OSP PCB surface finish — controlled process sequence01 Prepare copperClean and micro-etch to thequalified surface condition.Excessive removal must not erodesmall features.02 Rinse and conditionControl carryover and the incomingsurface chemistry so theprotective film can formconsistently.03 Apply the organic filmThe chosen chemistry forms aprotective coating on exposedcopper without adding a nickelbarrier.04 Measure and dryUse the chemistry-specific filmtest and controlled dryingsequence; metallic XRF is not auniversal OSP test.05 Pack and control exposureRecord lot identity, packagingconditions, opening time and theagreed assembly window.06 Assemble and verifyThe flux and thermal cycle exposecopper for soldering. Qualify thefull double-sided or mixed-technology sequence.Original engineering illustration · conceptual, not to scale