Moisture Sensitive Parts Opened before the Line Was Ready
Opening moisture-sensitive parts before line release exposes components to ambient humidity, risking thermal delamination during reflow unless floor life is tracked and restored.
Matte Tin Oxidation
Surface Degradation
The reaction between a tin plating finish and atmospheric oxygen creates a thin layer of tin oxide that interferes with the soldering process. While a matte tin finish is preferred for its resistance to tin whiskers, matte tin oxidation can reduce the wettability of the component leads. This layer of oxide has a much higher melting point than the underlying metal, acting as a barrier to the molten solder.
If the oxidation is too thick, the solder will fail to form a reliable intermetallic bond with the lead.
High Humidity
High humidity and elevated temperatures accelerate the growth of this oxide layer during storage. Parts stored in unsealed bags or in facilities without climate control are the most susceptible to matte tin oxidation. This chemical change is often invisible but can be detected through a standard solderability test.
Using an active flux during assembly can sometimes penetrate the oxide, but excessive oxidation will still lead to cold joints or total wetting failure.
Vacuum Sealing
Vacuum sealing components with desiccant is the standard practice for preserving the quality of the finish over time. Maintaining a first in first out inventory system ensures that parts are used before the surface quality degrades.