Study On Preparation And Properties Of New White LEDs

This paper focuses on design and optimization of the white LED package process to overcome the problems of traditional white LED packaging technology and meet requirements of the high quality and low cost. Three methods of white LEDs with the relatively good performance were studied. The main research work is summarized as follow:(1) Silicone doped with 0.4wt% TiO2(average particle diameter: 0.316μm) can effectively solve the side leakage of blue light and adjust color temperature of the flip-chip white LED. The luminous flux of flip-chip white LED with silicone doped with 0.4wt% TiO2 is 4% higher than that of without TiO2 dopant. In addition, when the surface of plastic package is roughened(the ratio of surface roughness: 0.015), the luminous flux of flip-chip white LED increases by about 6%.(2) The CSP(chip scale package) with five luminous faces was studied. Results show that this CSP can be optimized with good performance and viewing angle of 140° when the ratio of phosphor to silicone is 0.2:1, the silicone layer thickness is 150μm, and the width is 1.5mm.(3) The CSP with single luminous face was studied. Results show that the CSP emits light with Lambertian distribution and has the viewing angle of 120°.