Mixing, rheology, and stability of highly filled thermal pastes

Feger, C.; Gelorme, Jeffrey D.; McGlashan‐Powell, M.; Kalyon, Dilhan M.

doi:10.1147/rd.494.0699

Cited by 16 publications

(19 citation statements)

References 20 publications

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“…This is probably because the pastes of Feger et al are highly filled with solid components (>72 vol.%). Though the tan d value is not reported by Feger et al, 24 it can be estimated from the reported curve to be about 0.48, which is less than that of the nanoclay paste and the fumed alumina paste of this work. The paste of Feger et al shows a critical strain of 0.1%, which is similar to that of the CB(Tokai) paste of this work.…”

Section: Critical Strain Determined By Strain Sweepcontrasting

confidence: 75%

“…The thermal pastes in the form of a hydrocarbon oil filled with a mixture of alumina and aluminum particles, as reported by Feger et al, 24 show G¢ and G¢¢ values as high as 10 5 Pa, which is much higher than those of any of the thermal pastes addressed here (Table II). This is probably because the pastes of Feger et al are highly filled with solid components (>72 vol.%).…”

Section: Critical Strain Determined By Strain Sweepsupporting

confidence: 58%

“…24 These particles are 7.9 lm spherical aluminum 23 and presumably not in the nanoscale also for Ref. 24. The rheology is expected to be quite different when the particles are in the nanoscale.…”

Section: Introductionmentioning

confidence: 86%

“…Prior work involving rheometry of thermal pastes 23,24 has addressed the viscosity, yield stress, storage modulus, loss modulus, and the effect of temperature on the viscosity and moduli, but pastes were limited to those with high solid volume fractions, namely 40 vol.% to 60 vol.% aluminum particles 23 and above 72 vol.% mixture of aluminum and alumina particles. 24 These particles are 7.9 lm spherical aluminum 23 and presumably not in the nanoscale also for Ref.…”

Section: Introductionmentioning

confidence: 99%

“…24 The present work addresses the rheometry of thermal pastes with a polyol ester vehicle. This vehicle is widely used in state-of-the-art thermal pastes, due to its combination of fluidity and elevated temperature resistance.…”

Section: Introductionmentioning

confidence: 99%

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Rheological Behavior of Thermal Interface Pastes

Lin

Chung

2009

Journal of Elec Materi

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Polyol-ester-based thermal pastes containing carbon black, fumed alumina or nanoclay exhibit Bingham plastic behavior with shear thinning. Carbon black gives double yielding, but fumed alumina and nanoclay give single yielding. The plastic viscosity increases with the solid content. Antioxidants increase the plastic viscosity and yield stresses. Nanoclay (1.0 vol.%) gives low shear moduli, high critical shear strain, and high loss tangent, thus resulting in low bond-line thickness and high thermal contact conductance for smooth (0.009 lm) proximate surfaces. Carbon black (Tokai, 8.0 vol.%) gives high moduli, low critical strain, and low loss tangent, thus resulting in high bondline thickness, though the high thermal conductivity due to the high solid content results in high thermal contact conductance for rough (15 lm) proximate surfaces. Antioxidants enhance the solid-like character, increase the yield stress, plastic viscosity, and bond-line thickness, and decrease the thermal contact conductance.

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Section: Critical Strain Determined By Strain Sweepcontrasting

confidence: 75%

Section: Critical Strain Determined By Strain Sweepsupporting

confidence: 58%

Section: Introductionmentioning

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Rheological Behavior of Thermal Interface Pastes

Lin

Chung

2009

Journal of Elec Materi

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An analytical model for steady coextrusion of viscoplastic fluids in thin slit dies with wall slip

Kalyon

2009

Polym Eng Sci

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Coextrusion is widely used to fabricate multilayered products with each layer providing a separate functionality, including barrier resistance to gases, strength, and printability. Here an analytical model of the coextrusion die flow of two incompressible, viscoplastic fluids in a slit die, subject to nonlinear wall slip and under fully developed and isothermal conditions, is developed to allow the prediction of the steady-state velocity and shear stress distributions and the flow rate versus pressure gradient relationship. The resulting model is applied to the coextrusion of two layers of viscoplastic fluids in a thin rectangular slit die (slit gap, h ( slit width, W). The analytical solution recognizes a number of distinct flow conditions (eleven cases) that need to be treated separately. The solutions for all eleven cases are provided along with an apriori identification methodology for the determination of the applicable case, given the shear viscosity and wall slip parameters of the two viscoplastic fluids, the slit geometry and the flow conditions. Simplifications of the model would provide the solutions for the fully developed and isothermal coextrusion flows of any combination of Hershel-Bulkley, Bingham, power-law and Newtonian fluids with or without wall slip at one or both walls of the slit die. POLYM. ENG. SCI., 50:652-664,

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