Theoretical study and physical tests on the influence of process parameters of needle on dispensing quality

Reasonable design and control the movement parameters of the needle of the piezoelectric needle-collision jetting dispenser is the key to ensure the stable and reliable of opto-electronic packaging. Existing studies just focus on the impact speed and assume that the needle moves at constant speed. Therefore, the effect of the actual needle movement on the stability of the dispensing quality was investigated, especially the effect of the rising speed on the droplet weight and the bubble content of the glue droplets. First, based on the movement process of needle, the fluid dynamics model of glue is established. Second, based on the independently developed piezoelectric needle-collision jetting dispenser, laser vibrometer is used to test the displacement and variable speed of the needle, which further verified the correctness of the analysis results and the feasibility of the research technology. Third, based on the actual motion and numerical simulation, the effects of rising speed and drive voltage on air suction, glue volume and bubble content of spray glue are analyzed. Finally, the theoretical results are verified by experiments, which shows that in order to ensure the weight of the droplets, the rising speed of the needle should be reduced and the drive voltage should be increased. In order to avoid the formation of bubbles in the droplets, the rising speed and drive voltage should be reduced. The findings in this paper can guide the design and control of jetting dispenser, which is used to meet specific industrial requirements.