Feature: Thermal management
Figure 4: The operating principle of a phase-change material
or two-phase, with the latter offering even greater cooling capacity. Solid-state cooling is another option,
known as thermoelectric coolers (TECs). Tese use the Peltier effect to create a temperature difference under electric current; see Figure 4. TECs are unique in that they can both cool and heat electronic components, somewhat like the heat pumps used to heat and cool homes. Tis dual capability makes them a versatile solution for precise thermal management; see Figure 3. Phase-change materials (PCMs) are
another option. Tese are substances that absorb and release heat during phase transition, say from solid to liquid, etc. In electronic devices, PCMs act as thermal buffers, effectively absorbing excess heat and releasing it when the temperature decreases. They have proven most useful in applications where rapid temperature
changes occur, such as in hot spots on IC chips. There are other solutions available,
including newer materials with engineered properties that far exceed those of natural materials. Thermal interface materials (TIMs) deal very successfully with chips’ hot spots. TIM examples include graphene- based materials, which are atom- thick sheets of carbon. Their thermal conductivity properties are exceptional, so researchers have been exploring them as heat spreaders and for various other applications. Finally, there is integrated thermal
management, wherein the entirety of the electronic module or assembly is created with a thermal solution integrated into it. This is increasingly seen in heterogeneous integrated packaging solutions. This has also been
the objective of the Occam Process first described by Verdant Electronics. In such structures, the electronic assembly is built on the heat spreader in a reverse manufacturing process. This is done without solder, thus bypassing a stressful thermal excursion in the manufacturing process; see Figure 5.
Engineering a solution It’s worth noting that, while in the past much effort was of the trial-and- error type in dealing with thermal management challenges, with computers getting better all the time, computational techniques and finite element modelling software for thermal investigations have become indispensable tools. Today, engineers can design assemblies and simulate their thermal behaviour, to optimise their cooling solutions before ever making a product prototype.
Figure 5: Cross-section of a prospective integral thermal management solution described by Verdant Electronics, with both internal and external heat sinks offering 3D thermal relief
36 November 2023
www.electronicsworld.co.uk
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