In the manufacturing process of PCBA (Printed Circuit Board Assembly), the cleanliness of the board surface is a key factor determining the reliability and long-term performance of the product. Contaminants on the surface of PCBA (such as flux residues, dust, ionic contaminants, etc.) may cause circuit short circuits, signal interference or corrosion. Therefore, the cleanliness standards must be strictly controlled.
The core requirements for PCBA cleanliness
Ion residue: According to the IPC-J-STD-001 standard, the ion contamination on the surface of PCBA should be ≤1.56μg/cm² (in terms of NaCl equivalent) to prevent electrochemical migration.
Particle contamination: The particle size should be less than 25μm (the requirements for high-reliability PCBA are stricter) to avoid affecting the electrical performance of precision components.
Organic residue: The flux residue needs to pass the solvent extraction test (IPC-TM-650 2.3.28) to ensure that it does not affect the subsequent conformal coating spraying or welding quality.
The risk of insufficient cleanliness of PCBA
Electrochemical corrosion: Residual ions such as Cl⁻ and Na⁺ in a humid environment will accelerate the corrosion of PCBA, leading to its failure.
Signal integrity decline: Contaminants may alter the impedance characteristics of high-frequency PCBA, affecting communication quality.
Protective coating failure: A dirty PCBA surface will reduce the adhesion of the conformal coating and weaken its moisture-proof and salt spray resistance.
The requirements for PCBA cleanliness in different industries
Consumer PCBA (IPC-A-610 Class 1) : Allows for lower cleanliness.
Automotive/medical PCBA (Class 3) : It must meet the strictest standards and pass the HALT test.
The cleanliness of PCBA directly affects the product's lifespan and stability. It is necessary to optimize the entire process from material selection, process control to final inspection to ensure the long-term stable operation of high-reliability electronic devices.
