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Liquid metal is also called bulk amorphous. The atoms are arranged in disorder, without grain boundaries, with uniform microstructure and no precipitated phases; while traditional metal atoms are arranged in an orderly manner, with grain boundaries and precipitated phases, and the microstructure is uneven. The performance of the material is mostly determined by the internal structure. It is liquid under normal temperature and pressure. Due to its indeterminate liquid form, liquid metal has excellent electrical properties, thermodynamic properties and thermal conductivity. According to the composition ratio, liquid metal materials will have different functional properties, such as special functions such as phagocytosis and self-driving. They have important application prospects in electronic manufacturing, heat dissipation, space, biomedicine and other fields. The focus of attention. Among them, the application of liquid metal in the field of thermal management is mainly embodied in thermal interface materials, convective circulation and phase change energy storage.
Thermal interface material is a general term for materials used for coating between the heat dissipating device and the heating device to reduce the contact thermal resistance. At present, the commonly used thermal interface materials in the market are mainly silicone grease. The disadvantage is that the thermal conductivity is low, generally only about 0.2 W/(m·K), and its thermal conductivity is limited. Adding high thermal conductivity nanoparticles to thermally conductive silicone grease can improve its thermal conductivity. For example, adding copper or aluminum nanoparticles can make the thermal conductivity reach about 1 W/(m·K), but it is still difficult to meet the requirements of high heat flux. Actual demand. Compared with ordinary silicone grease thermal interface materials, liquid metal thermal interface materials have higher thermal conductivity, low thermal resistance and high reliability. The use of liquid metal in thermal interface materials mainly includes liquid metal thermal paste and metal thermal pads.
The micro-channel cooling technology based on liquid metal is considered to be an effective solution to the cooling problem of high heat flux chips [2]. Using liquid metal as a heat transfer medium, the main application field is the heat dissipation of small and compact electronic devices with small heat dissipation space, such as tablet computers and notebook computers. In 2002, the Institute of Physics and Chemistry of the Chinese Academy of Sciences proposed to introduce room temperature liquid metal into the cooling of high-performance computer chips. The introduction of room temperature liquid metal into the cooling of civilian electronic devices is an important breakthrough, which has changed people’s understanding of traditional liquid metal materials. This opened up the application of liquid metal in the field of electronic chip cooling. Table 2 shows the difference in physical parameters when water and liquid metal are used as cooling media in the circulating heat dissipation system. Due to the superior high thermal performance of liquid metal, it has significant advantages in the field of super chip cooling such as micro-channel cooling technology, and its heat dissipation capacity is far superior to traditional water cooling.
Case Analysis
Take the Xiaomi 9 pro5G version as an example. It uses a VC liquid cooling system, which adds 5 layers of graphite, high thermal conductivity copper foil, and thermal gel high thermal dissipation materials. The addition of these heat dissipation methods also allows the CPU of the mobile phone. The core temperature dropped by 10.2°C at the highest.
You should have noticed that the thermal gel is a high heat dissipation material. This heat dissipation material is a bit similar to the silicone grease on your computer CPU. It has the same function as the silicone grease. In order to effectively export the heat in the CPU to the heat pipe for heat dissipation, so This is also a case of using thermal interface materials from the computer end to the mobile end.
Liquid metal thermal interface material
For the thermal interface material of thermal conductive gel that appeared in the above cases, in fact, it may be better to use liquid metal to replace it. Generally speaking, the higher the thermal conductivity of the thermal interface material, the smaller the natural thermal resistance, and the smaller the corresponding interface thermal resistance, and the better the thermal conductivity.
The traditional thermal interface materials are mainly silicone greases. In recent years, the thermal conductivity has been controlled at the level of 4~8W/(m·K) through the doping of thermal nanoparticles. The thermal conductivity is increased by an order of magnitude, reaching the level of 10~40W/(m·K), which will make a breakthrough in heat dissipation.
For the 5G market, the heat dissipation problem may have become a rigid demand at the beginning, and liquid metal is also used as a heat dissipation technology reserve in this era. The efforts of various scientific researchers behind are to better do it when it is needed tomorrow. Used.
Facing the current demand of the heat dissipation market, the liquid metal phase change material series has also undergone relevant tests. In terms of performance, the temperature changes to meet the heat dissipation requirements of different temperature ranges, so that the heat dissipation is in a dynamic change to meet different requirements. Heat dissipation requirements.
Therefore, the entry of 5G mobile phone cooling market is a small step for liquid metal, but behind it is liquid metal's big step into the entire 5G market.
