Simulation of stamp-printed coating process in light-emitting diodes packaging by Lattice Boltzmann method

To get white light emission, it´s usual to use a blue LED chip covered with yellow emitting phosphor via a dispensing process. Stamp printing is such a process of free-surface flow, which decides the morphology of the phosphor gel, and thus has a great effect on the optical performance of LEDs. Therefore, it is important to study the phosphor gel flow in the stamp-printed coating process. In this paper, a flow model was established to simulate the coating process based on the two-dimensional Lattice Boltzmann method (LBM). With the model, dynamic morphology of phosphor gel was obtained. Two factors, the ratio of LED chip width to the width of stamp bump and phosphor gel volume, were investigated through simulations. In addition, complex phosphor layer morphology was achieved by adapting the two factors.