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Home > Parts cleaning > Processes > Ultrasonic cleaning
Ultrasonic cleaning
Ultrasonic cleaning uses sound waves passed at very high frequency through liquid cleaners, which can be
alkaline, acid, or even organic solvents. The passage of ultrasonic waves through the liquid medium
creates tiny gas bubble, which provide a vigorous scrubbing action on the parts being cleaned. Although
the mechanism of this action is not completely understood, it yields very effective cleaning.
It is ideal for lightly soiled work with intricate shapes, surfaces, and cavities that may not be easily
cleaned by spray or traditional immersion techniques. Highest degrees of cleanliness can be achieved.
The components of a basic ultrasonic system are the cleaning tank, ultrasonic transducers, and a power
supply (generator). A disadvantage of ultrasonic cleaning process is the high capital cost of the power
supplies and transducers that comprise the system.
Megasonic cleaning uses high-frequency acoustic energy produced by transducers to generate pressure waves
in a liquid. It is a higher frequency version (700-1,000 kHz) of acoustic cleaning than ultrasonics
(20-40 kHz). An important difference between the two methods is that there is no significant cavitation
in the megasonic range. This significantly reduces the likelihood of surface damage. Parts that are
damaged by ultrasonic energy might be cleaned without damage in a megasonic bath using the same solutions.
This technique is effective for removing submicron particles from silicon wafers without damage. Removal
of other contaminants depends on the solutions in the tank. Megasonic agitation will increase the removal
of other contaminants but is not as aggressive as ultrasonics.
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