Performance Characteristics of a High Frequency Jetting DispenserFeaturing Piezoelectric Actuator

摘要

This paper presents a new type of jetting dispenser driven by a ring type piezoelectric actuator. By operating at very high frequencies, the dispenser is expected to provide very small dispensing dot size of low viscous adhesives (viscosity of 50cp to 500cp) at high dispensing flow rate in semiconductor packaging processes. After describing the mechanism and operational principle of the dispenser, a mathematical model of the system is derived by considering behaviors of the piezostack, the actuating spring, the dispensing needle and the adhesive fluid dynamics. In the modeling, a lumped parameter method is applied to model the adhesive whose rheological property is approximately expressed by Bingham model. The governing equation of the whole dispenser is then derived by integrating the structural model with the fluid model. Based on the proposed model, the dispenser is designed and manufactured. Subsequently, the dispensing performances such as dot size and dispensing flow rate are investigated using the proposed model and then validated by experiment.