The influence of phosphor sedimentation on the white LEDs with different structure chip

The influence of phosphor sedimentation on the white light-emitting diode with different structure chip was investigated. The phosphor sedimentation phenomenon occurred seriously as encapsulant viscosity lowers. The influence of phosphor sedimentation on the white light-emitting diode with the vertical structure chip whose one side only emits is larger than that of lateral structure chip whose all sides emit. Hence, Difference in luminous efficacy by the phosphor sedimentation reached about 20 % in the case with the vertical structure chip due to optical loss stemmed from the phosphor sediment layer.