Other Definitions
heat sink (dict)
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Heat SinkA heat sink is strictly defined as: an environment or object capable of absorbing heat from another object with which it is in thermal contact (either direct contact or radiational "contact"). In common use, it is a device, usually made of metal, brought into contact with the hot surface of a component, such as a microprocessor chip, to help cool that component through thermal dissipation by conduction and convection. Heat sinks are widely used in electronics and computers, and have become almost essential to modern central processing units. On circuit boards, the heat sink assembly usually consists of a flat metal body protruding up from the board, often bonded to a metal fin structure that reduces the thermal resistance to air. A good heat sink is vital to overclocked computer systems because the cooler a microprocessor is, the faster it can be made to run without instability. Heat sinks are commonly made of a good heat dissipating material such as copper or aluminum. On higher-end heatsinks, the outside or bottom is plated with gold to increase thermal transfer. To increase the rate of dissipation, heat sinks usually have "fins," thin strips or spikes protruding from the heat sink body that provide greater surface area in contact with the cooler ambient air. A fan is generally used with a heat sink to increase airflow. A smoother surface of contact between the heat sink and the object being cooled yields better heat dissipation, as it decreases the number of gaps between the contacting surfaces. Computer chips often have a small internal heat sink within the chip body that presents a smooth metal exterior surface for better bonding to an external heat sink. Usually a thermal pad or thermal grease is placed between the heat sink and the device being cooled to aid in heat conduction by ensuring that no air, an insulator, is trapped between the surfaces. Thermal grease offers superior performance to Thermal pads, although it is more difficult to work with and is therefore not used by mass production PC assemblers. These greases may contain powdered silver, powdered carbon, aluminum oxide, ceramic materials, or other particles in order to transfer heat from the processor to the heat sink. Studies have shown that a great many of the thermal greases advertised to included powdered silver, including the offering from CompUSA, were shown NOT to include any silver or silver oxide whatsoever. Instead these products included the inferior conductor Aluminum Oxide. Heat sinks are usually rated on their thermal resistance. The greater the thermal resistance, the lower the quality of the heat sink. For example, copper has less thermal resistance than aluminum, and so is generally a better heat sink material. to recent technological developments and public interest, the market for commercial heat sink cooling for CPUs has reached an all time high; many companies now compete to make the best heat sink for PC overclocking enthusiasts. Some of the more prominent heat sink makers include: Thermalright, Thermaltake, Aero Cool, Cooler Master, Zalman, and Swiftech. Temporary heat sinks are sometimes used in soldering circuit boards in order to prevent the heat from damaging sensitive nearby electronics - in the simplest case, this means gripping part of a component to be soldered with a crocodile clip or similar. Other Meanings In urban planning, an urban area may be referred to as a heat sink (or urban heat island) because of its tendency to absorb sunlight and re-radiate it as heat, together with heat from energy usage.
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