In the Budget for 2024, the Government of India gave special impetus to lab-grown diamonds. Not only do these sparklers adorn jewellery, but they also find use in the industry — mainly for cutting. Now, a new application for synthetic diamonds is emerging — as heat-dissipating material in power electronics (electronics employed in controlling or converting electric power).

Power electronic components heat up as you increase their power density. Traditionally, copper is used to dissipate the heat, but for copper to not interfere with electricity, a thin layer of insulating material is kept around it. However one challenge remains — good insulators are bad conductors of heat. So, you need a substance that is very good at conducting heat but does not let electricity pass through.

One material fits the bill: diamond. “Diamond is electrically insulating but thermally conducting,” says Prof Satya Seshadri, Department of Applied Mechanics, IIT Madras. “That’s why it is a wonderful material for electronic cooling,” he told quantum.

Diamond’s capacity to conduct heat is about five times that of copper. Scientists have long been slavering at the prospect of using diamonds for cooling in power electronics.

In 2022, a group of researchers from China and Israel investigated the cooling enhancement of a cold plate made of single crystal diamond (SCD) that had microfluidic channels embedded on it. They studied the enhanced heat spreading due to conduction, followed by convective dissipation of a locally-heated resistor. “The results showed that cold plate made exhibited the highest cooling effect obtained for maximum applied power density and flow rate. Simulation results further support the improvement of the cooling capability due to the addition of microfluidic channels and the use of SCD as the substrate of the heat sink,” they say in their paper.

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While all this is fine in research, there is one practical problem: how to fabricate such an extremely thin sheet of diamonds.

Now, scientists at Fraunhofer USA Inc, Center Midwest CMW in East Lansing in Michigan, have developed nanomembranes from synthetic diamonds that are thinner than a human hair. These flexible materials can be integrated directly into electronic components to cool the power electronics.

Factor of ten

“The flexible, electrically insulating nanomembranes have the potential to reduce the local heat load of electronic components, such as current regulators in electric motors, by a factor of ten. The energy efficiency, service life and road performance of electric cars are improved significantly as a result,” says a Fraunhofer press release.

“We want to replace this intermediate layer with our diamond nanomembrane as diamond can be processed into conductive paths,” says Dr Matthias Mühle, head of the Diamond Technologies group at Fraunhofer. “As our membrane is flexible, it can be positioned anywhere on the component or the copper or integrated directly into the cooling circuit,” adds Mühle.