SOME SURFACE-TENSION AND CONTACT-ANGLE PROBLEMS IN INDUSTRY

Contact angle, surface tension and wetting properties are of fundamental importance in many industrial processes, e.g. coating of television screens and fluorescent lights. In addition, different stages of many processes may involve immersion cleansing and subsequent drying. We consider two different problems: one being very practical and involving cleansing and drying of silicon substrates in the semiconductor industry, and the other being theoretical whereby the problem of the shape of sessile and pendant drops is addressed with a possible practical application for making contact angle and surface tension measurements. In the case of cleansing of silicon substrates, we model a process whereby dirt particles are removed as a result of the surface tension forces exerted on a particle passing through a water/air interface and give a possible explanation as to why the efficiency of the process is velocity dependent. For the case of small liquid drops, a new formulation of the governing equation yields solutions for multiple pendant and extended sessile drops.