# US 5,706,840 A · Precision cleaning apparatus and method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,706,840 A - Document ID: US5706840A - Status: Granted - Kind: A - Application number: 08/398,276 - Filed: 1995-03-03 - Granted: 1998-01-13 - Earliest claimed: 1995-03-03 - Assignees: Sandia Corporation - Inventors: Thomas W. Schneider; Gregory C. Frye; Stephen J. Martin - Web page: https://patentgrep.com/patent/US5706840A ## CPC - B08B 3/00: Cleaning by methods involving the use or presence of liquid or steam (B08B9/00 takes precedence) - G01G 3/13: having piezoelectric or piezoresistive properties - G01H 13/00: Measuring resonant frequency - B08B: CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL - G01G: WEIGHING (sorting by weighing B07C5/16) - G01H: MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES ## Abstract A precision cleaning apparatus and method. The precision cleaning apparatus includes a cleaning monitor further comprising an acoustic wave cleaning sensor such as a quartz crystal microbalance (QCM), a flexural plate wave (FPW) sensor, a shear horizontal acoustic plate mode (SH--APM) sensor, or a shear horizontal surface acoustic wave (SH--SAW) sensor; and measurement means connectable to the sensor for measuring in-situ one or more electrical response characteristics that vary in response to removal of one or more contaminants from the sensor and a workpiece located adjacent to the sensor during cleaning. Methods are disclosed for precision cleaning of one or more contaminants from a surface of the workpiece by means of the cleaning monitor that determines a state of cleanliness and any residual contamination that may be present after cleaning; and also for determining an effectiveness of a cleaning medium for removing one or more contaminants from a workpiece. ## Claims ### Claim 1 Apparatus for precision cleaning of an accumulation of at least one contaminant from a surface of a workpiece during contact with a cleaning medium, the apparatus comprising: (a) a cleaning container having walls which define a cleaning zone wherein the workpiece is contacted by the cleaning medium for removal of the contaminant therefrom; and (b) a cleaning monitor comprising a sensor insertable into the cleaning zone with at least one exposed side thereof for accumulating prior to insertion of the sensor into the cleaning zone a layer of the contaminant thereon substantially equal to the accumulation on the workpiece, and measurement means connectable to the sensor for measuring at least one electrical response characteristic thereof that varies in response to removal of the layer of contaminant therefrom by contact with the cleaning medium. ### Claim 2 (depends on 1) The apparatus for precision cleaning of claim 1 in which the sensor is selected from the group of acoustic wave sensors consisting of quartz crystal microbalances, flexural plate wave sensors, acoustic plate mode sensors, and surface acoustic wave sensors. ### Claim 3 (depends on 2) The apparatus for precision cleaning of claim 2 in which the measurement means includes an oscillator circuit for activating the sensor and providing the at least one electrical response. ### Claim 4 (depends on 3) The apparatus for precision cleaning of claim 3 in which the electrical response characteristic is selected from the group consisting of a resonant frequency, a frequency shift, a damping voltage, a damping resistance, or a combination thereof. ### Claim 5 (depends on 3) The apparatus for precision cleaning of claim 3 in which the oscillator circuit is located proximate to the sensor within a housing having an opening for the exposed side of the sensor and a liquid-tight barrier between the oscillator circuit and the sensor. ### Claim 6 (depends on 3) The apparatus for precision cleaning of claim 3 in which the electrical response characteristic provides an indication of a state of cleanliness of the workpiece. ### Claim 7 (depends on 1) The apparatus for precision cleaning of claim 1 further including a heater and a temperature controller for maintaining the cleaning medium at an elevated temperature. ### Claim 8 (depends on 1) The apparatus for precision cleaning of claim 1 further including an ultrasonic agitator. ### Claim 9 (depends on 1) The apparatus for precision cleaning of claim 1 in which the sensor is attachable to the workpiece. ### Claim 10 (depends on 1) The apparatus for precision cleaning of claim 1 in which the sensor is attachable to a workpiece carrier. ### Claim 11 (depends on 1) The apparatus for precision cleaning of claim 1 in which the contaminant is an organic material. ### Claim 12 (depends on 11) The apparatus for precision cleaning of claim 11 in which the organic material comprises at least in part an oil. ### Claim 13 (depends on 1) The apparatus for precision cleaning of claim 1 in which the cleaning medium is an aqueous solution including a cleaning agent. ### Claim 14 (depends on 1) The apparatus for precision cleaning of claim 1 in which the cleaning medium is an organic solvent. ### Claim 15 (depends on 1) The apparatus for precision cleaning of claim 1 including at least one indicator for indicating a state of cleanliness of the workpiece. ### Claim 16 (depends on 15) The apparatus for precision cleaning of claim 15 in which the indicator provides a quantitative measure for the state of cleanliness. ### Claim 17 (depends on 15) The apparatus for precision cleaning of claim 15 in which the indicator provides a visual signal for indicating the state of cleanliness. ### Claim 18 (depends on 15) The apparatus for precision cleaning of claim 15 in which the indicator provides an audible signal for indicating the state of cleanliness. ### Claim 19 A cleaning monitor for determining an effectiveness of precision cleaning of an accumulation of at least one contaminant from a surface of a workpiece in contact with a cleaning medium within a cleaning zone comprising: (a) a sensor insertable into the cleaning zone and having at least one exposed side thereof for accumulation prior to insertion of the sensor into the cleaning zone of a layer of the contaminant substantially equal to the accumulation on the workpiece; and (b) measurement means connectable to the sensor for measuring at least one electrical response characteristic thereof that varies in response to removal of the layer of contaminants from the exposed side of the sensor by contact with the cleaning medium. ### Claim 20 (depends on 19) The cleaning monitor of claim 19 in which the sensor is selected from the group of acoustic wave sensors consisting of quartz crystal microbalances, flexural plate wave sensors, acoustic plate mode sensors, and surface acoustic wave sensors. ### Claim 21 (depends on 20) The cleaning monitor of claim 20 in which the measurement means includes an oscillator circuit for activating the sensor and providing the at least one electrical response characteristic for measuring removal of the layer of contaminant from the sensor. ### Claim 22 (depends on 21) The cleaning monitor of claim 21 in which the oscillator circuit is located proximate to the sensor within a housing having an opening for the exposed side of the sensor and a liquid-tight barrier between the oscillator circuit and the sensor. ### Claim 23 (depends on 21) The cleaning monitor of claim 21 including at least one indicator for indicating a state of cleanliness of the workpiece. ### Claim 24 (depends on 23) The cleaning monitor of claim 23 in which the indicator provides a quantitative measure for the state of cleanliness. ### Claim 25 (depends on 23) The cleaning monitor of claim 23 in which the indicator provides a visual signal for indicating the state of cleanliness. ### Claim 26 (depends on 23) The cleaning monitor of claim 23 in which the indicator provides an audible signal for indicating the state of cleanliness. ### Claim 27 Apparatus for precision cleaning of an accumulation of a contaminant from a surface of a workpiece during contact with a cleaning medium, the apparatus comprising: (a) a cleaning container having walls which define a cleaning zone wherein the workpiece is contacted by the cleaning medium for removal of the contaminant therefrom; and (b) a cleaning monitor comprising an acoustic-wave sensor insertable into the cleaning zone with at least one exposed side thereof for accumulating prior to insertion of the sensor into the cleaning zone a layer of the contaminant thereon substantially equal to the accumulation on the workpiece, and measurement means connectable to the sensor for measuring at least one electrical response characteristic thereof that varies in response to removal of the layer of contaminant therefrom by contact with the cleaning medium. ### Claim 28 (depends on 27) The apparatus of claim 27 in which the acoustic-wave sensor is selected from the group consisting of quartz crystal microbalances, flexural plate wave sensors, acoustic plate mode sensors, and surface acoustic wave sensors. ### Claim 29 (depends on 27) The apparatus of claim 27 in which the acoustic-wave sensor provides an indication of a state of cleanliness of the workpiece. ### Claim 30 (depends on 29) The apparatus of claim 29 further including means for agitating the cleaning medium. ### Claim 31 Apparatus for precision cleaning of a contaminant from a workpiece comprising: (a) means for contacting the workpiece with a cleaning medium; and (b) means for measuring removal of an accumulated layer of the contaminant from a sensor to provide an indication of removal of the contaminant from the workpiece. ### Claim 32 (depends on 31) The apparatus of claim 31 in which the measuring means includes an acoustic-wave sensor selected from the group consisting of quartz crystal microbalances, flexural plate wave sensors, acoustic plate mode sensors, and surface acoustic wave sensors. ### Claim 33 (depends on 31) The apparatus of claim 31 wherein the measuring means further includes means for indicating a state of cleanliness of the workpiece. ### Claim 34 Apparatus for precision cleaning of a contaminant from a workpiece comprising: (a) a container having a cleaning zone wherein the workpiece is in contact with a cleaning medium; and (b) a sensor located in the cleaning zone and in contact with the cleaning medium, the sensor being responsive to removal of a layer of the contaminant accumulated thereon to sense removal of the contaminant from the workpiece. ### Claim 35 (depends on 34) The apparatus of claim 34 in which the sensor is an acoustic-wave sensor selected from the group consisting of quartz crystal microbalances, flexural plate wave sensors, acoustic plate mode sensors, and surface acoustic wave sensors.