ABSTRACT
A systematic way to characterize the cleaning efficiency of a surface cleaning equipment is to derive relationships between before-clean and after-clean contamination levels on substrates. This procedure accounts for variations in incoming cleanliness levels of components, and is therefore a meaningful representation of the capability of the cleaner itself. In disk drive parts cleaning, various options are available, including sonication, spray, centrifugation and combinations of these. Water-based cleaning is typically accomplished in one of two modes-sonication and shear— or combinations of these. Spray cleaning accomplishes particle removal by exerting a shearing force tangential to the substrate. With sprays, the particle removal efficiency does not necessarily decrease steadily with application time. Particles must first become dislodged by the shear, and then have to be transported away by the flow. Multiple ultrasonic extraction and multiple spray extraction techniques have been demonstrated for the determination of particle removal characteristics of the two methods.
