What is the Purpose of Thermal Paste?

The device used to remove the processor’s heat is the cooler. Each processor requires a specific type of cooler. The use of an inefficient or wrongly dimensioned cooler can cause overheating problems.

However, the cooler alone doesn’t solve the overheating problem. There’s another “bad guy” in the story: heat transfer between the processor and the cooler.

From the microscopical point of view, the physical contact between the processor and the cooler isn’t perfect. Imperfections that exist both on the processor surface and the cooler surface prevent their being a 100% perfect contact between them.

As both surfaces aren’t perfectly even, minuscule gaps of air are formed when putting them together. Because air is a terrible heat conductor (its conductibility coefficient is 0.026 W/m°K), the heat will pass with more difficulty from the processor to the cooler, which can result in overheating.

Thermal GreaseFigure 1: Air gaps formed by the junction of the processor and cooler

To solve the problem and improve the heat transfer between the processor and the cooler, we should apply thermal paste between them in order to fill in the tiny gaps of air. By doing so, the heat transfer between the processor and the cooler is easier since the thermal paste has a higher conductibility coefficient than the air.

Thermal GreaseFigure 2: Gaps of air filled by thermal paste

Thermal paste can be found in electronics parts stores. Its use is indispensable and it’s a very inexpensive component.

On the following pages, we will discuss how to correctly apply thermal paste, as well as stating the most common mistakes made when applying it.

Daniel Barros lives in Brazil and used to be our motherboard reviewer. He is a partner at a local PC sales and maintenance store.