Lithium Doped Polyethylene-Glycol-Based Thermal Interface Pastes for High Thermal Contact Conductance

2002 ◽  
Vol 124 (3) ◽  
pp. 188-191 ◽  
Author(s):  
Yunsheng Xu ◽  
Xiangcheng Luo ◽  
D. D. L. Chung
Keyword(s):  
Polyethylene Glycol ◽  
Boron Nitride ◽  
Sodium Silicate ◽  
Trifluoroacetic Acid ◽  
Lithium Salt ◽  
Thermal Contact ◽  
Thermal Contact Conductance ◽  
Thermal Interface ◽  
Contact Conductance ◽  
Nitride Particle

Polyethylene-glycol-based thermal interface paste containing trifluoroacetic acid lithium salt (1.5 wt. percent optimum) and boron nitride particles (∼18.0 vol. percent optimum), as well as water and N, N-dimethylformamide for helping the dissociation of the salt to release Li+ ions, gives thermal contact conductance that is almost as high as that given by Sn-Pb solder, similar to that given by boron nitride particle filled sodium silicate, and much higher than that given by boron nitride particle filled silicone.

Sodium Silicate Based Thermal Interface Material for High Thermal Contact Conductance

1999 ◽  
Vol 122 (2) ◽  
pp. 128-131 ◽  
Author(s):  
Yunsheng Xu ◽  
Xiangcheng Luo ◽  
D. D. L. Chung
Keyword(s):  
Thermal Conductivity ◽  
Boron Nitride ◽  
Sodium Silicate ◽  
Hexagonal Boron Nitride ◽  
Thermal Contact ◽  
Mineral Oil ◽  
Thermal Interface Material ◽  
Thermal Contact Conductance ◽  
Thermal Interface ◽  
Contact Conductance

Sodium silicate based thermal interface pastes give higher thermal contact conductance across conductor surfaces than polymer based pastes and oils, due to their higher fluidity and the consequent greater conformability. Addition of hexagonal boron nitride particles up to 16.0 vol. percent further increases the conductance of sodium silicate, due to the higher thermal conductivity of BN. However, addition beyond 16.0 vol. percent BN causes the conductance to decrease, due to the decrease in fluidity. At 16.0 vol. percent BN, the conductance is up to 63 percent higher than those given by silicone based pastes and is almost as high as that given by solder. Water is almost as effective as sodium silicate without filler, but the thermal contact conductance decreases with time due to the evaporation of water. Mineral oil and silicone without filler are much less effective than water or sodium silicate without filler. [S1043-7398(00)00402-3]

Thermal Stability of Thermal Interface Pastes, Evaluated by Thermal Contact Conductance Measurement

2000 ◽  
Vol 123 (3) ◽  
pp. 309-311 ◽  
Author(s):  
Xiangcheng Luo, ◽  
Yunsheng Xu, and ◽  
D. D. L. Chung
Keyword(s):  
Sodium Silicate ◽  
Thermal Contact ◽  
The Other ◽  
Thermal Contact Conductance ◽  
Conductance Measurement ◽  
Thermal Interface ◽  
Contact Conductance ◽  
Before And After ◽  
Heating Up ◽  
Thermal Stability Of

Thermal interface pastes based on silicone, lithium doped polyethylene glycol (PEG), and sodium silicate were evaluated in their performance before and after heating up to 120°C. The thermal contact conductance of any of the pastes between copper disks decreased after heating, such that the fractional decrease was less for the silicone-based paste than the PEG-based and sodium-silicate-based pastes. Nevertheless, the conductance was lower for the silicone-based paste than the other pastes both before and after heating up to 100 cycles.

Boron Nitride Particle Filled Paraffin Wax as a Phase-Change Thermal Interface Material

2006 ◽  
Vol 128 (4) ◽  
pp. 319-323 ◽  
Author(s):  
Zongrong Liu ◽  
D. D. L. Chung
Keyword(s):  
Boron Nitride ◽  
Phase Change ◽  
Melting Temperature ◽  
Thermal Contact ◽  
Thermal Interface Material ◽  
Paraffin Wax ◽  
Thermal Contact Conductance ◽  
Thermal Interface ◽  
Contact Conductance ◽  
Increasing Temperature

Wax (predominantly tricosane paraffin wax, with a melting temperature of 48°C) filled with hexagonal boron nitride (BN) particles (5-11μm) was found to be an effective phase-change thermal interface material. The thermal contact conductance, as measured with the interface material between copper surfaces, decreased with increasing temperature from 22to48°C, but increased with increasing temperature from 48to55°C. The melting of the wax enhanced the conductance, due to increased conformability to the mating surfaces. For a given BN volume fraction and a given temperature, the thermal contact conductance increased with increasing contact pressure. However, a pressure above 0.30MPa resulted in no significant increase in the conductance. The conductance increased with BN content up to 6.2vol.%, but decreased upon further increase to 8.6vol.%. The highest conductance above the melting temperature was 18×104W∕m2.°C, as attained for a BN content of 4.0vol.% at 55°C and 0.30MPa. Below the melting temperature, the highest conductance was 19×104W∕m2.°C, as attained for a BN content of 6.2vol.% at 22°C and 0.30MPa.

Molecular Dynamics Modeling of the Effect of Thermal Interface Material on Thermal Contact Conductance

2008 ◽  
Author(s):  
U. B. Jayadeep ◽  
R. Krishna Sabareesh ◽  
R. Nirmal ◽  
K. V. Rijin ◽  
C. B. Sobhan
Keyword(s):  
Molecular Dynamics ◽  
Thermal Contact ◽  
Thermal Interface Material ◽  
Thermal Contact Conductance ◽  
Effect Of Temperature ◽  
Computation Method ◽  
Contact Interface ◽  
Dynamics Modeling ◽  
Thermal Interface ◽  
Contact Conductance

Thermal contact conductance is used to indicate the resistance offered by a contact interface to the flow of heat. When an interface material is applied as nano-layered coatings on super-finished contacting surfaces, the possibility of size effects necessitates the use of a discrete computation method for its analysis. Hence, a methodology is proposed which utilizes Molecular Dynamics (MD) simulations to obtain the size affected thermal conductivity of the interfacial layer, which in turn characterizes the thermal contact conductance behavior. Molecular Dynamics codes have been developed, making use of Sutton-Chen many-body potential, suitable for metallic materials. The model includes the asperities at the contact interface, assuming the asperities to be of a simplified geometry. The paper also presents the validation of the codes developed, and parametric studies on the effect of temperature, number of asperities and the material used for thermal interface coating on the size-affected interfacial conductivity.

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