Packaging design for improving the uniformity of Chip scale package (CSP) LED luminescence

Abstract In order to realize small package size, uniform performance and high manufacture efficiency, a chip scale packaging (CSP) technology has been developed by controlling the thickness of the phosphor film in this paper. Five CSP LEDs with different thicknesses of 4 side faces are prepared. Optical tests and thermal simulations were carried out to evaluate the performance of the five samples. The measurement results indicate that: 1) When the absorption of the blue light reached a certain extent, the luminous flux and correlated color temperature gradually decreased with the increase of the thickness of the film; 2) the color temperature of the CSP LED will reach the best uniformity when the ratio of thickness of top film to that of side film is close to 2:1; 3) when the ratio of thickness of top film to that of side film is not less than 2:1, the effective light angle can reach about 160°; 4) the thermal management for prepared CSP samples shows a slight decrease in temperature as the side film's thickness increases; 5) the aging test result shows that the thinner the package thickness is, the stronger the aging resistance will be.