Can water-based flux be completely removed through conventional water washing processes to avoid corrosion or insulation problems?
Publish Time: 2025-09-01
In modern electronics manufacturing, soldering quality is directly related to the reliability and long-term stability of circuit boards. As an essential auxiliary material in the soldering process, the selection and subsequent processing of flux are particularly critical. Water-based flux, due to its environmentally friendly nature and low volatile organic compound emissions, is gradually becoming a mainstream alternative to traditional solvent-based products. However, its core advantage lies not only in its green performance during production but also in its ability to be completely removed through conventional water washing processes after soldering, thus avoiding the risk of corrosion or insulation degradation caused by residual residues.The design concept of water-based flux stems from dual considerations of both the environment and reliability. Its primary carrier is water, replacing the organic solvents used in traditional fluxes, significantly reducing atmospheric pollution and potential health risks to operators. More importantly, the active ingredients in its chemical formula, after removing metal surface oxides and promoting solder wetting, leave a highly water-soluble residue. This means that after the soldering process, most residues can be removed from the PCB surface, component pins, and small gaps using standard water cleaning procedures—including spray, immersion, or ultrasonic cleaning. This cleanability is essential for long-term, stable circuit operation.If residues are not effectively removed, they may form a film on the circuit board surface, attracting moisture from the environment and inducing electrochemical migration. When powered, minute leakage currents can create pathways between adjacent conductors, leading to signal interference, short circuits, or reduced insulation resistance. More seriously, if the active ingredients in some flux remain in high-humidity environments, they may continue to slowly react with the metal surface, causing solder joint corrosion, pin oxidation, or copper foil erosion, ultimately leading to functional failure. Water-based flux, with its water-soluble design, fundamentally reduces these risks. After cleaning, the board surface should be clean and transparent, free of visible white spots, sticky residue, or water stains, ensuring that electrical insulation performance is not compromised.The feasibility of the cleaning process also determines the practicality of water-based flux. Conventional water cleaning typically uses deionized water or an aqueous solution with a small amount of neutral detergent. Equipment investment is relatively low, and it can be easily integrated into existing production lines. Compared to solvent cleaning, which requires specialized solvents and closed recovery systems, water cleaning is safer, more economical, and utilizes mature wastewater treatment technology. By carefully controlling the cleaning temperature, water pressure, nozzle angle, and cleaning time, even residues from densely populated boards, BGA packages, or beneath fine-pitch components can be effectively removed.Of course, cleaning effectiveness is also influenced by the flux formulation itself. A high-quality water-based flux ensures sufficient activity while ensuring that reaction products are readily soluble, avoiding the formation of insoluble salts or polymers. Furthermore, the purity and temperature of the cleaning water, as well as the adequacy of the drying process, directly impact the final cleanliness. Residual moisture after cleaning can redistribute residues during subsequent baking, causing localized accumulation and compromising insulation performance. Therefore, a complete cleaning process should include rinsing and thorough drying steps to ensure the board surface is completely dry.In high-temperature processes like lead-free soldering, flux may experience increased thermal stress, causing carbonization or crosslinking of some components, reducing water solubility. Therefore, the thermal stability of water-based flux is as important as its high-temperature residue properties. The ideal product should maintain washable residue even at high temperatures, avoiding the formation of stubborn stains due to carbonization.In summary, water-based flux, thanks to its water-soluble residue properties, can be effectively removed through conventional aqueous cleaning processes, significantly reducing the risk of corrosion and insulation defects. It not only meets the environmental and safety requirements of electronics manufacturing but also provides a solid guarantee for reliability. When the cleaning process is well-matched with the material properties, water-based flux offers a clean, efficient, and sustainable technology path for the production of high-density, high-reliability electronic products.
