Study on Optical Consistency of Centrifuged LEDs in Packaging Processes

Abstract

Light-emitting diodes (LEDs) are emerging lighting sources. However, it is still difficult to obtain good optical consistency of LEDs from the same batch due to phosphor sedimentation. In this paper, we introduce the centrifugation method to enhance the optical consistency of LEDs. The phosphor gradient concentration model is proposed to simulate the changes of phosphor concentration in different centrifugation time and acceleration. Moreover, the effect of these parameters on the optical performance of LEDs is discussed. The simulation results reveal that increasing centrifugal acceleration and time can enhance the optical consistency of LEDs by changing the phosphor distributions. It is suggested that the centrifugation parameters with 20 times gravitational acceleration and 6 min centrifugation time can ensure high optical consistency for LEDs, which can be taken as a reference to balance optical performance and consistency. Experimental results validate that the proposed method is beneficial to improve the optical consistency, including luminous flux and color coordinates, compared to LEDs without centrifugation.