An air-cooled heat sink utilizes the natural air flow for cooling and it conducts heat from the heat source to the fins of the heat sink via materials such as copper or aluminum in order to realize the cooling by natural convection. When the amount of heat is larger, it can be used with a cooling fan for more cooling capacity.
　　If we take a CPU cooler for PC as an example, the structure of an air-cooled heat sink is composed of four portions which include the cooling fan, cooling fins, fasteners, and accompanying speed-adjusting devices, each of which has different functions.

Fans used on a cooler for PCs can be classified into two categories as follows.
　The first category include the axial fans (square fans and round fans), which are widely used since their price is lower. The principle of operation is to utilize the lift generated by the fan blades so that air is flowing in the axial direction. Typically the impeller is directly coupled with the motor so that it is small in size and lightweight.
　The second category includes the centrifugal fans(blowers) which utilize the centrifugal force so that air is flowing on the radial direction of the blades. This results in a much higher air pressure so that it can be installed in locations where the ventilation impedance is higher. Most of graphics card cooling is utilizing this type of fans.
　For higher power devices which utilize air cooling, a cooling fan is very important since it can enhance the air flow and allows the heat on the fins to be better transferred to the ambient air so as to greatly enhance the cooling effect. The coolers that we often see on our daily lives on CPUs or power supplies are smaller heat sinks for lower power devices. Winshare Thermal is a professionalheat sink manufacturer,who produces not only this type of heat sinks for smaller power devices but also heat sinks for higher power devices such as heat sinks for medium-to-high voltage frequency converter, PV power inverters, etc.