Design And Fabrication Of Chip Scale Packaging Of High Performance White LED

Light emitting diode(LED)is a semiconductor device which can convert electrical energy into light energy directly,and has always been a research hotspot.Recently,the chip-scale packaged LED(CSP-LED)which has a good optical-electrical performance has emerged.It meet the requirements on minimizing the package size and increasing the stability of people.The luminous efficiency of phosphor-converted white LED is only about 30%.Most of the energy of chip is converted into thermal energy,which makes the junction temperature increase and affects its photoelectric performance seriously.How to reduce the junction temperature of LED and improve its photoelectric and thermal performance has been a problem.In order to realize the design and preparation of chip-scale packaging of high-performance white LEDs,we investigate the photoelectric and thermal performance of white LEDs in this paper.The three designed LED devices were analyzed by the combination of simulation analysis,experimental testing and theoretical calculation.The effects of different packaging structures and packaging materials on the performance of white LEDs were explored.Based on the guidance of simulation,the measures that can effectively improve the heat dissipation performance of white LEDs were proposed and verified.Secondly,the optical design software is used to implement secondary light distribution design for LED devices to achieve high lighting requirements.The specific research content and results are as follows:1.The design and preparation of CSP-LED.Combining with the thermal simulation software Flo EFD,we designed and prepared CSP-LED based on flip chip and white LED device packaged with plastic bracket by using traditional surface mount(SMD)technology(EMC-LED).The photoelectric thermal performance of the two LED lamp bead samples was tested under different environment conditions by the instrument.The results show that(1)The change in LED junction temperature has a serious impact on its photoelectric performance.The increase in junction temperature causes the red shift of its luminescence spectrum,the decrease of the yellow-blue ratio of the white light spectrum,and the increment of color temperature.(2)Comparing with the EMC-LED devices,CSP-LED devices have a lower thermal resistance3.31 ?/W.(3)Under different temperature and current conditions,the CSP-LED shows better stability and reliability.2.The design and preparation of chip-scale package LED based on ceramic substrate,CP-LED.The CP-LED device was designed and prepared,and its photoelectric and thermal parameters were tested,and simulated with the help of thermal simulation software.The test and simulation results of the three LED samples were compared and analyzed.Combining with theoretical calculations,experimental tests and simulations,the improvement schemes for CSP-LED with good reliability have been proposed and verified.The results show that:(1)the addition of ceramic substrate can reduce the junction temperature of CSP-LED and improve its photoelectric performance effectively.(2)The thermal conduction area of the connection layer and the interconnect surface material are important factors that affect the overall junction temperature of CSP-LED by optimization.The heat dissipation performance of CSP-LED can be improved.3.The optical design of an ultra-long-range LED flashlight.For the high-power white LEDs prepared in the laboratory before,the optical design was carried out by Trace Pro optical simulation software and theoretical calculations to design an integrated optical system that can achieve ultra-long irradiation,which not only improves the central concentrating effect,achieves collimated irradiation,also helps to reduce the loss of light and realize ultra-long-distance irradiation.