Reduction of Phosphor Precipitation in LED Packaging Process by Infrared Laser Curing Method

This paper investigated a method to cure silicone encapsulant in a light-emitting diode (LED) package by irradiating infrared (λ = 980 nm) laser in order to reduce phosphor precipitation in LED packaging process. When the laser is irradiated on a silicone encapsulant with phosphor, phosphor is directly heated, and then its thermal energy is transferred to the encapsulant. We optimized the output and irradiation time of the infrared laser adopted in the curing process and compared the characteristics of silicone encapsulant cured by the infrared laser to those cured by a convection oven. We show that phosphor precipitation is reduced when the silicone encapsulant is cured with the infrared laser curing, which resulted in a decrease in color coordinate deviation and an increase in luminous efficiency.