There are various pollutants on the substrate pad of advanced packaging product chips before and after soldering, which can be classified into two categories: ionic and non ionic. Ionic pollutants come into contact with moisture in the environment and undergo electrochemical migration after being electrified, forming dendritic structures that create low resistance pathways and disrupt the functionality of circuit boards. Non ionic pollutants can penetrate the insulation layer of the PCB and grow dendrites below the surface of the PCB board. These substances dominate all pollutants, and from the perspective of product failure, post weld residues are the main influencing factor affecting product quality. Ionic residues can easily cause electric migration and reduce insulation resistance, while rosin resin residues can easily adsorb dust or impurities and increase contact resistance, leading to open circuit failure. Therefore, strict cleaning must be carried out after welding to ensure the quality of circuit boards.

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