Optical performance enhancement of chip-on-board light-emitting diodes through ionic wind patterning.

Due to the total internal reflection at the upper interface of the encapsulation layer, the light extraction efficiency (LEE) of chip-on-board packaging light-emitting diodes is attenuated significantly. It is well known that the LEE can be enhanced by patterning the encapsulation layer. In this study, a novel method of patterning the encapsulation layer, which is based on the interaction between the ionic wind and liquid encapsulation, is proposed and demonstrated. Two kinds of encapsulation patterns, namely dual stripe and meniscus, were fabricated successfully. Compared with the traditional flat encapsulation structure, dual stripe and meniscus patterns enhanced the LEE by 17.78% and 20.48%, respectively. Meanwhile, light intensity distributions were observed to be more uniform. The proposed encapsulation patterning method demonstrates significantly simplified fabrication process and reduced cost.