Many consumers take today’s powerful computers and electronics for granted. Since most consumer electronics are enclosed in attractive plastic cases, it’s easy to ignore the amount of engineering that goes into developing these incredible devices.
While much attention is given to the development of new software and cloud-based systems, the entire consumer electronics industry depends on the existence of incredibly fast processors. And the challenges associated with developing them don’t lie only in the realm of designing circuits and microchips. In fact, one of the greatest challenges facing today’s efforts to make processors more powerful is the removal of excess heat using heat sinks.
In a processor, billions of calculations are performed every second. These calculations depend on electronic currents flowing through increasingly tiny metal pathways. As a result of the tiny cross-sectional area of the conductors, a lot of heat is generated in the same process that the wires in a toaster heat up when a current flows through them.
Traditionally, this heat has been absorbed by metal heat sinks, which absorb the heat from the processor and conduct it away, often to metal fins or posts that then release the heat into the air, which is typically carried away by a fan in high-powered applications.
The use of metals instead of plastics for the production of heat sinks has historically made sense – metals are natural conductors of electricity, while plastics are typically strong insulators. However, the inherent advantages of plastics – light weight, ease of molding, and resistance to conducting electricity – have cause some researchers and companies to begin to develop plastics that can conduct heat effectively. Typically, this is done by adding additives such as graphite or ceramics, including, aluminum nitride and boron nitride, to the plastic products.
The use of plastics for heat-absorbing applications has another major advantage – plastics do not expand nearly as much as metals when they become hot. This fact greatly simplifies the engineering of electronic devices containing plastic heat sinks.
The main cost currently holding back the expansion of the heat-conductive plastics industry is high production costs. According to publication Plastics Technology, heat conductive plastics still cost 2-2.5 times as much as traditional materials, limiting their use to high-end applications. If the history of the plastics industry is any guide, we should expect the costs of these high-tech materials to fall in the future.
If you’re interested in thermally conductive plastics, I would suggest reading this interesting article published in Popular Science, describing an intriguing plastic material that conducts heat in only one direction.