Why Not Ultrasonic Cleaning?
Many assemblers still shy away from using ultrasonic agitation to augment the cleaning power of various cleaning agents. This reluctance is due to fear of component damage that could come from use of single-frequency ultrasonic agitation of cleaning agents, back when TO-5 and similar metal-packaged semiconductor packages were widely used. Since much of this fear goes back 50 years, it is time to move ahead to meet today’s cleaning challenges, such as the tenacious residues from lead-free and low-residue fluxes, combined with much higher reflow temperatures. Laboratory Studies on Ultrasonic Cleaning GEC-Marconi Ltd. led the way here, undertaking a broad range of studies under the project heading of “A Study on the Effect of Ultrasonic Cleaning on Component Quality.” Multiple subsections of this study looked at different families of components and their survival when subjected to ultrasonic cleaning regimens. For a snapshot of power density (W/liter) vs. ultrasonic (U/S) exposure time (h
