Comparative Research On Bonding Materials In Ultraviolet LED Packaging

With the development of visible Light Emitting Diode(LED)technology,the profit of the products is gradually decreasing.The manufacturers have to look for new products and new profit growth points,and at the same time,with the continuous progress of ultraviolet LED chip technology,related manufacturers have to look for new products,new profit growth points,at the same time,with the continuous progress of ultraviolet LED chip technology,Ultraviolet LED technology has been widely used in more and more fields.For example,ultraviolet LED can not only improve the efficiency,but also replace the traditional high-pressure mercury lamp for bonding,curing and other fields.Energy conservation can avoid the pollution of mercury to the environment.These advantages make people have a better understanding of UV LED technology.The prospect is full of promise and brings more people into the study of UV LED related technologies.Due to the low light efficiency of ultraviolet LED chip,the ultraviolet high energy photons are easy to break the molecular chain of polymer organic compounds,and the power density required for ultraviolet application is very high.Therefore,the packaging technology of ultraviolet LED is different from that of ordinary visible light LED and uses new materials.It is necessary to improve the reliability and performance parameters of UV LED.In this paper,the reliability of bonding materials in ultraviolet LED packaging is studied.A new bonding material,nano-silver solder paste,is used in this paper.Nano-silver solder paste has higher thermal conductivity,smaller organic material gap and better performance in thermal conductivity,conductivity and reliability,so when using nano-silver solder paste as bonding material for chips,UV LED devices can be used in higher temperature environments.In this paper,UV LED chip with vertical structure of 397nm is used,and copper clad AlN ceramic substrate with good thermal conductivity is used to package the chip with COB(Chips on board).The component lens is a quartz glass lens with higher UV transmittance.The chip binder is made of silver nanocrystalline solder and traditional conductive silver glue as a contrast group.A single variable is strictly controlled throughout the whole package process.The whole package sample process is only different from the bonding material to ensure the effectiveness of the experiment.First of all,this paper introduces the whole process of sample packaging,including the performance and use of raw materials,packaging process testing equipment and performance.Some of the details to be noted during the packaging process include setting parameters,etc.Then,the encapsulated samples are tested for voidage and electron microscopy scanning to ensure the reliability of the package samples.The porosity of the conductive silver gel sample is 0.6%and that of the nano-silver sample is 0.5%The results of scanning electron microscope show that the ductility and uniformity of the two kinds of bonding materials are good after solidification,so the reliability of the sample is ensured.Secondly,the photoelectric properties of different samples of bonded materials were tested.The integral sphere test showed that the temperature was 35?,55?75?,and 95?The samples were tested for voltage-current(V-I),optical power-current()73((?)_e—I),luminous flux-current((?)—I),Luminous efficiency current(?—I)The results show that Nano-silver solder paste is superior to conductive silver colloid in optoelectronic performance as chip bonding material.Finally,the thermal properties of the two samples are tested.The instrument is T3Ster transient analyzer.The temperature sensitivity factor of the sample is measured by using 1mA small current,and then the working junction temperature of the sample is measured at the heating current through the 1000mA.Comparing with the junction temperature curve,it is found that the junction temperature of the traditional conductive silver colloid sample is 4.65?higher than that of the nano-silver sample.The integral structure function of the sample is obtained by the mathematical change of the junction temperature curve,that is,the thermal resistance-heat capacity curve.From the integral structure function curve,the thermal resistance of the sample can be obtained.The calculated results show that the thermal resistance of the conductive silver colloid sample is higher than that of the nano-silver sample1.37K/W.therefore know that the nano silver solder paste as a chip bond material in the thermal performance of performance is better than conductive silver.The thermal properties of the sheet bonded material are better than that of the conductive silver adhesive.