advanced materials to design low weight and compact systems. Many of the advanced materials have anisotropic thermal properties and their performances depend strongly on taking advantage of superior properties in the desired directions. Therefore, control of thermal conductivity plays an important role in utilization of such materials for cooling applications. Because of the complexity introduced by anisotropic properties, thermal performances of advanced materials are yet to be fully understood. Present study is an experimental and computational study on characterization of thermal performances of advanced materials for heat sink applications. Numerical simulations and experiments are performed to characterize thermal performances of four different materials. An estimated weight savings in excess of 75% with lightweight materials are observed compared to the traditionally used heat sinks.

Understanding the Impact of Flow Bypass on the Thermal Performance of Air Cooled Heat Sinks

2014 ◽  
Author(s):  
Krishna Kota ◽  
Mohamed M. Awad
Keyword(s):  
Energy Conservation ◽  
Thermal Resistance ◽  
Thermal Performance ◽  
Heat Sink ◽  
Heat Sinks ◽  
Laminar Regime ◽  
Flow Energy ◽  
Factor Α ◽  
The Impact ◽  
Fundamental Mass

In this effort, theoretical modeling was employed to understand the impact of flow bypass on the thermal performance of air cooled heat sinks. Fundamental mass and flow energy conservation equations across a longitudinal fin heat sink configuration and the bypass region were applied and a generic parameter, referred as the Flow Bypass Factor (α), was identified from the theoretical solution that mathematically captures the effect of flow bypass as a quantifiable parameter on the junction-to-ambient thermal resistance of the heat sink. From the results obtained, it was found that, at least in the laminar regime, the impact of flow bypass on performance can be neglected for cases when the bypass gap is typically less than 5% of the fin height, and is almost linear at high relative bypass gaps (i.e., usually for bypass gaps that are more than 10–15% of the fin height). It was also found that the heat sink thermal resistance is more sensitive to small bypass gaps and the effect of flow bypass decreases with increasing bypass gap.

Experimental Investigation of a PCM-Based Topology Optimized Heat Sink for Passive Cooling of Electronics

2020 ◽  
Author(s):  
Jin Yao Ho ◽  
Kai Choong Leong
Keyword(s):  
Thermal Performance ◽  
Heat Sink ◽  
Heat Dissipation ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Heat Fluxes ◽  
Heat Sinks ◽  
Base Temperature ◽  
Storage Unit ◽  
Cooling Of Electronics

Abstract A thermal energy storage unit filled with phase change material (PCM) can serve as a heat sink for the cooling of electronics with intermittent or periodic heat dissipation rates. The use of thermal conductive structures (TCS) is an effective method of improving the thermal performance of a PCM-based heat sink. In this paper, topology optimization is explored to develop a new class of TCS with a tree-like structure to enhance the thermal performance of a trapezoidal heat sink. The topology-optimized heat sink was then fabricated by Selective Laser Melting (SLM) using an aluminum alloy, AlSi10Mg, as the base powder. Experiments were performed to evaluate the thermal performance of the topology-optimized heat sink with the tree-like structure. In addition, a conventional longitudinal-fin heat sink of the same solid volume fraction (φ = 16.2%) and a heat sink without enhanced structure were also fabricated and experimentally investigated for comparison. Rubitherm RT-35HC paraffin wax was used as the PCM. Three different heat fluxes of 4.00 kW/m2, 5.08 kW/m2 and 7.24 kW/m2 were applied at the base of each specimen by a silicone rubber heater. The structure wall and the PCM temperatures were measured over time. Our results show that, for all heat rates tested, the topology-optimized heat sink was able to maintain a lower base temperature as compared to the fin-structure and the plain heat sinks. A thermal enhancement ratio (ε) is defined to evaluate the performance of the heat sinks with and without the use of PCM. From the experimental results, the highest ε value of 8.6 was achieved by the topology-optimized heat sink. These results indicate the better performance of the topology-optimized heat sink in dissipating heat as compared to the other specimens.

Thermal Management of Low Profile Applications

2007 ◽  
Author(s):  
Ed Walsh ◽  
Pat Walsh ◽  
Ronan Grimes ◽  
Vanessa Egan
Keyword(s):  
Thermal Management ◽  
Thermal Performance ◽  
Heat Sink ◽  
Optimal Solution ◽  
Battery Life ◽  
Heat Conducting ◽  
Pumping Power ◽  
Low Profile ◽  
Thermal Solution ◽  
Footprint Area

There is an increasing need for low profile thermal management solutions for applications in the range of five to ten watts targeted at portable electronic devices. This need is emerging due to enhanced power dissipation levels in portable electronics. This work focuses upon the optimization of such a solution within certain constraints of profile and footprint area. A number of fan geometries have been investigated where both the inlet and exit rotor angles are varied relative to the heat conducting fins on a heat sink. The ratio of fan diameter to heat sink fin length was also varied. The objective was to determine the optimal solution from a thermal management perspective within defined constraints. The results show good thermal performance for low profile thermal management solutions, and highlight the need to develop the heat sink and fan as an integrated thermal solution rather than in isolation as is the traditional methodology. It is also found that while increasing pumping power generally improves the thermal performance, only small gains are achieved for relatively large pumping power increases. This is important in optimizing portable systems which are powered by limited battery life.

Computational fluid dynamics for thermal performance of a water-cooled minichannel heat sink with different chip arrangements

2014 ◽  
Vol 24 (4) ◽  
pp. 797-810 ◽  
Author(s):  
Gongnan Xie ◽  
Shian Li ◽  
Bengt Sunden ◽  
Weihong Zhang
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Thermal Performance ◽  
Heat Sink ◽  
Electronic Devices ◽  
Heat Sinks ◽  
Bottom Surface ◽  
Moderate Pressure ◽  
Content Type

Purpose – With the development of electronic devices, including the desires of integration, miniaturization, high performance and the output power, cooling requirement of chips have been increased gradually. Water-cooled minichannel is an effective cooling technology for cooling of heat sinks. The minichannel flow geometry offers large surface area for heat transfer and a high convective heat transfer coefficient with only a moderate pressure loss. The purpose of this paper is to analyze a minichannel heat sink having the bottom size of 35 mm×35 mm numerically. Two kinds of chip arrangement are investigated: diagonal arrangement and parallel arrangement. Design/methodology/approach – Computational fluid dynamics (CFD) technique is used to investigate the flow and thermal fields in forced convection in a three-dimensional minichannels heat sink with different chip arrangements. The standard k-e turbulence model is applied for the turbulence simulations on the minichannel heat sink. Findings – The results show that the bottom surface of the heat sink with various chip arrangements will have different temperature distribution and thermal resistance. A suitable chip arrangement will achieve a good cooling performance for electronic devices. Research limitations/implications – The fluid is incompressible and the thermophysical properties are constant. Practical implications – New and additional data will be helpful as guidelines in the design of heat sinks to achieve a good thermal performance and a long lifetime in operation. Originality/value – In real engineering situations, chips are always placed in various manners according to design conditions and constraints. In this case the assumption of uniform heat flux is acceptable for the surfaces of the chips rather than for the entire bottom surface of the heat sink.

Improving the Thermal Performance of a Forced Convection Air Cooled Solution: Part 1 — Modification of Heat Sink Assembly

2013 ◽  
Author(s):  
Saeed Ghalambor ◽  
John Edward Fernandes ◽  
Dereje Agonafer ◽  
Veerendra Mulay
Keyword(s):  
Pressure Distribution ◽  
Forced Convection ◽  
Thermal Performance ◽  
Heat Sink ◽  
Heat Sinks ◽  
Thermal Interface Material ◽  
Air Cooling ◽  
Interfacial Pressure ◽  
Interfacial Contact ◽  
Torque Analysis

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.

scholarly journals Experimental investigations on Thermal Performance of Copper with Aluminium Based Finned Heat sinks for Electronics Cooling System

2016 ◽  
Vol 12 (12) ◽  
pp. 4582-4587
Author(s):  
Arulmurugan Loganathan ◽  
Ilangkumaran Mani
Keyword(s):  
Thermal Performance ◽  
Heat Sink ◽  
Cooling System ◽  
Research Work ◽  
Electronics Cooling ◽  
Heat Sinks ◽  
Major Constituent ◽  
Experimental Investigations ◽  
Pure Aluminium ◽  
Fixed Temperature

An Experimental investigation on the thermal performance of copper with aluminium based finned heat sinks for electronics cooling system was studied. The heat sinks have different material proportions containing major constituent of aluminium and minor constituent of copper. Considered with straight finned heat sink for the experiments for its easiness in fabrication and efficient heat transfer properties. The observational results for aluminium with copper alloy are compared with pure aluminium heat sink.  Heat sink geometry, fin pitch and its height were taken from the commercially available heat sinks. In this research work best heat sink geometry is chosen and cooked up with different volume of copper added with aluminium. Selected four different spots of heat sinks and the temperature raising characteristics were measured for natural convection. also the temperature is raised to a fixed temperature and the temperature lowering characteristics were measured in forced convection as the air circulation takes more heat to keep the heat sink temperature within the desired level.

The Development of an Integrated Fan and Heat Sink Solution for Thermal Management in Low Profile Applications

2006 ◽  
Author(s):  
Ed Walsh ◽  
Ronan Grimes
Keyword(s):  
Heat Flux ◽  
Thermal Management ◽  
Heat Sink ◽  
Heat Sinks ◽  
Portable Electronics ◽  
Low Profile ◽  
Convection Cooling ◽  
New Methodologies ◽  
Heat Sink Design ◽  
Management Issues

The increasing heat flux densities from portable electronics are leading to new methodologies being implemented to provide thermal management within such devices. Many technologies are under development to transport heat within electronic equipment to allow it to be transported into the surroundings via conduction, natural convection and radiation. Few have considered the approach of implementing a forced convection cooling solution in such devices. This work addresses the potential of a low profile integrated fan and heat sink solution to electronics thermal management issues of the future, particularly focusing upon possible solutions in low profile portable electronics. We investigate two heat sink designs with mini channel features, applicable to low profile applications. The thermal performance of the heat sinks is seen to differ by approximately 40% and highlights the importance of efficient heat sink design at this scale.

Thermally Conductive Plastics for Enhanced Thermal Management

2015 ◽  
Vol 2015 (1) ◽  
pp. 000530-000535
Author(s):  
Chandrashekar Raman
Keyword(s):  
Thermal Conductivity ◽  
Natural Convection ◽  
Thermal Management ◽  
Electronic Devices ◽  
Heat Sinks ◽  
Significant Challenge ◽  
Design Engineers ◽  
Thermally Conductive ◽  
New Material ◽  
Conductive Plastics

Electronic devices continue to shrink while continuing to offer increasing functionality. This trend poses a significant challenge to design engineers who need to adequately address the increasing thermal management requirements of these devices on a shrinking footprint. Thermally conductive plastics have been gaining attention as an innovative new material option to address this challenge. While plastics are typically poor conductors of heat, it is possible to increase the thermal conductivity with the use of certain additives. Unique ceramic additives like boron nitride offer the added advantage of enabling thermally conductive plastic formulations that are also electrically insulating. The replacement of aluminum heat sinks in free (natural) convection environments with thermally conductive plastics is discussed in this paper. The results show it may indeed be possible to replace aluminum with thermally conductive plastic heat sinks in convection limited environments, and if judicious redesign of the plastic heat sink is incorporated, an improved thermal management solution can be realized. Additionally, the benefits of enhancing existing plastic housings to enable an improved thermal management solution are discussed. The results also show that modest enhancements to the thermal conductivity of existing plastic housings can yield significant improvements to the overall thermal management solution as well.

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