Preparation And Properties Of Flexible Phosphor Films For White LED

Recent years,in the field of LED packaging,rapid development of chip level packaging(CSP)has become a research focus at home and abroad.LED filament lamps also occupy a big markets in the lighting field and constantly updated.However,the blowout development of the market leads to the uneven quality of these two products.CSP LED commonly known as chip scale package LED,which the encapsulation volume does not exceed 120% of the chip volume.At present,the technology is still immature.The main problem is that advantages,small size,and high brightness,cannot be applied in practice.Poor batch consistency,small luminous range and low light uniformity are barriers to the development of CSP LED.This topic started from improving the preparation process of CSP packaging.Firstly,the traditional film preparation technology and CSP packaging technology were fully mastered,and then the process was improved to designing the light distribution by controlling the film thickness of five faces around the chip.The optical,electrical and thermal properties of chips with different package thicknesses were tested.The thermal performance needs to be estimated by finite element simulation with software.By comparing the chip spectral data,distribution of light intensity,color temperature and temperature with different packing thickness ratios,the optimal packaging thickness ratio of each faces was obtained.Then,CSP LED as combined with flexible filament due to the virtue of its small size,high flexibility and high light efficiency.Laminated packages and segmented structures are used to improve light efficiency by reducing the spectral reabsorption effect of red and green fluorescent powder.Through the comparison of test data between ordinary LED filament and different phosphor dry and wet separation package filament,including photoelectric performance test,color coordinate calibration,color coordinate stability and light effect test.Finally,it is proved that flexible CSP filament with high light efficiency,high optical stability,strong plasticity and lower cost has designed by us.In this paper,the preparation technology of CSP was improved and the best packaging thickness ratio of CSP was obtained.At the same time,it provides a new idea of CSP LED for application,which has great reference significance in the application of CSP and the improvement of LED filament.