Thermal Performance of Liquid Metal Alloy with Graphene Addition as Thermal Interface Material

2016 ◽  
Vol 138 (8) ◽  
Author(s):  
Gen Li ◽  
Yulong Ji ◽  
Qingzhen Zhang ◽  
Bohan Tian ◽  
Hongbin Ma
Keyword(s):  
Thermal Conductivity ◽  
Liquid Metal ◽  
Thermal Performance ◽  
Laser Flash ◽  
Metal Alloy ◽  
Thermal Interface Material ◽  
Thermal Paste ◽  
Air Pocket ◽  
Liquid Metal Alloy ◽  
Air Pockets

A high thermal conductivity thermal paste can be developed by mixing the oxidized liquid metal alloy (OLMA) with graphene. Four kinds of graphene-OLMA pastes were synthesized at graphene concentrations of 0.25 wt%, 0.75 wt%, 1.5 wt%, and 2.0 wt%, respectively. The paste structures were characterized by MicroXCT-400, which can be used to readily measure the air pocket size, and their thermal conductivities measured by a laser flash analysis method. It is found that the OLMA structure is very different from the liquid metal alloy (LMA), and a small amount of air pockets were formed in the OLMA. The air pocket size significantly affected the thermal conductivity of the graphene-OLMA paste. When the graphene concentration increased, as shown in Fig. 1(c)-(e), the paste's thermal conductivity increased. However, more air pockets were formed around the graphene. In particular, when the graphene concentration increased to 2.0 wt%, clusters of graphene, as shown in Fig. 1(f), were formed resulting in the formation of big air pockets in the thermal paste, which directly affected the thermal conductivity as shown in Fig. 1(g). We thought that when the graphene concentration increases, the thermal conductivity should increases. But the results show that it was not and then we used MicroCT to see the internal structure of the thermal paste and found that the air pockets were formed and significantly affects the thermal performance.

Highly Conductive Thermal Paste of Liquid Metal Alloy Dispersed With Copper Particles

2016 ◽  
Author(s):  
Gen Li ◽  
Yulong Ji ◽  
Mengke Wu ◽  
Hongbin Ma
Keyword(s):  
Thermal Conductivity ◽  
Liquid Metal ◽  
Thermal Contact ◽  
Copper Particle ◽  
Metal Alloy ◽  
Copper Particles ◽  
Thermal Paste ◽  
Liquid Metal Alloy ◽  
Thermal Pastes ◽  
Thermal Conductivities

In this paper, a kind of highly conductive thermal paste is investigated, which consists of liquid metal alloy (LMA) and copper particles. The LMA used in the current research is a gallium-indium-tin eutectic alloy (Ga62.5In21.5Sn16). The copper particles dispersing into LMA have an average diameter of 9 μm. During the dispersing process, a degassing process was conducted in order to reduce air bubbles and increase the thermal conductivity of the investigated paste. A new method based on laser flash (LFA) was used to test the total thermal conductivities of the samples. Three types of thermal pastes were prepared and tested, i.e., LMA, oxidized liquid metal alloy (OLMA), and OLMA mixed with copper particles. Results show that when LMA, OLMA, and OLMA mixed with copper particles at a ratio of 5wt%, the resulting thermal conductivities of the investigated thermal pastes can achieve 44.48 W/mK, 13.55 W/mK, and 24.34 W/mK, which result in the corresponding thermal contact resistances of 4.044 mm2K/W, 5.638 mm2K/W, and 4.075 mm2K/W, respectively. In addition, the effect of the copper particle ratio on the thermal performance was investigated. Results show that when the ratio of copper particles increased from 5wt% to 10wt%, the thermal conductivity of investigated thermal paste increased from 24.34 W/mK to 29.07 W/mK, and the thermal contact resistance decreased from 4.075 mm2K/W to 3.37 mm2K/W.

Investigation on Carbon Nanotubes as Thermal Interface Material Bonded With Liquid Metal Alloy

2015 ◽  
Vol 137 (9) ◽  
Author(s):  
Yulong Ji ◽  
Gen Li ◽  
Chao Chang ◽  
Yuqing Sun ◽  
Hongbin Ma
Keyword(s):  
Thermal Conductivity ◽  
Thermal Diffusivity ◽  
Liquid Metal ◽  
Thermal Resistance ◽  
Plasma Treatment ◽  
Contact Surface ◽  
Thermal Interface Material ◽  
Thermal Interface ◽  
Bonding Material ◽  
Liquid Metal Alloy

Vertically aligned carbon nanotube (VACNT) films with high thermal conductance and mechanical compliance offer an attractive combination of properties for thermal interface applications. In current work, VACNT films synthesized by the chemical vapor deposition method were used as thermal interface material (TIM) and investigated experimentally. The liquid metal alloy (LMA) with melting point of 59 °C was used as bonding material to attach VACNT films onto copper plates. In order to enhance the contact area of LMA with the contact surface, the wettability of the contact surface was modified by plasma treatment. The thermal diffusivity, thermal conductivity, and thermal resistance of the synthesized samples were measured and calculated by the laser flash analysis (LFA) method. Results showed that: (1) VACNT films can be used as TIM to enhance the heat transfer performance of the contact surface; (2) the LMA can be used as bonding material, and its performance is dependent on the LMA wettability on the contact surface. (3) When applying VACNT film as the TIM, LMA is used as the bonding material. After plasma treatment, comparison of VACNT films with the dry contact between copper and silicon showed that thermal diffusivity can be increased by about 160%, the thermal conductivity can be increased by about 100%, and the thermal resistance can be decreased by about 31%. This study shows the advantages of using VACNT films as TIMs in microelectronic packaging.

Experimental Study of VACNT Arrays as Thermal Interface Material

2013 ◽  
Author(s):  
Yulong Ji ◽  
Gen Li ◽  
Hongbin Ma ◽  
Yuqing Sun
Keyword(s):  
Thermal Conductivity ◽  
Chemical Vapor ◽  
Laser Flash ◽  
Thermal Interface Material ◽  
Chemical Vapor Deposition Method ◽  
Free Standing ◽  
Thermal Interface ◽  
Thermal Paste ◽  
Laser Flash Analysis ◽  
Contact Thermal Conductivity

In order to improve thermal interface material (TIM), vertically aligned carbon nanotube (VACNT) arrays were synthesized by the chemical vapor deposition method, and then transferred by dipping in hydrofluoric acid (HF acid) solution to get a free standing VACNT array. Different TIM samples with sandwiched structures were fabricated by inserting the free standing VACNT arrays between two copper plates with and without bonding materials. The laser flash analysis method was applied to measure the overall thermal conductivity of these samples. Results show that: compared with two copper plates in direct contact, thermal conductivity of samples only with VACNT arrays as TIM can be enhanced about 142%–460% depending on the thickness of VACNT arrays. Conventional TIM made up of thermal paste (TG-550 with thermal conductivity of 5 W/mK) and a thermal pad (TP-260 US with thermal conductivity of 6 W/mK) was used as a bonding material between copper plates and VACNT arrays, thermal conductivity has been shown to further improve with the highest values at 8.904 W/mK and 10.17 W/mK corresponding to the different bonding materials and different thicknesses of VACNT arrays used. Results also show that the thicker the VACNT array is when used as a TIM, the lower the overall thermal conductivity of the corresponding samples. This lower thermal conductivity caused by more defects in amorphous carbon of thicker VACNT arrays and lower density of the corresponding sandwiched samples.

High Thermal Conductivity Silicone Elastomer Doped with Graphene Nanoplatelets and Eutectic GaIn Liquid Metal Alloy

2019 ◽  
Vol 8 (6) ◽  
pp. P357-P362 ◽  
Author(s):  
Yasaman Sargolzaeiaval ◽  
Viswanath Padmanabhan Ramesh ◽  
Taylor V. Neumann ◽  
Rebecca Miles ◽  
Michael D. Dickey ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Liquid Metal ◽  
Graphene Nanoplatelets ◽  
Metal Alloy ◽  
High Thermal Conductivity ◽  
Silicone Elastomer ◽  
Liquid Metal Alloy

Dynamic Processes During Pulsed Gas Injection Into Liquid Column

2016 ◽  
Author(s):  
P. D. Lobanov ◽  
O. N. Kashinsky ◽  
A. S. Kurdyumov ◽  
N. A. Pribaturin
Keyword(s):  
Liquid Metal ◽  
Gas Phase ◽  
Gas Injection ◽  
High Amplitude ◽  
Metal Alloy ◽  
Dynamic Processes ◽  
Flow Parameters ◽  
Liquid Metal Alloy ◽  
Inner Diameter ◽  
Gas Volume

An experimental study of dynamic processes during pulsed gas injection into quiescent liquids was performed. Both water and low melting temperature metal alloy were used as test liquids. Air and argon were used as gas phase. The test sections were vertical cylindrical columns 25 and 68 mm inner diameter. Measurements of flow parameters during gas injection were performed. Water – air experiments were performed at room temperature, the temperature of liquid metal alloy was 135 deg C. Time records of pressure in the liquid and in gas phase above the liquid were obtained. Measurements of liquid temperature and level of liquid surface were performed. It was shown that at pulse gas injection into liquid metal high amplitude pressure fluctuation may arise. Also the fluctuation variation of the free surface of the liquid may appear which are connected with the oscillations of the gas volume. Experimental data obtained may be used for verification & validation of modern CFD codes.

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