After the PCB assembly process, cleaning is an essential step to remove contaminants such as flux residues, dust, and solder splashes. If left uncleaned, these contaminants can cause electrical failures, corrosion, and reduced product lifespan.
To ensure reliable PCB performance, manufacturers must follow best cleaning practices tailored to different assembly methods, component types, and environmental conditions.
1. Why is PCB Cleaning Important?
During SMT (Surface Mount Technology) and THT (Through-Hole Technology) assembly, various residues are left behind, including:
Flux residues – From soldering processes, leading to corrosion and electrical leakage.
Solder balls – Small metal particles that can cause short circuits.
Dust and debris – Accumulated during manufacturing, reducing PCB reliability.
Oils and fingerprints – From handling, affecting adhesion and coating processes.
A well-cleaned PCB improves performance, longevity, and product reliability, especially in high-frequency, medical, and aerospace applications.
2. Best Practices for PCB Cleaning
(1) Choose the Right Cleaning Method
Different PCBs require different cleaning techniques based on flux type, component density, and board sensitivity.
Manual CleaningFor small-scale or delicate PCBs:
Use isopropyl alcohol (IPA) with lint-free wipes or brushes.
Ideal for prototypes, rework, and repairs.
Ultrasonic CleaningFor complex or high-density PCBs:
Uses high-frequency sound waves to remove contaminants.
Effective for removing flux under BGA components.
Not recommended for sensitive components like MEMS sensors.
Aqueous Cleaning (Water-Based Cleaning)For large-scale production with water-soluble flux:
Uses deionized water and mild detergents.
Requires proper drying techniques to prevent moisture damage.
Solvent CleaningFor no-clean and high-reliability applications:
Uses chemical solvents to dissolve residues.
Requires ventilation and safety precautions.
Vapor Phase CleaningFor high-precision PCBs:
Uses solvent vapors to dissolve contaminants.
Ensures thorough cleaning without mechanical stress.
(2) Proper Handling and Drying Techniques
After cleaning, proper drying is critical to prevent moisture-related failures.
Use compressed air or nitrogen to remove trapped water.
Bake at 60°C - 80°C for 30-60 minutes to ensure complete drying.
Store cleaned PCBs in a controlled humidity environment.
(3) Use No-Clean Flux When Possible
If cleaning is challenging in mass production, use no-clean flux, which:
Leaves minimal, non-conductive residues.
Reduces the need for extensive post-assembly cleaning.
Improves efficiency in consumer electronics and industrial PCBs.
However, for high-reliability applications (aerospace, medical, military), thorough cleaning is still recommended.
(4) Implement Quality Control and Inspection
Regular inspections ensure cleaning effectiveness and PCB reliability:
Visual inspection – Identifies visible contaminants under magnification.
Ionic contamination testing – Checks for residual conductive materials.
SIR (Surface Insulation Resistance) testing – Ensures no electrical leakage.
X-ray inspection – Detects hidden flux residues under components like BGAs.
3. Conclusion
Proper PCB cleaning is essential for preventing failures, ensuring reliability, and extending product lifespan. By selecting the right cleaning method, drying process, and quality inspection measures, manufacturers can enhance PCB performance across various industries.
At SUNSOAR, we provide high-quality PCB assembly with professional cleaning solutions, ensuring your boards meet the highest industry standards.
📧 Email: sales05@sunsoartech.com📞 Phone: +86 13632793113
🌐 Website: www.pcbsun.com
Comments