METHOD FOR CLEANING A WORKPIECE AFTER MACHINING WITH A CUTTING INSTRUMENT

摘要

The method for cleaning the cuts (24) machined into a workpiece (22) such as a printed electric circuit board, includes the steps of coating the cutting instrument (36) such as a drill bit, with a liquid tracer prior to the cutting operation. During the cutting operation, the liquid tracer becomes mixed with material such as an electrically insulating binder layer (50) disposed, e.g. between opposed metal plates (46, 48) of the workpiece (22). Any smear (52) of the insulating layer (50) upon exposed metal surfaces of the cut (24) contains elements of chemical compounds used in the tracer. After extraction of the cutting instrument (36) from the workpiece (22), the latter is placed in a plasma reactor (26) wherein the metal surfaces are etched to remove any smears and debris (52) of the insulation material found on the exposed metal surfaces. The tracer elements, such as deuterium and phosphorus are monitored in the effluent plasma of the reactor (26) to determine when the cleaning of the cuts (24) in the workpiece (22) is completed.