Influence of initial angle on trajectory and kinematics of freely falling chips in fluidic self-assembly

This paper takes the fluid self-assembly mass transfer technology of a miniature light emitting diode as an example to investigate the impact of different values of α on the free fall motion state and trajectory of chips. Here, α represents the angle between the chips and the horizontal direction at the moment of release. Experimental data were obtained by recording the free fall process of chips at different angles α using a camera. The Navier–Stokes equations and motion equations were solved using dynamic mesh technology to obtain simulation results. By integrating experimental data with simulation results, it was found that although there are variations in the motion trajectories of chips with different α, they all exhibit two phases: non-periodic oscillation and periodic tumbling. The direction of rotation upon descent varies with α, and the angle at which the chips touch down directly influences their final orientation. The self-assembly experiments were conducted by releasing the chips at an angle α=30° from a height of 45 mm. The transfer rate achieved was 87%, which represents a 67.2% increase in correct transfer filling rate compared to uncontrolled conditions. The study found that controlling the release angle of the chips can significantly enhance the efficiency of self-assembly transfer.