Many advanced assemblies require high-volume and cost-effective selective cleaning during various stages of assembly or rework operations. Due to component compatibility problems and drying challenges, partially assembled devices cannot be immersed in or sprayed with aqueous cleaners or solvents. Newer dry cleaning techniques such as carbon dioxide (CO2) aerosol spray cleaning processes (snow cleaning) have proven to be challenging to implement in automated high-volume manufacturing operations. Issues associated with conventional snow cleaning include high costs of operation, lack of process consistency, ineffective controls, and the requirements for a supply of high-purity liquid CO2.
Advanced CO2 composite spray [CO2(solid)-compressed dry air (CDA)(gas)] cleaning is an effective alternative to traditional spray and immersion cleaning processes and to conventional snow cleaning for selectively removing contaminants and films from partially assembled hard disk drive (HDD) components during the remanufacturing or rework process. CO2 consumption is reduced using a composite spray, while spray cleaning control and performance is improved. CO2 composite spray cleaning performance is dependent on the position, speed, and motions of the spray applicator, which are matched to comply with HDD factory output. Stored spray cleaning programs deliver precise cleaning seven days a week, 24 hours per day, with uptimes exceeding 99.9% over a 6-month period. Monitoring and controlling composite spray cleaning process parameters including spray pressure and composition, scanning speed, and pallet/part identification are done automatically. Operator interaction is limited to loading and unloading pallets for continuous system operation.