How to Clean a PCB with an Ultrasonic Cleaner — Complete Guide

A Printed Circuit Board (PCB) is the heart of every electronic device. Over time, PCBs can accumulate dirt, flux, oils, or even rust, especially in environments with moisture or dust. If contaminants are not removed quickly, they can lead to short circuits, overheating, or permanent damage. Proper cleaning is therefore essential for both professionals and electronics enthusiasts. One of the safest and most effective methods available today is ultrasonic cleaning.

Why Choose Ultrasonic Cleaning for PCBs?

Unlike manual cleaning with brushes or solvents, ultrasonic cleaning works on a microscopic level. The technology uses high-frequency sound waves to generate millions of microscopic cavitation bubbles in the cleaning solution. When these bubbles collapse, they release energy that removes dirt, flux, grease, and oxidation — even from the smallest grooves, joints, and soldered areas on the board. This ensures a level of cleanliness that traditional methods cannot match.

Key reasons to choose ultrasonic cleaning for PCBs:

• Precision: Reaches tight spaces between components where manual cleaning tools cannot.
• Safety: Gentle cleaning without scratching or damaging delicate circuits.
• Speed: Significantly reduces cleaning time compared to manual scrubbing.
• Consistency: Provides the same reliable cleaning results every time.

Step-by-Step Guide: Cleaning a PCB with an Ultrasonic Cleaner

Follow this detailed process to safely and effectively clean your PCB:

1. Take safety precautions: Work in a clean, ventilated area. Wear gloves and protective glasses to avoid accidental contact with chemicals.
2. Prepare the ultrasonic cleaner: Fill the tank with a recommended PCB cleaning solution. Never use aggressive solvents that can corrode metal or damage components.
3. Disassemble carefully: If the PCB is part of a larger module, remove detachable or sensitive parts to prevent exposure during cleaning.
4. Submerge the PCB: Place the board fully in the solution, ensuring it is not overcrowded. Proper spacing guarantees maximum cleaning efficiency.
5. Start ultrasonic cleaning: Set the frequency to 40–45 kHz, which is ideal for electronic components. Run the cycle for 3–10 minutes, depending on contamination level.
6. Rinse with pure water: After cleaning, rinse the PCB with deionized or distilled water to remove any leftover chemicals.
7. Dry completely: Use compressed air to blow away water droplets or let the board air dry in a ventilated area. Ensure it is fully dry before reassembly to avoid short circuits.
8. Final inspection: Check the PCB carefully for residue, dirt, or damage. Repeat the process if necessary for heavily contaminated boards.

Best Practices and Extra Tips

• Degas your solution: Before the first use, run the ultrasonic cleaner on Degas mode to remove dissolved gases from the solution. This improves cavitation power.
• Temperature control: Keep the solution between 50–60°C for optimal cleaning. Too high temperatures can damage delicate components.
• Replace the solution regularly: A dirty solution loses effectiveness. Change it when it becomes cloudy or contaminated.
• Test before mass cleaning: If working with high-value PCBs, always test the process on a less critical board first.

Cleaning Concentrates for PCB

Not every liquid is suitable for PCB cleaning. Specialized solutions are needed to ensure safe and efficient results. One of the most effective options is the ASONIC AS-PCB cleaning concentrate.

ASONIC AS-PCB Concentrate — Features:

• Designed specifically for PCBs and delicate electronics
• Removes flux, dirt, and oils without corroding or darkening components
• Mix with water at about 10% concentration (adjust depending on contamination)
• Optimal working temperature: 50–60°C
• Safe for regular use in both workshops and laboratories

Using a proper cleaning concentrate not only enhances results but also extends the life of your ultrasonic cleaner by preventing buildup inside the tank.

Applications of PCB Ultrasonic Cleaning

Ultrasonic cleaning is not limited to PCB restoration. It is widely used across industries where reliability is crucial:

• Electronics repair shops: Restoring damaged or dirty circuit boards from laptops, phones, and tablets.
• Manufacturing: Removing flux residues after soldering and assembly.
• Laboratories: Cleaning sensitive measurement equipment and testing boards.
• Industrial electronics: Maintaining PCBs exposed to dust, oil, or moisture in harsh environments.

Conclusion

Ultrasonic cleaning offers a safe, fast, and highly effective solution for maintaining printed circuit boards. By combining an ASONIC ultrasonic cleaner with ASONIC AS-PCB concentrate, you can ensure deep cleaning, protect delicate circuits, and extend the life of your electronics. Whether you are a professional repair technician, a manufacturer, or an electronics hobbyist, ultrasonic technology is the future of PCB maintenance.

For more information or to order, contact us at order@asonic.si