Degradation Characterization of Thermal Interface Greases

Joshua Major, Sreekant Narumanchi, Paul Paret, Gregory Blackman, Arnold Wong, Jeffery Meth

Research output: NRELPresentation


Thermal interface materials (TIMs) are used in power electronics packaging to minimize thermal resistance between the heat generating component and the heat sink. Thermal greases are one such class. The conformability and thin bond line thickness (BLT) of these TIMs can potentially provide low thermal resistance throughout the operation lifetime of a component. However, their performance degrades over time due to pump-out and dry-out during thermal and power cycling. The reliability performance of greases through operational cycling needs to be quantified to develop new materials with superior properties. NREL, in collaboration with DuPont, has performed thermal and reliability characterization of several commercially available thermal greases. Initial bulk and contact thermal resistance of grease samples were measured, and then the thermal degradation that occurred due to pump-out and dry-out during temperature cycling was monitored. The thermal resistances of five different grease materials were evaluated using NREL's steady-state thermal resistance tester based on the ASTM test method D5470. Greases were then applied, utilizing a 2.5 cm x 2.5 cm stencil, between invar and aluminum plates to compare the thermomechanical performance of the materials in a representative test fixture. Scanning Acoustic microscopy, thermal, and compositional analyses were performed periodically during thermal cycling from -40 degrees C to 125 degrees C. Completion of this characterization has allowed for a comprehensive evaluation of thermal greases both for their initial bulk and contact thermal performance, as well as their degradation mechanisms under accelerated thermal cycling conditions.
Original languageAmerican English
Number of pages20
StatePublished - 2017

Publication series

NamePresented at the Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems, 30 May - 2 June 2017, Orlando, Florida

NREL Publication Number

  • NREL/PR-5400-70012


  • greases
  • non-silicone
  • silicone
  • steady-state technique
  • thermal conductivity
  • thermal interface materials
  • thermal resistance


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