Article
In another article, we talked about power management with regard to various types of fuses. In particular, we discussed their applications in electronic devices and semiconductor applications. However, proper fusing isn't the only consideration when dealing with these types of circuits.

Managing Power in the Workplace – Heat Sinks

Steve Maurer, IME
In another article, we talked about power management with regard to various types of fuses. In particular, we discussed their applications in electronic devices and semiconductor applications.

However, proper fusing isn't the only consideration when dealing with these types of circuits. Often these applications generate considerable heat, which must be controlled and dissipated.

The dispersion of this heat is carried out by a heat sink. There are various types of these components, and we'll look at some in a minute.

However, let's talk about their purpose and why they're necessary. Every electrical and electronic component generates heat when active. High-power semiconducting components and devices generate considerable amounts of heat during operation. Some examples are power transistors, and optical electronics such as LEDs (light emitting diodes).

The heat generated must be removed in order to improve component efficiency, and prevent premature component failure.

Failure to remove the heat may lead to a fault or failure of the entire system of which the individual component is a part.

A heat sink disperses the excess heat into the surrounding media, such as air or liquid. While some components may dissipate heat adequately through radiation, others must be assisted, either by convection or conduction.

Two major types of heat sinks are active sinks and passive sinks.

Open up a personal computer and you'll see a heat sink comprised of a set of fins with a cooling fan. The fan draws hot air away from the electronic component an into the surrounding air.

While this is an effective method of heat dispersal, it may not be suitable for long term applications. As with any electrical component, eventual failure is something to be considered. Close monitoring and preventive maintenance may be necessary to prevent fan failure.

Enter the passive heat sink. The heat sink itself has no moving parts, and consists of a series of fins bonded to a baseplate that draws heat from the component. The fins are grouped on a plate, creating a large overall surface in a relatively small footprint. As air flows through the plates due to convection, heat is removed from the electronic components.

Obviously, these finned sinks must be kept clean and debris-free to ensure the passage of air isn't blocked and that the fins themselves don't become coated with dust and dirt, which would act as an insulator and keep the fins from dissipating head adequately.

Many finned heat sinks are bonded or glued to the base plate. This can cause some loss of efficiency as the bond, particularly glue, creates a thermal barrier. Additionally, the bonding process limits the size of the fins and can fail under harsh environments.

A better method of attaching fins to the baseplate is swaging. The swaging technology used on heat sinks eliminates bonding or gluing interfaces between fins and base plate. It provides a more robust design, suitable for use in higher operating temperatures in Silicon Carbide (SiC) applications.

Another type of heat sink is the heat pipe, which provide instantaneous cooling action. A heat pipe consists of an enclosed tube containing a liquid (methanol, water) in a vacuum. The pipe is embedded into the plate using a variety of methods and configurations. The liquid absorbs thermal energy from the heat sources and boils rising towards the condenser. Air cools the condenser section, condensing the fluid back to a liquid which travels back to the evaporator by gravity.

Other types of liquid cooled heat sinks continuously circulate a liquid medium to remove heat from the components.

So power management isn't just keeping circuits flowing via fuse protection. It also includes preventing premature component failure by controlling and dissipating the heat generated by the system itself.
Photo courtesy of Mersen
Arlington Steel Fan/Fixture Box
advertisement
Make code-compliant installations simple with Vive Wireless lighting solutions
advertisement