scholarly journals Effect of Contact Pressure on the Performance of Carbon Nanotube Arrays Thermal Interface Material

Nanomaterials ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 732 ◽  
Author(s):  
Yu Pei ◽  
Hongmei Zhong ◽  
Mengyu Wang ◽  
Peng Zhang ◽  
Yang Zhao
Keyword(s):  
Carbon Nanotube ◽  
Thermal Resistance ◽  
Contact Pressure ◽  
Surface Deformation ◽  
Strong Dependence ◽  
Thermal Conductance ◽  
Thermal Interface Material ◽  
Thermal Interface ◽  
Minimum Requirement ◽  
Cnt Arrays

Vertically aligned carbon nanotube (CNT) arrays are promising candidates for advanced thermal interface materials (TIMs) since they possess high mechanical compliance and high intrinsic thermal conductivity. Some of the previous works indicate that the CNT arrays in direct dry contact with the target surface possess low contact thermal conductance, which is the dominant thermal resistance. Using a phase sensitive transient thermo-reflectance (PSTTR) technique, we measure the thermal conductance between CNT arrays and copper (Cu) surfaces under different pressures. The experiments demonstrated that the contact force is one of the crucial factors for optimizing the thermal performance of CNT array-based TIMs. The experimental results suggest that the Cu-CNT arrays’ contact thermal conductance has a strong dependence on the surface deformation and has an order of magnitude rise as the contact pressure increases from 0.05 to 0.15 MPa. However, further increase of the contact pressure beyond 0.15 MPa has little effect on the contact thermal resistance. This work could provide guidelines to determine the minimum requirement of packaging pressure on CNT TIMs.

Transient Thermo-Reflectance Method for Characterization of Thermal Interface Material Based on Carbon Nanotube Array

2009 ◽  
Author(s):  
Yang Zhao ◽  
Rong-Shiuan Chu ◽  
Arun Majumdar
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotube ◽  
Thermal Resistance ◽  
Thermal Interface Material ◽  
Measuring System ◽  
Bonding Layer ◽  
Thermal Interface ◽  
Interface Resistance ◽  
Interface Thermal Resistance ◽  
Cnt Arrays

Vertically aligned carbon nanotube (CNT) arrays have been explored as advanced thermal interface materials because of their compliance and high cross-plane thermal conductivity. Our previous work showed that a CNT array directly bridging two surfaces by dry contact had a surface-surface interface resistance of order of 10 m2-K/MW. With an indium bonding layer, the interface thermal resistance was reduced by a factor of ten. Therefore, a more sensitive measuring system is needed to accurately determine the thermal resistance. In this paper, we achieved a higher sensitivity measurement by applying the phase sensitive transient thermo-reflectance technique to a front side heating and detecting system. A detailed analysis is presented. We used this technique to characterize a 71-μm long CNT array with packing density of 9.4 ± 1.4%. The CNT array was sequentially wetted with chromium/gold films and was bonded to a glass surface with an indium bonding layer. We found that the CNT array-surface interface resistance is 0.35 ± 0.11 m2-K/MW and the cross-plane thermal conductivity of CNT array is 94 ± 40 W/m-K.

Design, Synthesis, and Performance of a Carbon Nanotube/Metal Foil Thermal Interface Material

2007 ◽  
Author(s):  
Baratunde A. Cola ◽  
Xianfan Xu ◽  
Timothy S. Fisher
Keyword(s):  
Carbon Nanotube ◽  
Thermal Performance ◽  
Thermal Conduction ◽  
Thermal Interface Material ◽  
Metal Foil ◽  
Thermal Interface ◽  
Design Synthesis ◽  
Cnt Arrays ◽  
And Performance ◽  
Contact Spots

The thermal performance of an interface material comprised of a metal foil with dense, vertically oriented carbon nanotube (CNT) arrays synthesized on both of its surfaces is characterized for rough and smooth interfaces. The CNT/foil deforms in the interfaces by two mechanisms, CNT deformation and foil deformation, that may significantly increase the number of CNT contact spots on both sides of the foil. As a result, the thermal conduction at the CNT-array-free-tip interfaces is greatly increased from previous measurements.

Enhancement of Interfacial Thermal Transport by Carbon Nanotube-Graphene Junction

2013 ◽  
Author(s):  
Hua Bao ◽  
Shirui Luo ◽  
Ming Hu
Keyword(s):  
Carbon Nanotube ◽  
Thermal Resistance ◽  
Thermal Transport ◽  
Heat Dissipation ◽  
Thermal Conductance ◽  
Thermal Interface Material ◽  
Interfacial Thermal Resistance ◽  
Material Interfaces ◽  
Material Interface ◽  
Dynamics Simulations

Thermal transport across material interfaces is crucial for many engineering applications. For example, in microelectronics, small interfacial thermal resistance is desired to achieve efficient heat dissipation. Carbon nanotube (CNT) has extremely high thermal conductivity and can potentially serve as an efficient thermal interface material. However, heat dissipation through CNTs is limited by the large thermal resistance at the CNT-material interface. Here we have proposed a CNT-graphene junction structure to enhance the interfacial thermal transport. Non-equilibrium molecular dynamics simulations have been carried out to show that the thermal conductance can be significantly enhanced by adding a single graphene layer in between CNT and silicon. The mechanism of enhanced thermal transport is attributed to the efficient thermal transport between CNT and graphene and the good contact between graphene and silicon surface.

Combined Microstructure and Heat Transfer Modeling of Carbon Nanotube Thermal Interface Materials1

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Sridhar Sadasivam ◽  
Stephen L. Hodson ◽  
Matthew R. Maschmann ◽  
Timothy S. Fisher
Keyword(s):  
Heat Transfer ◽  
Thermal Resistance ◽  
Finite Volume ◽  
Pressure Dependence ◽  
Matrix Material ◽  
Three Dimensional ◽  
Coarse Grain ◽  
Total Thermal Resistance ◽  
Thermal Interface ◽  
Cnt Arrays

A microstructure-sensitive thermomechanical simulation framework is developed to predict the mechanical and heat transfer properties of vertically aligned CNT (VACNT) arrays used as thermal interface materials (TIMs). The model addresses the gap between atomistic thermal transport simulations of individual CNTs (carbon nanotubes) and experimental measurements of thermal resistance of CNT arrays at mesoscopic length scales. Energy minimization is performed using a bead–spring coarse-grain model to obtain the microstructure of the CNT array as a function of the applied load. The microstructures obtained from the coarse-grain simulations are used as inputs to a finite volume solver that solves one-dimensional and three-dimensional Fourier heat conduction in the CNTs and filler matrix, respectively. Predictions from the finite volume solver are fitted to experimental data on the total thermal resistance of CNT arrays to obtain an individual CNT thermal conductivity of 12 W m−1 K−1 and CNT–substrate contact conductance of 7 × 107 W m−2 K−1. The results also indicate that the thermal resistance of the CNT array shows a weak dependence on the CNT–CNT contact resistance. Embedding the CNT array in wax is found to reduce the total thermal resistance of the array by almost 50%, and the pressure dependence of thermal resistance nearly vanishes when a matrix material is introduced. Detailed microstructural information such as the topology of CNT–substrate contacts and the pressure dependence of CNT–opposing substrate contact area are also reported.

Characterization of a Liquid-Metal Micro Droplets Thermal Interface Material

2010 ◽  
Author(s):  
Amer M. Hamdan ◽  
Aric R. McLanahan ◽  
Robert F. Richards ◽  
Cecilia D. Richards
Keyword(s):  
Liquid Metal ◽  
Thermal Resistance ◽  
Contact Resistance ◽  
Applied Load ◽  
Thermal Interface Material ◽  
Thermal Interface ◽  
Interface Resistance ◽  
Thermal Interface Resistance ◽  
Droplet Array

This work presents the characterization of a thermal interface material consisting of an array of mercury micro droplets deposited on a silicon die. Three arrays were tested, a 40 × 40 array (1600 grid) and two 20 × 20 arrays (400 grid). All arrays were assembled on a 4 × 4 mm2 silicon die. An experimental facility which measures the thermal resistance across the mercury array under steady state conditions is described. The thermal interface resistance of the arrays was characterized as a function of the applied load. A thermal interface resistance as low as 0.253 mm2 K W−1 was measured. A model to predict the thermal resistance of a liquid-metal micro droplet array was developed and compared to the experimental results. The model predicts the deformation of the droplet array under an applied load and then the geometry of the deformed droplets is used to predict the thermal resistance of the array. The contact resistance of the mercury arrays was estimated based on the experimental and model data. An average contact resistance was estimated to be 0.14 mm2 K W−1.

scholarly journals Demonstration of a Compliant Micro-Spring Array As a Thermal Interface Material for Pluggable Optoelectronic Transceiver Modules

2019 ◽  
Author(s):  
Jin Cui ◽  
Liang Pan ◽  
Justin A. Weibel
Keyword(s):  
Heat Sink ◽  
Thermal Contact ◽  
Thermal Conductance ◽  
Thermal Interface Material ◽  
Thermal Contact Conductance ◽  
Compression Pressure ◽  
Thermal Interface ◽  
Operation Temperature ◽  
Optical Module ◽  
Dry Contact

Abstract Pluggable optoelectronic transceiver modules are widely used in the fiber-optic communication infrastructure. It is essential to mitigate thermal contact resistance between the high-power optical module and its riding heat sink in order to maintain the required operation temperature. The pluggable nature of the modules requires dry contact thermal interfaces that permit repeated insertion–disconnect cycles under low compression pressures (∼10–100 kPa). Conventional wet thermal interface materials (TIM), such as greases, or those that require high compression pressures, are not suitable for pluggable operation. Here we demonstrate the use of compliant micro-structured TIM to enhance the thermal contact conductance between an optical module and its riding heat sink under a low compression pressure (20 kPa). The metallized and polymer-coated structures are able to accommodate the surface nonflatness and microscale roughness of the mating surface while maintaining a high effective thermal conductance across the thickness. This dry contact TIM is demonstrated to maintain reliable thermal performance after 100 plug-in and plug-out cycles while under compression.

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.

Packaging of High Power UV-LED Modules on Ceramic and Aluminum Substrates

2012 ◽  
Vol 2012 (1) ◽  
pp. 000225-000232 ◽  
Author(s):  
Marc Schneider ◽  
Benjamin Leyrer ◽  
Christian Herbold ◽  
Stefan Maikowske
Keyword(s):  
Thermal Resistance ◽  
Heat Sink ◽  
Input Power ◽  
Thermal Interface Material ◽  
Maximum Temperature ◽  
Thermal Interface ◽  
Uv Led ◽  
Forward Current ◽  
Water Cooler ◽  
Forced Air

An LED module consisting of 98 UV-LEDs with an emission wavelength of 395 nm placed on a ceramic substrate of 211 mm2 is presented. The module is cooled by a forced air heat sink as well as a high performance microstructured water cooler to lower the thermal resistance. For high thermal conductance a liquid metal as the thermal interface material between substrate and heat sink is used. With the forced air heat sink a maximum irradiance of 27.3 W/cm2 at a forward current of 700 mA and 220 W electrical input power was achieved. The microstructured water cooler enabled an almost doubling of the electrical input power (430 W) while maintaining the chip's maximum temperature. For a reduction of the module's thermal resistance a thick film process for aluminum sheet metal substrates was developed. A prototype LED module with 25 UV-LED chips on an area of 54 mm2 achieved a maximum optical power density of 31.6 W/cm2 at a forward current of 900 mA using a forced air heat sink. For an improved cooling of the LED chips a chip-on-heat sink-technology with embedded water cooling channels is developed to eliminate the thermal interface between substrate and heat sink.

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