How to clean PCBs

Cleaning PCBAs before applying conformal coating is crucial for the reliability and performance of electronic devices. Conformal coatings protect PCBAs from environmental factors like moisture, dust, chemicals, and corrosion, enhancing their longevity and preventing product returns. However, inadequate cleaning can lead to problems such as contamination, coating delamination, reduced moisture protection, and increased corrosion vulnerability.

Even "no-clean" solder pastes can interfere with coating adhesion, negatively impacting the board's performance. Insufficient cleaning can also cause the formation of dendrites, microscopic conductive filaments that can bridge conductive traces, leading to short circuits, electrical failures, and compromised functionality.

4 Ways to clean PCBS

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.


This method uses sound waves to create bubbles, which implode on the PCBA surface to break up the flux residues.

Vapor degreasing

The cleaning is done either in the vapor phase of a solvent or submerged in a sump, which often includes ultrasonic action.

Batch or inline systems

Spray equipment with water-based cleaners to wash, rinse, and dry the PCBAs.