Editing Thermal paste (section)

== Composition ==
Thermal paste consists of a [[polymer]]izable liquid matrix and large volume fractions of electrically insulating, but thermally conductive filler. Typical matrix materials are [[epoxy|epoxies]], [[silicone]]s ([[silicone grease]]), [[polyurethane|urethanes]], and [[Acrylate polymer|acrylates]]; solvent-based systems, [[hot-melt adhesives]], and [[pressure-sensitive adhesive tape]]s are also available. [[Aluminum oxide]], [[boron nitride]], [[zinc oxide]], diamond and increasingly [[aluminum nitride]] are used as fillers for these types of adhesives. The filler loading can be as high as 70–80% by mass, and raises the [[thermal conductivity]] of the base matrix from 0.17–0.3&nbsp;W/(m·K) (watts per meter-kelvin)<ref>{{citation | author=Werner Haller | contribution=Adhesives | title=[[Ullmann's Encyclopedia of Industrial Chemistry]] | edition=7th | publisher=Wiley | year=2007 | pages=58–59 |display-authors=etal}}.</ref> up to about 4&nbsp;W/(m·K), according to a 2008 paper.<ref>{{cite conference | url = http://www.nrel.gov/docs/fy08osti/42972.pdf | title = Thermal interface materials for power electronics applications | last1 = Narumanchi | first1 = Sreekant | last2 = Mihalic | first2 = Mark | last3 = Kelly | first3 = Kenneth | last4 = Eesley | first4 = Gary | date = 2008 | publisher = IEEE | book-title = 11th Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems, 2008: ITHERM 2008: 28–31 May 2008 | at = Table 2 | doi = 10.1109/ITHERM.2008.4544297}}.</ref>

Silver thermal compounds may have a conductivity of 3 to 8 W/(m·K) or more, and consist of [[micronized]] silver particles suspended in a silicone/ceramic medium. However, metal-based thermal paste can be electrically conductive and capacitive; if some flows onto the circuits, it can lead to malfunction and damage.

The most effective (and most expensive) pastes consist almost entirely of [[liquid metal]], usually a variation of the alloy [[galinstan]], and have thermal conductivities in excess of 13 W/(m·K). These are difficult to apply evenly and have the greatest risk of causing malfunction due to spillage. Furthermore, these pastes contain [[gallium]] which is highly corrosive to [[aluminium]] and thus cannot be used on aluminium heat sinks.