Modeling Rotary-Screw-Driven Dispensing Systems for Electronics Packaging

Fluid dispensing is a process of delivering fluid materials in a controllable manner and has found extensive applications in electronics packaging manufacturing. Among various dispensing approaches, the rotary-screw-driven dispensing method has high versatility for dispensing a wide range of fluid materials. Given the fact that the flow rate of material dispensed has significant effects on the quality of electronics packaging, knowledge of the flow rate in rotary screw dispensing systems through mathematical models is desired. This paper presents the development of an integrated dynamic flow-rate model for rotary-screw-driven dispensing systems. The model is composed of two interconnected submodels, one model for the dynamics of the screw-driving system and the other for the flow-rate dynamics in the screw channel. Without loss of generality, a phenomenological model in the form of a linear state space model is adopted for the dynamics of the screw-driving system, and by considering the fluid compressibility, the flow-rate dynamics in the screw channel is represented. Dispensing experiments were performed for model parameter estimation and then for model verification. The results illustrate that the model developed can be used to predict the flow rate in the rotary-screw-driven dispensing systems.