Super-hydrophobic-hydrophilic surface vacuum cavity radiator
阅读说明：本技术 一种超疏水-亲水表面真空腔散热器 (Super-hydrophobic-hydrophilic surface vacuum cavity radiator ) 是由 曾敏 李年祺 王秋旺 于 2019-10-24 设计创作，主要内容包括：本发明公开了一种具备超疏水表面和亲水表面的真空腔散热器。该散热器利用光化学蚀刻、化学气相沉积方法制备超疏水表面和亲水表面作为腔体换热面,在腔体内注入去离子水作为相变传热介质,通过焊接将超疏水表面、亲水表面和密封圈连接密封,最后将腔体内空气抽出,构成闭环真空腔体散热器。该散热器利用超疏水表面和亲水表面的不同润湿性,超疏水表面作为冷凝侧,表面粘滞阻力低,液滴在合并过程中发生弹跳,到达亲水表面。亲水表面作为蒸发侧,具有主动液滴铺展特性,有助于散热,防止局部高温。闭环真空腔内循环由系统内力自发驱动,不需要外力协助。本发明设计的真空腔散热器具备高效率、体积小等优点,为电子元器件散热提供了解决方案。(The invention discloses a vacuum cavity radiator with a super-hydrophobic surface and a hydrophilic surface. The radiator utilizes photochemical etching and chemical vapor deposition methods to prepare a super-hydrophobic surface and a hydrophilic surface as cavity heat exchange surfaces, deionized water is injected into a cavity as a phase change heat transfer medium, the super-hydrophobic surface, the hydrophilic surface and a sealing ring are connected and sealed through welding, and finally air in the cavity is pumped out to form the closed-loop vacuum cavity radiator. The radiator utilizes different wettabilities of the super-hydrophobic surface and the hydrophilic surface, the super-hydrophobic surface is used as a condensation side, the surface viscous resistance is low, and liquid drops bounce in the merging process and reach the hydrophilic surface. The hydrophilic surface is used as an evaporation side, has the characteristic of active droplet spreading, is favorable for heat dissipation, and prevents local high temperature. The circulation in the closed-loop vacuum cavity is spontaneously driven by the internal force of the system without the assistance of external force. The vacuum cavity radiator designed by the invention has the advantages of high efficiency, small volume and the like, and provides a solution for heat dissipation of electronic components.)
1. A super-hydrophobic-hydrophilic surface vacuum cavity radiator comprises an evaporation side hydrophilic surface (1), a sealing ring (2), a condensation side super-hydrophobic surface (3) and a vacuum sealing port (4), and is characterized in that the evaporation side hydrophilic surface (1) is provided with a micron-scale continuous rectangular groove structure (11), the condensation side super-hydrophobic surface (3) is provided with a micron-scale square column array (31) and a nanometer-scale cylindrical array (32), the evaporation side hydrophilic surface (1), the sealing ring (2) and the condensation side super-hydrophobic surface (3) are sequentially arranged along the gravity direction, the evaporation side hydrophilic surface is arranged on the upper side, and the processed micron-scale rectangular continuous groove faces downwards; the super-hydrophobic surface of the condensation side is positioned at the lower part, and the processed micro-nano secondary array structure faces upwards.
2. The super hydrophobic-hydrophilic surface vacuum chamber heat spreader as recited in claim 1, wherein the evaporation side hydrophilic surface (1) is provided with a micron-scale continuous rectangular groove structure (11), and the micron-scale continuous rectangular groove structure (11) is prepared by a photochemical etching processing method.
3. The super hydrophobic-hydrophilic surface vacuum chamber heat sink according to claim 1, wherein the condensation side super hydrophobic surface (3) has a micro-scale square pillar array (31) and a nano-scale cylinder array (32), and the micro-scale square pillar array (31) and the nano-scale cylinder array (32) are prepared by photochemical etching and chemical vapor deposition.
4. The super hydrophobic-hydrophilic surface vacuum chamber heat spreader according to claim 1, wherein the vacuum sealing port (4) is used for liquid injection and vacuum sealing in the vacuum chamber.
Technical Field
The invention relates to a vacuum radiator for high-heat-flux electronic components such as a large-scale computer central processing unit, a 5G base station GaN inverter, a silicon-based crystal plate and the like. In particular to a vacuum cavity radiator with a super-hydrophobic surface and a hydrophilic surface, which can be prepared by adopting a photochemical etching method, a chemical vapor deposition method and a welding process.
Background
With the progress of chip manufacturing process, the electronic element size is smaller, but the heat generation quantity is larger and larger with the increase of processor frequency, so that the heat concentration and the heat flux of the core part of the electronic element are high. If the concentrated heat is not discharged quickly, the frequency of the concentrated heat is reduced due to overheating, the working performance of the electronic element is affected, and the electronic element is damaged in severe cases.
The traditional vacuum cavity radiator has the characteristics of a flat heat pipe and a thermal diode, and has the characteristics of closed-loop circulation of internal working media and unidirectional heat transfer. However, the return of condensate to the evaporation surface in conventional vacuum chamber radiators typically requires the use of a porous structure or capillary continuous grooves connecting the evaporation side and the condensation side, relying on capillary forces within the capillary structure to drive the condensate into motion. The method has low efficiency, and is difficult to process and prepare, thereby being difficult to realize production and application. On the super-hydrophobic surface, the contact angle of the liquid drop is larger than 150 degrees, and the mobility is better. And when the liquid drops are combined, due to the release of surface free energy and the limiting action of the wall surface, the combined liquid drops overcome the gravity, the surface viscous resistance and the internal dissipation to obtain upward kinetic energy, so that the combined liquid drops bounce off the wall surface. Therefore, the invention designs a novel super-hydrophobic-hydrophilic surface vacuum cavity radiator by combining the wetting characteristics of different characteristic surfaces, and provides a solution for the heat dissipation of high-heat-flux electronic components.
Disclosure of Invention
In order to realize efficient heat dissipation of electronic components under the working condition of high heat flux and reduce the processing difficulty and cost of a radiator, the invention provides a super-hydrophobic-hydrophilic surface vacuum cavity radiator. The novel vacuum cavity radiator further optimizes and improves the structure and the performance of the vacuum cavity radiator from two angles of self-driven motion of the life cycle of condensate droplets and enhanced heat transfer by applying different surface wetting principles and combining a capillary scale mechanics principle, a heat transfer theory and a micro-nano surface preparation technology. The super-hydrophobic surface and the hydrophilic surface are prepared by photochemical etching and chemical vapor deposition methods to be used as cavity heat exchange surfaces, the super-hydrophobic surface, the hydrophilic surface and the sealing ring are connected and sealed through welding, and finally air in the cavity is pumped out to form the closed-loop vacuum cavity radiator.
In order to achieve the purpose, the invention is realized by the following technical scheme:
a super-hydrophobic-hydrophilic surface vacuum cavity radiator comprises an evaporation side hydrophilic surface, a sealing ring, a condensation side super-hydrophobic surface and a vacuum sealing opening. The evaporation side hydrophilic surface, the sealing ring and the condensation side super-hydrophobic surface are sequentially arranged along the gravity direction, the evaporation side hydrophilic surface is positioned on the upper side, and the processed micron-sized rectangular continuous groove faces downwards; the super-hydrophobic surface of the condensation side is positioned at the lower part, and the processed micro-nano secondary array structure faces upwards.
The evaporation side hydrophilic surface is provided with a micron-scale continuous rectangular groove structure, and the micron-scale continuous rectangular groove structure is prepared by adopting a photochemical etching processing method.
The super-hydrophobic surface of the condensation side is provided with a micron-scale square column array and a nanometer-scale cylinder array, and the micron-scale square column array and the nanometer-scale cylinder array are prepared by adopting a photochemical etching method and a chemical vapor deposition method.
The vacuum sealing port is used for liquid injection and vacuum sealing in the vacuum cavity.
The invention has the technical advantages that the condensation heat transfer is enhanced in the bouncing process of liquid drops on the condensation side of ①, the system efficiency is improved, the liquid drops on the evaporation side of ② are actively spread to promote uniform heating, the heat transfer quantity is improved, and local high temperature is avoided, the bouncing of ③ liquid drops provides a new method for dredging liquid drops in a vacuum cavity, a capillary porous structure is not needed to be added, the structure is simplified, the processing difficulty and the cost are reduced, ④ the vacuum cavity radiator is prepared by adopting a photochemical etching method, a chemical vapor deposition method and a welding method, and the vacuum cavity radiator has excellent structural precision and strength.
Drawings
FIG. 1 is a schematic overall view and a partial sectional view of a vacuum chamber heat sink according to the present invention.
FIG. 2 is a schematic view and a partial enlarged view of the hydrophilic surface (evaporation side) of a vacuum chamber heat sink.
FIG. 3 is a schematic diagram and a partial enlarged view of a super-hydrophobic surface (condensing side) of a vacuum chamber heat sink.
FIG. 4 is a schematic view of the working process of the vacuum chamber heat sink.
Detailed Description
The following detailed description of embodiments of the invention refers to the accompanying drawings.
As shown in fig. 1, the vacuum chamber radiator is filled with deionized water through the vacuum sealing port 4, and then a vacuum sealing operation is performed. The vacuum sealing port 4 is not opened any more, and an internal closed loop system is formed.
As shown in fig. 2, a micron-scale continuous
As shown in fig. 3, the micro-nano secondary array structure is prepared on the surface of the substrate by photochemical etching and chemical vapor deposition. The nano-scale cylindrical array structure is used for promoting nucleation and condensation when steam contacts the surface, and the nucleation rate is improved; the micron-sized square column array structure is used for constructing the super-hydrophobicity of the surface, and liquid drops which are increased along with condensation heat transfer form a contact angle of more than 150 degrees on the surface under the action of the structure, so that the micron-sized square column array structure has stronger mobility and surface free energy. When the liquid drops collide and connect with surrounding liquid drops, extra surface free energy released in the merging process can overcome the work such as gravity, viscous resistance and the like, and the liquid drops have upward kinetic energy under the impact action of a liquid bridge. Causing the drop to bounce off the surface. In the present invention, droplet bounce has two effects: (1) the condensed liquid drops are promoted to spontaneously return to the evaporation side by bouncing, and the spontaneous closed-loop flow of the condensate is formed; (2) the liquid drops bounce off the wall surface to promote the generation of new liquid drops and strengthen the condensation heat transfer process.
As shown in fig. 4, the a process is a process in which the droplets release heat at the condensation side, bounce back to the evaporation side due to coalescence, and spread spontaneously; the process b is a process that the spreading liquid drop absorbs the heat of the electronic component, is heated and evaporated, and returns to the condensation side in a steam form for phase change heat transfer. The above processes all spontaneously form closed-loop circulation of the condensate working medium and heat under the action of the functional microstructure.
The evaporation side hydrophilic surface and the condensation side super-hydrophobic surface are arranged in sequence along the gravity direction. Specifically, the hydrophilic surface of the evaporation side is positioned at the upper part, and the processed micron-sized rectangular continuous groove faces downwards; the super-hydrophobic surface of the condensation side is positioned at the lower part, and the processed micro-nano secondary array structure faces upwards.
The evaporation side hydrophilic surface and the condensation side super-hydrophobic surface are connected through a sealing ring in a welding mode to form a cavity. Injecting deionized water through the vacuum sealing port and completing the operations of vacuumizing and sealing.
The evaporation side hydrophilic surface is provided with a micron-scale continuous rectangular groove structure. When the liquid drop contacts the surface, under the action of capillary force and surface tension, the liquid drop contact angle is less than 60 degrees, and the liquid drop contact angle can actively spread along the direction of the groove to cover the hydrophilic surface of the evaporation side, absorb the heat of the electronic element, promote uniform heat dissipation and avoid local overheating. Vertical corners within the trench provide efficient nucleation points for evaporation as surface-spread condensate evaporates upon heating.
The super-hydrophobic surface of the condensation side is provided with a micro-nano secondary array structure. When steam contacts the surface, the steam is condensed and nucleated under the action of the nano-scale cylindrical array, and the heat collar is released and continuously grows. When the liquid drops reach the critical dimension, the liquid drops are acted by the micron-sized square column array, and are combined with the surrounding liquid drops to bounce, the bounced liquid drops return to the hydrophilic surface of the evaporation side right above, and the circulation of evaporation-condensation by heating is repeated. The condensed liquid drops jump off the wall surface actively to promote condensation heat transfer.
The evaporation side hydrophilic surface micron-sized continuous rectangular groove structure is processed and prepared by the photochemical etching method, and has excellent structure precision and processing controllability; the micron-scale square column array of the super-hydrophobic surface on the condensation side is prepared on a silicon dioxide substrate through photochemical etching, and then the carbon nano tube is prepared at the top end of the square column through a chemical vapor deposition method, so that a micro-nano secondary structure is formed. The micro-nano structure prepared by photochemical etching and chemical vapor deposition has excellent precision and structural stability.
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