Metallic materials are widely used as heat dissipation materials, but there have been many attempts to replace the metallic materials with highly thermally conductive polymers. I need reasons and ways to use them.
because thermal conductivity is directly linked with electrical conductivity. Insulators like polymers are therefore very bad thermal conductors.
if polymers were to be used as thermal conductor, they need to be made conductive (using conductive fillers). This results in some limited conductivity and hence some improvement in thermal conductivcity, but again: limited.
You indeed need a rather high termal conductivity for dissipating heat, and polymers are very bad from this point of view. But if you are looking for a lightweight, conductive material, graphite is excellent and can be machined very easily. Carbides, nitrides and all these kinds of ceramics may also have high thermal conductivities, but are very hard and fragile, so they are difficult to process. And expensive !
Alain
Addition of synthetic/industrial diamond particles in the certain materials to use as a composite for thermal management is another way to do it.
Unlike metals, which are good electrical and heat conductors, crystalline solids such as diamond and semiconductors such as silicon are good heat conductors but poor electrical conductors. As a result, such materials find widespread use in the electronics industry. Despite their higher price, diamond heat sinks are used in the cooling of sensitive electronic components because of the excellent thermal conductivity of diamond. Silicon oils and gaskets are commonly used in the packaging of electronic components because they provide both good thermal contact and good electrical insulation.
Hi Ramesh,
Highly filled polymer system with ceramic material such as boron nitride is an alternative to metal counterpart, which requires very specific application. There are some applications where there is a need for higher thermal conductivity, and poor electrical conductivity (such as containers to carry sensitive electronics). The main disadvantages of highly filled thermally conductive polymer systems are cost, and processing complexity. That is the main reason why it is hard to replace existing metal heat sinks structures with highly filled polymer ones.
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