How can contaminated surfaces affect solder joints?

Contaminated surfaces significantly compromise the quality of solder joints by interfering with the necessary physical and chemical interactions during the soldering process. For solder to effectively bond to the components and the substrate, surfaces must be clean, allowing for proper wetting and adhesion. Contaminants, which can include oils, dirt, oxidation, or residues from previous processes, create barriers that prevent the solder from effectively penetrating and bonding to the surfaces.

When solder joints are made on contaminated surfaces, the resulting joints can exhibit weaknesses, such as poor electrical conductivity, mechanical strength, and susceptibility to failure during thermal cycling or mechanical stress. These weak or defective solder joints could eventually lead to electronic component failures, which can impact the reliability of the entire assembly. Therefore, maintaining clean surfaces is essential for ensuring high-quality solder joints and overall performance of electronic products.