Aqueous Based Cleaning
Aqueous (and semi-aqueous) cleaners are finding
increased usage for gross cleaning of items. This is particularly true in the
electronics industry where CFC cleaning materials are being replaced with
aqueous cleaners. Work at Martin Marietta has shown that an aqueous cleaner,
at an operating temperature of approximately 60ºC (140ºF) is a better soil
remover than the ozone depleting 1,1,1 Trichloroethane used in a vapor
degrease process (see reference 2). This method
was demonstrated using an immersion technique.
An aqueous cleaner is being used as a precleaner for precision cleaning
applications; to replace CFC 113 vapor degreasing, for gross cleaning of detail
parts, components, and assemblies where no entrapped areas are present. The
aqueous cleaner is being used in an ultrasonic tank and heated to 60 to 71 ºC
(140 to 160 ºF). Continuous filtering is used to remove particulate and skimmers
are in use to remove excess molecular contaminants. Solution monitoring is being
established to determine when to replace the aqueous solution. The spent cleaner
will be processed through Martin Marietta's water treatment plant or recycled
for use in a larger aqueous bath tank. Use of this aqueous cleaner eliminated
the need for vapor degrease and alkaline clean steps in the previous cleaning
process. A demonstration program (discussed later) was performed to define the
ultrasonic processing parameters and cleaning capabilities.
