Design and experiment of a new double needle type piezoelectric jetting dispenser

Abstract

To improve the performance of piezoelectric (PZT) jetting dispensers in the electronic packaging industry and address the problems of oversized, easily fatigued elastic hinges and low repetition accuracy of conventional PZT jetting dispensers with a compliant mechanism-based lever, a new double needle PZT jetting dispenser prototype was developed. The advantage of the proposed structure over compliant mechanism-based lever was demonstrated by dynamics analysis. Firstly, the design stroke of the needle and the modal state of the dispenser body were analyzed using ANSYS. Secondly, the theoretical model of adhesive injection was established, the fluid pressure change process inside the nozzle during the working cycle of the jetting dispenser was simulated using Fluent, and the effects of the supply pressure and needle stroke on the injection speed of the droplet were investigated. Finally, a test bench was built to conduct the experiment, and the results showed that the supply pressure and the driving signal duty cycle between 20% and 80% were positively correlated with the size of droplet diameter, whereas the driving signal frequency was negatively correlated with the droplet diameter, thereby validating the proposed adhesive injection model. Under the experimental conditions, the highest operating frequency of the designed PZT jetting dispenser was 400 Hz, which is close to the high-frequency level of existing studies, and the minimum droplet diameter obtained was 0.36 mm, which is 0.1–0.2 mm less than that of the existing PZT jetting dispenser with a compliant mechanism drive, meeting the industry requirements for the working performance of a PZT jetting dispenser.