What makes a flux no clean?
No-Clean Flux actually means that the amount of residue left behind is negligible to the point where there is no need for it to be cleaned. Thus it is in fact just very low residue flux that does not require cleaning in most cases.
Is it necessary to clean no clean flux?
PCBs with flux residue may face problems such as parasitic leakage, dendrite growth, electrochemical migration, and shorting. Therefore, cleaning the no-clean flux residue is no longer an optional process; rather it’s now indispensable for long-term PCB reliability, functionality, and performance.
What makes no clean flux residue benign?
These include: shorting dendrites growing under conformal coating/potting compounds; parasitic leakage issues under low standoff components, such as QFNs or Power FETs; dendrite shorting of SMT components and vias near selective solder regions on printed circuit board assemblies (PCBAs).
How long does no clean flux last?
As a result, no-clean type solder pastes typically have a longer shelf life and are more tolerant to higher storage temperatures than water-soluble/washable solder pastes. A solder paste typically has a shelf life of 6 months when refrigerated.
What does no clean mean?
The substance left behind is flux, which cleans the metal pads on the board when heated in order that the solder has a clean surface to bond to and you get the best possible quality joint. The “no-clean” aspect means that leaving this in place will not damage the board.
What is clean flux?
The most common way to clean flux residues from a repair area is to saturate a cotton or foam swab with isopropyl alcohol or another cleaning solvent, and rub it around the repair area.
What happens if you don’t clean flux?
Prevent Corrosion on Components and PCB – Flux residues left on electronic circuit boards are acidic. If they aren’t removed with a cleaning process, the residues can draw in ambient moisture from the air and lead to corrosion of component leads, and PCB contacts.
Is flux residue conductive?
Yes, flux can be conductive and affect your fine pitched component performance. Most PCB manufacturers use water soluble flux and rinse with warm DI water for cleaning.
What happens if you dont clean flux?
If they aren’t removed with a cleaning process, the residues can draw in ambient moisture from the air and lead to corrosion of component leads, and PCB contacts. When there are flux residues left on the PCB before the coating process, it is common to see the coating lift or delaminate from the surface of the board.
Is flux an insulator?
Flux on contact surfaces. Flux is an insulator at low voltages. It interferes with good, low-resistance connections by causing an insulating barrier between mating contacts.
