heat sink

Information about heat sink

as cooling devices. For alternative meanings see Heat sink (disambiguation)

CPU heat sink with fan attached

A heat sink (or heatsink) is an environment or object that absorbs and dissipates heat from another object using thermal contact (either direct or radiant). Heat sinks are used in a wide range of applications wherever efficient heat dissipation is required; major examples include refrigeration, heat engines and cooling electronic devices.

Principle

Heat sink in a workstation computer

A motherboard heat sink

Fire test where the steel pipe penetrants clearly act to absorb and conduct heat from the furnace, through to the unexposed side.

Heat sinks function by efficiently transferring thermal energy ("heat") from an object at 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.

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 result in the rapid transfer of thermal energy to the surrounding, cooler, air. 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.

Performance

Heat sink performance (including free convection, forced convection, liquid cooled, and any combination thereof) is a function of material, geometry, and overall surface heat transfer coefficient. Generally, forced convection heat sink thermal performance is improved by increasing the thermal conductivity of the heat sink materials, increasing the surface area (usually by adding extended surfaces, such as fins or foam metal) and by increasing the overall area heat transfer coefficient (usually by increase fluid velocity, such as adding fans, pumps, etc.).

Online heat sink calculators from companies such as Novel Concepts, Inc., can accurately estimate forced convection heat sink performance. For more complex heat sink geometries, and/or heat sinks with multiple materials, and/or heat sinks with multiple fluids, computation fluid dynamics (CFD) analysis is recommended (see graphics on this page).

Use in electronics

Explanation

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.

Construction and materials

A heat sink usually consists of a base with one or more flat surfaces and an array of comb or fin-like protrusions to 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.

Heat 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.

PC marketplace

Due to recent technological developments and public interest, the retail heat sink market has reached an all time high. In the early 2000s, CPUs were produced that emitted more heat than ever before, escalating requirements for quality cooling systems.

Overclocking has always meant greater cooling needs, and the inherently hotter chips meant more concerns for the enthusiast. Efficient heat sinks are vital to overclocked computer systems because the higher a microprocessor's cooling rate, the faster the computer can operate without instability; generally, faster operation leads to higher performance. 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.

In soldering

Temporary heat sinks were 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 heavy metal crocodile clip or similar clamp. Modern semiconductor devices, which are designed to be assembled by reflow soldering, can usually tolerate soldering temperatures without damage. On the other hand, electrical components such as magnetic reed switches can malfunction if exposed to higher powered soldering irons, so this practice is still very much in use. [1]

Recent developments

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.

As a problem in firestopping and fireproofing

A heat sink is rarely a desired thing in passive fire protection. Rather, it is usually a problem that must be overcome to maintain fire-resistance ratings. The proven ability to overcome heat sinks in construction is subject to building code and fire code regulations.

Firestopping

Problem - Metallic penetrants and sleeves, at a density of 7.9kg/L are more dense than common firestops or concrete. Consequently, during a fire, they will absorb more photons and seek to conduct these to the unexposed side of a fire barrier (thus "cooling" the exposed side at the expense of the unexposed side), such as the cold side of a firewall (construction). This is undesirable. Even if the fire is stopped by the barrier, one must keep the unexposed side cool to prevent autoignition of combustibles on the unexposed side of a fire barrier. The unexposed side may very well be an Area of refuge, which must be safeguarded to comply with the building code. Greater penetrant and sleeve conductivity leads to lower T-ratings. Higher density firestops, such as firestop mortars act as a heat sink to absorb heat away from small penetrants, such as cables, thus increasing T-ratings.
Benefit - a rare exception where heat sinks are beneficial in firestops is where intumescents must be activated, such as in a firestop containing a plastic pipe. Heat sinks such as wire mesh and extra metallic sleeving may be used to carry heat to intumescents to activate expansion such as to choke off a melting plastic pipe or melting pipe covering, such as foamed plastic or fibreglass.

Fireproofing

In fireproofing of structural steel as well as providing circuit integrity to cables, cable trays, junction boxes and electrical conduit, the metallic items that are protected by the fireproofing measures act as a heat sink. Fireproofing methods are used to defeat the heat sink properties of the items they protect. In the case of circuit integrity measures, electrical services will fuse and short circuit above 140°C.

External links

A heat sink is

a device used to conduct heat away from an object.
an urban area with a tendency to absorb sunlight and re-radiate it as heat, together with heat from energy usage. This may also be referred to as an urban heat island.

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In thermodynamics, a thermodynamic system is said to be in thermal contact with another system if it can exchange energy with it through the process of heat. Perfect thermal isolation is an idealization as real systems are always in thermal contact with their environment to some
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Refrigeration is the process of removing heat from an enclosed space, or from a substance, and rejecting it elsewhere for the primary purpose of lowering the temperature of the enclosed space or substance and then maintaining that lower temperature.
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A heat engine is a physical or theoretical device that converts thermal energy to mechanical output. The mechanical output is called work, and the thermal energy input is called heat. Heat engines typically run on a specific thermodynamic cycle.
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heat sink (or heatsink) is an environment or object that absorbs and dissipates heat from another object using thermal contact (either direct or radiant). Heat sinks are used in a wide range of applications wherever efficient heat dissipation is required; major examples include
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In thermal physics, thermal energy is the energy portion of a system that increases with its temperature. In a loose sense, "thermal energy" is a term often used to describe the energy content of a system related to heating effects, e.g. temperature increase or decrease.
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thermodynamic equilibrium when it is in thermal equilibrium, mechanical equilibrium, and chemical equilibrium. The local state of a system at thermodynamic equilibrium is determined by the values of its intensive parameters, as pressure, temperature, etc.
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thermal conductivity, k, is the property of a material that indicates its ability to conduct heat. It is used primarily in Fourier's Law for heat conduction.

It is defined as the quantity of heat, ΔQ, transmitted during time Δt
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FLUID (Fast Light User Interface Designer) is a graphical editor that is used to produce FLTK source code. FLUID edits and saves its state in text .fl files, which can be edited in a text editor for finer control over display and behavior.
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A Thermal Interface Material (aka TIM) is used to fill the gaps between thermal transfer surfaces, such as between microprocessors and heatsinks, in order to increase thermal transfer efficiency. These gaps are normally filled with air which is a very poor conductor.
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The Macro Expansion Template Attribute Language complements TAL, providing macros which allow the reuse of code across template files. Both were created for Zope but are used in other Python projects as well.
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Electronics is the study of the flow of charge through various materials and devices such as, semiconductors, resistors, inductors, capacitors, nano-structures, and vacuum tubes. All applications of electronics involve the transmission of power and possibly information.
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Microprocessor

Die of an Intel 80486DX2 microprocessor (actual size: 12×6.75 mm) in its packaging
Date Invented: Late 1960s/Early 1970s (see article for explanation)

Connects to:
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A semiconductor is a solid that has electrical conductivity in between that of a conductor and that of an insulator, and can be controlled over a wide range, either permanently or dynamically.^[1] Semiconductors are tremendously important in technology.
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Thermal mass, in the most general sense, is any mass that absorbs and holds heat. In the architectural sense, it is any mass that absorbs and stores heat during sunny periods when the heat is not desirable in the living space of a building, and then releases the heat during
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Heat conduction or thermal conduction is the spontaneous transfer of thermal energy through matter, from a region of higher temperature to a region of lower temperature, and hence acts to even out temperature differences.
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Convection in the most general terms refers to the movement of currents within fluids (i.e. liquids, gases and rheids).

Convection is one of the major modes of heat and mass transfer.
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Thermal radiation is electromagnetic radiation emitted from the surface of an object which is due to the object's temperature. Infrared radiation from a common household radiator or electric heater is an example of thermal radiation, as is the light emitted by a glowing
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integrated circuit (also known as IC, microcircuit, microchip, silicon chip, or chip) is a miniaturized electronic circuit (consisting mainly of semiconductor devices, as well as passive components) that has been manufactured in the surface of a
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A digital signal processor (DSP) is a specialized microprocessor designed specifically for digital signal processing, generally in real-time computing.

Characteristics of typical Digital Signal Processors

Designed for real-time processing

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graphics processing unit or GPU (also occasionally called visual processing unit or VPU) is a dedicated graphics rendering device for a personal computer, workstation, or game console.
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mechanical fan is a device used to produce an airflow for the purpose of creature comfort, ventilation, exhaust, or any other gaseous transport.

Mechanically, a fan can be any revolving vane or vanes used for producing currents of air.
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gradient of a scalar field is a vector field which points in the direction of the greatest rate of increase of the scalar field, and whose magnitude is the greatest rate of change.
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2, 1
(mildly basic oxide)
Electronegativity 1.90 (Pauling scale)
Ionization energies
(more) 1st: 745.5 kJmol⁻¹
2nd: 1957.9 kJmol⁻¹
3rd: 3666 kJmol⁻¹

Atomic radius 135 pm
Atomic radius (calc.
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Aluminium (IPA: /ˌæljʊˈmɪniəm/, /ˌæljəˈmɪniəm/) or aluminum (IPA: /əˈluːmɪnəm/
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Extrusion is a manufacturing process used to create long objects of a fixed cross-sectional profile. A material, often in the form of a billet, is pushed and/or drawn through a die of the desired profile shape.
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