Design and performance analysis of a flexible-hinged piezoelectric driving dispenser

Piezo-driven dispensers are precision dispensing devices for trace amounts of fluid and are widely used in the microelectronics packaging field. However, the preloading mechanism of piezo-driven dispensers easily loosens in high-frequency operation, and the design accuracy of the transmission ratio of the flexible displacement transmission mechanism (DTM) requires improvement. To address the aforementioned problems, we designed a self-locking preloading mechanism with an adjustable preloading amount for piezo-driven flexible transmission dispensers and investigated the method of designing the transmission ratio considering the non-expected directional deformation (parasitic deformation). First, the principle of the preloading mechanism was analyzed, and a method for adjusting the droplet diameter based on the preloading amount was proposed. Second, an asymmetric flexible-hinge compliance matrix calculation method was proposed, a transmission ratio model of the DTM was established, and the influence law of the structural parameters on the transmission ratio was comparatively analyzed using ANSYS software. Based on the output displacement requirement, transmission ratios were designed and structural parameters were determined. Finally, based on the piezoelectric coupling simulation, a piezo-driven dispenser was manufactured, and a test platform was built to conduct the relevant tests. The simulation and test results demonstrated that the maximum relative errors of the transmission-ratio calculated by the proposed transmission-ratio model were 1.54% and 3.6%, respectively, compared to the simulation and test results, confirming that the model was correct. Single-factor tests confirmed that a preloading mechanism can fix and preload the piezostack and that the droplet diameters can be adjusted with the preloading amounts. The operating frequency was up to 800 Hz with a diameter of 0.30 mm and a consistency of 4.32%, which meet the requirements of dispensing efficiency in the microelectronics packaging field. This study has practical significance for enhancing the transmission ratio design accuracy and dispensing performance of dispensers.