Very High Performance Thermal Interface Material and Attachment Technology

2003 ◽  
Author(s):  
Ralph L. Webb ◽  
Jin Wook Paek ◽  
David Pickrell
Keyword(s):  
Thermal Conductivity ◽  
Thermal Degradation ◽  
Contact Resistance ◽  
High Performance ◽  
Copper Substrate ◽  
Alloy Layer ◽  
Thermal Interface Material ◽  
Thermal Interface ◽  
Interface Resistance ◽  
Penn State

This paper provides an update on work at Penn State University on advanced thermal interface material (TIM) and attachment technology. The TIM concept consists of a “Low Melting Temperature Alloy” (LMTA) bonded to a thin copper substrate. The present work includes analytical modeling to separate the interface resistance (Rint) into “material” and “contact” resistance. Modeling indicates that contact resistance accounts for 1/3 of the interface resistance (Rint). Additional alloys have been identified that have thermal conductivity approximately three-times those identified in the previous 2002 publication. Thermal degradation of the LMTA TIM was also observed in the present work after extended thermal cycling above the melting point of the alloy. Possible mechanisms for this degradation are oxidation and contamination of the alloy layer rather than the inter-metallic diffusion. Use of the high thermal conductivity alloys, and soldered contact surfaces will provide very low Rint as well as minimizing the thermal degradation. It appears that Rint as small as, or less than, 0.005 cm2-K/W may be possible. Description of the modified Penn State TIM tester is provided, which will allow measurement of Rint = 0.01 cm2-K/W with less than 30% error.

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.

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.

scholarly journals RGO-Coated Polyurethane Foam/Segmented Polyurethane Composites as Solid–Solid Phase Change Thermal Interface Material

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3004
Author(s):  
Cong Zhang ◽  
Zhe Shi ◽  
An Li ◽  
Yang-Fei Zhang
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Phase Change ◽  
High Performance ◽  
In Situ Polymerization ◽  
Solid Phase ◽  
Thermal Interface Material ◽  
Segmented Polyurethane ◽  
Thermal Interface ◽  
Self Assembling

Thermal interface material (TIM) is crucial for heat transfer from a heat source to a heat sink. A high-performance thermal interface material with solid–solid phase change properties was prepared to improve both thermal conductivity and interfacial wettability by using reduced graphene oxide (rGO)-coated polyurethane (PU) foam as a filler, and segmented polyurethane (SPU) as a matrix. The rGO-coated foam (rGOF) was fabricated by a self-assembling method and the SPU was synthesized by an in situ polymerization method. The pure SPU and rGOF/SPU composite exhibited obvious solid–solid phase change properties with proper phase change temperature, high latent heat, good wettability, and no leakage. It was found that the SPU had better heat transfer performance than the PU without phase change properties in a practical application as a TIM, while the thermal conductivity of the rGOF/SPU composite was 63% higher than that of the pure SPU at an ultra-low rGO content of 0.8 wt.%, showing great potential for thermal management.

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.

A Numerical Study of Transport in a Thermal Interface Material Enhanced With Carbon Nanotubes

2005 ◽  
Vol 128 (1) ◽  
pp. 92-97 ◽  
Author(s):  
Anand Desai ◽  
Sanket Mahajan ◽  
Ganesh Subbarayan ◽  
Wayne Jones ◽  
James Geer ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
High Performance ◽  
Numerical Study ◽  
Temperature Drop ◽  
Thermal Interface Material ◽  
Thermal Interface ◽  
The Impact ◽  
Interface Materials

Power dissipation in electronic devices is projected to increase over the next 10years to the range of 150-250W per chip for high performance applications. 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 1-4W∕mK, even though the bulk thermal conductivity of the material may be significantly higher. In an attempt to improve the effective in situ thermal conductivity of interface materials nanoparticles and nanotubes are being considered as a possible addition to such interfaces. This paper presents the results of a numerical study of transport in a thermal interface material that is enhanced with carbon nanotubes. The results from the numerical solution are in excellent agreement with an analytical model (Desai, A., Geer, J., and Sammakia, B., “Models of Steady Heat Conduction in Multiple Cylindrical Domains,” J. Electron. Packaging (to be published)) of the same geometry. Wide ranges of parametric studies were conducted to examine the effects of the thermal conductivity of the different materials, the geometry, and the size of the nanotubes. An estimate of the effective thermal conductivity of the carbon nanotubes was used, obtained from a molecular dynamics analysis (Mahajan, S., Subbarayan, G., Sammakia, B. G., and Jones, W., 2003, Proceedings of the 2003 ASME International Mechanical Engineering Congress and Exposition, Washington, D.C., Nov. 15–21). The numerical analysis was used to estimate the impact of imperfections in the nanotubes upon the overall system performance. Overall the nanotubes are found to significantly improve the thermal performance of the thermal interface material. The results show that varying the diameter of the nanotube and the percentage of area occupied by the nanotubes does not have any significant effect on the total temperature drop.

Characterization of Carbon Nanotube Array Based Thermal Interface Material After Bonding Process

2010 ◽  
Author(s):  
Rong-Shiuan Chu ◽  
Yang Zhao ◽  
Arun Majumdar
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotube ◽  
Contact Resistance ◽  
Target Surface ◽  
Thermal Interface Material ◽  
Bonding Layer ◽  
Nanotube Array ◽  
Thermal Interface ◽  
Carbon Nanotube Array ◽  
Overall Resistance

Vertically Aligned Carbon Nanotube (CNT) Arrays are promising to use as advanced thermal interface material. While possessing high thermal conductivity for an individual tube, carbon nanotube array based thermal interface materials (TIMs) fell short of expectations due to poor CNTs-target surface contacts. Investigations suggested that the overall resistance can be potentially reduced to less than 1 m2-K/MW by increasing the number of tubes to target surface contacts. This paper use chromium/gold/indium assisted thermal pressure-bonding to enhance contacts. A CNT array with 12.7% areal density was bonded to an experimental glass surface with 2-μm indium bonding layer and 10 nm-chromium/150 nm-gold adhesion layers under pressure of 196 KPa and temperature of 350 °C. Phase sensitive photothermal reflectance method was used for thermal measurement. The overall resistance, including CNTs-glass contact resistance and effective CNT array thermal resistance, is 1.1 m2-K/MW ± 27%. Although the contact resistance was reduced to 0.39 m2-K/MW ± 15%, the effective thermal conductivity of the post-bonded 80 μm long CNTs was 114 W/m-K ± 22%, which was lower than the expected lower bound of the thermal conductivity of 12.7% filled CNT array. It was suggested that the deformation of CNT array after mechanical bonding reduced its performance.

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.

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.

GNPs Reinforced Epoxy Nanocomposites Used as Thermal Interface Materials

2016 ◽  
Vol 38 ◽  
pp. 18-25 ◽  
Author(s):  
A. Jiménez-Suárez ◽  
R. Moriche ◽  
S.G. Prolongo ◽  
M. Sánchez ◽  
A. Ureña
Keyword(s):  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Contact Resistance ◽  
Heat Sink ◽  
Thermal Interface Material ◽  
Thermal Interface Materials ◽  
Thermal Interface ◽  
Heat Increment ◽  
Interface Materials ◽  
Very High

The current tendency in electronics is the reduction of size while continuously increasing the power consumption due to new functionalities and applications. Both aspects generate a heat increment. Consequently, dissipating the heat to the environment is necessary in order to avoid component overheating. [1,2]. The most efficient way to achieve it is to allow the heat to flow from the hot component to a heat sink. In order to improve the efficiency of this process, thermal resistance between both components must be reduced which is usually done by using a thermal interface material (TIM) between both surfaces [3-5]. This material should fill the gaps created due to the microscopic roughness of both surfaces and it must have good thermal conductivity [6]. These air filled gaps result in a very high contact resistance between joined parts, as the air thermal conductivity is very low [7].

scholarly journals Noncured Graphene Thermal Interface Materials for High-Power Electronics: Minimizing the Thermal Contact Resistance

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1699
Author(s):  
Sriharsha Sudhindra ◽  
Fariborz Kargar ◽  
Alexander A. Balandin
Keyword(s):  
Contact Resistance ◽  
High Power ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Wide Band ◽  
Thermal Interface Material ◽  
Thermal Interface Materials ◽  
Total Thermal Resistance ◽  
Thermal Interface ◽  
Interface Materials

We report on experimental investigation of thermal contact resistance, RC, of the noncuring graphene thermal interface materials with the surfaces characterized by different degree of roughness, Sq. It is found that the thermal contact resistance depends on the graphene loading, ξ, non-monotonically, achieving its minimum at the loading fraction of ξ ~15 wt %. Decreasing the surface roughness by Sq~1 μm results in approximately the factor of ×2 decrease in the thermal contact resistance for this graphene loading. The obtained dependences of the thermal conductivity, KTIM, thermal contact resistance, RC, and the total thermal resistance of the thermal interface material layer on ξ and Sq can be utilized for optimization of the loading fraction of graphene for specific materials and roughness of the connecting surfaces. Our results are important for the thermal management of high-power-density electronics implemented with diamond and other wide-band-gap semiconductors.

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