A method for geometry control of phosphor layer in high-power white LEDs by package structure

Phosphor layer geometry is one of key factors which determine the optical performance of white LEDs in LED packaging. In order to gain the optimal phosphor geometries, a method for forming different geometries of phosphor layer based on microfluidics and structure control is reported. Through controlling the slanting angle of the reflector cups on basis of conventional dispensing coating process, different curvatures of phosphor layers can be realized to meet the packaging requirement. The numerical simulations and experiments on phosphor slurry dispensing into reflector cups with different slanting angles were conducted. The results reveal that different curvatures of phosphor layers can be easily obtained by varying the slanting angle of reflector cup. By the present method, we packaged several LED samples, one of optical parameters, angular color uniformity (ACU) was measured. The results reveal that the good ACU can be gained using this simple method to form flat phosphor layer in the reflector cup packaging structure.