Heatsinks are cooling mechanisms used to draw out thermal energy from a variety of electronic components. Without these devices, a wide variety of components would be subject to overheating. The most common heat sink applications are for computer CPU's, microprocessor chips and circuit boards. Ready made heat sinks are implemented for specific solutions, although they are often a part of a system's original design.
The standard materials used to construct a heat sink are aluminum and copper, due to the high conductivity of these metals. Gold plating is also a feature of the better quality heatsinks, as it is used for upping the high transfer of thermal energy. The basic design involves a flat surface placed directly onto the source of heat. Coming out from this is the body of the heatsink, which is often stacked with cooling fins that are used to carry the heat out into the air. The best designs promote thinner fins, so that a greater surface area is then exposed. Thicker fins, however, should be considered for optimal thermal transfer within the heatsink to its cooling fins.
Depending on the device's design, a fan can be applied to create heatsink airflow that benefits the cooling process. If a heat sink is constructed to be passive, then a fan pushing air through it will do little to the overall cooling effect. But regardless of the internal design, heatsink fans are necessary to cool the external air so that heatsinks can function properly.
A variety of measures are taken to decrease a heat sink's thermal resistance, and thereby increase its effectiveness in conducting heat. While the choice of which metal and plating to use is important, other resistance-lowering factors include the smoothness of the heat sink base because the flatter it is, the less resistant it will be. In addition, a special grease or padding can be applied in between the base and the heat source in order to further reduce thermal resistance.
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