A multi-disciplined product team comprised of Engineering,
Operations, Safety, and Environmental Management assessed the feasibility of
various cleaning materials and processing equipment for precision cleaning.
Precleaning using an aqueous based cleaner followed by isopropyl alcohol spray
final clean were the materials and methods selected to replace 1,1,1
trichloroethane preclean (vapor degrease) and CFC 113 final clean.
Alternative materials have replaced previously used
ozone depleting materials such as CFC 113 and 1,1,1 trichloroethane for
precision cleaning. Alternative cleaning techniques and equipment have also
been incorporated to utilize these new materials. A systems approach was
required to best match the alternative cleaning material and cleaning process
equipment to effectively meet the end cleanliness requirements. These new
requirements included not only the typical hardware cleanliness issues
(molecular and particulate levels), but the safety aspects of the cleaning
process, the reuse of the cleaning media, and the treatment of air emissions
from the cleaning chamber prior to exit into the atmosphere. These
requirements are listed in Table 1. The alternative cleaning materials and
process equipment systems were discussed in a previous paper (see reference 1
at end of report). High precision cleanliness requirements must be
met and a systems approach is illustrated to best meet the requirements. Alcohol
(isopropyl) is the cleaning material selected using spray application for
removal of both molecular and particulate contamination. Demonstration of this
system is complete and results to date are given. The first manual spray
cleaning system is operational and a second automated cleaning system is near
completion (planned to be on line in November 1992).
