Reserch On Processing Technology And Heat Transfer Performance Of Radiative Groove Type Vapor Chamber

In recent years,with the rapid development of modern micro-electronic technology to high power,high performance,high integration and other directions,the problems of high temperature,high heat concentration and other problems have become an important reason to hinder its own development.Vapor chamber is a kind of effective cooling element which is widely used to solve the problems of microelectronic products overheating and high heat flux density.The wick is an important part of the vapor chamber,which has a decisive influence on the heat transfer performance of the vapor chamber.Although the liquid core structure widely used at present has a wide range of material sources and relatively mature preparation process,it still has disadvantages of large mass,low heat transfer coefficient and high thermal resistance,which can not meet the heat dissipation requirements of some micro-electronic products.The effective innovation and optimization of the liquid absorption core structure inside the vapor chamber,so that the vapor chamber continuously develops to its own thin structure and high efficiency of heat transfer performance,is the research focus of scholars at home and abroad,and also the inevitable development trend in the future.In this thesis,a kind of radiative groove-core vapor chamber is proposed.Firstly,the heat transfer limit and the numerical model of heat and mass transfer are analyzed.Then,the technology of laser machining groove wick is studied.Finally,different structural parameters of radiative grooves were prepared and their heat transfer performance was studied.The specific work content is as follows:（1）According to the working principle of vapor chamber,the heat transfer limit of vapor chamber is analyzed.By using UDF software,the contact Angle on the surface of the wick is changed from fixed to changed with the change of position,and the numerical model of heat and mass transfer of the radiant grooved wick vapor chamber is established.The analysis results of heat transfer limit and numerical model show that increasing capillary limit of wick can improve heat transfer performance of vapor chamber most effectively.The radiative groove-type wick can effectively improve the heat transfer performance of the vapor chamber,but the homogeneous temperature performance of the vapor chamber with smaller radiative Angle of the groove is relatively poor.（2）First one dimensional double temperature diffusion model was used to analyze the mechanism of laser processing and on the basis of the microstructure observation groove,choose a nanosecond laser marking machine as the processing equipment,and then by single factor experiment and orthogonal experiment,analyzes the nanosecond laser processing parameters on the micro groove morphology,and the related parameters are optimized combination and validation,finally adopts the optimized laser processing parameters.By adjusting the laser scanning path,the grooved wick with different radiation angles was prepared,and the capillary performance of the wick was tested.The test results show that the smaller the radiation Angle of the grooved wick,the faster the working medium flow rate,the longer the flow distance,and the stronger the capillary performance of the wick.（3）Using the optimized laser processing parameters obtained above,radiating groove type vapor chamber with different structural parameters was prepared and obtained from the aspects of groove distribution,radiation angle,liquid filling rate and wettability of liquid core surface.Meanwhile,a platform for measuring the heat transfer performance of vapor chamber was built.The effect of different structural parameters on the heat transfer performance of the vapor chamber was studied.The results show that the distribution of the wick at both ends of the vapor chamber can improve the overall heat transfer performance.Relatively low liquid filling rate can accelerate the start-up time of the vapor chamber,but only appropriate liquid filling rate can effectively improve the heat transfer performance of the vapor chamber.Small radiation Angle can effectively reduce the average thermal resistance of the plate,but will make its homogenization worse.Hydrophobic core structure is only suitable for low power working environment.