YouTuber hardware enthusiast and Thermal Grizzly boss der8auer tested a two-year-old liquid metal thermal interface material (TIM) application with an electron microscope in his new video, discovering that it doesn’t dry out. Instead, the gallium bonds with the copper in a reaction to form a solid compound. On copper, that layer’s heat conduction performance is about one-quarter of the bare metal’s, and nickel plating keeps it about 10 times thinner.

His test showed the TIM as liquid after one hour, no liquid visible with crystals everywhere at the two-month mark, and then unchanged after two years. “After a total of two years, this honestly did not change further,” he said. The test relied on storing the setup in a vacuum or a nitrogen-filled box between sessions to avoid oxidation.

The TIM in question is an alloy of gallium and indium, often including tin, which is liquid at room temperature (Thermal Grizzly sells its own as Conductonaut); gallium melts at about 30 degrees Celsius, with the gallium-indium-tin mix melting at only 11 degrees. Improving cooling at the interface bottleneck is becoming a real issue as heat per surface area continues to rise. His examples are the RTX 5090 and RTX 5080, which he says have “twice” and “three times” the power density of the 8800 GTX.

How the liquid metal reacts depends on the cooler material. With aluminum, the gallium travels along the grain boundaries once the oxide layer is broken, and this weakens the metal. His demo on a scrap 2 mm aluminum sheet showed surface swelling after about five minutes, and it became brittle within half an hour.

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