Abstract
As a fundamental study of the photoetching of precision metal components, the spray etching rates of ferric chloride etchants were analyzed. A full-cone spray forms the most uniform flow distribution, and this configuration was employed in this analysis. The effects of temperature, spraying pressure and spraying distance on the spray etching rates on mild steel were quantitatively investigated to develop an empirical formula for spray etching rate. A physical evaluation of fluid flows in the spraying system was made to elucidate the effect of the impact of the etchant spray. Experimental results indicate that the spray etching rate is proportional to the 1.2th power of the velocity of the ferric chloride etchant, and that the spray etching rate is proportional to the 0.6th power of the kinetic energy of the etchant on metal surfaces. Spray etching behavior was found to be analogous to the mass transport phenomena in turbulent flows.
