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Title: Investigation of Thermal Interface Materials Using Phase-Sensitive Transient Thermoreflectance Technique: Preprint

Abstract

With increasing power density in electronics packages/modules, thermal resistances at multiple interfaces are a bottleneck to efficient heat removal from the package. In this work, the performance of thermal interface materials such as grease, thermoplastic adhesives and diffusion-bonded interfaces are characterized using the phase-sensitive transient thermoreflectance technique. A multi-layer heat conduction model was constructed and theoretical solutions were derived to obtain the relation between phase lag and the thermal/physical properties. This technique enables simultaneous extraction of the contact resistance and bulk thermal conductivity of the TIMs. With the measurements, the bulk thermal conductivity of Dow TC-5022 thermal grease (70 to 75 um bondline thickness) was 3 to 5 W/(m-K) and the contact resistance was 5 to 10 mm2-K/W. For the Btech thermoplastic material (45 to 80 μm bondline thickness), the bulk thermal conductivity was 20 to 50 W/(m-K) and the contact resistance was 2 to 5 mm2-K/W. Measurements were also conducted to quantify the thermal performance of diffusion-bonded interface for power electronics applications. Results with the diffusion-bonded sample showed that the interfacial thermal resistance is more than one order of magnitude lower than those of traditional TIMs, suggesting potential pathways to efficient thermal management.

Authors:
; ; ; ;
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy Vehicle Technologies Office
OSTI Identifier:
1150181
Report Number(s):
NREL/CP-5400-61106
DOE Contract Number:
AC36-08GO28308
Resource Type:
Conference
Resource Relation:
Conference: Presented at ITherm 2014, 27-30 May 2014, Orlando, Florida
Country of Publication:
United States
Language:
English
Subject:
30 DIRECT ENERGY CONVERSION; 33 ADVANCED PROPULSION SYSTEMS; THERMAL INTERFACE MATERIALS; PHASE-SENSITIVE TRANSIENT THREMOREFLECTANCE; CONTACT RESISTANCE; BULK THERMAL CONDUCTIVITY; THERMOPHYSICAL PROPERTIES; Transportation

Citation Formats

Feng, X., King, C., DeVoto, D., Mihalic, M., and Narumanchi, S. Investigation of Thermal Interface Materials Using Phase-Sensitive Transient Thermoreflectance Technique: Preprint. United States: N. p., 2014. Web. doi:10.1109/ITHERM.2014.6892430.
Feng, X., King, C., DeVoto, D., Mihalic, M., & Narumanchi, S. Investigation of Thermal Interface Materials Using Phase-Sensitive Transient Thermoreflectance Technique: Preprint. United States. doi:10.1109/ITHERM.2014.6892430.
Feng, X., King, C., DeVoto, D., Mihalic, M., and Narumanchi, S. Fri . "Investigation of Thermal Interface Materials Using Phase-Sensitive Transient Thermoreflectance Technique: Preprint". United States. doi:10.1109/ITHERM.2014.6892430. https://www.osti.gov/servlets/purl/1150181.
@article{osti_1150181,
title = {Investigation of Thermal Interface Materials Using Phase-Sensitive Transient Thermoreflectance Technique: Preprint},
author = {Feng, X. and King, C. and DeVoto, D. and Mihalic, M. and Narumanchi, S.},
abstractNote = {With increasing power density in electronics packages/modules, thermal resistances at multiple interfaces are a bottleneck to efficient heat removal from the package. In this work, the performance of thermal interface materials such as grease, thermoplastic adhesives and diffusion-bonded interfaces are characterized using the phase-sensitive transient thermoreflectance technique. A multi-layer heat conduction model was constructed and theoretical solutions were derived to obtain the relation between phase lag and the thermal/physical properties. This technique enables simultaneous extraction of the contact resistance and bulk thermal conductivity of the TIMs. With the measurements, the bulk thermal conductivity of Dow TC-5022 thermal grease (70 to 75 um bondline thickness) was 3 to 5 W/(m-K) and the contact resistance was 5 to 10 mm2-K/W. For the Btech thermoplastic material (45 to 80 μm bondline thickness), the bulk thermal conductivity was 20 to 50 W/(m-K) and the contact resistance was 2 to 5 mm2-K/W. Measurements were also conducted to quantify the thermal performance of diffusion-bonded interface for power electronics applications. Results with the diffusion-bonded sample showed that the interfacial thermal resistance is more than one order of magnitude lower than those of traditional TIMs, suggesting potential pathways to efficient thermal management.},
doi = {10.1109/ITHERM.2014.6892430},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Aug 01 00:00:00 EDT 2014},
month = {Fri Aug 01 00:00:00 EDT 2014}
}

Conference:
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  • The thermal resistance of the thermal interface material layer greatly affects the maximum temperature of the power electronics.
  • Thermal interface materials are an important enabler for low thermal resistance and reliable electronics packaging for a wide array of applications. There is a trend towards bonded interface materials (BIMs) because of their potential for low thermal resistivity (< 1 mm2K/W). However, BIMs induce thermomechanical stresses in the package and can be prone to failures and integrity risks. Deteriorated interfaces can result in high thermal resistance in the package and degradation and/or failure of the electronics. DARPA's Thermal Management Technologies program has addressed this challenge, supporting the development of mechanically-compliant, low resistivity nano-thermal interface (NTI) materials. In this work, wemore » describe the testing procedure and report the results of NREL's thermal performance and reliability characterization of an initial sample of four different NTI-BIMs.« less
  • Thermal interface materials (TIMs) are an integral and important part of thermal management in electronic devices. The electronic devices are becoming more compact and powerful. This increase in power processed or passing through the devices leads to higher heat fluxes and makes it a challenge to maintain temperatures at the optimal level during operation. Herein, we report a free standing nanocomposite TIM in which boron nitride nanosheets (BNNS) are uniformly dispersed in copper matrices via an organic linker, thiosemicarbazide. Integration of these metal-organic-inorganic nanocomposites was made possible by a novel electrodeposition technique where the functionalized BNNS (f-BNNS) experience the Brownianmore » motion and reach the cathode through diffusion, while the nucleation and growth of the copper on the cathode occurs via the electrochemical reduction. Once the f-BNNS bearing carbonothioyl/thiol groups on the terminal edges come into the contact with copper crystals, the chemisorption reaction takes place. We performed thermal, mechanical, and structural characterization of these nanocomposites using scanning electron microcopy (SEM), diffusive laser flash (DLF) analysis, phase-sensitive transient thermoreflectence (PSTTR), and nanoindentation. The nanocomposites exhibited a thermal conductivity ranging from 211 W/mK to 277 W/mK at a filler mass loading of 0-12 wt.percent. The nanocomposites also have about 4 times lower hardness as compared to copper, with values ranging from 0.27 GPa to 0.41 GPa. The structural characterization studies showed that most of the BNNS are localized at grain boundaries - which enable efficient thermal transport while making the material soft. PSTTR measurements revealed that the synergistic combinations of these properties yielded contact resistances on the order of 0.10 to 0.13 mm2K/W, and the total thermal resistance of 0.38 to 0.56 mm2K/W at bondline thicknesses of 30-50 um. The coefficient of thermal expansion (CTE) of the nanocomposite is 11 ppm/K, which lies between the CTEs of aluminum (22 ppm/K) and silicon (3 ppm/K), which are common heat sink and heat source materials, respectively. The nanocomposite can also be deposited directly on to heat sink which will simplify the packaging processes by removing one possible element to assemble. These unique properties and ease of assembly makes the nanocomposite a promising next-generation TIM.« less
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