Liquid Metal TIM Solidifies Over Time, Study Shows Implications for High-Performance Cooling

YouTuber der8auer applied a liquid-metal thermal interface material (TIM) to a copper cold plate and stored the assembly in a vacuum- or nitrogen-filled box. Electron-microscope images after one hour showed the TIM still liquid; after two months crystalline structures appeared. After two years the material stopped changing, indicating it chemically transforms into a solid compound rather than drying out.

Experiment shows liquid metal TIM doesn’t dry out; it turns solid — two-year electron microscope test finds gallium bonds with copper coolers, and nickel plating keeps the layer about 10 times thinner

• Copper: Gallium reacts with copper to form CuGa2, solid up to ~254 °C and conducting ~100 W/m·K (?¼ of bare copper). The layer grows ~1 µm per day, reaching 50–100 µm.

Experiment shows liquid metal TIM doesn’t dry out; it turns solid — two-year electron microscope test finds gallium bonds with copper coolers, and nickel plating keeps the layer about 10 times thinner

• Aluminum: Gallium penetrates grain boundaries once the oxide is broken, causing swelling within minutes and brittleness within half an hour.

Experiment shows liquid metal TIM doesn’t dry out; it turns solid — two-year electron microscope test finds gallium bonds with copper coolers, and nickel plating keeps the layer about 10 times thinner

• Nickel-Plated Surfaces: Gallium forms NiGa5, producing a thinner (1–5 µm) layer with lower conductivity than CuGa2, which limits gallium absorption into the substrate.

Experiment shows liquid metal TIM doesn’t dry out; it turns solid — two-year electron microscope test finds gallium bonds with copper coolers, and nickel plating keeps the layer about 10 times thinner

• Layer Growth: ~1 µm per day on copper, capping at 50–100 µm. Pure gallium between copper plates at 70 °C expanded ~4 µm over 96 hours.

Experiment shows liquid metal TIM doesn’t dry out; it turns solid — two-year electron microscope test finds gallium bonds with copper coolers, and nickel plating keeps the layer about 10 times thinner

• Thermal Conductivity: CuGa2 ? 100 W/m·K; copper ? 400 W/m·K. NiGa5 conducts less efficiently, exact values not disclosed.

Experiment shows liquid metal TIM doesn’t dry out; it turns solid — two-year electron microscope test finds gallium bonds with copper coolers, and nickel plating keeps the layer about 10 times thinner

Removing the solid film is difficult. der8auer recommends Thermal Grizzly’s TG Metal Polish & Restore, a surfactant-based product that lowers gallium’s surface tension and enables removal with a polishing pen and microfiber cloth. A forum user cleaned an Aqua Computer block that had used liquid metal on a delidded Skylake-X processor since 2018; the process took about an hour.

Experiment shows liquid metal TIM doesn’t dry out; it turns solid — two-year electron microscope test finds gallium bonds with copper coolers, and nickel plating keeps the layer about 10 times thinner

Gallium prices have risen from ~€300 kg?¹ to €2,500-€3,000 kg?¹ over five years. China supplies ~99 % of global gallium; its export ban to the United States remains suspended until late 2026, with licenses still required.

Experiment shows liquid metal TIM doesn’t dry out; it turns solid — two-year electron microscope test finds gallium bonds with copper coolers, and nickel plating keeps the layer about 10 times thinner

Thermal Grizzly’s September blog post described TG Metal Polish & Restore as a surfactant that binds gallium to prevent re-adhesion during cleaning. The company plans to replace nickel plating with new coating technologies “next year” and announced an upcoming KryoSheet graphene pad for bare dies, estimated to be only 3–4 °C less effective than liquid metal while offering a lower price.

Experiment shows liquid metal TIM doesn’t dry out; it turns solid — two-year electron microscope test finds gallium bonds with copper coolers, and nickel plating keeps the layer about 10 times thinner

Thermal Grizzly expects to launch the new coating solution within twelve months and release the updated KryoSheet graphene pad shortly thereafter, giving enthusiasts alternatives that avoid the solidification issues observed in the two-year study.

Experiment shows liquid metal TIM doesn’t dry out; it turns solid — two-year electron microscope test finds gallium bonds with copper coolers, and nickel plating keeps the layer about 10 times thinner