Package structure of polarized white chip-on-board light-emitting diode with high thermal conductivity

The package structure of high power white chip-on-board (COB) light-emitting diode (LED) is investigated. The temperature-dependent performance of the white COB LED combined with a polymeric wire-grid polarizer film (WGF) is optimized. The optimized packaging structure is with a modified phosphor resin layer encapsulated to blue COB LED and an optically transparent plate deposited on the modified phosphor resin layer. The modified phosphor resin comprises a mixture of yellow phosphor and AIN resin for reducing thermal resistance. Results show that the extinction ratio is 83 and the luminous efficacy is 61.4 lm/W at an input power of 8 W for the polarized white COB LED. Without the WGF, the luminous efficacy of the package structure of the COB LED is 90 lm/W.