Research On Packaging Process Improvement And Performance Optimization Of White LED Light Source

LEDs,whose full name is light-emitting diodes,is the "new darlings" of the lighting family.It is with the advantages of low price,green environmental protection,energy saving,high luminous efficiency,high brightness that LEDs has been widely used.Packaging technology plays an important role in the preparation of LED,in which fluorescent glue layer packaging is the widely used process for the preparation of white LED.The packaging technology determines the performance of the white LED light source.Therefore,in the process of popularization and application of LED light source,it is very necessary to improve the optical performance and reliability of LED light source by optimizing the packaging process.Based on this idea,my paper focuses on the packaging technology optimization and reliability of white LED light source.Some of the details is sum up as follows:1.Firstly,the background knowledge and basic principles of LED are described.The photometric and colorimetric principles and packaging technology of white LED are emphasized,which lays the theoretical groundwork for the research of the subject.In addition,the research of this topic is put forward from the current research gap and industrial production demand by describing the latest research of the current packaging technology.2.The characteristics of photochromic parameters of white LED light source were studied by preparing white LED with different color temperature points(3000K,5000 K,8000K).Through experimental analysis,it is found that the luminous flux and color temperature of white LED are increasing,while the luminous efficiency is decreasing when the input current increase.With the increase of ambient temperature,the voltage,color temperature and luminous flux of LED light source decrease under the condition of constant input current.3.The packaging process parameters or structure are changed to prepared different white LED samples.The packaging factors affecting the optical properties of white LED light source were studied,including the concave and convex shape of phosphor layer,the ratio of phosphor to silica gel and the particle size of phosphor.Through the analysis,this paper summarizes how the factors of the concave and convex degree of the fluorescent gel layer,the silica gel ratio package of the phosphor powder and the particle size of the phosphor powder affect the characteristics of the LED light source.It provides a theoretical basis for improving the optoelectronic performance of the LED light source.The experimental results show that:(1)The central light intensity of the flat rubber surface is 1870 LM,while the central light intensity of the convex one is 2100 LM.And the convex one is 10.95% higher than the flat one,which shows that the convex rubber surface is more conducive to focus.In the actual industrial production,priority should be given to using convex rubber surface packaging in order to achieve better output light intensity.(2)In the process of increasing the proportion of phosphor silica gel,the luminous flux and luminous efficiency of LED light source increase firstly and then decrease when it reaches the peak value.(3)The phosphor with large particle size contributes to improve the luminous efficiency and color rendering index Ra.And it also has the advantage of resistance to light decay.So in the actual production,it is necessary to comprehensively consider the particle size of the encapsulated phosphor.4.In the end,we conducted an aging experiment of white LED light source.The changes of luminous flux,color temperature,color rendering index Ra and fluorescent gel layer of LED light source before and after aging were measured.It was found that during the aging experiment of LED light source,the luminous flux decreased significantly.The average luminous flux decreased from the initial 560 LM to 350 LM,and the attenuation rate reached 37.5%.Besides,the CT increase significantly from 3062 K before aging to 3692 K after aging.The lighting-decayed mechanism of LED light source is analyzed by means of optical microscope and scanning electron microscope.In the aging process of LED light source,the fluorescent colloid is in a high temperature environment due to photothermal radiation.So the structure and chemical composition of the fluorescent are degraded.