| The modern field is constantly developing towards miniaturization and high performance.Because of its high heat generation,its performance will drop greatly when the temperature rises.If the electronic device is in a high temperature for a long time,its reliability will decrease 50%.The vapor chamber prepared in this paper is a copper powder sintered type,in which the wicking end of the condensing end adopts a foamed copper structure,and the wicking end of the evaporating end adopts a sintered structure of copper powder particles.The production process adopts two methods.One is to first sinter the upper and lower capillary cores,and then put them into the outer shell plate to weld the upper and lower outer shell plates.The second is to first sinter the upper and lower wicking cores and the outer shell plates respectively,and then sintering the upper and lower plates and the wick,respectively,and the wicking core of the vapor chamber evaporation end is designed with a copper powder column,which can not only improve the deformation of the vapor chamber.It can also shorten the return path of the condensed fluid working medium,which is beneficial to the improvement of the performance of the vapor chamber.Three kinds of copper powder sintered vapor chamber with different particle sizes are used,wherein the spherical and non-uniform copper powders have the following particle diameters: 30?m,50?m,30?m,30?m+90?m,and the dendritic copper powder has a particle size of 30?m.50?m,the effect of copper powder with different particle sizes on the performance of the vapor chamber was studied.The experiment shows that for the uneven copper powder,when the filling rate is 90% and the heating power is 90 W,the thermal resistance value is at least 0.11?/W;For the spherical copper powder,the performance of the vapor chamber with larger particle size is better.Preferably,in the case of a charging rate of 90% and an input power of 10 W,the thermal resistance of the 90?m vapor chamber is at least 0.08°C/W;For dendritic copper powder,the performance of the vapor chamber sintered with dendritic small-diameter copper powder is better.When the filling rate is 70%,the thermal resistance of the 30?m vapor chamber under the input power of 30 W,the minimum value is 0.26°C/W.Experiments show that for spherical copper powder,the performance of the vapor chamber with larger particle size is relatively good.When the filling rate is 90% and the input power of 10 W,the thermal resistance of the 90?m vapor chamber is 0.08°C/W;For dendritic copper powder,the performance of the average vapor chamber sintered with dendritic small-diameter copper powder is better.When the filling rate is 70%,the thermal resistance of the 30?m vapor chamber under the input power of 30 W,the minimum value is 0.26°C/W.Taking the sintered copper powder type vapor chamber as the research object,the spherical plate,the uneven shape and the dendritic copper powder sintered vapor chamber were respectively prepared,and the three filling rates of 70%,90% and 120% of the vapor chamber were compared and analyzed.The experimental results show that the optimum filling rate of spherical and dendritic copper powders with different particle size sintering is different;the vapor chamber of non-uniform copper powder is the lowest in the 90% filling rate 0.11°C/W.Taking the copper plate sintered by spherical copper powder as the research object,two different sizes of heated copper blocks were designed to compare the heat transfer performance of the vapor chamber under different heat flux conditions,and compared with the pure copper plate.The experiment shows that the thermal resistance of the vapor chamber measured by the large-area heat source is small,and the average temperature of the vapor chamber is better than that of the pure copper plate,and the maximum temperature difference at the condensation end is small,indicating that the process of the vapor chamber is effective.Two kinds of shape copper powders were selected: spherical and dendritic,and the heat transfer performance of the sintered four vapor chambers was compared and analyzed.Experiments show that the vapor chamber made of spherical copper powder has a smaller thermal resistance value than the dendritic plate made of dendritic powder.It is possible that the wick made of dendritic copper powder has more blind holes(that is,the pores are not connected),so that the number of flow channels of the liquid working medium is reduced,the flow is blocked,and the heat transfer performance of the vapor chamber is affected.The isothermal plates sintered with 30?m and 30?m+90?m uneven copper powder with a filling rate of 90% were selected for comparative analysis under different cooling water temperatures of 12°C and 28°C,respectively.The experiment shows that the thermal resistance of the 30?m+90?m vapor chamber is 0.2 ? /W when the cooling water temperature is 28°C and the heating power is 100 W. |
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