Evaluation of megasonic cleaning processes

To get an insight in the interaction of acoustic waves and an aqueous based cleaning chemistry, different monitoring tools were developed and the results compared to particle removal tests. A first tool is designed to capture sonoluminescence, coming from cavitation generated in the acoustic field. It will be shown that cavitation plays a central role in the particle removal. Different parameters as gas content, power and presence of surfactants are studied in relation to sonoluminescence. A second tool, based on a hydrophone, provides a detailed map of the power distribution of the acoustic waves in a cleaning tank. Diffraction patterns in the near field and attenuation profiles in the far field are extracted and the impact of bubbles to the dispersion of the acoustic power is studied.