(142cm) Bridge Dynamics for Liquid Micro-Deposition: Computations and Experiments

The dyanmics of liquid bridge is an important problem which occurs in a variety of physical and technological processes, including ink-jet printing, microlithography, coating processes etc. In this study, we focus on the behavior of liquid bridge formed between a capillary and a substract with a direction application in capillary based droplet deposition, an important component of microlithography.

The experimental process of the capillary based liquid deposition can be divided into two steps. First, a static liquid bridge between the capillary and the substrate is formed when the liquid meniscus on the capillary tip touches the substrate. Second, the capillary retraction away from the substrate causes the bridge elongation and rupture, leaving a micro/nano-droplet on the substrate.

A three-dimentional spectral boundary element method is applied to describe the bridge dynamics while the capillary is retracted away from the substrate. Modeling results are compared with experimental data.  The influences of the liquid properties, pressure, and retraction speed will be discussed and analyzed. The motion of the three-phase contact line as well as the relation between the contact line speed and the contact angle will be discussed based on experimental observations and numerical simulations.