Research On The Jetting Dispenser Driven By A Piezostack

Dispensing technology is a process to dispensing the fluid accurately in a controlledmanner which has become one of the key technologies of microelectronics packaging. Withthe development of technology, there is an evolution in the fluid dispensing technology forapplying fluids from contact methods to non-contact methods. Jetting technology is fast,effective, no limited by space and offers many advantages over traditional needle dispensingto deliver speed, quality, low cost of ownership and jetting dispensing technology representsthe developing trend of the fluid dispensing technology, which is bound to be widely appliedin the future.This paper presents a type of jetting dispenser which is driven by piezoelectric ceramic,The proposed jetting dispenser Consists of a piezostack and a micro displacement amplifierwhich is mainly made up of a fexible beam，next the research is carried out from boththeoretical and experimental.First of all, introducing the basics knowledge of piezoelectric materials andpiezoelectric stack, Testing the displacement characteristics and the stiffness characteristicsof the PST150/5/100piezoelectric stack which is used in this paper，and building themathematical model of piezoelectric stack from the electrical point.After describing thestructure and working principle of the jetting dispensing valve, the model of the jettingprocess was built and obtained the conditions of dispensing adhesive according to theanalysis of the adhesive’s flow characteristics. The flow field of adhesive in the nozzle wassimulated and obtained the influence on jet dispensing caused by the stem displacement, theadhesive viscosity and the driving pressure conducted a detailed analysis on the lever typeamplifie and obtained the relationship of magnification,input stiffness and output stiffness ofthe lever type amplifier. Also established the dynamic model of jetting dispensing valve,analyzed the dynamic model by using MATLAB and ANSYS software.Next, according to the requirements of the dispensing process in the field ofmicroelectronic packaging, manufactured a prototype of the jetting dispensing, the dispensingprototype included a piezoelectric jet dispensing valve, a three-dimensional motion platform,the constant pressure air supply system, the piezoelectric ceramic drive power and the controlsystem. Finally, a lot of tests carried out on the dispensing prototype in this paper, tested thedisplacement characteristic of stem, the dispensing speed of jetting dispensing valve,dispensing accuracy and the consistency of droplets. The test results showed that the dispensing speeds of this dispensing valve is up to277points/seconds, and the minimumvolume of the droplet is0.94ul.