scholarly journals Constant Interface Temperature Reliability Assessment Method: An Alternative Method for Testing Thermal Interface Material in Products

2000 ◽  
Author(s):  
Christian Amoah-Kusi
Author(s):  
Menglong Hao ◽  
Kimberly R. Saviers ◽  
Timothy S. Fisher

In order to measure thermal interface resistance (TIR) at temperatures up to 700 °C, a test apparatus based on two copper 1D reference bars has been developed. Design details are presented with an emphasis on how the system minimizes the adverse effects of heat losses by convection and radiation on measurement accuracy. Profilometer measurements of the contacting surface are presented to characterize surface roughness and flatness. A Monte Carlo method is applied to quantify experimental uncertainties, resulting in a standard deviation of thermal resistance as low as 2.5 mm2 K/W at 700 °C. In addition, cyclic measurements of a standard thermal interface material (TIM) sample (graphite foil) are presented up to an interface temperature of 400 °C. The interface resistance results range between approximately 40 and 100 mm2 K/W. Further, a bare Cu–Cu interface is evaluated at several interface temperatures up to 700 °C.


2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Hebing Luan ◽  
Jiachen Wang ◽  
Guowei Ma ◽  
Ke Zhang

Roof cutting has long been a potential hazard factor in longwall panels in some diggings in China. Meanwhile, the key strata structural reliability, which provides an assessment on the stability of overlying roof strata, may be a significant reference for support design in underground coal mines. This paper aims to investigate a practical nonprobabilistic reliability assessment method on key strata. The mechanical tests and the hollow inclusion triaxial strain tests were conducted to measure relevant mechanical parameters and in situ stress. Furthermore, against the typical failure features in Datong Diggings, China, a shear failure mechanical model of key strata is proposed. Then, an allowable-safety-factor based nonprobabilistic stability probability assessment method is given. The sensitivity of geometrical dimensions and uncertainty levels of friction angle and cohesion are further studied. It is found that thickness and span of key strata have more dominative effect on key strata’s stability compared with the other factor and the increase of uncertainty levels results in decrease of stability probability.


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.


2014 ◽  
Vol 49 (22) ◽  
pp. 7844-7854 ◽  
Author(s):  
J. Liu ◽  
U. Sahaym ◽  
I. Dutta ◽  
R. Raj ◽  
M. Renavikar ◽  
...  

2021 ◽  
pp. 002199832110595
Author(s):  
Weontae Oh ◽  
Jong-Seong Bae ◽  
Hyoung-Seok Moon

The microstructural change of graphite was studied after ultrasonic treatment of the graphite. When the graphite solution was treated with varying ultrasonic power and time, the microstructure changed gradually, and accordingly, the thermal conductivity characteristics of the composite containing the as-treated graphite was also different with each other. Thermal conductivity showed the best result in the silicone composite containing graphite prepared under the optimum condition of ultrasonic treatment, and the thermal conductivity of the composite improved proportionally along with the particle size of graphite. When the silicone composite was prepared by using a mixture of inorganic oxides and graphite rather than graphite alone, the thermal conductivity of the silicone composite was further increased. A silicone composite containing graphite was used for LED (light emitting diode) lighting system as a thermal interface material (TIM), and the temperature elevation due to heat generated, while the lighting was actually operated, was analyzed.


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