How do contaminants affect solder joints?

Contaminants can significantly undermine the quality of solder joints by disrupting the wetting process. Wetting refers to the ability of solder to adequately flow and adhere to the surfaces being joined. When contaminants such as oil, grease, dust, or oxidation are present, they create barriers that prevent the solder from fully adhering to the base materials. This inadequate wetting results in poor mechanical bonds, leading to weak joints that may fail under stress or during thermal cycling.

Furthermore, the presence of these contaminants can cause incomplete melting of the solder or reduce the effectiveness of flux, which is necessary for achieving a good solder joint. It is crucial in soldering and brazing to ensure that all surfaces are clean and free of contaminants to achieve strong, reliable joints. This understanding highlights the importance of proper surface preparation in any soldering or brazing application.