Liquid metal nano/micro-channels as thermal interface materials for efficient energy saving

2018 ◽  
Vol 6 (39) ◽  
pp. 10611-10617 ◽  
Author(s):  
Liuying Zhao ◽  
Huiqiang Liu ◽  
Xuechen Chen ◽  
Sheng Chu ◽  
Han Liu ◽  
...  

Thermal interface material (TIMs) pads/sheets with both high elasticity and low thermal resistance are indispensable components for thermal management.


Author(s):  
David Shaddock ◽  
Stanton Weaver ◽  
Ioannis Chasiotis ◽  
Binoy Shah ◽  
Dalong Zhong

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.



2019 ◽  
Vol 6 (1) ◽  
pp. 2 ◽  
Author(s):  
Barath Kanna Mahadevan ◽  
Sahar Naghibi ◽  
Fariborz Kargar ◽  
Alexander A. Balandin

Temperature rise in multi-junction solar cells reduces their efficiency and shortens their lifetime. We report the results of the feasibility study of passive thermal management of concentrated multi-junction solar cells with the non-curing graphene-enhanced thermal interface materials. Using an inexpensive, scalable technique, graphene and few-layer graphene fillers were incorporated in the non-curing mineral oil matrix, with the filler concentration of up to 40 wt% and applied as the thermal interface material between the solar cell and the heat sink. The performance parameters of the solar cells were tested using an industry-standard solar simulator with concentrated light illumination at 70× and 200× suns. It was found that the non-curing graphene-enhanced thermal interface material substantially reduces the temperature rise in the solar cell and improves its open-circuit voltage. The decrease in the maximum temperature rise enhances the solar cell performance compared to that with the commercial non-cured thermal interface material. The obtained results are important for the development of the thermal management technologies for the next generation of photovoltaic solar cells.



Author(s):  
S. Mahajan ◽  
G. Subbarayan ◽  
B. G. Sammakia ◽  
W. Jones

Thermal management in microelectronics is an important issue due to the projected increase in power dissipation in the electronic devices over the next 5–10 years. We seek a solution to this problem by exploring carbon nanotube-polymer matrix composites for use as thermal interface materials because of the reported high thermal conductivity and other remarkable thermal and mechanical properties of nanotubes. As an intermediate step to finding the composites’ conductivity, it is important to validate the use carbon nanotubes by calculating its diffusivity and conductivity first. This would facilitate later the estimating of important design parameters for thermal interface materials such as thermal diffusivity and conductivity. As polymer molecules are on the same size scale as nanotubes and the interaction at the polymer/nanotube interface is highly dependent on the molecular structure and bonding, Molecular Dynamic (MD) simulation is used to estimate the nano-scale properties. In this paper, until cell model consisting of a carbon nanotube was used and the diffusivity was measured. These findings would have implications in improving the thermal management efficiency and consequently improve the performance and reliability of future microelectronic devices.



2016 ◽  
Vol 38 ◽  
pp. 18-25 ◽  
Author(s):  
A. Jiménez-Suárez ◽  
R. Moriche ◽  
S.G. Prolongo ◽  
M. Sánchez ◽  
A. Ureña

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].



Author(s):  
Wei Yu ◽  
◽  
Changqing Liu ◽  
Lin Qiu ◽  
Ping Zhang ◽  
...  


2017 ◽  
Vol 7 (6) ◽  
pp. 589 ◽  
Author(s):  
Mohammed Saadah ◽  
Edward Hernandez ◽  
Alexander Balandin


Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1699
Author(s):  
Sriharsha Sudhindra ◽  
Fariborz Kargar ◽  
Alexander A. Balandin

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.



Author(s):  
Vadim Gektin ◽  
Sai Ankireddi ◽  
Jim Jones ◽  
Stan Pecavar ◽  
Paul Hundt

Thermal Interface Materials (TIMs) are used as thermally conducting media to carry away the heat dissipated by an energy source (e.g. active circuitry on a silicon die). Thermal properties of these interface materials, specified on vendor datasheets, are obtained under conditions that rarely, if at all, represent real life environment. As such, they do not accurately portray the material thermal performance during a field operation. Furthermore, a thermal engineer has no a priori knowledge of how large, in addition to the bulk thermal resistance, the interface contact resistances are, and, hence, how much each influences the cooling strategy. In view of these issues, there exists a need for these materials/interfaces to be characterized experimentally through a series of controlled tests before starting on a thermal design. In this study we present one such characterization for a candidate thermal interface material used in an electronic cooling application. In a controlled test environment, package junction-to-case, Rjc, resistance measurements were obtained for various bondline thicknesses (BLTs) of an interface material over a range of die sizes. These measurements were then curve-fitted to obtain numerical models for the measured thermal resistance for a given die size. Based on the BLT and the associated thermal resistance, the bulk thermal conductivity of the TIM and the interface contact resistance were determined, using the approach described in the paper. The results of this study permit sensitivity analyses of BLT and its effect on thermal performance for future applications, and provide the ability to extrapolate the results obtained for the given die size to a different die size. The suggested methodology presents a readily adaptable approach for the characterization of TIMs and interface/contact resistances in the industry.



Author(s):  
Amer M. Hamdan ◽  
Aric R. McLanahan ◽  
Robert F. Richards ◽  
Cecilia D. Richards

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.



2018 ◽  
Vol 7 (4.33) ◽  
pp. 530
Author(s):  
Mazlan Mohamed ◽  
Mohd Nazri Omar ◽  
Mohamad Shaiful Ashrul Ishak ◽  
Rozyanty Rahman ◽  
Zaiazmin Y.N ◽  
...  

Epoxy mixed with others filler for thermal interface material (TIM) had been well conducted and developed. There are problem occurs when previous material were used as matrix material likes epoxy that has non-uniform thickness of thermal interface material produce, time taken for solidification and others. Thermal pad or thermal interface material using graphene as main material to overcome the existing problem and at the same time to increase thermal conductivity and thermal contact resistance. Three types of composite graphene were used for thermal interface material in this research. The sample that contain 10 wt. %, 20 wt. % and 30 wt. % of graphene was used with different contain of graphene oxide (GO).  The thermal conductivity of thermal interface material is both measured and it was found that the increase of amount of graphene used will increase the thermal conductivity of thermal interface material. The highest thermal conductivity is 12.8 W/ (mK) with 30 w. % graphene. The comparison between the present thermal interface material and other thermal interface material show that this present graphene-epoxy is an excellent thermal interface material in increasing thermal conductivity.  



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