Ultrasonic cleaning is an effective aid in the removal of flux residues from surface mounted circuits. However, an over‐intensive and too extended ultrasonic load of surface‐mounted electronic circuits, on ceramic substrates, occasionally causes the fracture of component leads. In a metallurgical study, it was found that the fracture mechanism is fatigue. The fundamental cure for this problem is to limit the ultrasonic load to a level below the fatigue limit of the leads. This can be achieved by limiting the ultrasonic power input in the bath. Other beneficial measures are to limit the cleaning time and the ultrasonic frequency, and to prevent the components from coming into contact with other parts during cleaning.
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