Vapor Chamber development and application
With the emergence and rapid development of the fifth generation mobile communication technology (5G technology), electronic products, especially smartphones, tablets, and other products, are increasingly moving towards high performance, high integration, and miniaturization, resulting in ultra-high heat flux density in extremely narrow spaces. As an efficient heat transfer element, the Vapor chamber has the characteristics of low thermal resistance and uniform temperature, and is widely used in the heat dissipation module of high heat flux equipment.
The progress of the electronic industry has led to the development of electronic products towards small size and high integration, resulting in higher power consumption of electronic components. For example, the estimated dissipation of bandgap amplifiers in military and aerospace exceeds 1000W/cm2. Ordinary heat sinks can no longer meet the needs of high heat flux density heat dissipation. Two types of heat sinks driven by capillaries, such as heat pipes, flat heat pipes, and Vapor chamber , have been proven to be the most effective passive cooling devices among the two cooling devices. They have advantages such as strong thermal conductivity, good temperature equalization effect, and strong structural adaptability. Vapor chamber have become a research hotspot for many scholars at home and abroad due to their higher heat dissipation performance.
At present, the heat dissipation methods used for electronic devices mainly include graphite heat dissipation, graphene heat dissipation, heat conduction gel heat dissipation, heat pipe heat cooling ,vapor chamber cooling etc., as shown in Table 1. Among them, graphite heat dissipation, graphene heat dissipation and thermal conductive gel heat dissipation belong to heat dissipation materials with limited heat dissipation effect, mainly used in small electronic products; Heat pipes and heat plates are heat dissipation components with high heat dissipation efficiency, and are mainly used in large and medium-sized electronic equipment. Although both heat pipes and vapor chamber use phase change to achieve heat dissipation, including four main steps of conduction, evaporation, convection, and condensation, their heat conduction methods are different. Heat pipes are one-dimensional heat transfer, while soaking plates are two-dimensional heat transfer, with a larger contact area with the heat dissipation medium, more uniform heat dissipation, and better adaptability to the needs of applications in fields such as miniaturized electronic devices in the 5G era. Related studies have shown that the performance of a heat sink with a uniform heat plate is 20% to 30% higher than that of a heat pipe, which can further improve the thermal conductivity efficiency.
The vapor chamber consists of a sealed tube shell, a porous liquid absorbing core, and a working fluid. The liquid working fluid absorbs heat and evaporates at the evaporation end, and is then transported in a gaseous form to the condensation end in the cavity, where it releases heat and condenses. The condensed liquid working fluid is driven by capillary force and transported back to the evaporation end through a porous suction core. In this cycle, the heating plate can operate independently without external power drive, thus completing efficient heat transfer. The soaking plate can be divided into two types according to the direction of heat transfer, and the two types of vapor chamber transfer heat along the thickness and length directions, The former can take away more heat through large-scale condensation; The latter can transmit over long distances and maintain excellent temperature uniformity performance. The vapor chamber is mainly divided into standard vapor chamber (≥ 2mm), ultra-thin vapor chamber (<2mm), and extreme ultra-thin vapor chamber (≤ 0.6mm) according to different thicknesses.
The application ofvapor chambers can be divided into two categories based on different application environments, namely ground environment applications and aerospace environment applications. The former is in a gravity environment, such as 5G base stations, electronic products such as mobile phones and computers, automotive electronic cooling, etc., while the latter is in a zero gravity, microgravity, or supergravity environment, such as in the aerospace field.
Electronic components generate a large amount of heat in a small volume, and effective heat dissipation has become one of the main difficulties in further technological development. Compared with traditional heat pipes, the uniform heat plate, as a new type of heat conduction device, can directly contact the heat source and uniformly transfer heat in all directions. It has efficient and uniform heat conduction performance and is widely used in fields such as electronics, aerospace, and new energy vehicles.
