PCBA cleaning methods - which one is right for you?
Flux residues on assemblies can cause corrosion and leakage currents. This guide compares aqueous, semi-aqueous and solvent cleaning and explains when removing residue is genuinely required under IPC guidance.
View cleaning productsWhy do assemblies need to be cleaned at all?
Soldering leaves flux residue on the assembly. Under humidity, activators and rosins can trigger corrosion, leakage currents and dendritic growth, all of which threaten long-term reliability.
Whether cleaning is needed depends on the flux type and the application. No-clean fluxes are formulated so their residue is benign, whereas water-soluble fluxes must be removed because their activators are aggressive.
- Water-soluble (OA) flux: always clean, activators are strongly corrosive.
- No-clean (ROL0/REL0): usually left in place, cleaned for coating or hi-rel.
- Residue under BGA and QFN packages is especially hard to reach.
How do the cleaning methods compare?
Three methods dominate PCBA cleaning: aqueous cleaning with deionised water plus additive, semi-aqueous cleaning with a solvent then a water rinse, and pure solvent cleaning. They differ in cleaning power, environmental profile and cost.
Aqueous cleaning is the workhorse of volume production: environmentally friendly, easy to control and economical, but it needs a drying stage. Solvent processes reach tight gaps under components better, yet require closed systems and emission control.
When does IPC require cleaning and how is it verified?
IPC-A-610 (acceptance criteria) and J-STD-001 (manufacturing requirements) define when residue is acceptable. High-reliability assemblies (Class 3) and boards about to receive conformal coating face stricter cleanliness requirements.
- Ionic cleanliness is testable by ROSE test, historic benchmark 1.56 µg/cm² NaCl equivalent.
- Localised residue is assessed per IPC via ion chromatography (IC).
- Validate the cleaning process before coating to avoid delamination and blistering.
- Qualify the process with SIR (surface insulation resistance) measurement.
In practice that means the cleaning process is qualified once, then monitored with simple metrics such as rinse-water conductivity. This keeps every assembly reproducibly within the required cleanliness.
Frequently asked questions
Do no-clean assemblies need cleaning?
In principle no, the flux is designed for that. But with conformal coating, a high reliability class or tight component spacing, boards are often cleaned anyway.
Which method is most environmentally friendly?
Aqueous cleaning with deionised water and an additive is regarded as the greenest volume solution, though it needs process-water treatment and a drying step.
What does the 1.56 µg/cm² value mean?
It is the historic ROSE benchmark for ionic contamination as a NaCl equivalent. Today it serves as process control rather than a sole IPC release criterion.
Can I clean assemblies by hand?
For rework and small runs yes, using isopropanol, an ESD-safe brush and a lint-free wipe. For volume and hi-rel electronics, qualified wash systems are preferable.
Looking for the right cleaning solution?
We supply cleaning agents, ESD brushes, lint-free wipes and accessories for IPC-compliant PCBA cleaning.
Standards-based
Guidance aligned with IPC-A-610 and J-STD-001.
Every method
From aqueous to isopropanol hand cleaning.
Verifiably clean
Cleanliness measurable by ROSE and SIR.
Expert advice
Specialists help you choose the process.