How do you set-up a new PCBA cleaning process?

The best cleaning method for your operation depends on your volume, throughput desired, criticality of the electronics, regulatory restrictions, and floor space.

The main options for board cleaning are…

1. Manual cleaning - This can involve aerosol or pump sprays, or solvents in a pan or tray. Agitation can be applied with a brush, swab or wipe.
2. Ultrasonic - This method uses sound waves to create bubbles, which implode on the PCBA surface to break up the flux residues.
3. Vapor degreasing - The cleaning is done either in the vapor phase of a solvent, or submerged in a sump, which often includes ultrasonic action.
4. Batch or inline systems - Spray equipment with water-based cleaners wash, rinse, and dry the PCBAs.

I’ll focus on aerosol cleaning, because that is the most practical if you are setting up a new cleaning operation. All defluxing processes basically involve…

1. Dissolving the flux residue: Choose a cleaner that works best with your flux. A good match will reduce the need for extra soak time and agitation. When flux has been sitting for a long period of time, or has been baked on at high temperature or long reflow cycle, addition brushing might be required.
2. Flushing or rinsing off the dissolved residues: Remember, once flux residues are dissolved, they won’t just evaporate off. They need a chance to flow off the circuit board. Holding the board at an angle while you are cleaning can help. A final rinse is always a good idea, and required if you are using a water-based cleaner.
3. Drying the printed circuit board assembly (PCBA): For fast-drying solvents, this isn’t usually an issue. For water-based cleaners, you can accelerate drying with a duster, or use alcohol as a drying agent.