NDLI: The Effect of Polydispersivity on the Thermal Conductivity of Particulate Thermal Interface Materials

Content Provider	IEEE Xplore Digital Library
Author	Kanuparthi, S. Subbarayan, G. Siegmund, T. Sammakia, B.
Copyright Year	1999
Abstract	A critical need in developing thermal interface materials (TIMs) is an understanding of the effect of particle/matrix conductivities, volume loading of the particles, the size distribution, and the random arrangement of the particles in the matrix on the homogenized thermal conductivity. Commonly, TIM systems contain random spatial distributions of particles of a polydisperse (usually bimodal) nature. A detailed analysis of the microstructural characteristics that influence the effective thermal conductivity of TIMs is the goal of this paper. Random microstructural arrangements consisting of lognormal size-distributions of alumina particles in silicone matrix were generated using a drop-fall-shake algorithm. The generated microstructures were statistically characterized using the matrix-exclusion probability function. The filler particle volume loading was varied over a range of 40%-55%. For a given filler volume loading, the effect of polydispersivity in the microstructures was captured by varying the standard deviation(s) of the filler particle size distribution function. For each particle arrangement, the effective thermal conductivity of the microstructures was evaluated through numerical simulations using a network model previously developed by the authors. Counter to expectation, increased polydispersivity was observed to increase the effective conductivity up to a volume loading of 50%. However, at a volume loading of 55%, beyond a limiting standard deviation of 0.9, the effective thermal conductivity decreased with increased standard deviation suggesting that the observed effects are a tradeoff between resistance to transport through the particles versus transport through the interparticle matrix gap in a percolation chain.
Sponsorship	IEEE Components, Packaging, and Manufacturing Technology Society
Starting Page	424
Ending Page	434
Page Count	11
File Size	2269360
File Format	PDF
ISSN	15213331
Volume Number	32
Issue Number	2
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2009-06-01
Publisher Place	U.S.A.
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Thermal conductivity Conducting materials Thermal loading Microstructure Thermal resistance Character generation Probability Distribution functions Numerical simulation Counting circuits thermal interface materials (TIMs) Network models polydispersvitiy
Content Type	Text
Resource Type	Article
Subject	Electronic, Optical and Magnetic Materials Electrical and Electronic Engineering

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