Heat Sink is a component designed to lower the temperature of an electronic device by dissipating heat into the surrounding air. A heat sink without a fan is called a passive heat sink; a heat sink with a fan is called an active heat sink.Heat sinks are generally made of an aluminum alloy and often have fins.
A heat sink is a passive heat exchanger that transfers the heat generated by an electronic or a mechanical device into a coolant fluid in motion. Then-transferred heat leaves the device with the fluid in motion, therefore allowing the regulation of the device temperature at physically feasible levels. In computers, heat sinks are used to cool central processing units or graphics processors. Heat sinks are used with high-power semiconductor devices such as power transistors and optoelectronics such as lasers and light emitting diodes (LEDs), where the heat dissipation ability of the basic device is insufficient to moderate its temperature.
A heat sink is designed to maximize its surface area in contact with the cooling medium surrounding it, such as the air. Air velocity, choice of material, protrusion design and surface treatment are factors that affect the performance of a heat sink. Heat sink attachment methods and thermal interface materials also affect the die temperature of the integrated circuit. Thermal adhesive or thermal grease improve the heat sink's performance by filling air gaps between the heat sink and the heat spreader on the device.
Though the most common heat sink material isaluminium alloys various types of heat sinking materials are used in LED lighting systems. Any material that can conduct heat away from the LED can serve as a heat sink. Most metals are excellent conductors of heat and therefore many LED manufacturers suggest that mounting materials containing metal frames, fasteners and connectors be used, and that the contact area between the LED and its mounting surface be maximized. It is also important to make a good thermal contact between the LED and its mounting surface.
Recent illumination-grade LEDs contain metal fins and wings to assist in heat sinking as well as large, flat areas suitable for attachment to heat sinks. Even larger heat sinking devices, such as those used in some computer systems, consisting of metal slugs shaped to maximize their surface area, can be incorporated into LED systems containing arrays of LEDs. These could even be integrated into the design of the system to increase attractiveness.