Study On Reliability In Vacuum And Thermal Management Of High Flux Device

High tem perature ind uced failu re is one of the m ost im portant failuremechanisms for electro nic devices. Because of the high therm al dissipation, th ecooling demand of hi gh heat flux device s cannot be met by conventional thermalmanagement methods. At the same time, comparing to the atmospheric environm ent,the operating temperature rise will increas e sharply in vacuum environment becausethe heat conduction and convection declines badly in vacuum and t he dissipationpower could only be removed by heat radiat ion. Further more, the lightweight andminiaturization of m ilitary equ ipments will b e lim ited b y using reg ular coolingmethods, such as additional heat sink, air-cooling and water-cooling.Aiming at therm al management of high he at flux devices in vacuum , estimatesand analysis of various thermal management schemes are studied in this paper. On thebasis of the study , optimization of therm al management for a project is carried out,which provides reference data for the application of high heat flux devices.This paper can be summarized to the following several aspects:Firstly, the theoretical basis and techniques of thermal management for high heatflux devices is introduced. And therm al management of hi gh heat flux devices isanalyzed and calculated. The model of thermal management for high heat flux devicesin vacuum is revised.Secondly, several therm al experiments of high heat flux devices in vacuum isprocessed, and several cooling methods, such as surface coating, silica gel landfill andpadding under devices are analyzed. On the basis of experim ents, cooling m ethods,such as surface coating, silica gel landfill, padding under devices, heat transfer bydevices feet and PCB are studied. Affection of the case temperature by above coolingmethods is detailed analyzed. So, constr uctive suggestion and reference of theirapplication in engineering is proposed.Thirdly, the structures and types of commonly used heat sink are introduced, andfactors which affect cooling performance of heat sink are analyzed. Thermal model ofheat sink with staggered fingers shapes in the atmosphere and vacuum are studied bysimulation and experiment, respectively . The causes of case tem perature increasedsharply in vacuum are analyzed, and so me improving measures are proposed. Thecross-section shape of fins is studied a nd optimized, and constructive suggestion andreference of its application in engineering is proposed on the basis of the above works.Fourth, therm al m anagement of high power LED street lam p produc ed by acompany is processed. Temperature uniformity of the plate which assembles LEDs isoptimized, and the temperature difference on the whole plate surface is controlled in 1℃; The length shortens of heat sink is studied, and the length is shorten by 4/7 to savea lot of materials; And the cross-section shape of fins is replaced by isosceles triangle for optimization. So, cooling performance of heat sink is enhanced, and raw m aterialalso be saved.