Heat sinks are mechanical devices that are used in electronic products as heat exchangers. Heat energy caused by the dissipation of power in components is directed away from them by heat sinks, reducing the associated temperature rise.

Heat sinks are available in a number of mounting options, attachment methods, and particular component-intended-to-be-cooled packages.  Shape and size also varies. They may also be accompanied by a fan or liquid cooling system. Many materials are used for heat sinks including aluminum, aluminum alloys, beryllium oxides, brass, ceramic and copper. These are available in different material surface finishing options.

Beryllium oxide is used in high power RF devices. Great care must be taken when handling beryllium oxide as it breaks easily. The powder form is more dangerous to inhale than asbestos.  Special disposal precautions are mandatory in some countries.

Heat sinks have several important specifications associated with their suitability for use in an application. Power dissipation at temperature rise indicates the maximum amount of heat that can be dissipated by the heat sink when sitting in an environment with the specified temperature. Thermal resistance at force airflow is a measure of the temperature rise per watt of power dissipated that would be expected based upon airflow through the heat sink fins. This is usually specified in liters per minute (LPM). Thermal resistance at natural or still air is the fan-less, stagnant temperature rise expected per watt dissipated.

Heat sinks have many attachment methods including adhesives, bolts, clips, board locks, press-fits, thermal tapes and soldering. Silicon thermal grease or thermal pads may be used to provide a good thermal coupling between the heat sink and the device being cooled. Care must be taken to ensure the part of the device being attached is not electrically live. If this is the case, insulating thermal pads need to be used. Phase change based interfacing materials are available in paste and pad form that utilize the phase change between solid and liquid to create highly efficient interfaces. These need to be thermally cycled once, which enables them to flow into interface voids and work as specified.