Design and dispensing volume estimation of a piezo-driven dispenser with rigid-flexible combined transmission mechanism

This study developed a piezo-driven dispenser for microelectronic packaging. The dispenser utilizes a rigid-flexible combined piezo-driven mechanism with a unilateral preloading feature, and the study examined how to estimate droplet volume. Firstly, a static model of the displacement transmission mechanism was established, and the transmission ratio was designed. Secondly, the droplet formation mechanism was studied, and the pressure change process during droplet distribution was simulated and analyzed. Lastly, a linearized dispensing volume estimation model was proposed, synthesizing the Hagen-Poiseuille and pore-flow equations, based on the limiting method and the curtain area assumption. A dispenser prototype was then fabricated and tested. The static model calculated a relative error of 2.85% and 2.7%, respectively, in comparison with simulation and test results. Single-factor tests confirmed that the designed dispenser worked stably, with droplet volumes and diameters having a consistency of 5.2% and 4.2%, respectively. The droplet volumes estimated by the proposed model were consistent with the trend of the test and had a mean relative error of 5.3%, verifying the validity of the proposed volume estimation model. When the dispensing frequency reached 400 Hz, the minimum diameter and volume were 0.43 mm and 0.09

, respectively. This study provides a new method to design the structure of piezo-driven dispensers and estimate the dispensing volume of droplets.