immersion tin PCB — controlled process sequence01 Prepare copperClean the exposed features andcontrol roughness and micro-etchbefore the immersion reaction.02 Deposit tinA controlled chemical displacementprocess forms the tin finish oncopper; it is not HASL or thickelectroplating.03 Rinse and dryFollow the chemistry-specificsequence and prevent fingerprints,residues and incompatiblepackaging contact.04 Measure the depositDistinguish total finish thicknessfrom remaining free tin and recordwhen the measurement was taken.05 Protect the assembly windowStorage and heat promote copper-tin reaction; keep the actuallogistics and reflow sequencewithin the qualified plan.06 Verify final useCheck solderability after theagreed exposure and verifyfinished-hole compatibility forthe selected press-fit connector.Original engineering illustration · conceptual, not to scale