a recent article from norwood, mass.-based thermal engineering design and manufatcuring company advanced thermal solutions, inc. (ats) explores some of the more recent industry developments in thermal interface materials (tims) and how they are used in the thermal management of electronics.
new tims are more effective than thermal grease in conducting heat. (wikimedia commons)
“as a product line, tims have continuously evolved, driven by market needs for higher thermal conductivity, lower thermal impedance, new applications and lower costs,” the article explained.
the article outlines three material categories for tims – polymers with thermally-conductive filler, solder-based, and carbon-based tims that utilize new materials, such as graphene, but have not been commercialized.
one of the new tim fillers that the article looked at is boron nitride nanosheets (bnns), which are two-dimensional crystalline forms of hexagonal boron nitride (white graphene). the nanosheets are as thin as a few atomic layers and provides high thermal conductivity while also being an electrical insulator.
studies at rice university have explored the possibility of this material enhancing tim performance. according to the article, “thermal performance improved with the bn coating due to its anisotropic thermal conductivity. it had a high in-plane thermal conductivity of 140 w/mk for spreading and a low cross-plane thermal conductivity of 4 w/mk to avoid a hot spot beneath the tested device.”
solder-based tims are a replacement for thermal grease because of its improved thermal conductivity, the lack of pump-out that affects grease, and the lack of bake-out over time.
“recent solder-based tims developed by indium corporation include a new sma-tim (soft metal alloy),” the article continued. “this is made from an indium solder base and offers uniform thermal resistance at lower applied stresses in compressed interfaces. it is provided as a compressible metal foil that can be used as a tim between a heat source and a heat sink, heat spreader, or heat pipe.”
carbon-based tims are focused on using graphene, graphite, diamonds, and carbon nanotubes and their exciting properties as fillers. as the article noted, these materials are often used in combination to make them more cost-effective without losing the efficiency.
the article concluded, “costs and other factors pose development challenges to tims with carbon-based heat transfer schemes. but given the high thermal conductivity and various configurations available from carbon-based materials, these will likely be at the heart of many upcoming performance advancements in tims.”
watch the video below to see how ats uses tims with its heat sinks:
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