scholarly journals Non-Curing Thermal Interface Materials with Graphene Fillers for Thermal Management of Concentrated Photovoltaic Solar Cells

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.


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):  
Corey Thompson ◽  
Matt Gordon ◽  
Ajay P. Malshe ◽  
Deep Gupta

Superconducting integrated circuits (SCICs) require cooling to about 4 K for proper circuit operation. Current efforts are being made to transfer SCIC technology from lab experiments to viable consumer and military products. In order for this to be feasible, SCICs must function in cryogen-free closed-cycle refrigerator (or cryocooler) based systems. Design constraints for SCICs utilizing rapid single-flux-quantum (RSFQ) logic require a maximum temperature gradient across the package of less than 50 mK for proper circuit operation when implemented in cryocooler mounted systems. Also, to achieve increased functional density and decreased signal delays, it is desired to implement multichip module (MCM) SCICs in which RSFQ signals are passed from chip-to-chip through a common MCM substrate. Satisfying these constraints requires innovative packaging and thermal interface materials for harsh environment packaging (low temperature, high vacuum). The objective of this modeling work is to: explain the role of underfill in harsh environment cryogenic packages, explore the role of polymers and nanocomposites in filling this role, and anticipate the role of manufacturing defects on thermal management of 4 K packages. A characteristic model is developed in COMSOL MultiPhysics that allows for investigation of the dependence of temperature gradients across the package on these variables. It is found that at 4 K thermal interface resistances act as major bottlenecks to heat removal from the active die. It is also shown that as bump diameter decreases below 100 microns due to device miniaturization, the need for effective thermal interface materials is exacerbated. A novel nanoengineered cryogenic adhesive (nECA) comprised of nanoparticles dispersed in an epoxy matrix is proposed to act as a heat transfer medium between chip and substrate. Incorporation of nECA into the FEA model of a single chip package reduces the overall temperature gradient from 78 mK to 44 mK. This advance in thermal management of low temperature SCICs is paramount for the advancement of MCM packaging requiring efficient removal of heat from densely packaged chips.


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

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.


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.  


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 12 ◽  
pp. 80-85 ◽  
Author(s):  
Chang Ping Feng ◽  
Lu Bai ◽  
Rui-Ying Bao ◽  
Shi-Wei Wang ◽  
Zhengying Liu ◽  
...  

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