There is a common misconception that cleaning circuit boards after soldering is merely for aesthetic purposes, with no other significant benefits. However, neglecting cleaning during the PCBA (Printed Circuit Board Assembly) manufacturing process can lead to various issues, causing operational costs to skyrocket due to faults, rework, or product recalls during long-term customer use. Let’s explore the importance of cleaning PCBA circuit boards together with Silman Tech.
Throughout the PCBA production process, which involves multiple stages, each stage is subject to varying degrees of contamination. Therefore, residues or impurities accumulate on the surface of PCBA circuit boards, which can degrade product performance and even lead to product failure. For example, during the soldering of electronic components, solder paste and flux are used for soldering assistance. Residues generated after soldering contain organic acids and ions. Organic acids can corrode PCBA circuit boards, while the presence of ions may cause short circuits, resulting in product failure.
Contaminants on PCBA circuit boards can be broadly categorized into ionic and non-ionic types. Ionic contaminants, upon contact with moisture in the environment and subsequent electrical current, undergo electrochemical migration, forming dendritic structures that create low-resistance pathways, thereby impairing the functionality of PCBA circuit boards. Non-ionic contaminants can penetrate the insulation layer of PCBs and grow dendrites beneath the surface layer. In addition to ionic and non-ionic contaminants, there are particulate contaminants, such as solder balls, flux residues, dust, and debris inside solder flux reservoirs, which can lead to various defects during soldering, such as reduced solder joint quality, solder bridging, voids, and short circuits.
Among these contaminants, which ones are the most concerning? Flux residues or solder pastes are commonly used in reflow soldering and wave soldering processes. They consist of various components such as solvents, wetting agents, resins, corrosion inhibitors, and activators. Residues left after soldering inevitably play a dominant role among all contaminants. In terms of product failure, post-soldering residues are the primary influencing factors. Ionic residues are prone to causing electrical migration, leading to decreased insulation resistance. Rosin residues can adsorb dust or impurities, leading to increased contact resistance and, in severe cases, open circuit failures. Therefore, rigorous cleaning after soldering is essential to ensure the quality of PCBA circuit boards.
From this perspective, the cleaning of PCBA circuit boards is crucial. “Cleaning” is a critical process directly related to the quality of PCBA circuit boards and is indispensable.
