SUBSTITUTION OF LIQUID CO2 AEROSOLS FOR CFC-113 IN CLEANING OF PRECISION SURFACES AND MICROELECTRONICS

A SIX-MONTH, PHASE I, SMALL BUSINESS INNOVATION RESEARCH (SBIR) PROGRAM IS PROPOSED TO ESTABLISH THE FEASIBILITY OF SUBSTITUTING A NOVEL, PATENTED PROCESS AND COMBINATION OF MATERIALS FOR THE FREON (CFC 113) MATERIALS NOW USED IN HIGH SHEAR CONDITIONS TO CLEAN PRINTED CIRCUIT BOARDS AND OTHER MECHANICAL AND ELECTRONIC COMPONENTS OF INTEREST TO THE DEPARTMENT OF DEFENSE, THROUGH DARPA. THE TECHNOLOGY CONSISTS IN PART IN USING HIGH PRESSURE AND APPROPRIATE ORIFICE TO CREATE AEROSOLS OF SOLVENT, SUCH THAT DISCRETE DROPLETS KNOCK OFF EVEN SUBMICRON SURFACE CONTAMINANT PARTICLES, AS COVERED UNDER U.S. PATENT 4,832,753, ROGER L. CHERRY ET AL., MAY, 1989. A SECOND ASPECT OF THE TECHNOLOGY, COVERED IN A CONTINUATION-IN-PART ISSUED AS U.S. PATENT 4,936,922, JUNE 26, 1990, TREATS THE REFINEMENT OF THE ORIGINAL METHOD BY SUBSTITUTION OF LIQUID C02 FOR THE CHLORINATED SOLVENTS USED IN EARLIER COMMERCIAL PRACTICE. THESE LATER REFINEMENTS HAVE NOT BEEN FULLY DEMONSTRATED TO DATE. IT IS THE PURPOSE OF THIS PHASE I WORK TO REVIEW THE STATUS OF RELATED WORK IN THE LITERATURE, AND TO CONDUCT LIMITED EXPERIMENTAL DEMONSTRATIONS OF THE EFFECT OF C02 AEROSOLS ON STANDING COUPONS, SIMULATING PRINTED WIRING CONTAMINATED WITH TYPICAL FABRICATION RESIDUES. OPTICAL AND ANALYTIC METHODS WILL BE USED TO COMPARE RESULTS WITH CONVENTIONAL TECHNOLOGY. THE RESULTS OF PHASE I ARE EXPECTED TO PROVIDE A CLEAR WARRANT FOR ADAPTING EARLIER, CFC-BASED SYSTEM DESIGNS TO OPERATE WITH SUPERCRITICAL C02 AS A SOLVENT, PRODUCING A COMMERCIALLY USEFUL AND HIGHLY COST-EFFECTIVE TECHNOLOGY IN A PHASE II FOLLOW UP PROJECT. SUBSTITUTION OF LIQUID OR SUPERCRITICAL C02 FOR CFC-113 IN CLEANING OF ELECTRONIC AND MECHANICAL PARTS WILL HAVE AN IMPACT ON THE ORDER OF 19% OF THE BILLION KILOGRAMS OF CFCS CONSUMED ON THE GLOBAL MARKET (1986 ESTIMATE). THESE SOLVENTS ARE USED DOMESTICALLY TO PRODUCE ABOUT $5 BILLION IN GOODS. BENEFICIAL IMPACTS ON AEROSPACE, BIOTECHNOLOGY AND ELECTRONIC INDUSTRIES CAN COME IF BENIGN, EFFECTIVE AND LOW COST SOLVENTS ARE IDENTIFIED.