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Thermal interface materials (TIMs) play a key role in connecting
the heat source with the heat-spreader or the heat sink, ensuring
the efficient transfer of heat. The effective thermal resistance
at the interface has two components: The bulk resistance 
of the TIM arising from its finite thermal conductivity and the
contact resistance 
between the TIM and the adjoining solids:
where BLT is the bond-line thickness of the TIM, 
is the thermal conductivity of the TIM, and 
and 
are the contact resistances of the TIM with the two adjoining surfaces.
The thermal conductivity of a TIM is enhanced by loading a polymeric
matrix with conducting solid particles, such as aluminum, alumina
and boron nitride. Thermal conductivity of particle-laden TIMs depend
on the filler thermal conductivity, and volume fraction, as well
as on the contact resistance between the particles and the polymeric
matrix.
One of the main problems of particle-filled materials is their
limited stability in terms of phase segregation and paste pumping.
The latter effect is the interpenetration of a thin paste layer
by an air bubble, which can be understood using the Hele-Shaw theory.
» Back to High-performance
thermal interfaces
References
| [1] |
T. Brunschwiler, U. Kloter, H. Rothuizen, and B. Michel, "Hierarchically
nested channels for fast squeezing interfaces with reduced thermal resistance,"
21st IEEE SEMI-THERM Symposium, San Jose, CA (2000).
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| [2] |
T. Brunschwiler, U. Kloter, R. Linderman, H. Rothuizen, and B. Michel, "Hierarchically
nested channels for fast squeezing interfaces with reduced thermal resistance,"
Trans. Comp. Packag. Technol., in press.
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