How does high environmental humidity impact soldering processes?

High environmental humidity can significantly impact soldering processes, primarily due to its tendency to facilitate the oxidation of metal surfaces. When humidity levels are elevated, moisture in the air can react with exposed metal surfaces, such as copper pads on printed circuit boards (PCBs) or the leads of components. This oxidation leads to a layer of oxide forming on these surfaces, making them less conductive and adversely affecting solderability.

Oxidized surfaces can create barriers that prevent solder from properly wetting and adhering to the metal, which can result in poor-quality solder joints. Effective soldering requires clean, unoxidized surfaces to ensure strong mechanical and electrical connections. Therefore, managing humidity levels in the environment where soldering takes place is crucial to maintain the integrity of the soldering process and to avoid defects related to oxidation.

While other options suggest benefits such as increased solderability or better adhesion, these are not valid under high humidity conditions. Similarly, contamination risks are not eliminated by moisture; in fact, increased humidity can often exacerbate issues related to residues or contaminants on surfaces.