Chemtronics FAQ: Why Clean a PCBA After Soldering?
There are a number of contaminants that are commonly found on PCBAs…
• Residual etchants from the original bare board fabrication.
• Dust from bare board drilling, cutting and scoring.
• Fingerprints and skin oils from board handling.
• Silicone and other oils migrating from other processes.
What we’re going to be focusing on are flux residues, because they’re the most common concern.
During the soldering process, flux is used to facilitate the soldering of components onto the PCB.
If not properly cleaned, leftover flux residues can lead to coating issues, corrosion, electrical leakage and shorts.
Rosin and aqueous fluxes should always be removed as soon as possible after the soldering process. This is because these fluxes leave behind ionic material. Dendrites, or conductive branches, are formed when ionic residue meets with humidity and an electrical current. These conductive branches have been known to even form underneath conformal coating, leading to current leakage and eventually electrical shorts.
It’s pretty much universally understood that rosin and aqueous fluxes need to be cleaned, so they’re not our main concern here. On the other hand, no-clean fluxes are often left on the PCBA, even when the boards will be coated.
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https://www.chemtronics.com/flux-remo...
Proper maintenance is critical to ensure reliable circuitry. Not only unsightly, some flux residue can promote short circuits and corrosion, degrading or destroying the printed circuit board. The type of flux to be removed, solvent compatibility and ease of application are all factors to consider when choosing the appropriate product. Flux-Off is available in aerosol, BrushClean™ System, and liquid form for vapor degreasers, spray systems, ultrasonics, and dip tank applications.
Flux-Off products are specially formulated to remove all types of rosin (types R, RA, and RMA), no-clean, water-soluble and synthetic (type SA) flux. Flux remover spray can spray in any direction, even upside down.
Flux removers are recommended for post-solder operations, PC boards, sensitive circuit components, component leads, SMD pads, chip carriers, plugs, sockets and heat sinks, and Thru-hole and SMT devices.
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https://www.chemtronics.com
Chemtronics is the leading manufacturer of superior performing specialty products used in electronics, electrical systems, medical equipment, avionics, and telecom service, repair, prototype and manufacturing. Product offerings include dusters, flux removers, precision cleaners, contact cleaners, swabs, wipers, desoldering wick, and conformal coatings. For more information on Chemtronics products, technical questions and sales support, contact Chemtronics® Technical Hotline at 1-800-TECH-401.