Challenges in Package Cooling of High Performance Servers

2007 ◽  
Author(s):  
Jie Wei
Keyword(s):  
Thermal Conductivity ◽  
Power Dissipation ◽  
High Performance ◽  
Heat Pipes ◽  
High Thermal Conductivity ◽  
Thermal Interface Material ◽  
Heat Spreader ◽  
Asymmetric Power ◽  
Heat Spreading ◽  
Silver Composite

Cooling technologies for dealing with high-density and asymmetric power dissipation are discussed, arising from thermal management of high performance server CPU-packages. In this paper, investigation and development of associated technologies are introduced from a viewpoint of industrial application, and attention is focused on heat conduction and removal at the package and heatsink module level. Based on analyses of power dissipation and package cooling characteristics, properties of a new metallic thermal interface material are presented where the Indium-Silver composite was evaluated for integrating the chip and its heat-spreader, effects of heat spreading materials on package thermal performance are investigated including high thermal conductivity diamond composites, and evaluations of enhanced heatsink cooling capability are illustrated where high thermal conductivity devices of heat pipes or vapor chambers were applied for improving heat spreading in the heatsink base.

Thermal Contact Resistance of Phase Change and Grease Type Polymeric Materials

2000 ◽  
Author(s):  
Ravi S. Prasher ◽  
Craig Simmons ◽  
Gary Solbrekken
Keyword(s):  
Thermal Conductivity ◽  
Contact Resistance ◽  
Phase Change ◽  
High Performance ◽  
Phase Change Materials ◽  
Thermal Contact ◽  
Polymeric Materials ◽  
Thermal Interface Material ◽  
Heat Spreader ◽  
Thermal Grease

Abstract Thermal interface material (TIM) between the die and the heat spreader or between the heat spreader and the heat sink in any electronic package plays a very important role in the thermal management of electronic cooling. Due to increased power and power density high-performance TIMs are sought every day. Phase change materials (PCM) seem to be very good alternative to traditionally used thermal greases because of various reasons. These phase change materials also have the advantage of being reworked easily without damaging the die. Typically these phase change materials are polymer based and are particle laden to enhance their thermal conductivity. The thermal conductivity of these materials is relatively well understood than their contact resistance. Current work focuses on explicitly measuring the contact resistance and the thermal conductivity of a particular phase change TIM and some silicon-based greases. Effect of various parameters, which can affect the contact resistance of theses TIMs and Greases, are also captured. The steady state measurements of the thermal conductivity and the contact resistance was done on an interface tester. In general the work on the contact resistance of fluid-like polymer based TIM, such as thermal grease or phase change polymer has been experimental in the past. A semi-analytical model, which captures the various parameters affecting the contact resistance of two class of materials; the phase change and the thermal grease is also developed in this paper. This model fits very well with the experimental data.

Analytical Model of Heat Conduction in a Tubular Geometry With Application to a Nano-Structured Thermal Interface

2005 ◽  
Author(s):  
Anand Desai ◽  
James Geer ◽  
Bahgat Sammakia
Keyword(s):  
Thermal Conductivity ◽  
Power Dissipation ◽  
High Performance ◽  
Analytical Study ◽  
Thermal Interface Material ◽  
Thermal Interface ◽  
Inner Diameter ◽  
Parametric Analyses ◽  
Interface Materials

Power dissipation in electronic devices is projected to increase significantly over the next ten years to the range of 50-150 Watts per cm2 for high performance applications [1]. This increase in power represents a major challenge to systems integration since the maximum device temperature needs to be around 100 C. One of the primary obstacles to the thermal management of devices operating at such high powers is the thermal resistance between the device and the heat spreader or heat sink that it is attached to. Typically the in situ thermal conductivity of interface materials is in the range of 1 to 4 W/mK, even though the bulk thermal conductivity of the material may be significantly higher. In order to improve the effective in-situ thermal conductivity of interface materials nanotubes are being considered as a possible addition to such interfaces. The primary approach taken in the current study is to analyze the enhancement of the thermal interface by adding carbon nano tubular cylinders that are oriented in the direction of transport. This paper presents the results of an analytical study of transport in a thermal interface material that is enhanced with carbon nanotubes. A variety of parametric analyses are carried out, such as by varying the inner diameter of the nanotube and the power dissipation, and the effect on spreading resistance is calculated. The results indicate that for high thermal conductivity nanotubes there is a significant increase in the effective thermal conductivity of the thermal interface material.

scholarly journals An Integrated Approach to Design and Develop High-Performance Polymer-Composite Thermal Interface Material

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 807
Author(s):  
Syed Sohail Akhtar
Keyword(s):  
Thermal Conductivity ◽  
Aspect Ratio ◽  
High Performance ◽  
High Thermal Conductivity ◽  
Thermal Interface Material ◽  
Design Stage ◽  
Filler Concentration ◽  
Melt Mixing ◽  
Thermal Interface ◽  
Wide Range

A computational framework based on novel differential effective medium approximation and mean-field homogenization is used to design high-performance filler-laden polymer thermal interface materials (TIMs). The proposed design strategy has the capability to handle non-dilute filler concentration in the polymer matrix. The effective thermal conductivity of intended thermal interface composites can be tailored in a wide range by varying filler attributes such as size, aspect ratio, orientation, as well as filler–matrix interface with an upper limit imposed by the shear modulus. Serval potential polymers and fillers are considered at the design stage. High-density polyethylene (HDPE) and thermoplastic polyurethane (TPU) with a non-dilute concentration (~60 vol%) of ceramic fillers exhibit high thermal conductivity (4–5 W m−1 K−1) without compromising the high compliance of TIMs. The predicted thermal conductivity and coefficient of thermal expansion are in excellent agreement with measured data of various binary composite systems considering HDPE, TPU, and polypropylene (PP) loaded with Al2O3 and AlN fillers in varying sizes, shapes, and concentrations, prepared via the melt-mixing and compression-molding route. The model also validates that manipulating filler alignment and aspect ratio can significantly contribute to making heat-conducting networks in composites, which results in ultra-high thermal conductivity.

An Integrated Nano-Structured Heat Spreader for High Heat Flux Electronic Systems

2010 ◽  
Author(s):  
Siddharth Bhopte ◽  
Seshu B. Desu ◽  
Bahgat Sammakia
Keyword(s):  
Thermal Conductivity ◽  
Thermal Management ◽  
Thermal Stresses ◽  
High Heat ◽  
High Thermal Conductivity ◽  
Thermal Interface Material ◽  
High Heat Flux ◽  
Heat Spreader ◽  
Ongoing Research ◽  
Electronic Package

With the increase in power densities and decrease in chip and electronic package dimensions, their thermal management is a challenge and is a focus of several ongoing research efforts. To achieve the desired thermal management for optimal device operation, heat generated by the chip has to be effectively transferred to the ambient via several structures of the electronic package. Hence the need for development of high thermal conductivity structures is of prime importance. Heat spreaders quickly spread the heat generated by the chips over a larger area from where it is conducted to the ambient via heat sink. Heat-spreading research from a materials view point involves direct combination of high thermal conductivity materials within the microprocessor substrate. In this paper, a novel nano heat spreader design is proposed. Highly conductive graphene layer is integrated on a silicon carbide substrate on one side and thin films of carbon nano tubes as thermal interface material on the other side. Analytical solutions and case studies are presented to show that the proposed approach for the heat spreader design can yield very high effective thermal conductivity while remaining mechanically flexible, as required for reducing thermal stresses.

Development of a Compliant Nanothermal Interface Material

2011 ◽  
Author(s):  
David Shaddock ◽  
Stanton Weaver ◽  
Ioannis Chasiotis ◽  
Binoy Shah ◽  
Dalong Zhong
Keyword(s):  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Thermal Stresses ◽  
Performance Testing ◽  
High Thermal Conductivity ◽  
Thermal Interface Material ◽  
Thermal Interface Materials ◽  
Thermal Interface ◽  
Bondline Thickness ◽  
Interface Materials

The power density requirements continue to increase and the ability of thermal interface materials has not kept pace. Increasing effective thermal conductivity and reducing bondline thickness reduce thermal resistance. High thermal conductivity materials, such as solders, have been used as thermal interface materials. However, there is a limit to minimum bondline thickness in reducing resistance due to increased fatigue stress. A compliant thermal interface material is proposed that allows for thin solder bondlines using a compliant structure within the bondline to achieve thermal resistance <0.01 cm2C/W. The structure uses an array of nanosprings sandwiched between two plates of materials to match thermal expansion of their respective interface materials (ex. silicon and copper). Thin solder bondlines between these mating surfaces and high thermal conductivity of the nanospring layer results in thermal resistance of 0.01 cm2C/W. The compliance of the nanospring layer is two orders of magnitude more compliant than the solder layers so thermal stresses are carried by the nanosprings rather than the solder layers. The fabrication process and performance testing performed on the material is presented.

Design and Optimization of a Composite Heat Spreader to Improve the Thermal Management of a 3D Integrated Circuit

2021 ◽  
Author(s):  
Andisheh Tavakoli ◽  
Kambiz Vafai
Keyword(s):  
Thermal Conductivity ◽  
Heat Sink ◽  
Variable Temperature ◽  
Heat Removal ◽  
High Conductivity ◽  
High Thermal Conductivity ◽  
Maximum Temperature ◽  
Optimal Distribution ◽  
Heat Spreader ◽  
The Impact

Abstract The present study analyzes the optimal distribution of a limited amount of high thermal conductivity material to enhance the heat removal of circular 3D integrated circuits, IC. The structure of the heat spreader is designed as a composite of high thermal conductivity (Boron Arsenide) and moderate thermal conductivity (copper) materials. The volume ratio of high-conductivity inserts to the total volume of the spreader is set at a fixed pertinent ratio. Two different boundary conditions of constant and variable temperature are considered for the heat sink. To examine the impact of adding high-conductivity inserts on the cooling performance of the heat spreader, various patterns of the single and double ring inserts are studied. A parametric study is performed to find the optimal location of the rings. Moreover, the optimal distribution of the high-conductivity material between the inner and outer rings is found. The results show that for the optimal conditions, the maximum temperature of the 3D IC is reduced up to 10%; while the size of the heat sink, and heat spreader can be diminished by as much as 200%.

A thermal interface material based on foam-templated three-dimensional hierarchical porous boron nitride

2018 ◽  
Vol 6 (36) ◽  
pp. 17540-17547 ◽  
Author(s):  
Zhilin Tian ◽  
Jiajia Sun ◽  
Shaogang Wang ◽  
Xiaoliang Zeng ◽  
Shuang Zhou ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Boron Nitride ◽  
Three Dimensional ◽  
High Thermal Conductivity ◽  
Thermal Interface Material ◽  
Thermal Interface ◽  
Hierarchical Porous ◽  
Templated Method

A high thermal conductivity boron nitride based thermal interface material was developed by a foam-templated method.

Investigation of Micro-Drilling for Printed Circuit Boards Containing High-Hardness Fillers

2012 ◽  
Vol 565 ◽  
pp. 442-447 ◽  
Author(s):  
Taiji Funabiki ◽  
Toshiki Hirogaki ◽  
Eiichi Aoyama ◽  
Keiji Ogawa ◽  
Hiroyuki Kodama
Keyword(s):  
Thermal Conductivity ◽  
Cutting Force ◽  
High Performance ◽  
Printed Circuit Boards ◽  
High Hardness ◽  
High Thermal Conductivity ◽  
Digital Cameras ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Micro Drilling

This paper describes micro-drilling processes for printed circuit boards (PCBs) containing fillers with high hardness and high thermal conductivity. Inspired primarily by devices such as digital cameras, laptop computers, and wireless communications devices, the electronics field today is continuously demanding smaller, lighter, and more technologically advanced high performance devices. However, that the increase in semiconductor-generated heat tends to affect such devices negatively. Additionally, from the viewpoint of environmental problems, electric vehicles and LEDs are being developed actively. PCBs are one of the principal components for building such devices. In recent years, PCBs containing alumina fillers with high thermal conductivity have been developed and begun to be widely used. However, when processing these PCBs, the drill tools become severely worn because of the filler’s high hardness. We therefore examined the drill wear characteristics. The results show the filler is the main factor that causes drill wear, while the increase in cutting force does not affect it. The cutting force increases with the drill wear linearly. Moreover, the characteristic of PCBs with higher filler content rates is close to that of inorganic material like ceramics.

Development of a Metal Micro-Textured Thermal Interface Material

2009 ◽  
Author(s):  
R. Kempers ◽  
R. Frizzell ◽  
A. Lyons ◽  
A. J. Robinson
Keyword(s):  
Thermal Conductivity ◽  
Applied Pressure ◽  
Solid Particles ◽  
High Thermal Conductivity ◽  
Thermal Interface Material ◽  
Filler Materials ◽  
Mechanical And Thermal Properties ◽  
Metal Foil ◽  
Thermal Interface ◽  
Thermally Conductive

Typical thermal interface materials (TIMs) consist of high thermal conductivity solid particles dispersed in a continuous, low thermal conductivity organic compound. Despite using filler materials of very high thermal conductivity, the effective thermal conductivity of these TIMs is often two orders of magnitude lower than the pure filler materials. In addition, dispensing and flow of the particle-matrix composite results in voids being trapped within the bond. To address these issues, a novel metal micro-textured thermal interface material (MMT-TIM) has been developed. This material consists of a thin metal foil with raised micro-scale features that plastically deform under an applied pressure thereby creating a continuous, thermally conductive, path between the mating surfaces. Numerical tools have been developed that couple the mechanical and thermal properties and behaviour of MMT-TIMs as they undergo large-plastic deformation during assembly. This study presents the modelling approach and predictions of MMT-TIM performance based on these numerical techniques. The predictions show good agreement with experimental results, which were obtained using prototype MMT-TIMs and an advanced TIM characterization facility. Finally, a future outlook for this technology is presented based on these promising initial results.

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