Requirements for PCBA Surface Cleanliness
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Requirements for PCBA Surface Cleanliness
Importance of Cleanliness:
1. Preventing Corrosion: Residues such as flux and solder paste left during the soldering process may be corrosive. Over time, these residues can corrode metal components on the circuit board, affecting circuit performance.
2. Avoiding Short Circuits: Conductive particles like solder balls or metal shavings can cause short circuits, leading to equipment failure.
3. Improving Insulation Performance: Contaminants may reduce the insulation performance of the circuit board, resulting in leakage or high-voltage breakdown.
4. Enhancing Coating Effectiveness: Before applying conformal coatings (e.g., anti-corrosion coatings), the board surface must be clean to ensure proper adhesion between the coating and the circuit board.
Cleanliness Requirements:
1. No Visible Contaminants: The PCBA surface should be free of visible contaminants such as solder slag, solder balls, dust, and fibers.
2. Ionic Contamination Control: Ionic contaminants (e.g., chloride ions, sodium ions) can cause corrosion and must be controlled within specified limits. Detailed standards are provided in IPC guidelines.
3. Organic Residue Control: Residues from flux, solder paste, and other organic materials should be kept within acceptable limits to avoid impacting circuit performance.
4. Compliance with Industry Standards: PCBA cleanliness must meet relevant industry standards, such as IPC-A-610.
Cleaning Methods:
1. Cleaning Agent Cleaning: Use specialized PCBA cleaning agents and methods such as ultrasonic cleaning or spray cleaning to remove contaminants.
2. Deionized Water Rinsing: After cleaning, thoroughly rinse with deionized water to remove any remaining cleaning agent residues.
3. Drying Process: After cleaning, ensure the circuit board is completely dry to eliminate moisture.
Conclusion:
The cleanliness of the PCBA surface is a critical factor in ensuring product quality and must be strictly controlled.
