Hello JB,
Based on the double sided assemblies, the misprint cleaning process can demand the cleaning system to remove both raw solder paste from the misprinted side of the board, and, reflowed flux residues from the assembled side.
Recognizing and setting this as the requirement, the Austin American Technology development team conducted a study to select highest performing technology for the development of a misprint cleaning system. The findings were as follows:
Double sided Misprint assemblies � Spray in air systems demonstrated the ability to use of a diverse range of chemistries to effectively clean both sides, while not diminishing the mechanical energy contribution. At the time of AAT's study, ultrasonic energy allowed only a limited range of chemistries. Chemistries aggressive enough to remove reflowed flux residues diminished the ultrasonics mechanical energy contribution.
Dislodging and displacing raw solder paste � Spray in air effectively dislodged and displaced solder spheres away from a broad range of assemblies. Due to flushing and filtering associated with spray in air, dislodged solder paste were flushed away and the metal content filtered out of the active process solution. Ultrasonic energy effectively dislodged solder spheres, while it demonstrated less effectiveness in displacing the solder away from complex assemblies. AAT's in house test showed ultrasonic technology did not sufficiently carry the metal content away, rather, the dislodged spheres fell under components and into via's.
Spray in air technology also demonstrated higher marks in the technologies ability to rinse and dry complex assemblies, and, lends itself to simple and low cost of ownership maintenance procedures. While Austin American Technology offers both ultrasonic and spray in air systems, based on the results of the study, spray in air was chosen as the technology to integrate into the cleaning systems AAT offers for Misprint applications.
Hope this is useful information for your consideration of avaialable misprint cleaning technologies.
Shean Dalton www.aat-corp.com (512) 335-6400
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