Heat sink
In common use, it is a metal object brought into contact with an
electronic component's hot surface — though in most cases, a thin
thermal interface material mediates between the two surfaces.
Microprocessors and power handling semiconductors are examples of
electronics that need a heat sink to reduce their temperature through
increased thermal mass and heat dissipation (primarily by conduction and
convection and to a lesser extent by radiation). Heat sinks are widely
used in electronics, and have become almost essential to modern
integrated circuits like microprocessors, DSPs, GPUs, and more.
A heat sink usually consists of a base with one or more flat surfaces
and an array of comb or fin-like protrusions increase the heat sink's
surface area contacting the air, and thus increasing the heat
dissipation rate. While a heat sink is a static object, a fan often aids
a heat sink by providing increased airflow over the heat sink — thus
maintaining a larger temperature gradient by replacing the warmed air
more quickly than passive convection achieves alone — this is known as a
forced air system.
CPU heat sink with fan attachedHeat sinks are made from a good
thermal conductor such as copper or aluminum alloy. Copper (401 W/(m·K)
at 300 K) is significantly more expensive than aluminum (237 W/(m·K) at
300 K) but is also roughly twice as efficient as a thermal conductor.
Aluminum has the significant advantage that it can be easily formed by
extrusion, thus making complex cross-sections possible. The heat sink's
contact surface (the base) must be flat and smooth to ensure the best
thermal contact with the object needing cooling. Frequently a thermally
conductive grease is used to ensure optimal thermal contact, such
compounds often contain colloidal silver. Further, a clamping mechanism,
screws, or thermal adhesive hold the heat sink tightly onto the
component, but specifically without pressure that would crush the
component.
A motherboard heat sinkDue to recent technological developments and
public interest, the retail heat sink market has reached an all time
high; many companies now compete to offer the best heat sink for PC
overclocking enthusiasts. Prominent aftermarket heat sink manufacturers
include: Aero Cool, Cooler Master, Foxconn, Thermalright, Thermaltake,
Swiftech, and Zalman. Efficient heat sinks are vital to overclocked
computer systems because the better the various microprocessors' cooling
rate, the faster the computer can operate without instability;
generally, faster operation leads to higher performance.
Temporary heat sinks are sometimes used while soldering circuit
boards, preventing excessive heat from damaging sensitive nearby
electronics. In the simplest case, this means partially gripping a
component using a metal crocodile clip or similar clamp.
More recently, synthetic diamond cooling sinks are being researched
to provide better cooling. Also, some heat sinks are constructed of
multiple materials with desirable characteristics, such as phase change
materials, which can store a great deal of energy due to their heat of
fusion.