What is a temperature equalizing plate and its applications

A temperature equalization plate is a vacuum chamber with a fine structure on the inner wall, usually made of copper. When heat is conducted from the heat source to the evaporation zone, the cooling liquid in the chamber begins to vaporize after being heated in a low vacuum environment. At this time, it absorbs heat energy and rapidly expands in volume. The cooling medium in the gas phase quickly fills the entire chamber. When the gas phase refrigerant comes into contact with a relatively cold area, condensation occurs. The phenomenon of condensation releases the accumulated heat during evaporation, and the condensed coolant will return to the evaporation heat source through microstructured capillary tubes. This operation will repeat itself in the chamber.

Material: Usually made of copper

Structure: Vacuum chamber with fine structure on the inner wall

Mainly used for: servers, high-end graphics cards and other products

Thermal resistance value:? 0.25℃/W

Application temperature: 0 ℃~100 ℃

The four main steps of solidification. The isothermal plate is a two-phase fluid device composed of pure water injected into a container filled with microstructures. Heat enters the plate through heat conduction from the external high-temperature zone, and the water near the point heat source quickly absorbs heat and vaporizes into steam, taking away a large amount of thermal energy. By reusing the latent heat of water vapor, when the vapor inside the plate diffuses from the high-pressure zone to the low-pressure zone (i.e. the low-temperature zone), and comes into contact with the lower temperature inner wall, the water vapor will quickly condense into a liquid and release heat energy. The condensed water flows back to the heat source point through the capillary action of the microstructure, completing a heat transfer cycle and forming a two-phase circulation system where water and water vapor coexist. The gasification of water in the uniform temperature plate continues, and the pressure inside the chamber will maintain equilibrium with changes in temperature. When water operates at low temperatures, its thermal conductivity coefficient is relatively low. However, due to the viscosity of water changing with temperature, the heat dissipation plate can also operate at 5 ℃ or 10 ℃. Due to the capillary action of liquid reflux, the uniform temperature plate is less affected by gravity, and the application system design space can be used at any angle. The temperature equalizing plate does not require a power supply or any moving components, and is a completely sealed passive device.

Copper mesh diffusion bonding and composite microstructure

Unlike heat pipes, the production of temperature equalization plates involves first vacuuming and then injecting pure water to fill all microstructures. The filling medium does not use methanol, alcohol, acetone, etc., but uses purified water with degassing, which will not have environmental problems and can improve the efficiency and durability of the temperature equalization plate. There are mainly two types of microstructures inside the uniform heating plate: powder sintering and multi-layer copper mesh, both of which have the same effect. However, the microstructure of powder sintering is difficult to control in terms of powder quality and sintering quality, while the multi-layer copper mesh microstructure with diffusion bonded copper sheets and copper mesh on top and bottom of the isothermal plate has better consistency and controllability in pore size than the microstructure of powder sintering, and its quality is more stable. Higher consistency can make liquid flow smoother, thereby significantly reducing the thickness of microstructures and lowering the thickness of the heat dissipation plate. The industry has already achieved a plate thickness of 3.00mm at a heat transfer capacity of 150W. The uniform heat plate with copper powder sintered microstructure is difficult to control in quality, and the overall heat dissipation module usually requires the design of heat pipes.

The multi-layer copper mesh bonded by diffusion bonding has the same bonding strength as the base material, and does not require any solder due to its high airtightness. During the bonding process, there will be no microstructure blockage, resulting in better quality and longer durability of the uniformly heated plate. If there is air leakage in the holes after production using diffusion bonding method, they can also be repaired through rework. In addition to diffusion bonding, the layered design of bonding smaller pore copper mesh near the heat source can also facilitate rapid replenishment of pure water in the evaporation zone and smoother circulation of the overall temperature equalization plate. Furthermore, some advances have modularized microstructures into regional designs, which can be applied to heat dissipation designs with multiple heat sources. Therefore, the uniform temperature plate designed with diffusion bonding and regional hierarchical structure significantly increases the heat flux per unit area, and the heat transfer effect is better than that of the uniform temperature plate with sintered microstructure.

Application of temperature equalization plate on computer

Due to the mature technology and low cost of heat pipe cooling modules, the current market competitiveness of temperature equalization plates is still inferior to that of heat pipes. However, due to the fast heat dissipation characteristics of the temperature equalization board, its current application is aimed at the market of electronic products such as CPUs or GPUs with power consumption of 80W to 100W or more. Therefore, temperature equalization plates are mostly customized products, suitable for electronic products that require small volume or rapid heat dissipation. At present, it is mainly used in servers, high-end graphics cards and other products. In the future, it can also be applied to the heat dissipation of high-end telecommunications equipment, high-power brightness LED lighting, etc.

The future development of the uniform temperature plate

At present, the main methods for producing two-dimensional heat dissipation capillary structures for temperature equalization plates include sintering, copper mesh, grooves, metal films, and other methods. In terms of technological development, how to further reduce the thermal resistance of the heat dissipation plate and enhance its thermal conductivity effect in order to match lighter fins such as aluminum has always been the goal of R&D personnel. Improving production yield and finding cost reducing solutions for overall heat dissipation are all directions for industrial development. In terms of product application, the heat conduction of the uniform heat plate has expanded from one-dimensional to two-dimensional compared to the heat pipe. In the future, solutions for uniform heat plates are being developed to solve other possible heat dissipation applications. At present, pragmatically speaking, for the products that have already been developed, how to expand their application market is the top priority for the various temperature equalization board industries. and Dongguan Huazhou Machinery Technology Co., Ltd The ultra-thin VC temperature equalization plate etching machine can better combine the above working principles and apply products with different market demands.