UV/Ozone Cleaning of Surfaces

Abstract

The ultraviolet (UV)/ozone cleaning procedure is shown to be an effective method of rapidly removing a variety of contaminants from surfaces. It is a simple-to-use dry process which is inexpensive to set up and operate. It can produce · clean surfaces in air, at ambient temperatures. The experiments were performed on quartz and metal surfaces. The contaminants which were successfully removed include oils and greases (including silicones), fluxes, skin oils, and contamination adsorbed during prolonged exposure to air. The experiments were aimed at defining the variables and determining the optimum conditions for producing clean surfaces by UV irradiation. The important variables are: the contaminants initially present, the precleaning procedure, the wavelengths emitted by the UV source, the atmosphere between the source and sample, the distance between the source and' sample, and the time of exposure. For surfaces which are properly precleaned and placed within a few millimeters of an ozone-producing UV source, the process can consistently produce a clean surface in less than 1 rain. Experiments performed with two low-pressure mercury discharge UV sources, one which generates ozone and one which does not, indicate that the combination of short-wave UV light plus ozone produces a clean surface substantially faster than either short-wave UV light without ozone or ozone without UV light.