DfR- DESIGN for Rinse-Ability: The Effect of SMT Component Package Design on Cleaning Circuit Card Assemblies (CCA) manufactured using Surface Mount Technology SMT processes have exhibited cleaning residues remaining after subsequent conformal coating required for Mil/Aero products within electronic component/package housings with degradation/corrosion of internal parts that may detrimentally affect the electrical performance of the components. Certain components or package configurations exhibited more entrainment and/or entrapment of cleaning residues with experiments performed resulting in “Design for Rinse-ability” specifications or guidelines implemented.
Evaluation of SMT Solder Pastes for Flux Residues Mitigation in Cleaning Machines Increased volumes of CCAs being cleaned after SMT have resulted in more flux residue building up on cleaning machine wash/rinse tanks, “gumming-up” sump-pumps, causing sensor failures, as well as, increasing PM cleaning cycles with residue difficult to remove. Residue is attributed to the presence of an insoluble additive in the current solder paste. An alternate solder paste was evaluated that did not have this insoluble flux constituent and was found to be metallurgically equivalent and has since been run in production CCAs with no assembly, electrical performance issues or physical solder-joint defects.
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