Moisture Sensitivity Level Three Parts Arriving without a Dry Pack
Compromised MSL 3 packaging instantly voids floor life: quarantine components, verify humidity cards, and require J-STD-033 dry baking before SMT reflow.
Component Solderability
Surface Performance
Metallic terminal wetting evaluates the ease with which molten solder alloys form a reliable metallurgical bond with a component lead or termination. Testing for component solderability ensures that electronic assemblies do not suffer from cold joints or detached components during the reflow process. The evaluation establishes the limits of surface contamination or oxidation before assembly takes place.
Wetting Evaluation
Wetting balance analysis measures the vertical force exerted by molten solder on a suspended lead as it is dipped into a heated crucible. A transducer records the dynamic changes from an initial upward buoyancy force to a downward capillary wetting force as the alloy adheres to the metal surface. The time taken to reach ninety percent of maximum wetting force represents the primary qualification metric.
Longer wetting times indicate that oxidation or organic residues have degraded the surface.
Storage Limit
Environmental exposure to humidity and temperature accelerates the growth of intermetallic compounds that reduce the thickness of the solderable finish. Finished leads typically undergo simulated aging, consisting of steam conditioning for eight hours, before testing begins. Component solderability declines steadily beyond this point.
Qualification Standard
IPC-J-STD-002 defines the standard criteria for wetting forces and visual coverage across different package types. A component must exhibit at least ninety-five percent continuous solder coverage to pass the visual assessment.