How to Select Heat Sink Paste


The microprocessors in your computer generate a lot of heat and they have to be led away by the integrated heat sink (or IHS) that covers the CPU, and through thermal paste. This is a dense substance that enhances the transfer of energy between the microprocessor and the heat sink, improving its performance.

A great thermal paste will withstand years of heat cycling without pumping out or separating from the surfaces it is applied to. It should have a very high thermal conductivity rating and be easy to spread. It should be able to fill the microscopic imperfections on the surfaces of the IHS and the heat sink base.

Besides the thermal conductivity, other things to consider in selecting a thermal paste are ease of use and cost. You should also be able to find one that is RoHS compliant.

There are a few different types of thermal pastes available, and they are generally grouped into three categories: metal-based, ceramic-based, or silicone-based. The metal-based ones are the most highly conductive, and can have conductivities of 13 W/m*K or more. They are usually based on silver, and contain micronized silver particles in a ceramic medium. However, they are also electrically conductive and capacitive and can cause circuit malfunction if they flow onto the components’ electronic pathways. They are also corrosive to aluminum, so they should not be used with aluminum heat sinks. Other types of thermal compounds are based on silicon and have lower thermal conductivities.Heat sink paste