Mixing, rheology, and stability of highly filled thermal pastes

Claudius Feger, Jeffrey D. Gelorme, Maurice McGlashan-Powell, Dilhan M. Kalyon

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

Thermal pastes play an important role in transmitting heat generated by an integrated circuit chip from its back side to a cooling cap or heat sink which transfers the heat to the environment. Most thermal pastes are formulations of solid, thermally conducting particles in a liquid matrix loaded to very high solids content. The mixing process for such pastes is complex but important, since it determines several of the paste properties. In particular, paste rheology is related to the work imparted to the paste during the mixing process. It determines the minimum bondline between solid surfaces that can be attained with a particular paste during the assembly process, which is essentially a squeezeflow process. Paste stability depends on the amount of entrapped ah" incorporated during the mixing process; this is demonstrated by infrared (IR) visualization of the degradation of air-containing paste in a computer-chip-heat-sink gap and the absence of this degradation mechanism in vacuum-mixed paste. This paper describes two different mixing processes for highly filled thermal pastes, the associated changes in their rheological behavior, and paste degradation in chip-heat-sink gaps during thermal stressing.

Original languageEnglish
Pages (from-to)699-707
Number of pages9
JournalIBM Journal of Research and Development
Volume49
Issue number4-5
DOIs
StatePublished - 2005

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