Integration of phosphor printing and encapsulant dispensing processes for wafer level LED array packaging

Phosphor converted LEDs (pc-LEDs), which employ blue LEDs with yellow phosphor deposition to generate white light illumination is a widely used solid-state lighting source. This paper presents the integration of two major processes, namely, phosphor screen printing and moldless encapsulant dispensing, for wafer level pc-LED packaging. In the present study, the processing procedures and parameters of phosphor screen printing were developed and investigated in detail. The attributes of the phosphor layer by screen printing such as packing density, thickness, uniformity and adhesive strength, which control the performance of final white light illumination, were characterized. Subsequently a moldless encapsulant dispensing process was applied at the wafer level. Optical performance of the packaged LEDs was evaluated. The prototype of 5×5 white light LED arrays demonstrated that a wafer level LED packaging can be achieved with the integration of the two novel processes.