Abstract: A method and apparatus for cleaning printed electrical circuit boards having surface mount components by ultrasonic energy in the frequency range between 300 kHz and 1.0 MHz. The ultrasonic energy is produced by an array of piezoelectric wafers mounted to the inside surface of an immersible transducer assembly which, in turn, is disposed in a tank accomodating a bath of cleaning liquid. The ultrasonic energy provided by the transducer assembly and the circuit board to be cleaned are disposed to cause the ultrasonic wave beam to be incident upon a board to be cleaned at an angle of 90.+-.60 degrees relative to the surface plane of the board. This arrangement will remove solder flux residue and other contaminants from spaces ranging from 0.001 to 0.010 inch present underneath a surface mount component.

Abstract: A multiple-fill dishwasher and method includes a wash chamber having a sump at the bottom thereof, a remotely controlled inlet valve for supplying cleansing liquid into the sump, a drain for draining liquid and entrained soil from the sump, and a recirculating pump having a spraying system receiving the output thereof for spraying liquid onto soiled ware contained within the chamber. A control circuit controls the valve, drain means, and pump to perform a selected one of a plurality of different cleansing cycles which are automatically selected according to the extent of soil on the ware. An operator-actuated switch for commencing operating of the control circuit, and a chamber for collecting soil particles in a concentrated fashion during liquid recirculation, are also provided.