Jettig Type Of Precision Dispensing Valve Design And Analysis

Fluid dispensing is an essential approach to distribute low volume liquid accuratelyin many processes of microelectronic packaging. It has been widely used in manyprocesses of microelectronic packaging, suc as die attaching, epoxy based encapsulationand underfilling. To meet up the fast development of microelectronic packaging in thelast decade and to improve production efficiency, fluid dispensing technology hasinevitably transformed from contact dispensing to non-contact dispensing. This thesishas introduced fluid dispensing technology in detail. In addition, this paper presents atype of jetting dispenser which is driven by piezoelectric ceramic.Firstly, analyzed the influence factors of the drop formation, and the principle thatthe process of piezoelectric drop jet with fluid dynamics. Governing equations are setup for a viscous and imcompressible laminar flow. Changes of liquid surface in ambientair are tracked with Volume of Fluid method, and Continuum Surface Force method isemployed to describe the surface tension effect between liquid and air. The flow field ofadhesive in the nozzle was simulated and obtained the influence caused by theball-needle displacement, the adhesive viscosity, the adhesive surface tension and thedriving pressure. Besides, the reason which csuses the satellite drop is analyzed, and putforword a method to judge the satellite drops.Secondly,this thesis analyzes the flexure-based bridge-type displacement amplifierin detail and derives its amplification ratios fomula based on two different models. Thefnite element method was used for comparison with the mathematical model, andsimilar results were obtained. Particle swarm optimization method has been adoptedto get the optimum solution. The fnite element method was used to analyze the shapemode of the structure. This paper designs appropriate displacement amplifier to meetthe dispensing valve.Finally, according to the requirements of the dispensing process, a non-contactfluid dispenser actuated by stacked piezoceramics is manufactured. And correspondingmoving platform is designed to ensure the efficiency and stability of fluid jetting.Withthis platform, dispensing experiments are carried on. Based on the experimental data,the effects of key factors, such as fluid supply pressure, jetting frequency and drivingvoltage, are analyzed and compared with simulation result. Experiments prove that thedispensing valve has good performance.