Cooling fins & heat sinks

Heat sinks function by efficiently transferring thermal energy ("heat") from an object at a relatively high temperature to a second object at a lower temperature with a much greater heat capacity. This rapid transfer of thermal energy quickly brings the first object into thermal equilibrium with the second, lowering the temperature of the first object, fulfilling the heat sink's role as a cooling device. Efficient function of a heat sink relies on rapid transfer of thermal energy from the first object to the heat sink, and the heat sink to the second object.

Mdm Koo:
Therefore, a good conductor is being used for rapid transfer of thermal energy.

The most common design of a heat sink is a metal device with many fins. The high thermal conductivity of the metal combined with its large surface area due to the fins results in the rapid transfer of thermal energy to the surrounding, cooler material. This cools the heat sink and whatever it is in direct thermal contact with. Use of fluids (for example coolants in refrigeration) and thermal interface material (in cooling electronic devices) ensures good transfer of thermal energy to the heat sink. Similarly a fan may improve the transfer of thermal energy from the heat sink to the air by moving cooler air between the fins.

Mdm Koo:
Many thin metal fins with gaps in between
-> large surface area in contact with surrounding cooler air
-> rapid transfer of thermal energy away from source to surrounding

SOURCE - http://en.wikipedia.org/wiki/Heat_sink



To overcome the problem of overheating, conduction, convection and radiation are used to remove as much heat as possible from the device to keep it cool.

Conduction - the cooling fins are made from a good conductor and fastened firmly to the engine/chip. This allows thermal energy to be conducted effectively from the engine/chip to the cooling fins.

Convection - the surface area of the metal in contact with air is increased by shaping the cooling fins into many flat layers. Once the thermal energy is conducted to the air, convection will bring the thermal energy away. In the case of a microprocessor chip, fan is usually mounted to increase the rate of convection.

Radiation - the increased surface area of the cooling fins increases the rate of energy transfer by radiation.