Heat Sinks Information

Extruded Heat Sink image

Heat sinks are thermally conductive components or devices that absorb and dissipate heat generated by electronic components. Heat sinks cool high-powered devices to prevent overheating. The reliability of electronic components is generally reduced by the square of an increase in temperature. For example, doubling the ambient temperature around a component renders the component 25% less reliable than at the lower temperature. Heat sinks are therefore essential in dissipating generated heat and improving component longevity.

A list of devices which commonly use heat sinks is found below.

  • Computers: central processing units (CPU) and graphics cards. Heat sinks became essential to computers in the 1990s when processor speeds, and therefore the heat generated by the processor, increased exponentially.
  • Optoelectronics: light-emitting diodes (LED) and lasers. Cooling is essential in LED and laser use, as device performance and lifespans are functions of their temperature.
  • Soldering. Heat sinks were commonly used to protect nearby electronic components during soldering processes, although modern semiconductors can typically dissipate heat without protection. Some components, such as reed switches, still require heat sink protection when in close proximity to soldering.
  • High-power semiconductors, such as transistors.

Types of Heat Sinks

Heat sinks are typically classified by production method and form factor. Information about the most prominent types is contained in the table below.









Useful in most situations; easy to automate production after design is completed.



Low cost

Limited to dimensions of extruded aluminum

Extruded Heat Sink image


Stamped from a single piece of metal; easy to automate production.



Low cost

Poor performance

Stamped Heat Sink image

Bonded Fin

Produced by bonding individual fins to a base; relatively difficult to manufacture.

Large devices


Available in large sizes


Bonded Fin Heat Sink image

Folded Fin

Fin pitch is optimized for air flow; may be plastic.

Ducted air


High heat-flux density

Expensive; ducting necessary

Folded Fin Heat Sink image


Includes a powered fan or blower for air movement; not a viable long-term solution; moving parts wear and break down.

Emergency or quick-fix situations


Simple, “Band-aid” solution

Poor reliability; high cost; recirculation of warm air

Active Heat Sink image


Manufactured by compressing aluminum or copper.



Low cost

Limited design

heat sinks selection guide


Similar to forged heat sinks; manufactured by forming metal to a die.



Ideal for power devices

Heavy and unwieldy; poor flow management

Swaged Heat Sink image

Single Fin

Versatile devices; designed to be employed in tight spaces.



Lightweight, low profile


Single Fin Heat Sink image


Fins are cut (skived) from a single block of metal (usually copper).



High fin density

Thick base and high weight; directionally sensitive

Skived Heat Sink image

Table image credits: IXBT Labs | Kunze | Carlton-Bates | IXBT | Electronics Cooling | Advanced Thermal Solutions | IXBT

Theory and Design

Heat sinks transfer thermal energy from a high-temperature device to a lower temperature medium. This medium is typically air, but may also be water, a refrigerant, or oil.

An excellent, comprehensive video on heat sink design and its relation to electrical design.

Video credit: EEVblog / CC BY-SA 4.0

Heat sink design depends heavily on Fourier's law of conduction; the formula with regards to a single axis (x) is shown below. (It is important to note, as shown in the video above, that Fourier's law is the thermal analog of Ohm's law.)

heat sinks selection guide


qk = heat flow per area and time

k = conductivity constant

A = surface area of heat transfer

dT = temperature difference

dx = material thickness

The image below illustrates the importance of this formula in heat sink design. As shown in the heat flow diagram at the bottom right of the image, heat sinks must have sufficient surface area and thickness to properly dissipate temperature.

Fourier's Law of Conduction equations

Image credit: Patrick M. Len

The simplest heat sink could consist of a single piece of thermally conductive metal. The protective case of the device containing the heat-generating component could theoretically function as a heat sink as well. However, most heat sinks use fins to increase surface area and create optimal air flow patterns, as shown in the table above.

Material Considerations

Heat sinks are typically constructed using aluminum alloys, most of which have high thermal conductivity values. Copper is considerably denser and more expensive than aluminum, but has superior thermal conductivity, corrosion resistance, and more efficient heat absorption. Various applications and industries, such as power plants, HVAC systems, geothermal heaters and coolers, and electronic systems employ copper heat sinks.

Composite materials such as synthetic diamond, AISIC, Dymalloy, and copper-tungsten pseudoalloy are occasionally used as chip substrates or submounts, which double as heat sinks.


Heat sinks may be produced, tested, and used according to specific published standards. A list of example standards is found below.

NAS4122 - Extruded heat sinks

SAE AIR1957 - Heat sinks for airborne vehicles

NAS4121 - Formed heat sinks

References and Resources

ATS—Heat sink types: The pros and cons (2 parts)

Sukhvinder S. Kang, "Advanced Cooling for Power Electronics," paper presented by invitation at International Conference on Integrated Power Electronics Systems, 6-8 March 2012, Nuremberg, Germany (pdf).

Image credits:

Ohmite Manufacturing Co. | Rego Electronics


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