Fundamental understanding on the dynamic reactions of liquid gallium with aluminum

High-powered electronic devices require liquid gallium (Ga) and Ga-based alloys as highly conductive thermal interface materials (TIMs) to efficiently dissipate heat from devices into heat sinks, often made of aluminum (Al). However, Ga reacts rapidly with Al and severely damages the heatsink, which can significantly shorten the use life of the electronic devices. We hypothesized that adding a nanometer-thick coating, such as aluminum oxide (Al2O3), which is chemically stable due to its strong ionic bonds, or Iridium (Ir), which is chemically stable due to its full 6s and 4f outer electron shell, on the surface of Al can slow the reaction between liquid Ga and Al, thereby extending the heatsink’s lifespan. To test this hypothesis, we studied the dynamic reaction of Ga with Al, Ga with nanometer Al2O3-coated Al, and Ga with nanometer Ir-coated Al at device operating temperature of 50°C using an in situ digital optical microscope. We observed that liquid Ga penetrates and diffuses faster into Al than into Al2O3-coated Al at 50°C, causing more severe surface damage on bare Al. Furthermore, Ir-coated Al prevents the chemical reaction between Ga and Al within the same reaction time frame, resulting in no obvious surface damage from liquid Ga. Our findings demonstrate that Ir-coated Al can potentially serve as an innovative heatsink material for system-level cooling architectures that use liquid Ga-based TIM in high-powered electronic devices.